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Bermed Earth-Sheltered Wall for Low-Income House: Thermal and Energy Measure to Face Climate Change in Tropical Region

Bermed Earth-Sheltered Wall for Low-Income House: Thermal and Energy Measure to Face Climate... applied sciences Article Bermed Earth-Sheltered Wall for Low-Income House: Thermal and Energy Measure to Face Climate Change in Tropical Region 1 , 2 3 Ivan Julio Apolonio Callejas * , Raquel Moussalem Apolonio , Emeli Lalesca Aparecida da Guarda , 1 1 2 Luciane Cleonice Durante , Karyna de Andrade Carvalho Rosseti , Filipa Roseta and Leticia Mendes do Amarante Departamento de Arquitetura e Urbanismo, Faculdade de Arquitetura, Engenharia e Tecnologia, Universidade Federal de Mato Grosso, Av. Fernando Corrêa da Costa, 2367, Boa Esperança, Cuiabá 78060-900, Brazil; luciane.durante@hotmail.com (L.C.D.); karyna.rosseti@gmail.com (K.d.A.C.R.); leticiamendes.arq@outlook.com.br (L.M.d.A.) CIAUD—Faculdade de Arquitetura da Universidade de Lisboa, Rua Sá Nogueira, Pólo Universitário, Alto da Ajuda, 1649-004 Lisbon, Portugal; raquelmoussalem@hotmail.com (R.M.A.); filipa.roseta@psd.parlamento.pt (F.R.) Programa de Pós-graduação em Arquitetura e Urbanismo, Universidade de Santa Catarina, R. Eng. Agronômico Andrei Cristian Ferreira, s/n, Trindade 88040-900, Brazil; emeliguarda@gmail.com * Correspondence: ivancallejas@ufmt.br; Tel.: +55-65-3615-8774 Abstract: Climate change impact is one of the most important global concerns at present. In the build- ing environment, climate-responsive design may help to enhance the adaptation capacity through a better building energy performance. In this sense, this study addresses an adaptation strategy to reduce the effects of global warming on low-income houses, for which bioclimatic passive strategies should be prioritized, aiming to improve environmental sustainability. The technique chosen to be analyzed is thermal mass for cooling. Thus, the goal is to evaluate the energy consumption Citation: Callejas, I.J.A.; and thermal performance impact of implementing bermed earth-sheltered walls on bedrooms in Apolonio, R.M.; Guarda, E.L.A.d.; low-income housing (LIH), considered deployed in tropical climate regions. For that, a base scenario Durante, L.C.; de Andrade Carvalho (1961–1990) is considered, alongside two future scenarios: 2020 (2011 to 2040) and 2050 (2041 to 2070), Rosseti, K.; Roseta, F.; Amarante, both considering the effects of climate change, according to the Fourth Report (AR4) of the Inter- L.M.d. Bermed Earth-Sheltered Wall governmental Panel on Climate Change (IPCC). The methodologies adopted are (i) computational for Low-Income House: Thermal and simulation to estimate the annual energy consumption demand and (ii) quantification of the cooling Energy Measure to Face Climate degree-hours (CDH), with the subsequent comparative analysis based on Brazilian regulation for Change in Tropical Region. Appl. Sci. energy efficiency in buildings (RTQ-R). The predictions show that there will be an increase in the 2021, 11, 420. https://doi.org/ 10.3390/app11010420 energy consumption for cooling and in the CDH in both 2020 and 2050 scenarios, regardless of using a bermed earth-sheltered wall. Nonetheless, this adaptive measure enables the building to be resilient Received: 19 November 2020 in terms of cooling energy demand in the 2020s, since it is 12.3% lower than in the building without Accepted: 24 December 2020 the strategy use, compared with the base scenario. In the 2050s, resilience was almost reached with Published: 4 January 2021 energy consumption only 10.7% higher, for the same conditions described previously. Therefore, bermed earth-sheltered walls work as a climate-responsive design strategy to face the potential global Publisher’s Note: MDPI stays neu- warming effects, promoting building sustainability in tropical climate regions. tral with regard to jurisdictional clai- ms in published maps and institutio- Keywords: thermal performance; building simulation; climate-responsive; energy consumption; nal affiliations. cooling degree-hours; bioclimatic measure; passive measure Copyright: © 2021 by the authors. Li- censee MDPI, Basel, Switzerland. 1. Introduction This article is an open access article Vast knowledge about climate change, motivated by anthropogenic actions and based distributed under the terms and con- on greenhouse gas (GHG) emissions, has been released by the Intergovernmental Panel on ditions of the Creative Commons At- Climate Change (IPCC). The IPCC has published various scientific reports on which the tribution (CC BY) license (https:// behavior of terrestrial ecosystems is studied by scientists from a wide range of fields [1,2]. creativecommons.org/licenses/by/ An increase in the number of hot days in most land regions is expected, with the highest 4.0/). Appl. Sci. 2021, 11, 420. https://doi.org/10.3390/app11010420 https://www.mdpi.com/journal/applsci Appl. Sci. 2021, 11, 420 2 of 22 increases in the tropics, therefore, the potential effect of climate change in the building environment is a critical issue, especially concerning its design and operation. Furthermore, global warming will directly affect the thermal behavior of buildings, increasing hot season cooling, and decreasing cold heating demand, raising its energy consumption during the operational phase [3]. Thus, the strategic framework conceived to mitigate and adapt buildings environments to climate change increases the importance of the thermal mass effect as a strategy to counterattack its impacts, especially within warm regions located in South America with tropical Savannah climate (Aw), which is the second most common climate in the world, covering 11.5% of the world’s land area, 60.1% of South America [4], and 81.4% of the Brazilian territory [5]. Mitigation and adaptation are two strategies to address climate change. The first focuses on the causes (accumulation of greenhouse gases in the atmosphere) whereas the second on adaptation to the impacts [6]. Adaptation may respond mainly by reducing or eliminating the risks of climate change impacts, and on the building environment, it can be done by enabling the capacity of adaptation through a better building energy performance. In the last decade, some studies have evaluated the potential of buildings’ energy efficiency adaptation measures to face climate changes effects. In Australia, a study investigated, in five regional climates (from cold to hot humid), the potential impact of climate change on the heating and cooling energy requirements of residential houses. It was observed that energy-efficient or high star rating houses may experience fewer absolute changes in energy requirement due to their better thermal insulation [7]. In the Netherlands, three traditional residential house projects were used to investigate the effectiveness of passive climate change adaptation measures. The following strategies were tested in the building components using thermal simulation analysis: (i) increased thermal resistance, (ii) changed thermal capacity, (iii) increased short-wave reflectivity (albedo), (iv) vegetation roofs, (v) solar shading, and (vi) additional natural ventilation. The increase in thermal resistance/ thermal capacity and short-wave reflectivity resulted in a higher and lower number of overheating hours, respectively. The application of a vegetated roof, the use the natural ventilation, and the addition of operable exterior solar shading produced a decrease in the number of overheating hours [8]. A study conducted in three different bioclimatic zones in Brazil (at Curitiba, Florianópolis, and Belém cities) accessed individual passive strategies, such as solar shading, low absorptance, and thermal insulation, to reduce energy consumption in a low-income house under the global warming effects. The aforementioned measures were able to reduce up to 50% of the future annual cooling and heating energy demand in houses, contributing to their sustainability [9]. In Guangdong Province, South China, the global warming impacts on multi-family residences were predicted in two edification typologies: one with lower thermal insulation (3.5 stars-building envelope) and the other with higher performance (5.5 stars-building envelope). The total heating and cooling energy demand of 3.5 and 5.5 star-buildings due to global warming are projected to increase 20% and 25% in the 2080s, respectively, despite their better insulation compared to the existing housing stock [10]. A medium-sized office building located in five US cities (Miami—FL, Phoenix—AZ, Los Angeles—CA, Washington—DC, and Akron—CO) was accessed under the climate change impacts. The adaptation measures focused on the operation heating, ventilation, and air conditioning system (HVAC), which included the adjustment of thermostat set- points, the reduction of HVAC operation hours, the reduction of the variable air volume box minimum flow setting, and mixed-mode ventilation, strategies considered to neutralize the increased energy consumption in the research building. The mixed ventilation strategy proved to be an effective measure to reduce energy consumption, and thus mitigate the impacts of climate change in most research cities in the 2020s and 2050s scenarios [11]. Low-income housing located in the cities of São Paulo and Salvador, Brazil had its envelope improved with isolated and combined measures to face the impact of climate change. The most effective isolated adaptation measures to improve thermal performance and energy Appl. Sci. 2021, 11, 420 3 of 22 consumption were those related to lower solar absorptance of the walls, insulated roofs with lower solar absorptance, and shading to windows in all main rooms. For both cities, it was demonstrated that it is possible to obtain a good performance in the 2050 period, compared to the current climate, with the combination of isolated measures [12]. Practical measures were proposed to counterattack the impact of climate change on en- ergy consumption in a house located at Cuiabá, a region of Tropical Savannah climate (Aw), Brazil. The house envelope was enhanced, elevating the building system’s thermal resis- tance and reducing the solar absorptance. Despite the improvements, energy consumption is predicted to increase by 19.6% in the 2020s and 30.1% in the 2050s, compared to the base scenario [13]. A study quantified the application of an adaptive comfort control measure in mixed-mode office buildings in Cadiz, southern Spain. A daily setpoint temperature, based on the adaptive thermal comfort approach, was applied in a building to simulate the present and future conditions under climate change. Taking the current scenario as a reference, a 74.6% reduction in energy demand and a 59.7% drop in energy consumption was quantified when the adaptive comfort control was implemented in the model [14]. Thus, the specified previous predictions indicated that, despite the enhancement in the building energy performance, no individual passive strategies might completely neutralize the increasing of cooling and heating energy usage, suggesting the combination of passive strategies to counteract the effects of climate change. Some typical measures prescribed in bioclimatic codes and energy-efficient regulations have been considered in these studies, however, to reduce energy use for cooling/ heating demands, additional measures must be considered, especially those that act as a climate-responsive design strategy. When designing new buildings to face climate change, the traditional strategies, such as construction elements of the envelope, building geometry, and orientation, may not be sufficient to achieve adequate levels of energy consumption and thermal performance. Thus, alternative bioclimatic passive techniques are also important measures to be con- sidered during the design phase. For hot regions, thermal mass for cooling is an alternative measure to accumulate and retain heat during the day and return it to the exterior envi- ronment at night, acting as a climate-responsive design strategy. This behavior reduces the indoor air temperature fluctuations and maximizes the thermal lag of heat transfer of the walls, which oscillate in a damped manner [15–17]. Thus, this bioclimatic measure may reduce the use of active air conditioning systems during hot days, potentially saving energy and improving thermal comfort in an indoor environment [8]. In a hilly site, building walls may be designed to be in contact with the earth, increasing its thermal mass properties. In the “elevational” bermed design, the house’s main elevation or face, usually with a south-facing wall in cold regions and with a north-facing wall in hot climatic zones, remains unexposed, while the rest may be bermed by the earth. This type of construction, named earth sheltered building, are defined as structures built with the use of earth mass against building walls working as external thermal mass to the wall, which reduces heat loss and maintains a steady indoor air temperature throughout the seasons [18]. When the earth is in contact with building walls, it acts as a reservoir, storing the heat in vast spaces inside the soil and modulating indoor air temperatures at different meteorological conditions [19]. For this reason, the bermed type of construction may contribute to resilience to the urban heat island phenomenon, and constitutes an alternative measure to adapt buildings to the impacts of climate change, one of the most important global concerns at present. Thus, this research strategy is aligned to the principles of sustainable development goals (SDGs) to promote the 2030 agenda, especially the SDG 7 (affordable and clean energy) and SDG 11 (sustainable cities and communities), which should guide the production of sustainable and efficient buildings [20]. Besides, this passive measure, understood as a measure that does not use the energy once implemented in the building, may help designers and builders to attend the premises of bioclimatic architecture and thus achieve the fulfillment of sustainable performance requirements established by the building’s Appl. Sci. 2021, 11, x FOR PEER REVIEW 4 of 23 help designers and builders to attend the premises of bioclimatic architecture and thus Appl. Sci. 2021, 11, 420 4 of 22 achieve the fulfillment of sustainable performance requirements established by the building’s certifications systems, especially concerning energy efficiency and application of climate-responsive design [21]. certifications systems, especially concerning energy efficiency and application of climate- Thus, this study aims to evaluate the potential thermal and energy impact of im- responsive design [21]. plementing bermed earth-sheltered walls as a passive cooling strategy for a residential Thus, this study aims to evaluate the potential thermal and energy impact of im- building’s bedrooms, located in a region with a tropical climate to face climate change plementing bermed earth-sheltered walls as a passive cooling strategy for a residential effects. The study helps to deepen the knowledge of this potential climate-responsive building’s bedrooms, located in a region with a tropical climate to face climate change strategy as an adaptation measure for building to be deployed in the regions with hot effects. The study helps to deepen the knowledge of this potential climate-responsive climate conditions, where future scenario projections of climate change have indicated strategy as an adaptation measure for building to be deployed in the regions with hot the increase of hot days frequency, which will induce changes in building energy de- climate conditions, where future scenario projections of climate change have indicated mand due to the increase of air conditioning systems used for cooling [22,23]. The anal- the increase of hot days frequency, which will induce changes in building energy demand yses are made considering a base scenario (without the influence of climate change) and due to the increase of air conditioning systems used for cooling [22,23]. The analyses are two future scenarios (2020 and 2050) contemplating potential climate change effects, ac- made considering a base scenario (without the influence of climate change) and two future cording to the Fourth Report (AR4) of the Intergovernmental Panel on Climate Change scenarios (2020 and 2050) contemplating potential climate change effects, according to the (IPCC). Fourth Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC). 2. Materials and Methods 2. Materials and Methods 2.1. Local Climate Identification and Bioclimatic Zone Characterization 2.1. Local Climate Identification and Bioclimatic Zone Characterization A A single-family single-family low low-income -income house house (LIH) (LIHselected ) selected for for t thishstudy is study is consider is consider ed to ed be tolo- be cated locate in d in a r a egion region o of Tropical f Trop Savannah ical Savann climate ah clim (Aat w), e ( characterized Aw), charactby erized by high air hi temperatur gh air tem- e throughout the year, wide hygrothermal variations, and undefined or absent winter sea- perature throughout the year, wide hygrothermal variations, and undefined or absent son wint [24 er se ]. Similar ason [2climat 4]. Simi e lclassification ar climate class can ific be atfound ion can b in several e found in locations several ar loc ound ation the s aro world, und such as Australia, Africa, and South America, especially in regions located between the the world, such as Australia, Africa, and South America, especially in regions located Equator and Tropics of Capricorn (Figure 1). The climate database of the Cuiabá city, which between the Equator and Tropics of Capricorn (Figure 1). The climate database of the 0 00 is located in the Mid-East, Brazil, in the geometric center of Latin America (15 36 56 S; Cuiabá city, which is located in the Mid-East, Brazil, in the geometric center of Latin 0 00 56 06 01 W) is used as a base of this research. America (15°36′56″ S; 56°06′01″ W) is used as a base of this research. Figure 1. Location of the city of Cuiabá in South America. Source: adapted from Peel et al. [4]. Figure 1. Location of the city of Cuiabá in South America. Source: adapted from Peel et al. [4]. The The Bra Brazilian zilian Assoc Association iation of of Technic Technical al Standar Standards ds (ABNT) (ABNT) for for B Bioclimatic ioclimatic Zoni Zoning ng establishes establishes a a set set ofof technical technica and l anconstr d constructi uctive ve recom recommendations mendations for the regi for the region, to on, to opti optimize- the mizthermal e the therma performance l performa of nce of buildings buildings through a through a better better cl climatic imatadaptation ic adaptation [16 [1 ].6]. The The rrecommendat ecommendations ions and and cons constr tr uct uct ive ive gu guidelines idelinesfor for a adequ dequ ate ateLIH LIH for forthe the Sav Savannah annah clim climate ate region are detailed in Table 1, in accordance with the Brazilian Bioclimatic and as prescribed region are detailed in Table 1, in accordance with the Brazilian Bioclimatic and as pre- by the Brazilian Technical Quality Regulation for Energy Efficiency Level of Residential scribed by the Brazilian Technical Quality Regulation for Energy Efficiency Level of Buildings (RTQ-R) [25]. As indicated in Table 1, thermal mass for cooling is a strategy Residential Buildings (RTQ-R) [25]. As indicated in Table 1, thermal mass for cooling is a recommended to adapt the building to the climate where it is located. Thus, this research focuses on verifying if this potential passive strategy may be adequate to adapt a building to the projected climate change scenarios. Appl. Sci. 2021, 11, 420 5 of 22 Table 1. Recommendations and constructive guidelines for the bioclimatic zoning of the building location. Guidelines for Building Envelope Strategies for Passive Thermal Opening’s Code Conditioning Recommendations Wall System Roof System A: NR A:NR Evaporative Cooling; Thermal Small openings: 10% < A Type: Heavy Type: Heavy mass for cooling; Selective NBR 15220 < 15% U  2.2; CT:NR U  2.0; CT: NR ventilation Shade openings '  6.5 h '  6.5 h (T > T ) ext int SF  3.5% SF  6.5% 0.6 > 0.6  0.4 > 0.4 No requirement established A  5% U  3.70 U  2.50 U 2.30 U 1.50 RTQ-R CT  130 CT  130 NR NR 1 2 2 A: floor area (%); : absorptance (dimensionless); U: total thermal transmittance (W/m K); CT: thermal capacity (kJ/(m K); ': thermal lag; SF: sun factor; NR: no requirement established; T : internal temperature; T : external temperature. int ext 2.2. Characterization of the Study Case A typical low-income house, widely replicated in all regions of Brazil by the Brazilian government under the social housing program named “My House My Life”, was chosen for this study [26] (Figure 2a). This choice is based on the fact that this population is the most vulnerable to the impact of climate change, especially in developing countries. This typology is handed out to the users without any concern about climatic adaptation to the implantation region, with a poor thermal performance [9,12,13], compromising its indoor thermal comfort conditions as well as increasing energy consumption for cooling [13,27]. Due to these facts and how this research focuses on the thermal mass strategy as a climate- responsive measure, the original standard building project was redesign to attend Brazilian RTQ-R level ‘A’ of efficiency [25], thereafter named as “LIHe”. It is characterized by a one-story detached house in contact with the ground. LIHe presents 39.18 m of total area and 34.54 m of internal floor area, distributed in four designated areas, namely: 2 2 2 living room/kitchen (17.44 m ), bedroom 1 (7.78 m ), bedroom 2 (7.57 m ), and bathroom (1.75 m ) (Figure 2a–c). The roof construction is dual pitched with an overhang of 0.30 m depth. The rooms’ ceiling height is 3.00 m. Regarding openings, living room and bedroom spaces present metallic sliding win- dows with dimensions of 1.50  1.00 m and 1.20  1.00 m, respectively, composed of four panels, two of them being single glass fixed panels and the other two sliding metallic Venetian panels. The kitchen’s window is a metallic tilting type of 1.00 1.00 m. The exter- nal doors are made of metallic sheets, while interior doors are wood-made. The thermal resistance of the external walls and roof were improved to provide building efficient level “A”. The external walls consist of ceramic bricks (six-hole type) coated on the outside with expanded polystyrene sheets (EPS) (0.04 m) and plaster (0.025 m) in the outermost and innermost layers. The internal partitions consist of ceramic brick (six-hole type) coated on both sides with plaster (0.015 m). The external walls absorptance was reduced from 0.3 to 0.15 by changing the painting to white color. The roof system is composed of ceramic tile, aluminum foil for thermal insulation, an air gap layer, and ceiling panels of polyvinyl chloride (PVC) (0.01 m). The outermost layer of the tiles was painted with white color (ranging the absorptance of the roof from 0.8 to 0.15). Regarding the roof air gap, this layer presents 0.61 m K/W thermal resistance (R-value), with a thickness greater than 0.05 m and low thermal emissivity due to the installation of aluminum foil. The Brazilian Association of Technical Standards NBR 15.220 [16] was used to redesign the building envelope and to determine the thermal properties of the building system envelope of the efficient low-income house (LIHe), which are presented in Table 2. Appl. Sci. 2021, 11, x FOR PEER REVIEW 6 of 23 Appl. Sci. 2021, 11, 420 6 of 22 (a) External image and 3D DesignBuilder model of the low-income house (LIH). (b) Floor plan (dimensions in meters) (c) Sections AA’ and BB’ Figure 2. (a) Standard low-income housing picture, (b) floor plan, and (c) section plans. Figure 2. (a) Standard low-income housing picture, (b) floor plan, and (c) section plans. Regarding openings, living room and bedroom spaces present metallic sliding To evaluate the thermal inertia strategy, bermed earth-sheltered walls were imple- windows with dimensions of 1.50 × 1.00 m and 1.20 × 1.00 m, respectively, composed of mented in the original housing design (hereafter named as LIHb), so that bedrooms walls came four pane into ls, dir tect wo of t contact hem with being the sin soil gle (Figur glasse f2 ixed ), resulting panels and in the th“LIHb” e other tdesign wo slid strategy ing meta (see llic pr Venet operties ian p in an T e able ls. The 2). For kitcthat, hen’s window the external is walls a met of albedr lic tilt ooms ing t1 yp and e of 2, 1. which 00 × 1. do 00 m not . The ex- present openings, were selected to be 3.00 m (ceiling height) grounded earth-sheltered (Figure 3). ternal doors are made of metallic sheets, while interior doors are wood-made. The ther- The mal r bermed esistanc eart e of t h-shelter he exte ed rnal w walls alls wer an e d evaluated roof were inimproved t all four cardinal o provide bu orientations ilding (Figur effici eent 4). This strategy allows taking advantage of natural sloping ground while providing a passive level “A”. The external walls consist of ceramic bricks (six-hole type) coated on the out- design measure to improve indoor thermal comfort conditions. side with expanded polystyrene sheets (EPS) (0.04 m) and plaster (0.025 m) in the outermost and innermost layers. The internal partitions consist of ceramic brick (six-hole type) coated on both sides with plaster (0.015 m). The external walls absorptance was reduced from 0.3 to 0.15 by changing the painting to white color. The roof system is composed of ceramic tile, aluminum foil for thermal insulation, an air gap layer, and ceiling panels of polyvinyl chloride (PVC) (0.01 m). The outermost layer of the tiles was painted with white color (ranging the absorptance of the roof from 0.8 to 0.15). Regarding the roof air gap, this layer presents 0.61 m K/W thermal resistance (R-value), with a thickness greater than 0.05 m and low thermal emissivity due to the installation of alu- minum foil. The Brazilian Association of Technical Standards NBR 15.220 [16] was used to redesign the building envelope and to determine the thermal properties of the building system envelope of the efficient low-income house (LIHe), which are presented in Table Appl. Sci. 2021, 11, x FOR PEER REVIEW 7 of 23 Table 2. Thermophysical properties adopted for building systems envelope of the efficient low-income house (LIHe) and bermed earth-sheltered low-income house (LIHb). Envelope Materials Thickness 1 2 Building Characteristics R-Value (m²K/W) U (W/m²K) CT (J/m²K) α Layers (m) White paint- Appl. Sci. 2021, 11, x FOR PEER REVIEW 7 of 23 ing Appl. Sci. 2021, 11, x FOR PEER REVIEW 7 of 23 Wall System Appl. Sci. 2021, 11, x FOR PEER REVIEW 7 of 23 Appl. Sci. 2021, 11, x FOR PEER REVIEW 7 of 23 Mortar 0.025 Appl. Sci. 2021, 11, x FOR PEER REVIEW 7 of 23 Appl. Sci. 2021, 11, 420 7 of 22 EPS sheet 0.040 1.128 0.886 169.38 0.15 Ceramic brick 0.09 Table 2. Thermophysical properties adopted for building systems envelope of the efficient low-income house (LIHe) and Table 2. Thermophysical properties adopted for building systems envelope of the efficient low-income house (LIHe) and Table 2. Thermophysical properties adopted for building systems envelope of the efficient low-income house (LIHe) and bermed earth-sheltered low-income house (LIHb). Mortar 0.025 Table 2. Thermophysical properties adopted for building systems envelope of the efficient low-income house (LIHe) and bermed earth-sheltered low-income house (LIHb). bermed earth-sheltered low-income house (LIHb). bermed earth-sheltered low-income house (LIHb). White paint- Table 2. Thermophysical properties adopted for building systems envelope of the efficient low-income house (LIHe) and Effic T iable ent low- 2. Thermophysical income Envelope properties adopted Materials for building Thickness systems envelope of the efficient low-income house (LIHe) and 1 2 Building Char bermed earth-sheltered acteristics low-income house (LIHb). ing R-Value (m²K/W) U (W/m²K) CT (J/m²K) α Envelope Materials Thickness Envelope Materials Thickness 1 2 house systems (LIHe) Envelope Materials Layers Thickness (m) bermed earth-sheltered low-income house (LIHb). Building Characteristics R-Value 1 (m²K/W) U 2 (W/m²K) CT (J/m²K) α Building Characteristics R-Value (m²K/W) 1 U (W/m²K) 2 CT (J/m²K) α Building Characteristics R-Value (m²K/W) U (W/m²K) CT (J/m²K) α White paint- Layers (m) Layers (m) Layers (m) Envelope White paint- Materials Thickness 1 2 ing Building Characteristics White paint- R-Value (m²K/W) U (W/m²K) CT (J/m²K) α Materials R-Value White paint- 2 2 2 White paint- ing Building Characteristics Envelope Layers Thickness (m) (m) U (W/m K) CT (J/m K) Wall System Roof System Layers (m K/W) Ceramic tiles 0.01 ing ing Wall System ing White paint- Mortar 0.025 Wall System Wall System Aluminum 0.847 1.18 41.92 0.15 WhiteMortar 0.025 painting Mortar 0.025 EPS sheetMortar 0.025 ing 0.040- Wall System Wall System foil 1.128 0.886 169.38 0.15 EPS sheet 0.040 Mortar 0.025 EPS sheet 0.040 EPS sheet 0.040 Ceramic brick Mortar 0.025 0.09 1.128 0.886 169.38 0.15 1.128 0.886 169.38 0.15 Attic space >0.05 m 1.128 0.886 169.38 0.15 0.15 Ceramic brick 0.09 Ceramic brick EPS sheet 0.040 0.09 Ceramic brick 0.09 EPS sheet Mortar 0.025 0.040 1.128 0.886 169.38 PVC ceiling 0.01 1.128 0.886 169.38 0.15 Mortar 0.025 Mortar 0.025 Ceramic Ceramic brick White paint- Mortar 0.025 brick 0.09 0.09 Wall System Efficient low-income White paint- White paint- White paint- Mortar 0.025 ing Efficient low-income Mortar 0.025 Efficient low-income Efficient low-income house systems (LIHe) ing ing White paint- ing house systems (LIHe) White paint- Similar Layer and Thickness Efficient low-income White painting house systems (LIHe) house systems (LIHe) Efficient low-income White paint- Similar properties of the LIHe White paint- house systems (LIHe) White paint- ing ing of the Efficient LIH White painting house systems (LIHe) ing ing Roof System ing Ceramic tile White paint- s 0.01 Roof System Ceramic Ceramic tile tiles s 0.01 0.01 Roof System Roof System Ceramic tiles 0.01 Roof System Ceramic tile ing s 0.01 Aluminum 0.847 1.18 41.92 0.15 Aluminum 0.847 1.18 41.92 0.15 Aluminum foil - Wall System in con- 0.847 1.18 41.92 0.15 Aluminum 0.847 1.18 41.92 0.15 Roof System Ceramic tile Alumi foil num s 0.01 0.847 1.18 41.92 0.15 Bermed earth-sheltered - foil tact with ground Attic space foil >0.05 m Attic space foil >0.05 m Aluminum 0.847 1.18 41.92 0.15 low-income house sys- Attic space >0.05 m Attic space >0.05 m Similar Layer and Thickness Evaluated by the Energyplus program according to the Attic space >0.05 m PVC PVC ceiling ceiling foil 0.01 0.01 tems (LIHb) PVC ceiling 0.01 PVC ceiling of the LIHe + ground contact 0.01 Basement (GDomain) input data. PVC ceiling 0.01 Wall System Attic space >0.05 m Wall System Wall System Wall System Wall System PVC ceiling 0.01 Similar Layer and Thickness Similar Layer and Thickness of Wall System Similar properties of the LIHe Similar Layer and Thickness Similar properties of the LIHe Similar Layer and Thickness Similar of the E Layer a fficient nd Thickness LIH the Efficient LIH Similar properties of the LIHe Roof System Similar properties of the LIHe Similar properties of the LIHe of the Efficient LIH of the Efficient LIH Similar Layer and Thickness of the Efficient LIH Similar Layer and Thickness Similar properties of the LIHe Similar properties of the LIHe of the LIHe of the Efficient LIH Wall System in con- Wall System Bermed earth-sheltered 1 2 Wall System in con- Thermal Resistance and Transmittance include the internal e external superficial air resistance. Properties estimated Wall System in con- Wall Sys tact with tem in ground con- Bermed earth-sheltered in contact Bermed earth-sheltered low-incom Bermed earth-sheltered e house sys- Bermed earth-sheltered tact with ground by NBR 15.220 [16]. tact with with gr ground ound tact with ground low-income house sys- Wall System in con- Similar Layer and Thickness Evaluated by the Energyplus program according to the low-incom low-income e house sy house s- low-incom tems (LIHb) e hous e sys- Bermed earth-sheltered Similar Layer and Thickness Evaluated by the Energyplus program according to the Similar Similar Layer Layer a andn Thickness d Thickness of Evaluated by Evaluatedthe Energyplus program according to the by the Energyplus program according to the tact with ground of the LIHe Similar Layer a + ground contact nd Thickness Evaluated by Base the Energyplus program according to the ment (GDomain) input data. tems (LIHb) systems (LIHb) To evaluate the thermal inertia strategy, bermed earth-sheltered walls were imple- tems (LIHb) tems (LIHb) low-income house sys- the LIHe + ground contact Basement (GDomain) input data. of the LIHe + ground contact Basement (GDomain) input data. of the LIHe + ground contact Basement (GDomain) input data. of the LIHe + ground contact Basement (GDomain) input data. Similar Layer and Thickness Evaluated by the Energyplus program according to the mented in the original housing design (hereafter named as LIHb), so that bedrooms walls tems (LIHb) of the LIHe + ground contact Basement (GDomain) input data. came into direct contact with the soil (Figure 2), resulting in the “LIHb” design strategy Roof System (see properties in Table 2). For that, the external walls of bedrooms 1 and 2, which do not Roof System Similar Layer and Thickness Roof System Roof System Similar properties of the LIHe Roof System present openings, were Similar Layer an se d Thickness lected to be 3.00 m (ceiling height) grounded earth-sheltered Similar Layer and Thickness Similar Layer a of the LIHe nd Thickness Similar properties of the LIHe Similar Layer and Thickness of Similar properties of the LIHe Roof System Similar properties of the LIHe of the LIHe (Figure 3). The bermed earth-sheltered walls were e Similar valuat pr ed operties in alof l fou the r LIHe cardinal orienta- of the LIHe of the LIHe the LIHe Similar Layer and Thickness 1 2 Similar properties of the LIHe Thermal Resistance and Transmittance in clude the internal e external superficial air resistance. Properties estimated tions (Figure 4). This strategy allows taking advantage of natural sloping ground while 1 2 of the LIHe Thermal Resistance and Transmittance include the internal e external superficial air resistance. Properties estimated 1 2 Therm 1 al Resistance and Tr 2 ansmittance include the internal e external superficial air resistance. Properties estimated by NBR 15 Therm 1 al Res .220 i[16]. stance and2 Transmittance include the internal e external superficial air resistance. Properties estimated providing a passive design measure to improve indoor thermal comfort conditions. Thermal Resistance and Transmittance include the internal e external superficial air resistance. Properties estimated by NBR 15.220 [16]. by NBR 15.220 [16]. by NBR 15.220 [16]. 1 2 by NBR 15.220 [16]. Thermal Resistance and Transmittance include the internal e external superficial air resistance. Properties estimated To evaluate the thermal inertia strategy, bermed earth-sheltered walls were imple- by NBR 15.220 [16]. To evaluate the thermal inertia strategy, bermed earth-sheltered walls were imple- To evaluate the thermal inertia strategy, bermed earth-sheltered walls were imple- To evaluate the thermal inertia strategy, bermed earth-sheltered walls were imple- mented in the original housing design (hereafter named as LIHb), so that bedrooms walls mented in the original housing design (hereafter named as LIHb), so that bedrooms walls mented in the original housing design (hereafter named as LIHb), so that bedrooms walls ment To evaluate t ed in the origh in e thermal in al housing d ertia str esign (h ategy, ereaftbermed er name e d as LIHb arth-shel), tered so that bedroo walls were ms walls imple- came into direct contact with the soil (Figure 2), resulting in the “LIHb” design strategy came into direct contact with the soil (Figure 2), resulting in the “LIHb” design strategy came into direct contact with the soil (Figure 2), resulting in the “LIHb” design strategy ment came int ed in t o di he r orig ect cont inal ho act wit using d h the soil ( esign (h Ferea igurft e 2 er n ), re ame sult d as LIHb ing in the ), “ so L that bedroo IHb” designms walls strategy (see properties in Table 2). For that, the external walls of bedrooms 1 and 2, which do not (see properties in Table 2). For that, the external walls of bedrooms 1 and 2, which do not (see properties in Table 2). For that, the external walls of bedrooms 1 and 2, which do not came int (see properti o dires i ect cont n Tabl act e wit 2). For tha h the soil ( t, the exte Figurrnal w e 2), reasu llslt of b ing in t edroom he “s L1 IHb” des and 2, wh ign ic st h do not rategy present openings, were selected to be 3.00 m (ceiling height) grounded earth-sheltered present openings, were selected to be 3.00 m (ceiling height) grounded earth-sheltered present openings, were selected to be 3.00 m (ceiling height) grounded earth-sheltered ( (Figure present openings, were see properti 3). Th es i e bermed ear n Table 2)se . For tha tlected to be 3.00 h-sheltere t, the exte d walls we rnal w m (ce rea i e ling llv sal of b height) uat edroom ed in a grounded earth-sheltered ls l fou 1 and r car 2, wh dina ic l orient h do not a- (Figure 3). The bermed earth-sheltered walls were evaluated in all four cardinal orienta- (Figure 3). The bermed earth-sheltered walls were evaluated in all four cardinal orienta- (Figure 3). The bermed earth-sheltered walls were evaluated in all four cardinal orienta- present openings, were tions (Figure 4). This stra se te lected to be 3.00 gy allows taking a m (ce dvant iling ag height) e of natugrounded earth-sheltered ral sloping ground while tions (Figure 4). This strategy allows taking advantage of natural sloping ground while tions (Figure 4). This strategy allows taking advantage of natural sloping ground while tions (Figure 4). This strategy allows taking advantage of natural sloping ground while (Figure providing 3). Th a pa e bermed ear ssive design tmeas h-sheltere ure to d walls we improve indo re ev or t aluat herma ed in a l co ll fou mfort r car condit dina io l orient ns. a- providing a passive design measure to improve indoor thermal comfort conditions. providing a passive design measure to improve indoor thermal comfort conditions. tproviding ions (Figu a re p4) ass . This st ive desi ra gn tegy a meas llow ure t s t oa ik m ing a prove indo dvantag or t e of nat herma ul co ral s mfort loping gro conditu io nns. d whil e providing a passive design measure to improve indoor thermal comfort conditions. (a) (b) Figure 3. (a) Schematic section and (b) modeled bermed earth-sheltered wall located in the bedrooms. 2.3. Simulation Method The impact of the bermed earth-sheltered wall in the building performance was eval- uated through computer simulation, using the DesignBuilder Software (Gloucestershire, United Kingdom, England) [28], to compare the performance of the LIHe and LIHb mod- els. The simulation results were evaluated following the RTQ-R [25] methodology, which (a) (b) considers the quantification of the energy consumption and the cooling degree-hours for a (a) (b) (a) (b) (a) (b) full year of operation. The simulation was carried out considering three distinct climatic (a) (b) 3.0 3.0 3.0 3.0 3.0 3.0 Appl. Sci. 2021, 11, 420 8 of 22 Appl. Sci. 2021, 11, x FOR PEER REVIEW 8 of 23 scenarios: base scenario (1961 to 1990 period), 2020 future scenario (2011 to 2040), and 2050 Figure 3. (a) Schematic section and (b) modeled bermed earth-sheltered wall located in the bedrooms. future scenario (2041 to 2070), the last two presenting the climate change influence. North (0°) South (180°) East (90°) West (270°) Figure 4. Variation of the embedded earth-sheltered wall orientation. Figure 4. Variation of the embedded earth-sheltered wall orientation. 2.3. Simul Theaearth-shelter tion Method ed wall strategy was configured within the simulation model through the GroundDomain: Basement (GDomain) input (Table 3), which calculates the temperature The impact of the bermed earth-sheltered wall in the building performance was of the interface between the soil, the external walls, and the slab of the bermed earth- evaluated through computer simulation, using the DesignBuilder Software (Gloucester- sheltered spaces, obtained three-dimensionally by the simulations [29]. The simulation shire, United Kingdom, England) [28], to compare the performance of the LIHe and LIHb was carried out considering the “Finite Difference” model as the ground temperature models. The simulation results were evaluated following the RTQ-R [25] methodology, type, which considers the weather data to define boundary conditions [30]. The manual which considers the quantification of the energy consumption and the cooling de- developed by [31] was used as a reference to the GroundDomain input data. gree-hours for a full year of operation. The simulation was carried out considering three distinct climatic scenarios: base scenario (1961 to 1990 period), 2020 future scenario (2011 Table 3. Input data considered in GDomain simulation. to 2040), and 2050 future scenario (2041 to 2070), the last two presenting the climate change influence. Input Data Adopted Input Values The earth-sheltered wall strategy was configured within the simulation model Ground Domain Depth (m) 15 through the GroundDomain: Basement (GDomain) input (Table 3), which calculates the Soil Thermal Conductivity (W/m K) 0.52 [32] temperature of the interface between the soil, the external walls, and the slab of the Soil Density (kg/m ) 1700 [32] bermed earth-sheltered spaces, obtained three-dimensionally by the simulations [29]. The simulation was carried out considering the “Finite Difference” model as the ground Soil Specific Heat (J/kg K) 840 [32] temperature type, which considers the weather data to define boundary conditions [30]. Mesh Density Parameter 6 The manual developed by [31] was used as a reference to the GroundDomain input data. The GroundDomain requires the monthly soil temperature data under the dwelling, Table 3. Input data considered in GDomain simulation. since it influences, significantly, the thermo-energy simulation. Thus, the Slab input Input Data Adopted Input Values tool was used to obtain the soil temperature under the LIH for the base and future Ground Domain Depth (m) 15 scenarios (Table 4). Soil Thermal Conductivity (W/m K) 0.52 [32] The occupancy and equipment power density data were adopted following RTQ-R [25], Soil Density (kg/m) 1700 [32] considering two people in each bedroom and four people in the living room. Regarding the Soil Specific Heat (J/kg K) 2 840 [32] 2 occupancy metabolic activity rate, 45 W/m was considered in bedrooms and 60 W/m Mesh Density Parameter 6 was set in the living room. The lighting power densities adopted were 5.0 W/m in the living room and 6.0 W/m in the bedrooms. The occupancy schedule estimates that the The GroundDomain requires the monthly soil temperature data under the dwelling, bedrooms are used from 9 p.m. to 8 a.m. during the weekdays and from 9 p.m. to 10 a.m. since it influences, significantly, the thermo-energy simulation. Thus, the Slab input tool on the weekend days, while the living room is used from 2 p.m. to 9 p.m. during the was used to obtain the soil temperature under the LIH for the base and future scenarios weekdays and from 11 a.m. to 9 p.m. on the weekend days. (Table 4). Table 4. Monthly soil temperature for the base scenario (1961–1990) and future estimates (2020/2050). Month 1961–1990 2020s 2050s January 27.94 28.73 29.87 February 27.76 28.32 29.71 March 27.73 28.63 30.11 April 26.78 27.65 29.59 May 26.10 27.05 29.04 Appl. Sci. 2021, 11, 420 9 of 22 Table 4. Monthly soil temperature for the base scenario (1961–1990) and future estimates (2020/2050). Month 1961–1990 2020s 2050s January 27.94 28.73 29.87 February 27.76 28.32 29.71 March 27.73 28.63 30.11 April 26.78 27.65 29.59 May 26.10 27.05 29.04 June 25.67 26.90 28.32 July 24.35 24.87 26.51 August 26.38 28.95 30.82 September 27.36 29.08 31.13 October 28.36 30.78 32.62 November 27.83 29.09 30.91 December 28.21 28.87 30.26 2.4. Generating Future Climate Scenarios Weather Data The “morphing” methodology, developed and described in [33], was adopted in this research, aiming to analyze the implications of climate change on the building’s thermal/ energy performance. The morphing method has been used to generate future Energy- Plus Weatherfiles (EPW) for any location in the world using the Climate Change World Weather File Generator for World-Wide Weather Data (CCWorldWeatherGen) tool (Southampton, United Kingdom) [33–35]. This methodology considers the climatic anomaly by modify- ing a set of historical climatic variables (1961–1990) of 8760 h per year, disregarding the influence of urbanization while incorporating the effects of global warming on the climate archives, making obtaining projections of future climate data possible. The CCWorldWeatherGen tool consists of an excel template that couples the EPW weather files to the “Hadley Centre Coupled Model version 3” (HadCM3) General Circula- tion Model (GCM). The HadCM3 is a coupled atmosphere–ocean general circulation model and has a resolution of 417 km 278 km in the Equator region and 295 km 278 km at 45 latitude, coupling the A2 Scenario of the IPCC 4th Assessment Report (AR4) for the 2020s time-slice (which covers the 2011–2040 period) and also the 2050s time-slice (2041–2070 period). The selected time-slices were based on a 50-year period, which is the building life expected for low-income houses [36]. 2.5. Indicators for Energy Consumption and Thermal Performance Evaluation 2.5.1. Estimation of the Cooling and Heating Energy Consumption Through the use of computer simulation, it is possible to obtain the thermal perfor- mance and the energy demand for heating and cooling when heating, ventilation, and air conditioning (HVAC) system is utilized in the indoors environment. In energy con- sumption analysis, two different conditions were utilized that express the habits of local habitants: (i) from 8 a.m to 9 p.m building operating naturally ventilated, considering 20 C as the indoor temperature control of the windows; and (ii) from 9 p.m. to 8 a.m with use of artificial conditioning system operating in the bedrooms, considering the split system with heating and cooling setpoint adjusted to 18 C and 24 C, respectively. In this case, the thermal load due to occupation, equipment, lighting, and energy performance of the air conditioning system followed the prescription of the Brazilian regulation for energy efficiency in buildings (RTQ-R) [25]. The energy consumption was assessed only for cooling, excluding heating demand, because the local population does not use heating systems due to the hot weather conditions in the region, while attending the RTQ-R methodology for the region under evaluation [25]. Appl. Sci. 2021, 11, 420 10 of 22 The air conditioning system was considered only in the bedrooms, which is a common behavior observed in the residences of this region [37]. The coefficient of performance (COP) for cooling was assumed to be 3.00 W/W (level “A” in the Brazilian Energy Labelling), and continuous fan operation mode (fan efficiency 0.7 and motor efficiency 0.9), following the simulation parameters for air conditioning system modeling used in the Brazilian Energy Label for residential buildings [25]. The estimated final cooling consumption of the (LIHe and LIHb) typologies were analyzed in terms of kWh/ (m /year) in both the base (1961–1990) and future climate change scenarios (2020 and 2050). Since the sum of energy spent by equipment and lighting remained almost constant between the present and future time-slices, not affecting building performance, it was not presented in final energy results. In this study, energy demand was only quantified for the bedroom zones where the bermed earth-sheltered walls were deployed, focusing on capturing the influence of the thermal mass as a passive strategy for cooling. 2.5.2. Indicator of the Envelope Performance by RTQ-R The cooling degree-hours (CDH) parameter was used as an indicator of building thermal performance under natural ventilation conditions, based on the RTQ-R recommen- dations [25]. The heating degree-hours parameter (HDH) was ignored due to their low occurrence in the study region. The base temperature used to calculate the CDH was set at 26 C, which was obtained by means of Equation (1): 8760 for T > 26 ; T 26 op op CDH = , (1) i = 0 for T  26 ; 0 ( ) op This indicator was estimated annually based on the hourly indoors operative tem- peratures (T ), with the two bedrooms and living room/kitchen considered as long op permanence rooms. Only one indicator was considered in the thermal performance eval- uation, obtained by the ponderation of the room areas. To classify the building’s energy efficiency, the indicator proposed for the Brazilian bioclimatic zone in the RTQ-R was used. In this evaluation, the naturally ventilated condition was considered for 24 h a day [23]. The efficiency level of the envelope varies from level A (CDH  12.566 Ch) to level E (CDH > 30.735 Ch), as presented in Table 5. Occupancy and internal thermal loads were considered in the simulation, which was carried out for the 8.760 h/ year [25]. Table 5. Building envelope efficiency for the researched bioclimatic zone according to the Brazilian Technical Quality Regulation for Energy Efficiency Level of Residential Buildings (RTQ-R). Level of Efficiency Cooling Degree-Hours Condition A CDH  12,566 Ch B 12,566 < CDH  18,622 Ch C 18,622 < CDH  24,679 Ch D 24,679 < CDH  30,735 Ch E CDH > 30,735 Ch 2.5.3. Adaptive Thermal Comfort Conditions in the Indoors Long Permanence Rooms The effectiveness of the bermed earth-sheltered walls measure adopted for improving indoor building thermal comfort was evaluated, since it is common for the low-income population not to have an air conditioning system installed at home due to the costs of its operation. In this way, it was considered the index based on the study of adaptive thermal comfort proposed by De Dear and Brager [38]. The methodology may be applied to represent the user ’s thermal comfort conditions inside of buildings naturally ventilated, considering only the user ’s occupancy and internal heat sources. The thermal comfort levels are defined by the ideal indoor operative temperature or the monthly neutral temperature Appl. Sci. 2021, 11, 420 11 of 22 (T , in C) related to the monthly averages of outdoor air temperature (T , in C), n Emed following Equation (2). This equation is only valid for T between 10.0 C and 33.5 C. Emed T = 17.8 + 0.31  T (2) Emed Thermal comfort ranges were determined by the definition of the month neutral temperature (T ) following procedures established in Standard 55 [39]. The monthly upper and lower limits for 90% of satisfied users were obtained by the use of Equation (3), where T represents the hourly indoor operative temperature. Indoor thermal comfort is reached op when the operative temperature is between the intervals prescribed in Equation (3). (T 2.5)  T  (T + 2.5), (3) n op n To quantify hot or cold discomfort hours and thermal comfort conditions of the long permanence rooms for the base scenario and future climate projections, the building was considered to operate in exclusive use of natural ventilation 24 h per day. Only one indoor operative temperature pondered by the area of the long permanence rooms was considered to assess the effectiveness of the measure to improve building performance. In turn, it was also considered the indoor operative temperature pondered by the area of bedrooms where the strategy was deployed. 3. Results and Discussion 3.1. Energy Consumption in Accordance with RTQ-R The energy consumption of both models was quantified by summing only the energy consumption of the bedrooms, which was not considered in living room/kitchen spaces since the strategy had a low impact on their performance. Since the region does not present a well-defined winter season, there are few hours of heating demand, with lower temperatures only occurring during cold weather fronts. With the climate change impact projections, it is reduced to almost nil values in 2020 and 2050 scenarios. Thus, heating loads were disregarded in this study, as the main consumption in typologies comes from cooling demand in the long permanence rooms. The energy consumption of both the reference typology (LIHe) and the thermal mass strategy with the bermed earth-sheltered walls (LIHb) can be seen in Figure 5. In the LIHe typology, the highest and lowest average energy demand in the bedrooms 2 2 occurs when walls are oriented to the north (66 kWh/m ) and to the west (63 kWh/m ), respectively. Similar results to the latter are obtained when they are oriented east and north (~64 kWh/m ). Thus, when the thermal mass strategy is not set in the building, the bedroom’s wall orientations have a low impact on energy demand (reduction of 2% from north to west). This behavior may be attributed to the building envelope, which has been improved by increasing its thermal insulation in order to obtain level A of energy efficiency [40]. In fact, the energy consumption for cooling demand observed in this study is slightly lower to that quantified for LIHs with combined passive measures located in the Salvador and Belém city (both Am Köppen–Geiger climate type), in the northern region 2 2 of Brazil, which displayed annual energy consumption of 75 kWh/m and 85 kWh/m , respectively [9,12]. Thus, the combined adaptation measures implemented in the standard LIH are more effective in improving the building energy performance in the base scenario than in the previous studies. The incorporation of the thermal mass strategy in the LIH provides a reduction in the bedroom’s energy demand for cooling for all the orientations considered (Figure 5). In the LHIb, differently from the LIHe demand pattern, the highest year energy demand of the bedrooms can be seen when the strategy is oriented to the south (42.7 kWh/m ), while the lowest is obtained when the strategy is oriented west (39.6 kWh/m ), provid- ing a reduction of 7.8% in the annual energy demand. Thus, the design consideration for thermal mass strategy orientation aiming to improve energy performance follows a different recommendation, regarding that observed for buildings without its use. In this Appl. Sci. 2021, 11, 420 12 of 22 Appl. Sci. 2021, 11, x FOR PEER REVIEW 12 of 23 sense, the adoption of the strategy in bedrooms with the bermed earth-sheltered in the orientations tested present a 34% to 38% reduction in energy demand for cooling, with a established for the region of 34.48 kWh/m to achieve level A efficiency. Thus, from a greater reduction in the west, almost reaching the relative cooling consumption indicator technical perspective, even for building envelopes already displaying an adequate ther- established for the region of 34.48 kWh/m to achieve level A efficiency. Thus, from a mal performance, the bermed earth-sheltered wall is recommended for the tropical cli- technical perspective, even for building envelopes already displaying an adequate thermal mate region as an alternative passive measure to improve building cooling energy per- performance, the bermed earth-sheltered wall is recommended for the tropical climate formance. region as an alternative passive measure to improve building cooling energy performance. Figure 5. Annual energy consumption of the bedrooms. Figure 5. Annual energy consumption of the bedrooms. The strategy impacts are similar to those observed in previous building simulation The strategy impacts are similar to those observed in previous building simulation studies. Thermal performance analysis of earth-sheltered residential buildings was con- studies. Thermal performance analysis of earth-sheltered residential buildings was con- ducted for the city of Yazd, in Iran (hot and dry region) [41]. Building Case 900 ASHRAE ducted for the city of Yazd, in Iran (hot and dry region) [41]. Building Case 900 ASHRAE was employed in a prospective study, with progressively changing depth of the soil sur- was employed in a prospective study, with progressively changing depth of the soil rounding the housing prototype [42]. In this case, the highest energy consumption was surrounding the housing prototype [42]. In this case, the highest energy consumption found when the main façade (not in contact with the earth) was oriented to the north, i.e., was found when the main façade (not in contact with the earth) was oriented to the north, when the bermed earth-sheltered wall was displayed in the south, confirming the best i.e., when the bermed earth-sheltered wall was displayed in the south, confirming the disposition obtained in this research. However, southern orientation had the lowest energy best disposition obtained in this research. However, southern orientation had the lowest consumption, while west obtained the best performance in this research, due to the fact energy consumption, while west obtained the best performance in this research, due to that current LIHb has only one wall sheltered by earth, and different opening locations the fact that current LIHb has only one wall sheltered by earth, and different opening for ventilation in the facades. The total energy consumption of a residential 1.0 m deep locations for ventilation in the facades. The total energy consumption of a residential 1.0 earth-sheltered (which corresponds to an entire wall sheltered by the earth, as in this study) m deep earth-sheltered (which corresponds to an entire wall sheltered by the earth, as in was reduced by about 67% (south orientation), bringing annual energy consumption to this study) was reduced by about 67% (south orientation), bringing annual energy con- 80 kWh/m . Despite the reduction being more expressive than in this work, final energy sumption to 80 kWh/m . Despite the reduction being more expressive than in this work, consumption for cooling was close to that found here. In another study in the Mediter- final energy consumption for cooling was close to that found here. In another study in the ranean climate (temperate), the annual air conditioning energy demand of a prototype Mediterranean climate (temperate), the annual air conditioning energy demand of a building with southern elevation located in Poznan (Poland) was evaluated. The building prototype building with southern elevation located in Poznan (Poland) was evaluated. wall was installed above and completely under the ground, with 0.1 m of thermal insulation The building wall was installed above and completely under the ground, with 0.1 m of thickness on the walls. This configuration provided reductions varying from 12% to 30%, thermal insulation thickness on the walls. This configuration provided reductions vary- depending on the type of soil on which the building was founded, which demonstrates ing from 12% to 30%, depending on the type of soil on which the building was founded, the soil type influence on the building performance of bermed houses [43]. The highest which demonstrates the soil type influence on the building performance of bermed reduction was obtained for the soil with similar physical and thermal characteristics to houses [43]. The highest reduction was obtained for the soil with similar physical and those considered in the current study. thermal characteristics to those considered in the current study. Despite of the implementation of combined adaptation measures and bermed earth- Despite of the implementation of combined adaptation measures and bermed sheltered strategy in the standard typology envelope, it is observed that the global warming earth-sheltered strategy in the standard typology envelope, it is observed that the global projections influence the annual cooling energy demand within the spaces under study. In warming projections influence the annual cooling energy demand within the spaces under study. In the 2020 future scenario, the impacts are high in the LIHe typology, varying from Appl. Sci. 2021, 11, 420 13 of 22 the 2020 future scenario, the impacts are high in the LIHe typology, varying from 28% to 32%, when compared to the base scenario, depending on the orientation. The same trend is observed for the LIHb typology, but with higher percentages, between 36% and 39%. In the 2050 scenario, the increase in energy demand exceeds 50% for all orientations when compared to the base scenario: from 64% to 70% in LIHe, and from 71% to 75% in LIHb. The projected increase in terms of percentage corroborates with previous studies conducted in cities located in other countries with the same climate type (Aw). In Darwin, Australia, the projected increase in air temperature for some emissions scenarios varied between 1.8 C to 2.5 C in the 2050 scenario, inducing an increment in energy consumption for cooling which varied between 40% and 80%, depending on the type of thermal insula- tion considered for the building envelope [7]. In Miami, The Unites States, the projected increase in air temperature in the 2050 scenario (2.52 C) is similar to those predicted for Australia and lower than in the current research (3.2 C). Despite having similar projections for air temperature to Australia, the possible induced increase in energy consumption for cooling is lower (between 27% and 37% in 2050 emissions scenarios), including in relation to this research [44]. In Brazil, similar projections have been observed for low-income houses deployed in regions with hot weather conditions. At Salvador (Af), the cooling energy demand is expected to increase by 30% and 46.6% in 2020 and 2050 scenarios, while at Belém (Af), 43.5% and 70.5% and, at Cuiabá (Aw), 20% and 30%, respectively [9,12,13]. The projection variations are attributed to the different types of passive strategies used in building envelopes. However, they are lower than those observed for the standard LIH studied in the same region, where the energy demand reaches more than double in the 2050 scenario due to its lack of adequate thermal insulation [45]. Despite the thermal load reduction, the LIHb serves as an effective passive strategy to counteract the effects of climate change, since its performance always remains superior to that of LIHe typology. For the 2020 scenario, the reduction provided by the strategy, when compared to the annual cooling energy demand of the building without its implementation, is significant, varying from 32% to 35% depending on the orientation. The same occurs for the 2050 scenario, with a variation between 33% and 36%. The highest reduction in thermal load was observed when the thermal mass strategy was positioned facing west, with a 36% average reduction. Notice that a partially-bermed earth-sheltered wall has the potential increased building resilience to face the global warming impacts, since cooling energy consumption in the 2020s is on average 12.3% lower than the base scenario, while in 2050, it is surpassed only by 10.7%. For the last time-slice, resilience is almost achieved, providing a considerable reduction in energy consumption (on average 37 kWh/m /year, based on energy consumption for LIHe in the 2050s) and promoting sustainability in tropical climate regions. Previously isolated measures tested in similar low-income houses located in the southeastern and northeast regions of Brazil were also effective in reducing the building energy consumption of HVAC [12]. The three best performing solutions were found when the wall absorptance in buildings was reduced to 0.3 (base scenario reduction: 21.86%|2050 Scenario reduction: 20.98%) when the brick wall was substituted by insulated concrete (40.82%|21.74%), and when the clay roof was replaced by a metal roof with 0.07 m of insulation and solar absorptance 0.3 (34.07%|23.64%). Note that the thermal mass strategy provided by the bermed earth-sheltered walls, when compared to the previous strategies, is more effective at counterbalancing the climate change effects, in turn, reducing the energy consumption of the building. Thus, as an isolated passive adaptation measure, as well as the other strategies tested in the previous study, it is not capable of completely counterbalancing the impact of climate change on cooling energy consumption. However, when combined with other adaptation measures, as proposed in this research, it may be an alternative to improve the building envelope and counterattack the effect of global warming, as observed in this study and previous ones [9,12,13]. For cities under hot weather conditions, the idealization of climate-responsive design on residential buildings Appl. Sci. 2021, 11, x FOR PEER REVIEW 14 of 23 Appl. Sci. 2021, 11, 420 14 of 22 residential buildings in the design phase is an alternative to reducing energy consump- tion demand due to the increase of air conditioning systems used for cooling. in the design phase is an alternative to reducing energy consumption demand due to the increase of air conditioning systems used for cooling. 3.2. Envelope Performance According to RTQ-R The CDH performance behavior differs from that observed in energy demand. 3.2. Envelope Performance According to RTQ-R When operating with an HVAC conditioning system, the thermal exchanges caused by The CDH performance behavior differs from that observed in energy demand. When the winds, that may affect the indoor’ spaces, are minimized since the windows remain operating with an HVAC conditioning system, the thermal exchanges caused by the winds, closed and the winds basically remove heat from external facades, entering indoors that may affect the indoor ’ spaces, are minimized since the windows remain closed and the spaces by fenestrations that exist on the window’s panel (Figure 6). For the LIHe typol- winds basically remove heat from external facades, entering indoors spaces by fenestrations ogy, the worst average performance is observed when walls are oriented to the north that exist on the window’s panel (Figure 6). For the LIHe typology, the worst average (10,269 °Ch). In contrast, the best average performance is obtained when the walls are performance is observed when walls are oriented to the north (10,269 Ch). In contrast, the oriented west (9,339 °Ch). In this case, a 9% reduction in the CDH is achieved, being the best average performance is obtained when the walls are oriented west (9339 Ch). In this best orientation for the building without the bermed earth-sheltered wall. Similar to the case, a 9% reduction in the CDH is achieved, being the best orientation for the building cooling energy demand, the incorporation of the thermal mass strategy with bermed without the bermed earth-sheltered wall. Similar to the cooling energy demand, the earth-sheltered walls provides a CDH reduction in bedrooms for all orientations (Figure incorporation of the thermal mass strategy with bermed earth-sheltered walls provides a 6). For LIHb, the worst performance is seen when the bermed earth-sheltered walls are CDH reduction in bedrooms for all orientations (Figure 6). For LIHb, the worst performance oriented to the north (7585 °Ch), and the best performance when the walls are oriented to is seen when the bermed earth-sheltered walls are oriented to the north (7585 Ch), and t the he west best performance (5810 °Ch, 23when .4% reduct the walls ion).ar e oriented to the west (5810 Ch, 23.4% reduction). Figure 6. Weighted annual average cooling-degree hours (CDH) indicator in baseline and future Figure 6. Weighted annual average cooling-degree hours (CDH) indicator in baseline and fu- ture scenarios ( scenarios (colors colors in we in west orientation st orientation for for LIHb LIHb in in the 20 the 2050s 50s was changed to was changed to match match with the with the colors colors established in the RTQ-R). established in the RTQ-R). Regarding the performance of the CDH, the same design recommendation for the Regarding the performance of the CDH, the same design recommendation for the orientation of the thermal mass strategy for buildings without the tested strategy should orientation of the thermal mass strategy for buildings without the tested strategy should be followed for the building with the bermed earth-sheltered wall. CDH reduction is be followed for the building with the bermed earth-sheltered wall. CDH reduction is expressive, varying from 26% to 38%, as much as those observed in the previous cool- expressive, varying from 26% to 38%, as much as those observed in the previous cooling ing demand analysis. For the LIH implanted in Salvador city, the combined adaptation demand analysis. For the LIH implanted in Salvador city, the combined adaptation measures in the current climate resulted in decreasing in cooling degree-hours ranging measures in the current climate resulted in decreasing in cooling degree-hours ranging between 33% to 68%, compared to the standard LIH, reaching CDH varying between between 33% to 68%, compared to the standard LIH, reaching CDH varying between higher than 5000 Ch and lower than 12,000 Ch [12]. Notice that LIHe typology presented higher than 5,000 °Ch and lower than 12,000 °Ch [12]. Notice that LIHe typology pre- level “A” energy efficiency rating (CDH  12,566 Ch) in all orientations evaluated in the sented level “A” energy efficiency rating (CDH ≤ 12,566 °Ch) in all orientations evaluated base scenario, as well as LIHb which had its envelope improved with the implementation in the base scenario, as well as LIHb which had its envelope improved with the imple- of the partially-bermed earth-sheltered walls. mentation of the partially-bermed earth-sheltered walls. The raising of the air temperature, due to climatic conditions that may prevail in future periods due to climate change, will progressively impact the possibility of transferring heat Appl. Sci. 2021, 11, 420 15 of 22 from the indoors to the outdoors environments, reducing the potential use of naturally ventilated strategy in the residential buildings. In the 2020 scenario, an increase in the CDH inside LIHe rooms (18% to 30%) was observed, with the best performance strategy orientation (west) in the base scenario being the most impacted due to global warming effects. In the LIHb, the scenario was even more drastic, with CDH doubling (reduction from 61% to 111%). In the 2050 scenario, the CDH exceeded double in some orientations, when compared to the base scenario, for both LIHe (148% to 173%) and LIHb (227% to 327%) (Figure 6). The impact in the CDH may be assigned to the predicted increasing of the outdoor air environment (projected rising of 1.5 C and 3.3 C for 2020 and 2050, respectively) and reduction in the humidity, but also due to the elevation of global hori- zontal radiation. In turn, the rising in ground temperature (see Table 4) also corroborates degeneration of the building’s thermal performance [9,13]. Despite the observed impacts, LIHb typology is proposed as a climate-responsive design strategy to counterbalance the effects caused by climate change in a situation where natural ventilation occurs 24 h per day, However, its impact is lower than that observed in cooling energy demand, in which the HVAC system is switched on at night when the indoor temperature is above the thermostat temperature, defined as a baseline thermal comfort temperature in the RTQ-R [23]. In the 2020 scenario, the reduction provided by the implementation of the strategy varies from 11% to 16%, depending on the orientation, when compared to the thermal performance of the building without the strategy. The same occurs in the 2050 scenario, with a variation between 9% and 12%. The highest reduction in the thermal performance was shown when the thermal mass strategy was oriented to the west, with a 13.9% average reduction, even so, less expressive than that shown for energy consumption. These projections corroborate the previous study conducted with the same low-income house, but with different types of passive strategies used in building envelopes and without the bermed earth-sheltered wall. Projections in the CDH indicator are expected to increase 31.3% and 28.6% in 2020 and 2050 scenarios [13]. However, in the standard LIH without any adaptation measures and with the use of bermed earth walls, the reduction in CDH is similar to that observed in this research [45]. The bermed earth-sheltered wall strategy, when compared with other isolated mea- sures, displays a lower reduction in terms of percentage [12]: the wall with solar absorp- tance 0.3 (base scenario reduction: 34.28%|2050 Scenario reduction: 25.97%), concrete wall with insulation (55.55%|37.14%), and clay roof replaced by a metal roof with 0.07 m of insulation and solar absorptance 0.3 (57.87%|39.88%). Thus, in terms of CDH, the bermed earth-sheltered strategy in this study is less expressive when compared to the isolated measures tested in the previous study. One may note CDH is weighted by the areas of the long permanence rooms, including the living room/kitchen, which has the same area as the sum of the bedrooms area and is not in contact with the bermed earth-sheltered walls. Thus, this room reduced the potential strategy impact (by at least half) due to its lower performance than the ones in contact with the ground. Yet, this behavior may be attributed to the fact that before simulations, LIH was redesigned to improve original buildings’ thermal and energy performance, which makes it difficult to improve its envelope due to its already high thermal insulation. Due to the future trend of air temperature raising, foreseen in the future climate change scenarios, the building efficiency level, which is “A” for LIHe and LIHb in the base scenario, decreases when the future potential impacts of climate change are incorporated into the weather data. In the 2020 scenario, the building energy efficiency is reduced to level “C”, with an exception in LIHb for west orientation, where level “B” is reached. In the 2050 scenario, all orientation became level “E”, again with an exception in LIHb for west orientation, with level “D”. Thus, this orientation must be preferred to achieve the best energy and thermal performance. Similar decreasing in building energy efficiency is also reported for five-star buildings analyzed in Darwin, Australia, and in Guangdong Province, South China, due to the raising of the energy requirement in the 2050 scenario [7,10]. This Appl. Sci. 2021, 11, 420 16 of 22 fact indicates the need to establish specific design guidelines in the building environmental certification codes to deal with this potential issue. 3.3. Indoor Operative Temperatures and Thermal Comfort Conditions The raising in energy consumption and the reduction in the thermal performance previously discussed is related to the tendency of the outdoor air temperature observed in the future scenarios generated by the tool CCWorldWeatherGen (Figure 7). In the base scenario, the annual average air temperature is 26.7 C and in the futures, a gradual increase is caused due to global warming projections, reaching 28.5 C and 29.9 C in the 2020s and the 2050s, respectively. In this sense, an increase of 3.2 C is predicted until the 2050s, as mentioned previously. The highest increase is observed in the dry season in September (1.9 C and 4 C in the 2020s and 2050s, respectively) and the lowest in the wet season in January (1.2 C and 2.3 C in the 2020s and 2050s, respectively). The potential global warming is more pronounced in the research region than those observed in other Brazilian cities characterized by different climates [9,12]. This is an important issue, as dwellings in the region usually operate predominantly with natural ventilation, compromising the possibility to maintain adequate indoors thermal comfort in the warming predicted context, as is described below. The indoors operative temperatures in the house’s rooms accompany the observed rise in the outdoor air temperature, progressively moving upwards in each time-slice. In the LIHe, the integrated living room/kitchen operative temperatures related to the building orientations are higher than in the bedrooms, but the differences are small, causing the curves to overlap each other (Figure 7a). This is not happening in the LIHb, where the introduction of bermed earth-sheltering walls caused thermal damping inside the bedrooms (Figure 7b). The observed modulation is an effective measure to reduce temperature fluctuations during the day; however, it can also lead to a slower reduction of the operative temperature during the night, which makes important the use of natural ventilation through the window openings during this period [8]. It is possible to notice that thermal damp is progressively reduced, due to the outdoors air temperature warming and also the raising on the ground temperature, compromising the tested measure effectiveness. Thus, for this reason, thermal comfort conditions inside the building are accessed in the sequence. The adaptation measure implemented in the LIHb is effective in improving the build- ing thermal performance in the base scenario, increasing the comfort, and reducing hot discomfort hours inside the building (Figure 8). The west orientation is the most effective in providing the highest thermal comfort hours (82%), 12% higher than the LIHe for the same orientation. Therefore, a properly designed bioclimatic passive measure may become an alternative to improve the building’s habitability for the researched location, also, in the current weather conditions. In future scenarios, thermal comfort levels have progressively deteriorated inside the houses, and the raise in the hot discomfort hours is observed in both typologies with the projections established by the IPCC. The small number of cold discomfort hours almost vanishes, due to the forecast outdoor air temperature elevation. Despite that, in the 2020 scenario, the typologies are still capable of providing more hours of thermal comfort than discomfort. Note that LIHb, on average, provides better thermal habitability for the users (59%), when compared to LIHe (51%), which is near the borderline to have a warm environment inside its rooms. The LIHe oriented to the north has higher hot discomfort hours than comfort (49%). In this sense, the impact of climate change is more pronounced in LIHe than in LIHb. Therefore, bermed earth-sheltering walls are a climate- responsive alternative design to help to improve the building’s habitability. In turn, in the 2050 scenario, thermal comfort hours are below 50% in both typologies and orientations, with a hot environment predominating within the buildings. In the LIHb, this behavior is attributed to the fact that thermal comfort has been assessed considering all the long permanence rooms, including the living room/kitchen that does not have the researched strategy deployed. This room has a hotter environment than the bedrooms, as described Appl. Sci. 2021, 11, 420 17 of 22 above. This way, it requires a more detailed analysis of the bedrooms without a living room/kitchen thermal influence. (a) LIHe (b) LIHb Base Scenario Figure 7. Annual diary course of outdoor air temperature and indoor long permanence rooms operative temperatures for the base and future scenarios in (a) LIHe and (b) LIHb. Appl. Sci. 2021, 11, x FOR PEER REVIEW 18 of 23 The adaptation measure implemented in the LIHb is effective in improving the building thermal performance in the base scenario, increasing the comfort, and reducing hot discomfort hours inside the building (Figure 8). The west orientation is the most ef- fective in providing the highest thermal comfort hours (82%), 12% higher than the LIHe for the same orientation. Therefore, a properly designed bioclimatic passive measure may become an alternative to improve the building’s habitability for the researched lo- Appl. Sci. 2021, 11, 420 18 of 22 cation, also, in the current weather conditions. Figure 8. Weighted percentage of comfort and discomfort hours inside the LIHe and LIHb in the Figure 8. Weighted percentage of comfort and discomfort hours inside the LIHe and LIHb in base and future scenarios. the base and future scenarios. Figure 9 depicts thermal comfort conditions inside the bedrooms where the strategy In future scenarios, thermal comfort levels have progressively deteriorated inside was implemented. Notice that behavior is similar to that displayed in Figure 8; however, the houses, and the raise in the hot discomfort hours is observed in both typologies with thermal comfort conditions preponderates in most orientations and time-slices. All building the projections established by the IPCC. The small number of cold discomfort hours al- orientations present the highest percentage of comfort hours than discomfort in the base Appl. Sci. 2021, 11, x FOR PEER REVIEW 19 of 23 most vanishes, due to the forecast outdoor air temperature elevation. Despite that, in the and 2020 scenario. However, the west orientation is the only one that provides more hours 2020 scenario, the typologies are still capable of providing more hours of thermal comfort of thermal comfort conditions (51%) in the 2050s. than discomfort. Note that LIHb, on average, provides better thermal habitability for the users (59%), when compared to LIHe (51%), which is near the borderline to have a warm environment inside its rooms. The LIHe oriented to the north has higher hot discomfort hours than comfort (49%). In this sense, the impact of climate change is more pronounced in LIHe than in LIHb. Therefore, bermed earth-sheltering walls are a climate-responsive alternative design to help to improve the building’s habitability. In turn, in the 2050 sce- nario, thermal comfort hours are below 50% in both typologies and orientations, with a hot environment predominating within the buildings. In the LIHb, this behavior is at- tributed to the fact that thermal comfort has been assessed considering all the long per- manence rooms, including the living room/kitchen that does not have the researched strategy deployed. This room has a hotter environment than the bedrooms, as described above. This way, it requires a more detailed analysis of the bedrooms without a living room/kitchen thermal influence. Figure 9 depicts thermal comfort conditions inside the bedrooms where the strategy Figure 9. Weighted percentage of comfort and discomfort hours for the bedrooms inside the LIHb Figure 9. Weighted percentage of comfort and discomfort hours for the bedrooms inside the LIHb in was in the base and future scenarios. implemented. Notice that behavior is similar to that displayed in Figure 8; however, the base and future scenarios. thermal comfort conditions preponderates in most orientations and time-slices. All build 4. Con 4. Conclusions ing or clusie io nt ns ations present the highest percentage of comfort hours than discomfort in the base and 2020 scenario. However, the west orientation is the only one that provides The ener The energy gy consu consumption mption and and ther thermal mal analysis analysindicated is indicated thattha thet use the use of of bermed beearth- rmed more hours of thermal comfort conditions (51%) in the 2050s. sheltered walls as a thermal mass for the bedrooms is a successful measure to improve earth-sheltered walls as a thermal mass for the bedrooms is a successful measure to improve buil building ding pe performance rformance an and d hhabitability abitability, ac , acting ting as asa pot a potential ential cli climate-r mate-responsi esponsive ve stra strategy tegy to to adapt buildings to face and counterbalance global warming effects that might prevail adapt buildings to face and counterbalance global warming effects that might prevail in in tropical climate regions. Higher impacts are observed in cooling energy demand than tropical climate regions. Higher impacts are observed in cooling energy demand than in the in the thermal performance, once the spaces in the former are not exposed to the thermal thermal performance, once the spaces in the former are not exposed to the thermal exchanges exchanges resulting from natural ventilation, since the windows remain closed when resulting from natural ventilation, since the windows remain closed when the HVAC system the HVAC system is operating. Due to the expected increase in air temperature in the is operating. Due to the expected increase in air temperature in the region (1.5 °C and 3.3 °C region (1.5 C and 3.3 C for 2020 and 2050, respectively), the potential use of naturally for 2020 and 2050, respectively), the potential use of naturally ventilated strategy in the resi- ventilated strategy in the residential buildings is affected, restricting the possibility to dential buildings is affected, restricting the possibility to transfer heat from the indoors to the transfer heat from the indoors to the outdoors environments, compromising building outdoors environments, compromising building thermal performance. thermal performance. The reduction in cooling energy consumption varied from 34% to 38% between the base and future scenarios, being more relevant when the bermed earth-sheltered walls are oriented to the west, that is, the main façade of the building is oriented to the east. Similar reductions for cooling degree-hours, evaluated when the building is in a natu- rally ventilated mode, are observed, ranging from 26% to 38%, with better performance also following the previous results, i.e., the main façade of the building oriented to the east. The effects of climate change impact on both operating modes idealized for the building long permanence rooms, i.e., when the building environments are operating naturally ventilated and with the use of HVAC. In the 2020 scenario, the increase in cooling energy consumption is over 28% for LIH, with and without the implementation of the bioclimatic strategy of bermed earth-sheltered walls, while in the 2050 scenario, it exceeds 64%. In the thermal performance, the projected increase in cooling degree-hours is more drastic, reaching 111% and 327% in the 2020 and 2050 scenarios, respectively. In these future scenarios, the reduction provided by the implemented measure depends on its orientation and varied between 32% to 36%, compared to the energy consumption of the building without this passive strategy. Again, the highest reduction in cooling energy consumption was shown when the thermal mass strategy was oriented to the west, with a 36% reduction, on average. Thus, because of future potential impacts of climate change, building efficiency level, which is “A” in the base scenario, decreases to level “E” in the 2050 scenario, an exception in LIHb for west orientation, in which level remains “D”. However, it should be pointed out that, for a fair judgment, the energy efficiency benchmarks should also be corrected for the climate change effects. Based on these po- tential impacts, specific design guidelines should be established by the international sustainable building organizations to enable designers, builders, and stakeholders to an- Appl. Sci. 2021, 11, 420 19 of 22 The reduction in cooling energy consumption varied from 34% to 38% between the base and future scenarios, being more relevant when the bermed earth-sheltered walls are oriented to the west, that is, the main façade of the building is oriented to the east. Similar reductions for cooling degree-hours, evaluated when the building is in a naturally ventilated mode, are observed, ranging from 26% to 38%, with better performance also following the previous results, i.e., the main façade of the building oriented to the east. The effects of climate change impact on both operating modes idealized for the building long permanence rooms, i.e., when the building environments are operating naturally ventilated and with the use of HVAC. In the 2020 scenario, the increase in cooling energy consumption is over 28% for LIH, with and without the implementation of the bioclimatic strategy of bermed earth-sheltered walls, while in the 2050 scenario, it exceeds 64%. In the thermal performance, the projected increase in cooling degree-hours is more drastic, reaching 111% and 327% in the 2020 and 2050 scenarios, respectively. In these future scenarios, the reduction provided by the implemented measure depends on its orientation and varied between 32% to 36%, compared to the energy consumption of the building without this passive strategy. Again, the highest reduction in cooling energy consumption was shown when the thermal mass strategy was oriented to the west, with a 36% reduction, on average. Thus, because of future potential impacts of climate change, building efficiency level, which is “A” in the base scenario, decreases to level “E” in the 2050 scenario, an exception in LIHb for west orientation, in which level remains “D”. However, it should be pointed out that, for a fair judgment, the energy efficiency benchmarks should also be corrected for the climate change effects. Based on these potential impacts, specific design guidelines should be established by the international sustainable building organizations to enable designers, builders, and stakeholders to anticipate the behavior of the built environment under the potential future global warming scenarios. The increase in cooling energy consumption, as well as in the cooling degree-hours, can be easily seen when the effects of climate change are incorporated into the weather data and thermos-energetic simulation is performed. However, the building with bermed earth-sheltered walls (LIHb) always presents better performance than the building without it (LIHe) in all orientations, demonstrating the positive impact of this measure. It can be considered as a climate-responsive design strategy because of the improvement in the housing resilience when facing the global warming impacts, since the cooling energy consumption in the 2020s on LIHb is on average 12.3% lower than in the base scenario, compared to LIHe, almost being able to provide full demand in the 2050s (consumption of LIHb surpassed the LIHe in base scenario only by 10.7%). The same behavior is not observed for CDH, due to the way this indicator is calculated, weighing the areas of the long permanence building rooms, including living room/kitchen, which is not in contact with the bermed earth-sheltered walls. This room, considered in the CDH calculation, presents lower thermal performance than the bedrooms, which influenced the final performance, reducing the positive impact of the implementation of the earth-sheltered wall. LIHb provides better thermal habitability for the users, when compared to LIHe, in all time-slices researched. Despite the progressive deterioration of thermal comfort conditions within the building rooms, the bermed earth-sheltered walls are an alternative to partially neutralize the global warming effects. When its impact, together with environments that do not have the measure deployed (which reduce the positive impact as described above), is analyzed, more hours of thermal comfort conditions may be achieved only until the 2020 scenario. However, considering only the rooms where the strategy is deployed, this condition may be guaranteed until the 2050 scenario by the building’s west orientation. Thus, given the impacts presented, it is possible to verify that bermed earth-sheltered walls correspond to an alternative strategy for the adaptation effects of climate change and should be thought of as an adaptive measure to promote building sustainability, in terms of cooling energy consumption. Therefore, the use of the thermal mass, combined with other passive adaptation strategies, may help to counterattack the climatic conditions that may prevail in future periods due to global warming on tropical climates. A cost–benefit analysis Appl. Sci. 2021, 11, 420 20 of 22 between the studied climate change adaptation measure investment and the energy-saving should be assessed in future work, aiming to evaluate the payback period. The thermal and energy analysis conducted in this study deals with uncertainties regarding the internal climate variability related to the climate model and premises adopted for future scenario definitions. The latter are based on economic growth, social trends, adaptation/ mitigation policies, technological development, and demographic factors. Therefore, the evaluation conducted in this study for the future scenarios should be treated as a possible trend, rather than as absolute values. However, the potential uncertainties in the future climate data do not invalidate the predictions made by the CCWorldWeatherGen tool, which can confidently be used to anticipate the behavior of the built environment in the potential future global warming scenarios. Author Contributions: Conception and execution of the building simulation—I.J.A.C., R.M.A. and E.L.A.d.G.; methodology—I.J.A.C., R.M.A. and E.L.A.d.G.; formal analysis—I.J.A.C. and L.C.D.; writing—I.J.A.C. and R.M.A.; reviewing and editing—L.C.D. and R.M.A.; visualization—F.R., K.d.A.C.R. and L.M.d.A. All authors have read and agreed to the published version of the manuscript. Funding: This research was funded by the Federal University of Mato Grosso (UFMT) (Edict number 01/2020, Process N. 23108.066371/2020-11) and by the Mato Grosso State Research Support Foundation (FAPEMAT) by a master contract granted (Edict number 017/2015). Institutional Review Board Statement: This study did not require ethical approval. Informed Consent Statement: Informed consent was obtained from all subjects involved in the study. Data Availability Statement: Data sharing is not applicable to this article. Acknowledgments: The authors would like to thank the Federal University of Mato Grosso/ Brazil and the Mato Grosso State Research Support Foundation (FAPEMAT) to support this research. Conflicts of Interest: The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results. Abbreviations Absorptance (dimensionless) LIH Single-family low-income house ' Thermal lag LIHe Efficient Single-family low-income house Efficient Single-family low-income house with Bermed A Floor area LIHb Earth-Sheltered in the bedrooms walls ABNT Brazilian Association of Technical Standards HadCM3 Hadley Centre Coupled Model version 3 Fourth Report of the Intergovernmental Panel on AR4 HVAC Heating, ventilation, and air conditioning Climate Change Aw Tropical Savannah climate PVC Polyvinyl chloride chloride CDH Cooling Degree-Hours R-value Thermal resistance COP Coefficient of performance RTQ-R Energy Efficiency Level of Residential Buildings CT Thermal capacity (kJ/(m K) SF Sun factor EPS Expanded polystyrene T Internal temperature int EPW EnergyPlus Weather file T External temperature ext GCM General Circulation Model T Monthly average neutral temperature GHG Greenhouse gas T Operative temperature op HDH Heating Degree-Hours T Monthly average outdoor air temperature Emed IPCC Intergovernmental Panel on Climate Change U Total thermal transmittance References 1. 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Bermed Earth-Sheltered Wall for Low-Income House: Thermal and Energy Measure to Face Climate Change in Tropical Region

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applied sciences Article Bermed Earth-Sheltered Wall for Low-Income House: Thermal and Energy Measure to Face Climate Change in Tropical Region 1 , 2 3 Ivan Julio Apolonio Callejas * , Raquel Moussalem Apolonio , Emeli Lalesca Aparecida da Guarda , 1 1 2 Luciane Cleonice Durante , Karyna de Andrade Carvalho Rosseti , Filipa Roseta and Leticia Mendes do Amarante Departamento de Arquitetura e Urbanismo, Faculdade de Arquitetura, Engenharia e Tecnologia, Universidade Federal de Mato Grosso, Av. Fernando Corrêa da Costa, 2367, Boa Esperança, Cuiabá 78060-900, Brazil; luciane.durante@hotmail.com (L.C.D.); karyna.rosseti@gmail.com (K.d.A.C.R.); leticiamendes.arq@outlook.com.br (L.M.d.A.) CIAUD—Faculdade de Arquitetura da Universidade de Lisboa, Rua Sá Nogueira, Pólo Universitário, Alto da Ajuda, 1649-004 Lisbon, Portugal; raquelmoussalem@hotmail.com (R.M.A.); filipa.roseta@psd.parlamento.pt (F.R.) Programa de Pós-graduação em Arquitetura e Urbanismo, Universidade de Santa Catarina, R. Eng. Agronômico Andrei Cristian Ferreira, s/n, Trindade 88040-900, Brazil; emeliguarda@gmail.com * Correspondence: ivancallejas@ufmt.br; Tel.: +55-65-3615-8774 Abstract: Climate change impact is one of the most important global concerns at present. In the build- ing environment, climate-responsive design may help to enhance the adaptation capacity through a better building energy performance. In this sense, this study addresses an adaptation strategy to reduce the effects of global warming on low-income houses, for which bioclimatic passive strategies should be prioritized, aiming to improve environmental sustainability. The technique chosen to be analyzed is thermal mass for cooling. Thus, the goal is to evaluate the energy consumption Citation: Callejas, I.J.A.; and thermal performance impact of implementing bermed earth-sheltered walls on bedrooms in Apolonio, R.M.; Guarda, E.L.A.d.; low-income housing (LIH), considered deployed in tropical climate regions. For that, a base scenario Durante, L.C.; de Andrade Carvalho (1961–1990) is considered, alongside two future scenarios: 2020 (2011 to 2040) and 2050 (2041 to 2070), Rosseti, K.; Roseta, F.; Amarante, both considering the effects of climate change, according to the Fourth Report (AR4) of the Inter- L.M.d. Bermed Earth-Sheltered Wall governmental Panel on Climate Change (IPCC). The methodologies adopted are (i) computational for Low-Income House: Thermal and simulation to estimate the annual energy consumption demand and (ii) quantification of the cooling Energy Measure to Face Climate degree-hours (CDH), with the subsequent comparative analysis based on Brazilian regulation for Change in Tropical Region. Appl. Sci. energy efficiency in buildings (RTQ-R). The predictions show that there will be an increase in the 2021, 11, 420. https://doi.org/ 10.3390/app11010420 energy consumption for cooling and in the CDH in both 2020 and 2050 scenarios, regardless of using a bermed earth-sheltered wall. Nonetheless, this adaptive measure enables the building to be resilient Received: 19 November 2020 in terms of cooling energy demand in the 2020s, since it is 12.3% lower than in the building without Accepted: 24 December 2020 the strategy use, compared with the base scenario. In the 2050s, resilience was almost reached with Published: 4 January 2021 energy consumption only 10.7% higher, for the same conditions described previously. Therefore, bermed earth-sheltered walls work as a climate-responsive design strategy to face the potential global Publisher’s Note: MDPI stays neu- warming effects, promoting building sustainability in tropical climate regions. tral with regard to jurisdictional clai- ms in published maps and institutio- Keywords: thermal performance; building simulation; climate-responsive; energy consumption; nal affiliations. cooling degree-hours; bioclimatic measure; passive measure Copyright: © 2021 by the authors. Li- censee MDPI, Basel, Switzerland. 1. Introduction This article is an open access article Vast knowledge about climate change, motivated by anthropogenic actions and based distributed under the terms and con- on greenhouse gas (GHG) emissions, has been released by the Intergovernmental Panel on ditions of the Creative Commons At- Climate Change (IPCC). The IPCC has published various scientific reports on which the tribution (CC BY) license (https:// behavior of terrestrial ecosystems is studied by scientists from a wide range of fields [1,2]. creativecommons.org/licenses/by/ An increase in the number of hot days in most land regions is expected, with the highest 4.0/). Appl. Sci. 2021, 11, 420. https://doi.org/10.3390/app11010420 https://www.mdpi.com/journal/applsci Appl. Sci. 2021, 11, 420 2 of 22 increases in the tropics, therefore, the potential effect of climate change in the building environment is a critical issue, especially concerning its design and operation. Furthermore, global warming will directly affect the thermal behavior of buildings, increasing hot season cooling, and decreasing cold heating demand, raising its energy consumption during the operational phase [3]. Thus, the strategic framework conceived to mitigate and adapt buildings environments to climate change increases the importance of the thermal mass effect as a strategy to counterattack its impacts, especially within warm regions located in South America with tropical Savannah climate (Aw), which is the second most common climate in the world, covering 11.5% of the world’s land area, 60.1% of South America [4], and 81.4% of the Brazilian territory [5]. Mitigation and adaptation are two strategies to address climate change. The first focuses on the causes (accumulation of greenhouse gases in the atmosphere) whereas the second on adaptation to the impacts [6]. Adaptation may respond mainly by reducing or eliminating the risks of climate change impacts, and on the building environment, it can be done by enabling the capacity of adaptation through a better building energy performance. In the last decade, some studies have evaluated the potential of buildings’ energy efficiency adaptation measures to face climate changes effects. In Australia, a study investigated, in five regional climates (from cold to hot humid), the potential impact of climate change on the heating and cooling energy requirements of residential houses. It was observed that energy-efficient or high star rating houses may experience fewer absolute changes in energy requirement due to their better thermal insulation [7]. In the Netherlands, three traditional residential house projects were used to investigate the effectiveness of passive climate change adaptation measures. The following strategies were tested in the building components using thermal simulation analysis: (i) increased thermal resistance, (ii) changed thermal capacity, (iii) increased short-wave reflectivity (albedo), (iv) vegetation roofs, (v) solar shading, and (vi) additional natural ventilation. The increase in thermal resistance/ thermal capacity and short-wave reflectivity resulted in a higher and lower number of overheating hours, respectively. The application of a vegetated roof, the use the natural ventilation, and the addition of operable exterior solar shading produced a decrease in the number of overheating hours [8]. A study conducted in three different bioclimatic zones in Brazil (at Curitiba, Florianópolis, and Belém cities) accessed individual passive strategies, such as solar shading, low absorptance, and thermal insulation, to reduce energy consumption in a low-income house under the global warming effects. The aforementioned measures were able to reduce up to 50% of the future annual cooling and heating energy demand in houses, contributing to their sustainability [9]. In Guangdong Province, South China, the global warming impacts on multi-family residences were predicted in two edification typologies: one with lower thermal insulation (3.5 stars-building envelope) and the other with higher performance (5.5 stars-building envelope). The total heating and cooling energy demand of 3.5 and 5.5 star-buildings due to global warming are projected to increase 20% and 25% in the 2080s, respectively, despite their better insulation compared to the existing housing stock [10]. A medium-sized office building located in five US cities (Miami—FL, Phoenix—AZ, Los Angeles—CA, Washington—DC, and Akron—CO) was accessed under the climate change impacts. The adaptation measures focused on the operation heating, ventilation, and air conditioning system (HVAC), which included the adjustment of thermostat set- points, the reduction of HVAC operation hours, the reduction of the variable air volume box minimum flow setting, and mixed-mode ventilation, strategies considered to neutralize the increased energy consumption in the research building. The mixed ventilation strategy proved to be an effective measure to reduce energy consumption, and thus mitigate the impacts of climate change in most research cities in the 2020s and 2050s scenarios [11]. Low-income housing located in the cities of São Paulo and Salvador, Brazil had its envelope improved with isolated and combined measures to face the impact of climate change. The most effective isolated adaptation measures to improve thermal performance and energy Appl. Sci. 2021, 11, 420 3 of 22 consumption were those related to lower solar absorptance of the walls, insulated roofs with lower solar absorptance, and shading to windows in all main rooms. For both cities, it was demonstrated that it is possible to obtain a good performance in the 2050 period, compared to the current climate, with the combination of isolated measures [12]. Practical measures were proposed to counterattack the impact of climate change on en- ergy consumption in a house located at Cuiabá, a region of Tropical Savannah climate (Aw), Brazil. The house envelope was enhanced, elevating the building system’s thermal resis- tance and reducing the solar absorptance. Despite the improvements, energy consumption is predicted to increase by 19.6% in the 2020s and 30.1% in the 2050s, compared to the base scenario [13]. A study quantified the application of an adaptive comfort control measure in mixed-mode office buildings in Cadiz, southern Spain. A daily setpoint temperature, based on the adaptive thermal comfort approach, was applied in a building to simulate the present and future conditions under climate change. Taking the current scenario as a reference, a 74.6% reduction in energy demand and a 59.7% drop in energy consumption was quantified when the adaptive comfort control was implemented in the model [14]. Thus, the specified previous predictions indicated that, despite the enhancement in the building energy performance, no individual passive strategies might completely neutralize the increasing of cooling and heating energy usage, suggesting the combination of passive strategies to counteract the effects of climate change. Some typical measures prescribed in bioclimatic codes and energy-efficient regulations have been considered in these studies, however, to reduce energy use for cooling/ heating demands, additional measures must be considered, especially those that act as a climate-responsive design strategy. When designing new buildings to face climate change, the traditional strategies, such as construction elements of the envelope, building geometry, and orientation, may not be sufficient to achieve adequate levels of energy consumption and thermal performance. Thus, alternative bioclimatic passive techniques are also important measures to be con- sidered during the design phase. For hot regions, thermal mass for cooling is an alternative measure to accumulate and retain heat during the day and return it to the exterior envi- ronment at night, acting as a climate-responsive design strategy. This behavior reduces the indoor air temperature fluctuations and maximizes the thermal lag of heat transfer of the walls, which oscillate in a damped manner [15–17]. Thus, this bioclimatic measure may reduce the use of active air conditioning systems during hot days, potentially saving energy and improving thermal comfort in an indoor environment [8]. In a hilly site, building walls may be designed to be in contact with the earth, increasing its thermal mass properties. In the “elevational” bermed design, the house’s main elevation or face, usually with a south-facing wall in cold regions and with a north-facing wall in hot climatic zones, remains unexposed, while the rest may be bermed by the earth. This type of construction, named earth sheltered building, are defined as structures built with the use of earth mass against building walls working as external thermal mass to the wall, which reduces heat loss and maintains a steady indoor air temperature throughout the seasons [18]. When the earth is in contact with building walls, it acts as a reservoir, storing the heat in vast spaces inside the soil and modulating indoor air temperatures at different meteorological conditions [19]. For this reason, the bermed type of construction may contribute to resilience to the urban heat island phenomenon, and constitutes an alternative measure to adapt buildings to the impacts of climate change, one of the most important global concerns at present. Thus, this research strategy is aligned to the principles of sustainable development goals (SDGs) to promote the 2030 agenda, especially the SDG 7 (affordable and clean energy) and SDG 11 (sustainable cities and communities), which should guide the production of sustainable and efficient buildings [20]. Besides, this passive measure, understood as a measure that does not use the energy once implemented in the building, may help designers and builders to attend the premises of bioclimatic architecture and thus achieve the fulfillment of sustainable performance requirements established by the building’s Appl. Sci. 2021, 11, x FOR PEER REVIEW 4 of 23 help designers and builders to attend the premises of bioclimatic architecture and thus Appl. Sci. 2021, 11, 420 4 of 22 achieve the fulfillment of sustainable performance requirements established by the building’s certifications systems, especially concerning energy efficiency and application of climate-responsive design [21]. certifications systems, especially concerning energy efficiency and application of climate- Thus, this study aims to evaluate the potential thermal and energy impact of im- responsive design [21]. plementing bermed earth-sheltered walls as a passive cooling strategy for a residential Thus, this study aims to evaluate the potential thermal and energy impact of im- building’s bedrooms, located in a region with a tropical climate to face climate change plementing bermed earth-sheltered walls as a passive cooling strategy for a residential effects. The study helps to deepen the knowledge of this potential climate-responsive building’s bedrooms, located in a region with a tropical climate to face climate change strategy as an adaptation measure for building to be deployed in the regions with hot effects. The study helps to deepen the knowledge of this potential climate-responsive climate conditions, where future scenario projections of climate change have indicated strategy as an adaptation measure for building to be deployed in the regions with hot the increase of hot days frequency, which will induce changes in building energy de- climate conditions, where future scenario projections of climate change have indicated mand due to the increase of air conditioning systems used for cooling [22,23]. The anal- the increase of hot days frequency, which will induce changes in building energy demand yses are made considering a base scenario (without the influence of climate change) and due to the increase of air conditioning systems used for cooling [22,23]. The analyses are two future scenarios (2020 and 2050) contemplating potential climate change effects, ac- made considering a base scenario (without the influence of climate change) and two future cording to the Fourth Report (AR4) of the Intergovernmental Panel on Climate Change scenarios (2020 and 2050) contemplating potential climate change effects, according to the (IPCC). Fourth Report (AR4) of the Intergovernmental Panel on Climate Change (IPCC). 2. Materials and Methods 2. Materials and Methods 2.1. Local Climate Identification and Bioclimatic Zone Characterization 2.1. Local Climate Identification and Bioclimatic Zone Characterization A A single-family single-family low low-income -income house house (LIH) (LIHselected ) selected for for t thishstudy is study is consider is consider ed to ed be tolo- be cated locate in d in a r a egion region o of Tropical f Trop Savannah ical Savann climate ah clim (Aat w), e ( characterized Aw), charactby erized by high air hi temperatur gh air tem- e throughout the year, wide hygrothermal variations, and undefined or absent winter sea- perature throughout the year, wide hygrothermal variations, and undefined or absent son wint [24 er se ]. Similar ason [2climat 4]. Simi e lclassification ar climate class can ific be atfound ion can b in several e found in locations several ar loc ound ation the s aro world, und such as Australia, Africa, and South America, especially in regions located between the the world, such as Australia, Africa, and South America, especially in regions located Equator and Tropics of Capricorn (Figure 1). The climate database of the Cuiabá city, which between the Equator and Tropics of Capricorn (Figure 1). The climate database of the 0 00 is located in the Mid-East, Brazil, in the geometric center of Latin America (15 36 56 S; Cuiabá city, which is located in the Mid-East, Brazil, in the geometric center of Latin 0 00 56 06 01 W) is used as a base of this research. America (15°36′56″ S; 56°06′01″ W) is used as a base of this research. Figure 1. Location of the city of Cuiabá in South America. Source: adapted from Peel et al. [4]. Figure 1. Location of the city of Cuiabá in South America. Source: adapted from Peel et al. [4]. The The Bra Brazilian zilian Assoc Association iation of of Technic Technical al Standar Standards ds (ABNT) (ABNT) for for B Bioclimatic ioclimatic Zoni Zoning ng establishes establishes a a set set ofof technical technica and l anconstr d constructi uctive ve recom recommendations mendations for the regi for the region, to on, to opti optimize- the mizthermal e the therma performance l performa of nce of buildings buildings through a through a better better cl climatic imatadaptation ic adaptation [16 [1 ].6]. The The rrecommendat ecommendations ions and and cons constr tr uct uct ive ive gu guidelines idelinesfor for a adequ dequ ate ateLIH LIH for forthe the Sav Savannah annah clim climate ate region are detailed in Table 1, in accordance with the Brazilian Bioclimatic and as prescribed region are detailed in Table 1, in accordance with the Brazilian Bioclimatic and as pre- by the Brazilian Technical Quality Regulation for Energy Efficiency Level of Residential scribed by the Brazilian Technical Quality Regulation for Energy Efficiency Level of Buildings (RTQ-R) [25]. As indicated in Table 1, thermal mass for cooling is a strategy Residential Buildings (RTQ-R) [25]. As indicated in Table 1, thermal mass for cooling is a recommended to adapt the building to the climate where it is located. Thus, this research focuses on verifying if this potential passive strategy may be adequate to adapt a building to the projected climate change scenarios. Appl. Sci. 2021, 11, 420 5 of 22 Table 1. Recommendations and constructive guidelines for the bioclimatic zoning of the building location. Guidelines for Building Envelope Strategies for Passive Thermal Opening’s Code Conditioning Recommendations Wall System Roof System A: NR A:NR Evaporative Cooling; Thermal Small openings: 10% < A Type: Heavy Type: Heavy mass for cooling; Selective NBR 15220 < 15% U  2.2; CT:NR U  2.0; CT: NR ventilation Shade openings '  6.5 h '  6.5 h (T > T ) ext int SF  3.5% SF  6.5% 0.6 > 0.6  0.4 > 0.4 No requirement established A  5% U  3.70 U  2.50 U 2.30 U 1.50 RTQ-R CT  130 CT  130 NR NR 1 2 2 A: floor area (%); : absorptance (dimensionless); U: total thermal transmittance (W/m K); CT: thermal capacity (kJ/(m K); ': thermal lag; SF: sun factor; NR: no requirement established; T : internal temperature; T : external temperature. int ext 2.2. Characterization of the Study Case A typical low-income house, widely replicated in all regions of Brazil by the Brazilian government under the social housing program named “My House My Life”, was chosen for this study [26] (Figure 2a). This choice is based on the fact that this population is the most vulnerable to the impact of climate change, especially in developing countries. This typology is handed out to the users without any concern about climatic adaptation to the implantation region, with a poor thermal performance [9,12,13], compromising its indoor thermal comfort conditions as well as increasing energy consumption for cooling [13,27]. Due to these facts and how this research focuses on the thermal mass strategy as a climate- responsive measure, the original standard building project was redesign to attend Brazilian RTQ-R level ‘A’ of efficiency [25], thereafter named as “LIHe”. It is characterized by a one-story detached house in contact with the ground. LIHe presents 39.18 m of total area and 34.54 m of internal floor area, distributed in four designated areas, namely: 2 2 2 living room/kitchen (17.44 m ), bedroom 1 (7.78 m ), bedroom 2 (7.57 m ), and bathroom (1.75 m ) (Figure 2a–c). The roof construction is dual pitched with an overhang of 0.30 m depth. The rooms’ ceiling height is 3.00 m. Regarding openings, living room and bedroom spaces present metallic sliding win- dows with dimensions of 1.50  1.00 m and 1.20  1.00 m, respectively, composed of four panels, two of them being single glass fixed panels and the other two sliding metallic Venetian panels. The kitchen’s window is a metallic tilting type of 1.00 1.00 m. The exter- nal doors are made of metallic sheets, while interior doors are wood-made. The thermal resistance of the external walls and roof were improved to provide building efficient level “A”. The external walls consist of ceramic bricks (six-hole type) coated on the outside with expanded polystyrene sheets (EPS) (0.04 m) and plaster (0.025 m) in the outermost and innermost layers. The internal partitions consist of ceramic brick (six-hole type) coated on both sides with plaster (0.015 m). The external walls absorptance was reduced from 0.3 to 0.15 by changing the painting to white color. The roof system is composed of ceramic tile, aluminum foil for thermal insulation, an air gap layer, and ceiling panels of polyvinyl chloride (PVC) (0.01 m). The outermost layer of the tiles was painted with white color (ranging the absorptance of the roof from 0.8 to 0.15). Regarding the roof air gap, this layer presents 0.61 m K/W thermal resistance (R-value), with a thickness greater than 0.05 m and low thermal emissivity due to the installation of aluminum foil. The Brazilian Association of Technical Standards NBR 15.220 [16] was used to redesign the building envelope and to determine the thermal properties of the building system envelope of the efficient low-income house (LIHe), which are presented in Table 2. Appl. Sci. 2021, 11, x FOR PEER REVIEW 6 of 23 Appl. Sci. 2021, 11, 420 6 of 22 (a) External image and 3D DesignBuilder model of the low-income house (LIH). (b) Floor plan (dimensions in meters) (c) Sections AA’ and BB’ Figure 2. (a) Standard low-income housing picture, (b) floor plan, and (c) section plans. Figure 2. (a) Standard low-income housing picture, (b) floor plan, and (c) section plans. Regarding openings, living room and bedroom spaces present metallic sliding To evaluate the thermal inertia strategy, bermed earth-sheltered walls were imple- windows with dimensions of 1.50 × 1.00 m and 1.20 × 1.00 m, respectively, composed of mented in the original housing design (hereafter named as LIHb), so that bedrooms walls came four pane into ls, dir tect wo of t contact hem with being the sin soil gle (Figur glasse f2 ixed ), resulting panels and in the th“LIHb” e other tdesign wo slid strategy ing meta (see llic pr Venet operties ian p in an T e able ls. The 2). For kitcthat, hen’s window the external is walls a met of albedr lic tilt ooms ing t1 yp and e of 2, 1. which 00 × 1. do 00 m not . The ex- present openings, were selected to be 3.00 m (ceiling height) grounded earth-sheltered (Figure 3). ternal doors are made of metallic sheets, while interior doors are wood-made. The ther- The mal r bermed esistanc eart e of t h-shelter he exte ed rnal w walls alls wer an e d evaluated roof were inimproved t all four cardinal o provide bu orientations ilding (Figur effici eent 4). This strategy allows taking advantage of natural sloping ground while providing a passive level “A”. The external walls consist of ceramic bricks (six-hole type) coated on the out- design measure to improve indoor thermal comfort conditions. side with expanded polystyrene sheets (EPS) (0.04 m) and plaster (0.025 m) in the outermost and innermost layers. The internal partitions consist of ceramic brick (six-hole type) coated on both sides with plaster (0.015 m). The external walls absorptance was reduced from 0.3 to 0.15 by changing the painting to white color. The roof system is composed of ceramic tile, aluminum foil for thermal insulation, an air gap layer, and ceiling panels of polyvinyl chloride (PVC) (0.01 m). The outermost layer of the tiles was painted with white color (ranging the absorptance of the roof from 0.8 to 0.15). Regarding the roof air gap, this layer presents 0.61 m K/W thermal resistance (R-value), with a thickness greater than 0.05 m and low thermal emissivity due to the installation of alu- minum foil. The Brazilian Association of Technical Standards NBR 15.220 [16] was used to redesign the building envelope and to determine the thermal properties of the building system envelope of the efficient low-income house (LIHe), which are presented in Table Appl. Sci. 2021, 11, x FOR PEER REVIEW 7 of 23 Table 2. Thermophysical properties adopted for building systems envelope of the efficient low-income house (LIHe) and bermed earth-sheltered low-income house (LIHb). Envelope Materials Thickness 1 2 Building Characteristics R-Value (m²K/W) U (W/m²K) CT (J/m²K) α Layers (m) White paint- Appl. Sci. 2021, 11, x FOR PEER REVIEW 7 of 23 ing Appl. Sci. 2021, 11, x FOR PEER REVIEW 7 of 23 Wall System Appl. Sci. 2021, 11, x FOR PEER REVIEW 7 of 23 Appl. Sci. 2021, 11, x FOR PEER REVIEW 7 of 23 Mortar 0.025 Appl. Sci. 2021, 11, x FOR PEER REVIEW 7 of 23 Appl. Sci. 2021, 11, 420 7 of 22 EPS sheet 0.040 1.128 0.886 169.38 0.15 Ceramic brick 0.09 Table 2. Thermophysical properties adopted for building systems envelope of the efficient low-income house (LIHe) and Table 2. Thermophysical properties adopted for building systems envelope of the efficient low-income house (LIHe) and Table 2. Thermophysical properties adopted for building systems envelope of the efficient low-income house (LIHe) and bermed earth-sheltered low-income house (LIHb). Mortar 0.025 Table 2. Thermophysical properties adopted for building systems envelope of the efficient low-income house (LIHe) and bermed earth-sheltered low-income house (LIHb). bermed earth-sheltered low-income house (LIHb). bermed earth-sheltered low-income house (LIHb). White paint- Table 2. Thermophysical properties adopted for building systems envelope of the efficient low-income house (LIHe) and Effic T iable ent low- 2. Thermophysical income Envelope properties adopted Materials for building Thickness systems envelope of the efficient low-income house (LIHe) and 1 2 Building Char bermed earth-sheltered acteristics low-income house (LIHb). ing R-Value (m²K/W) U (W/m²K) CT (J/m²K) α Envelope Materials Thickness Envelope Materials Thickness 1 2 house systems (LIHe) Envelope Materials Layers Thickness (m) bermed earth-sheltered low-income house (LIHb). Building Characteristics R-Value 1 (m²K/W) U 2 (W/m²K) CT (J/m²K) α Building Characteristics R-Value (m²K/W) 1 U (W/m²K) 2 CT (J/m²K) α Building Characteristics R-Value (m²K/W) U (W/m²K) CT (J/m²K) α White paint- Layers (m) Layers (m) Layers (m) Envelope White paint- Materials Thickness 1 2 ing Building Characteristics White paint- R-Value (m²K/W) U (W/m²K) CT (J/m²K) α Materials R-Value White paint- 2 2 2 White paint- ing Building Characteristics Envelope Layers Thickness (m) (m) U (W/m K) CT (J/m K) Wall System Roof System Layers (m K/W) Ceramic tiles 0.01 ing ing Wall System ing White paint- Mortar 0.025 Wall System Wall System Aluminum 0.847 1.18 41.92 0.15 WhiteMortar 0.025 painting Mortar 0.025 EPS sheetMortar 0.025 ing 0.040- Wall System Wall System foil 1.128 0.886 169.38 0.15 EPS sheet 0.040 Mortar 0.025 EPS sheet 0.040 EPS sheet 0.040 Ceramic brick Mortar 0.025 0.09 1.128 0.886 169.38 0.15 1.128 0.886 169.38 0.15 Attic space >0.05 m 1.128 0.886 169.38 0.15 0.15 Ceramic brick 0.09 Ceramic brick EPS sheet 0.040 0.09 Ceramic brick 0.09 EPS sheet Mortar 0.025 0.040 1.128 0.886 169.38 PVC ceiling 0.01 1.128 0.886 169.38 0.15 Mortar 0.025 Mortar 0.025 Ceramic Ceramic brick White paint- Mortar 0.025 brick 0.09 0.09 Wall System Efficient low-income White paint- White paint- White paint- Mortar 0.025 ing Efficient low-income Mortar 0.025 Efficient low-income Efficient low-income house systems (LIHe) ing ing White paint- ing house systems (LIHe) White paint- Similar Layer and Thickness Efficient low-income White painting house systems (LIHe) house systems (LIHe) Efficient low-income White paint- Similar properties of the LIHe White paint- house systems (LIHe) White paint- ing ing of the Efficient LIH White painting house systems (LIHe) ing ing Roof System ing Ceramic tile White paint- s 0.01 Roof System Ceramic Ceramic tile tiles s 0.01 0.01 Roof System Roof System Ceramic tiles 0.01 Roof System Ceramic tile ing s 0.01 Aluminum 0.847 1.18 41.92 0.15 Aluminum 0.847 1.18 41.92 0.15 Aluminum foil - Wall System in con- 0.847 1.18 41.92 0.15 Aluminum 0.847 1.18 41.92 0.15 Roof System Ceramic tile Alumi foil num s 0.01 0.847 1.18 41.92 0.15 Bermed earth-sheltered - foil tact with ground Attic space foil >0.05 m Attic space foil >0.05 m Aluminum 0.847 1.18 41.92 0.15 low-income house sys- Attic space >0.05 m Attic space >0.05 m Similar Layer and Thickness Evaluated by the Energyplus program according to the Attic space >0.05 m PVC PVC ceiling ceiling foil 0.01 0.01 tems (LIHb) PVC ceiling 0.01 PVC ceiling of the LIHe + ground contact 0.01 Basement (GDomain) input data. PVC ceiling 0.01 Wall System Attic space >0.05 m Wall System Wall System Wall System Wall System PVC ceiling 0.01 Similar Layer and Thickness Similar Layer and Thickness of Wall System Similar properties of the LIHe Similar Layer and Thickness Similar properties of the LIHe Similar Layer and Thickness Similar of the E Layer a fficient nd Thickness LIH the Efficient LIH Similar properties of the LIHe Roof System Similar properties of the LIHe Similar properties of the LIHe of the Efficient LIH of the Efficient LIH Similar Layer and Thickness of the Efficient LIH Similar Layer and Thickness Similar properties of the LIHe Similar properties of the LIHe of the LIHe of the Efficient LIH Wall System in con- Wall System Bermed earth-sheltered 1 2 Wall System in con- Thermal Resistance and Transmittance include the internal e external superficial air resistance. Properties estimated Wall System in con- Wall Sys tact with tem in ground con- Bermed earth-sheltered in contact Bermed earth-sheltered low-incom Bermed earth-sheltered e house sys- Bermed earth-sheltered tact with ground by NBR 15.220 [16]. tact with with gr ground ound tact with ground low-income house sys- Wall System in con- Similar Layer and Thickness Evaluated by the Energyplus program according to the low-incom low-income e house sy house s- low-incom tems (LIHb) e hous e sys- Bermed earth-sheltered Similar Layer and Thickness Evaluated by the Energyplus program according to the Similar Similar Layer Layer a andn Thickness d Thickness of Evaluated by Evaluatedthe Energyplus program according to the by the Energyplus program according to the tact with ground of the LIHe Similar Layer a + ground contact nd Thickness Evaluated by Base the Energyplus program according to the ment (GDomain) input data. tems (LIHb) systems (LIHb) To evaluate the thermal inertia strategy, bermed earth-sheltered walls were imple- tems (LIHb) tems (LIHb) low-income house sys- the LIHe + ground contact Basement (GDomain) input data. of the LIHe + ground contact Basement (GDomain) input data. of the LIHe + ground contact Basement (GDomain) input data. of the LIHe + ground contact Basement (GDomain) input data. Similar Layer and Thickness Evaluated by the Energyplus program according to the mented in the original housing design (hereafter named as LIHb), so that bedrooms walls tems (LIHb) of the LIHe + ground contact Basement (GDomain) input data. came into direct contact with the soil (Figure 2), resulting in the “LIHb” design strategy Roof System (see properties in Table 2). For that, the external walls of bedrooms 1 and 2, which do not Roof System Similar Layer and Thickness Roof System Roof System Similar properties of the LIHe Roof System present openings, were Similar Layer an se d Thickness lected to be 3.00 m (ceiling height) grounded earth-sheltered Similar Layer and Thickness Similar Layer a of the LIHe nd Thickness Similar properties of the LIHe Similar Layer and Thickness of Similar properties of the LIHe Roof System Similar properties of the LIHe of the LIHe (Figure 3). The bermed earth-sheltered walls were e Similar valuat pr ed operties in alof l fou the r LIHe cardinal orienta- of the LIHe of the LIHe the LIHe Similar Layer and Thickness 1 2 Similar properties of the LIHe Thermal Resistance and Transmittance in clude the internal e external superficial air resistance. Properties estimated tions (Figure 4). This strategy allows taking advantage of natural sloping ground while 1 2 of the LIHe Thermal Resistance and Transmittance include the internal e external superficial air resistance. Properties estimated 1 2 Therm 1 al Resistance and Tr 2 ansmittance include the internal e external superficial air resistance. Properties estimated by NBR 15 Therm 1 al Res .220 i[16]. stance and2 Transmittance include the internal e external superficial air resistance. Properties estimated providing a passive design measure to improve indoor thermal comfort conditions. Thermal Resistance and Transmittance include the internal e external superficial air resistance. Properties estimated by NBR 15.220 [16]. by NBR 15.220 [16]. by NBR 15.220 [16]. 1 2 by NBR 15.220 [16]. Thermal Resistance and Transmittance include the internal e external superficial air resistance. Properties estimated To evaluate the thermal inertia strategy, bermed earth-sheltered walls were imple- by NBR 15.220 [16]. To evaluate the thermal inertia strategy, bermed earth-sheltered walls were imple- To evaluate the thermal inertia strategy, bermed earth-sheltered walls were imple- To evaluate the thermal inertia strategy, bermed earth-sheltered walls were imple- mented in the original housing design (hereafter named as LIHb), so that bedrooms walls mented in the original housing design (hereafter named as LIHb), so that bedrooms walls mented in the original housing design (hereafter named as LIHb), so that bedrooms walls ment To evaluate t ed in the origh in e thermal in al housing d ertia str esign (h ategy, ereaftbermed er name e d as LIHb arth-shel), tered so that bedroo walls were ms walls imple- came into direct contact with the soil (Figure 2), resulting in the “LIHb” design strategy came into direct contact with the soil (Figure 2), resulting in the “LIHb” design strategy came into direct contact with the soil (Figure 2), resulting in the “LIHb” design strategy ment came int ed in t o di he r orig ect cont inal ho act wit using d h the soil ( esign (h Ferea igurft e 2 er n ), re ame sult d as LIHb ing in the ), “ so L that bedroo IHb” designms walls strategy (see properties in Table 2). For that, the external walls of bedrooms 1 and 2, which do not (see properties in Table 2). For that, the external walls of bedrooms 1 and 2, which do not (see properties in Table 2). For that, the external walls of bedrooms 1 and 2, which do not came int (see properti o dires i ect cont n Tabl act e wit 2). For tha h the soil ( t, the exte Figurrnal w e 2), reasu llslt of b ing in t edroom he “s L1 IHb” des and 2, wh ign ic st h do not rategy present openings, were selected to be 3.00 m (ceiling height) grounded earth-sheltered present openings, were selected to be 3.00 m (ceiling height) grounded earth-sheltered present openings, were selected to be 3.00 m (ceiling height) grounded earth-sheltered ( (Figure present openings, were see properti 3). Th es i e bermed ear n Table 2)se . For tha tlected to be 3.00 h-sheltere t, the exte d walls we rnal w m (ce rea i e ling llv sal of b height) uat edroom ed in a grounded earth-sheltered ls l fou 1 and r car 2, wh dina ic l orient h do not a- (Figure 3). The bermed earth-sheltered walls were evaluated in all four cardinal orienta- (Figure 3). The bermed earth-sheltered walls were evaluated in all four cardinal orienta- (Figure 3). The bermed earth-sheltered walls were evaluated in all four cardinal orienta- present openings, were tions (Figure 4). This stra se te lected to be 3.00 gy allows taking a m (ce dvant iling ag height) e of natugrounded earth-sheltered ral sloping ground while tions (Figure 4). This strategy allows taking advantage of natural sloping ground while tions (Figure 4). This strategy allows taking advantage of natural sloping ground while tions (Figure 4). This strategy allows taking advantage of natural sloping ground while (Figure providing 3). Th a pa e bermed ear ssive design tmeas h-sheltere ure to d walls we improve indo re ev or t aluat herma ed in a l co ll fou mfort r car condit dina io l orient ns. a- providing a passive design measure to improve indoor thermal comfort conditions. providing a passive design measure to improve indoor thermal comfort conditions. tproviding ions (Figu a re p4) ass . This st ive desi ra gn tegy a meas llow ure t s t oa ik m ing a prove indo dvantag or t e of nat herma ul co ral s mfort loping gro conditu io nns. d whil e providing a passive design measure to improve indoor thermal comfort conditions. (a) (b) Figure 3. (a) Schematic section and (b) modeled bermed earth-sheltered wall located in the bedrooms. 2.3. Simulation Method The impact of the bermed earth-sheltered wall in the building performance was eval- uated through computer simulation, using the DesignBuilder Software (Gloucestershire, United Kingdom, England) [28], to compare the performance of the LIHe and LIHb mod- els. The simulation results were evaluated following the RTQ-R [25] methodology, which (a) (b) considers the quantification of the energy consumption and the cooling degree-hours for a (a) (b) (a) (b) (a) (b) full year of operation. The simulation was carried out considering three distinct climatic (a) (b) 3.0 3.0 3.0 3.0 3.0 3.0 Appl. Sci. 2021, 11, 420 8 of 22 Appl. Sci. 2021, 11, x FOR PEER REVIEW 8 of 23 scenarios: base scenario (1961 to 1990 period), 2020 future scenario (2011 to 2040), and 2050 Figure 3. (a) Schematic section and (b) modeled bermed earth-sheltered wall located in the bedrooms. future scenario (2041 to 2070), the last two presenting the climate change influence. North (0°) South (180°) East (90°) West (270°) Figure 4. Variation of the embedded earth-sheltered wall orientation. Figure 4. Variation of the embedded earth-sheltered wall orientation. 2.3. Simul Theaearth-shelter tion Method ed wall strategy was configured within the simulation model through the GroundDomain: Basement (GDomain) input (Table 3), which calculates the temperature The impact of the bermed earth-sheltered wall in the building performance was of the interface between the soil, the external walls, and the slab of the bermed earth- evaluated through computer simulation, using the DesignBuilder Software (Gloucester- sheltered spaces, obtained three-dimensionally by the simulations [29]. The simulation shire, United Kingdom, England) [28], to compare the performance of the LIHe and LIHb was carried out considering the “Finite Difference” model as the ground temperature models. The simulation results were evaluated following the RTQ-R [25] methodology, type, which considers the weather data to define boundary conditions [30]. The manual which considers the quantification of the energy consumption and the cooling de- developed by [31] was used as a reference to the GroundDomain input data. gree-hours for a full year of operation. The simulation was carried out considering three distinct climatic scenarios: base scenario (1961 to 1990 period), 2020 future scenario (2011 Table 3. Input data considered in GDomain simulation. to 2040), and 2050 future scenario (2041 to 2070), the last two presenting the climate change influence. Input Data Adopted Input Values The earth-sheltered wall strategy was configured within the simulation model Ground Domain Depth (m) 15 through the GroundDomain: Basement (GDomain) input (Table 3), which calculates the Soil Thermal Conductivity (W/m K) 0.52 [32] temperature of the interface between the soil, the external walls, and the slab of the Soil Density (kg/m ) 1700 [32] bermed earth-sheltered spaces, obtained three-dimensionally by the simulations [29]. The simulation was carried out considering the “Finite Difference” model as the ground Soil Specific Heat (J/kg K) 840 [32] temperature type, which considers the weather data to define boundary conditions [30]. Mesh Density Parameter 6 The manual developed by [31] was used as a reference to the GroundDomain input data. The GroundDomain requires the monthly soil temperature data under the dwelling, Table 3. Input data considered in GDomain simulation. since it influences, significantly, the thermo-energy simulation. Thus, the Slab input Input Data Adopted Input Values tool was used to obtain the soil temperature under the LIH for the base and future Ground Domain Depth (m) 15 scenarios (Table 4). Soil Thermal Conductivity (W/m K) 0.52 [32] The occupancy and equipment power density data were adopted following RTQ-R [25], Soil Density (kg/m) 1700 [32] considering two people in each bedroom and four people in the living room. Regarding the Soil Specific Heat (J/kg K) 2 840 [32] 2 occupancy metabolic activity rate, 45 W/m was considered in bedrooms and 60 W/m Mesh Density Parameter 6 was set in the living room. The lighting power densities adopted were 5.0 W/m in the living room and 6.0 W/m in the bedrooms. The occupancy schedule estimates that the The GroundDomain requires the monthly soil temperature data under the dwelling, bedrooms are used from 9 p.m. to 8 a.m. during the weekdays and from 9 p.m. to 10 a.m. since it influences, significantly, the thermo-energy simulation. Thus, the Slab input tool on the weekend days, while the living room is used from 2 p.m. to 9 p.m. during the was used to obtain the soil temperature under the LIH for the base and future scenarios weekdays and from 11 a.m. to 9 p.m. on the weekend days. (Table 4). Table 4. Monthly soil temperature for the base scenario (1961–1990) and future estimates (2020/2050). Month 1961–1990 2020s 2050s January 27.94 28.73 29.87 February 27.76 28.32 29.71 March 27.73 28.63 30.11 April 26.78 27.65 29.59 May 26.10 27.05 29.04 Appl. Sci. 2021, 11, 420 9 of 22 Table 4. Monthly soil temperature for the base scenario (1961–1990) and future estimates (2020/2050). Month 1961–1990 2020s 2050s January 27.94 28.73 29.87 February 27.76 28.32 29.71 March 27.73 28.63 30.11 April 26.78 27.65 29.59 May 26.10 27.05 29.04 June 25.67 26.90 28.32 July 24.35 24.87 26.51 August 26.38 28.95 30.82 September 27.36 29.08 31.13 October 28.36 30.78 32.62 November 27.83 29.09 30.91 December 28.21 28.87 30.26 2.4. Generating Future Climate Scenarios Weather Data The “morphing” methodology, developed and described in [33], was adopted in this research, aiming to analyze the implications of climate change on the building’s thermal/ energy performance. The morphing method has been used to generate future Energy- Plus Weatherfiles (EPW) for any location in the world using the Climate Change World Weather File Generator for World-Wide Weather Data (CCWorldWeatherGen) tool (Southampton, United Kingdom) [33–35]. This methodology considers the climatic anomaly by modify- ing a set of historical climatic variables (1961–1990) of 8760 h per year, disregarding the influence of urbanization while incorporating the effects of global warming on the climate archives, making obtaining projections of future climate data possible. The CCWorldWeatherGen tool consists of an excel template that couples the EPW weather files to the “Hadley Centre Coupled Model version 3” (HadCM3) General Circula- tion Model (GCM). The HadCM3 is a coupled atmosphere–ocean general circulation model and has a resolution of 417 km 278 km in the Equator region and 295 km 278 km at 45 latitude, coupling the A2 Scenario of the IPCC 4th Assessment Report (AR4) for the 2020s time-slice (which covers the 2011–2040 period) and also the 2050s time-slice (2041–2070 period). The selected time-slices were based on a 50-year period, which is the building life expected for low-income houses [36]. 2.5. Indicators for Energy Consumption and Thermal Performance Evaluation 2.5.1. Estimation of the Cooling and Heating Energy Consumption Through the use of computer simulation, it is possible to obtain the thermal perfor- mance and the energy demand for heating and cooling when heating, ventilation, and air conditioning (HVAC) system is utilized in the indoors environment. In energy con- sumption analysis, two different conditions were utilized that express the habits of local habitants: (i) from 8 a.m to 9 p.m building operating naturally ventilated, considering 20 C as the indoor temperature control of the windows; and (ii) from 9 p.m. to 8 a.m with use of artificial conditioning system operating in the bedrooms, considering the split system with heating and cooling setpoint adjusted to 18 C and 24 C, respectively. In this case, the thermal load due to occupation, equipment, lighting, and energy performance of the air conditioning system followed the prescription of the Brazilian regulation for energy efficiency in buildings (RTQ-R) [25]. The energy consumption was assessed only for cooling, excluding heating demand, because the local population does not use heating systems due to the hot weather conditions in the region, while attending the RTQ-R methodology for the region under evaluation [25]. Appl. Sci. 2021, 11, 420 10 of 22 The air conditioning system was considered only in the bedrooms, which is a common behavior observed in the residences of this region [37]. The coefficient of performance (COP) for cooling was assumed to be 3.00 W/W (level “A” in the Brazilian Energy Labelling), and continuous fan operation mode (fan efficiency 0.7 and motor efficiency 0.9), following the simulation parameters for air conditioning system modeling used in the Brazilian Energy Label for residential buildings [25]. The estimated final cooling consumption of the (LIHe and LIHb) typologies were analyzed in terms of kWh/ (m /year) in both the base (1961–1990) and future climate change scenarios (2020 and 2050). Since the sum of energy spent by equipment and lighting remained almost constant between the present and future time-slices, not affecting building performance, it was not presented in final energy results. In this study, energy demand was only quantified for the bedroom zones where the bermed earth-sheltered walls were deployed, focusing on capturing the influence of the thermal mass as a passive strategy for cooling. 2.5.2. Indicator of the Envelope Performance by RTQ-R The cooling degree-hours (CDH) parameter was used as an indicator of building thermal performance under natural ventilation conditions, based on the RTQ-R recommen- dations [25]. The heating degree-hours parameter (HDH) was ignored due to their low occurrence in the study region. The base temperature used to calculate the CDH was set at 26 C, which was obtained by means of Equation (1): 8760 for T > 26 ; T 26 op op CDH = , (1) i = 0 for T  26 ; 0 ( ) op This indicator was estimated annually based on the hourly indoors operative tem- peratures (T ), with the two bedrooms and living room/kitchen considered as long op permanence rooms. Only one indicator was considered in the thermal performance eval- uation, obtained by the ponderation of the room areas. To classify the building’s energy efficiency, the indicator proposed for the Brazilian bioclimatic zone in the RTQ-R was used. In this evaluation, the naturally ventilated condition was considered for 24 h a day [23]. The efficiency level of the envelope varies from level A (CDH  12.566 Ch) to level E (CDH > 30.735 Ch), as presented in Table 5. Occupancy and internal thermal loads were considered in the simulation, which was carried out for the 8.760 h/ year [25]. Table 5. Building envelope efficiency for the researched bioclimatic zone according to the Brazilian Technical Quality Regulation for Energy Efficiency Level of Residential Buildings (RTQ-R). Level of Efficiency Cooling Degree-Hours Condition A CDH  12,566 Ch B 12,566 < CDH  18,622 Ch C 18,622 < CDH  24,679 Ch D 24,679 < CDH  30,735 Ch E CDH > 30,735 Ch 2.5.3. Adaptive Thermal Comfort Conditions in the Indoors Long Permanence Rooms The effectiveness of the bermed earth-sheltered walls measure adopted for improving indoor building thermal comfort was evaluated, since it is common for the low-income population not to have an air conditioning system installed at home due to the costs of its operation. In this way, it was considered the index based on the study of adaptive thermal comfort proposed by De Dear and Brager [38]. The methodology may be applied to represent the user ’s thermal comfort conditions inside of buildings naturally ventilated, considering only the user ’s occupancy and internal heat sources. The thermal comfort levels are defined by the ideal indoor operative temperature or the monthly neutral temperature Appl. Sci. 2021, 11, 420 11 of 22 (T , in C) related to the monthly averages of outdoor air temperature (T , in C), n Emed following Equation (2). This equation is only valid for T between 10.0 C and 33.5 C. Emed T = 17.8 + 0.31  T (2) Emed Thermal comfort ranges were determined by the definition of the month neutral temperature (T ) following procedures established in Standard 55 [39]. The monthly upper and lower limits for 90% of satisfied users were obtained by the use of Equation (3), where T represents the hourly indoor operative temperature. Indoor thermal comfort is reached op when the operative temperature is between the intervals prescribed in Equation (3). (T 2.5)  T  (T + 2.5), (3) n op n To quantify hot or cold discomfort hours and thermal comfort conditions of the long permanence rooms for the base scenario and future climate projections, the building was considered to operate in exclusive use of natural ventilation 24 h per day. Only one indoor operative temperature pondered by the area of the long permanence rooms was considered to assess the effectiveness of the measure to improve building performance. In turn, it was also considered the indoor operative temperature pondered by the area of bedrooms where the strategy was deployed. 3. Results and Discussion 3.1. Energy Consumption in Accordance with RTQ-R The energy consumption of both models was quantified by summing only the energy consumption of the bedrooms, which was not considered in living room/kitchen spaces since the strategy had a low impact on their performance. Since the region does not present a well-defined winter season, there are few hours of heating demand, with lower temperatures only occurring during cold weather fronts. With the climate change impact projections, it is reduced to almost nil values in 2020 and 2050 scenarios. Thus, heating loads were disregarded in this study, as the main consumption in typologies comes from cooling demand in the long permanence rooms. The energy consumption of both the reference typology (LIHe) and the thermal mass strategy with the bermed earth-sheltered walls (LIHb) can be seen in Figure 5. In the LIHe typology, the highest and lowest average energy demand in the bedrooms 2 2 occurs when walls are oriented to the north (66 kWh/m ) and to the west (63 kWh/m ), respectively. Similar results to the latter are obtained when they are oriented east and north (~64 kWh/m ). Thus, when the thermal mass strategy is not set in the building, the bedroom’s wall orientations have a low impact on energy demand (reduction of 2% from north to west). This behavior may be attributed to the building envelope, which has been improved by increasing its thermal insulation in order to obtain level A of energy efficiency [40]. In fact, the energy consumption for cooling demand observed in this study is slightly lower to that quantified for LIHs with combined passive measures located in the Salvador and Belém city (both Am Köppen–Geiger climate type), in the northern region 2 2 of Brazil, which displayed annual energy consumption of 75 kWh/m and 85 kWh/m , respectively [9,12]. Thus, the combined adaptation measures implemented in the standard LIH are more effective in improving the building energy performance in the base scenario than in the previous studies. The incorporation of the thermal mass strategy in the LIH provides a reduction in the bedroom’s energy demand for cooling for all the orientations considered (Figure 5). In the LHIb, differently from the LIHe demand pattern, the highest year energy demand of the bedrooms can be seen when the strategy is oriented to the south (42.7 kWh/m ), while the lowest is obtained when the strategy is oriented west (39.6 kWh/m ), provid- ing a reduction of 7.8% in the annual energy demand. Thus, the design consideration for thermal mass strategy orientation aiming to improve energy performance follows a different recommendation, regarding that observed for buildings without its use. In this Appl. Sci. 2021, 11, 420 12 of 22 Appl. Sci. 2021, 11, x FOR PEER REVIEW 12 of 23 sense, the adoption of the strategy in bedrooms with the bermed earth-sheltered in the orientations tested present a 34% to 38% reduction in energy demand for cooling, with a established for the region of 34.48 kWh/m to achieve level A efficiency. Thus, from a greater reduction in the west, almost reaching the relative cooling consumption indicator technical perspective, even for building envelopes already displaying an adequate ther- established for the region of 34.48 kWh/m to achieve level A efficiency. Thus, from a mal performance, the bermed earth-sheltered wall is recommended for the tropical cli- technical perspective, even for building envelopes already displaying an adequate thermal mate region as an alternative passive measure to improve building cooling energy per- performance, the bermed earth-sheltered wall is recommended for the tropical climate formance. region as an alternative passive measure to improve building cooling energy performance. Figure 5. Annual energy consumption of the bedrooms. Figure 5. Annual energy consumption of the bedrooms. The strategy impacts are similar to those observed in previous building simulation The strategy impacts are similar to those observed in previous building simulation studies. Thermal performance analysis of earth-sheltered residential buildings was con- studies. Thermal performance analysis of earth-sheltered residential buildings was con- ducted for the city of Yazd, in Iran (hot and dry region) [41]. Building Case 900 ASHRAE ducted for the city of Yazd, in Iran (hot and dry region) [41]. Building Case 900 ASHRAE was employed in a prospective study, with progressively changing depth of the soil sur- was employed in a prospective study, with progressively changing depth of the soil rounding the housing prototype [42]. In this case, the highest energy consumption was surrounding the housing prototype [42]. In this case, the highest energy consumption found when the main façade (not in contact with the earth) was oriented to the north, i.e., was found when the main façade (not in contact with the earth) was oriented to the north, when the bermed earth-sheltered wall was displayed in the south, confirming the best i.e., when the bermed earth-sheltered wall was displayed in the south, confirming the disposition obtained in this research. However, southern orientation had the lowest energy best disposition obtained in this research. However, southern orientation had the lowest consumption, while west obtained the best performance in this research, due to the fact energy consumption, while west obtained the best performance in this research, due to that current LIHb has only one wall sheltered by earth, and different opening locations the fact that current LIHb has only one wall sheltered by earth, and different opening for ventilation in the facades. The total energy consumption of a residential 1.0 m deep locations for ventilation in the facades. The total energy consumption of a residential 1.0 earth-sheltered (which corresponds to an entire wall sheltered by the earth, as in this study) m deep earth-sheltered (which corresponds to an entire wall sheltered by the earth, as in was reduced by about 67% (south orientation), bringing annual energy consumption to this study) was reduced by about 67% (south orientation), bringing annual energy con- 80 kWh/m . Despite the reduction being more expressive than in this work, final energy sumption to 80 kWh/m . Despite the reduction being more expressive than in this work, consumption for cooling was close to that found here. In another study in the Mediter- final energy consumption for cooling was close to that found here. In another study in the ranean climate (temperate), the annual air conditioning energy demand of a prototype Mediterranean climate (temperate), the annual air conditioning energy demand of a building with southern elevation located in Poznan (Poland) was evaluated. The building prototype building with southern elevation located in Poznan (Poland) was evaluated. wall was installed above and completely under the ground, with 0.1 m of thermal insulation The building wall was installed above and completely under the ground, with 0.1 m of thickness on the walls. This configuration provided reductions varying from 12% to 30%, thermal insulation thickness on the walls. This configuration provided reductions vary- depending on the type of soil on which the building was founded, which demonstrates ing from 12% to 30%, depending on the type of soil on which the building was founded, the soil type influence on the building performance of bermed houses [43]. The highest which demonstrates the soil type influence on the building performance of bermed reduction was obtained for the soil with similar physical and thermal characteristics to houses [43]. The highest reduction was obtained for the soil with similar physical and those considered in the current study. thermal characteristics to those considered in the current study. Despite of the implementation of combined adaptation measures and bermed earth- Despite of the implementation of combined adaptation measures and bermed sheltered strategy in the standard typology envelope, it is observed that the global warming earth-sheltered strategy in the standard typology envelope, it is observed that the global projections influence the annual cooling energy demand within the spaces under study. In warming projections influence the annual cooling energy demand within the spaces under study. In the 2020 future scenario, the impacts are high in the LIHe typology, varying from Appl. Sci. 2021, 11, 420 13 of 22 the 2020 future scenario, the impacts are high in the LIHe typology, varying from 28% to 32%, when compared to the base scenario, depending on the orientation. The same trend is observed for the LIHb typology, but with higher percentages, between 36% and 39%. In the 2050 scenario, the increase in energy demand exceeds 50% for all orientations when compared to the base scenario: from 64% to 70% in LIHe, and from 71% to 75% in LIHb. The projected increase in terms of percentage corroborates with previous studies conducted in cities located in other countries with the same climate type (Aw). In Darwin, Australia, the projected increase in air temperature for some emissions scenarios varied between 1.8 C to 2.5 C in the 2050 scenario, inducing an increment in energy consumption for cooling which varied between 40% and 80%, depending on the type of thermal insula- tion considered for the building envelope [7]. In Miami, The Unites States, the projected increase in air temperature in the 2050 scenario (2.52 C) is similar to those predicted for Australia and lower than in the current research (3.2 C). Despite having similar projections for air temperature to Australia, the possible induced increase in energy consumption for cooling is lower (between 27% and 37% in 2050 emissions scenarios), including in relation to this research [44]. In Brazil, similar projections have been observed for low-income houses deployed in regions with hot weather conditions. At Salvador (Af), the cooling energy demand is expected to increase by 30% and 46.6% in 2020 and 2050 scenarios, while at Belém (Af), 43.5% and 70.5% and, at Cuiabá (Aw), 20% and 30%, respectively [9,12,13]. The projection variations are attributed to the different types of passive strategies used in building envelopes. However, they are lower than those observed for the standard LIH studied in the same region, where the energy demand reaches more than double in the 2050 scenario due to its lack of adequate thermal insulation [45]. Despite the thermal load reduction, the LIHb serves as an effective passive strategy to counteract the effects of climate change, since its performance always remains superior to that of LIHe typology. For the 2020 scenario, the reduction provided by the strategy, when compared to the annual cooling energy demand of the building without its implementation, is significant, varying from 32% to 35% depending on the orientation. The same occurs for the 2050 scenario, with a variation between 33% and 36%. The highest reduction in thermal load was observed when the thermal mass strategy was positioned facing west, with a 36% average reduction. Notice that a partially-bermed earth-sheltered wall has the potential increased building resilience to face the global warming impacts, since cooling energy consumption in the 2020s is on average 12.3% lower than the base scenario, while in 2050, it is surpassed only by 10.7%. For the last time-slice, resilience is almost achieved, providing a considerable reduction in energy consumption (on average 37 kWh/m /year, based on energy consumption for LIHe in the 2050s) and promoting sustainability in tropical climate regions. Previously isolated measures tested in similar low-income houses located in the southeastern and northeast regions of Brazil were also effective in reducing the building energy consumption of HVAC [12]. The three best performing solutions were found when the wall absorptance in buildings was reduced to 0.3 (base scenario reduction: 21.86%|2050 Scenario reduction: 20.98%) when the brick wall was substituted by insulated concrete (40.82%|21.74%), and when the clay roof was replaced by a metal roof with 0.07 m of insulation and solar absorptance 0.3 (34.07%|23.64%). Note that the thermal mass strategy provided by the bermed earth-sheltered walls, when compared to the previous strategies, is more effective at counterbalancing the climate change effects, in turn, reducing the energy consumption of the building. Thus, as an isolated passive adaptation measure, as well as the other strategies tested in the previous study, it is not capable of completely counterbalancing the impact of climate change on cooling energy consumption. However, when combined with other adaptation measures, as proposed in this research, it may be an alternative to improve the building envelope and counterattack the effect of global warming, as observed in this study and previous ones [9,12,13]. For cities under hot weather conditions, the idealization of climate-responsive design on residential buildings Appl. Sci. 2021, 11, x FOR PEER REVIEW 14 of 23 Appl. Sci. 2021, 11, 420 14 of 22 residential buildings in the design phase is an alternative to reducing energy consump- tion demand due to the increase of air conditioning systems used for cooling. in the design phase is an alternative to reducing energy consumption demand due to the increase of air conditioning systems used for cooling. 3.2. Envelope Performance According to RTQ-R The CDH performance behavior differs from that observed in energy demand. 3.2. Envelope Performance According to RTQ-R When operating with an HVAC conditioning system, the thermal exchanges caused by The CDH performance behavior differs from that observed in energy demand. When the winds, that may affect the indoor’ spaces, are minimized since the windows remain operating with an HVAC conditioning system, the thermal exchanges caused by the winds, closed and the winds basically remove heat from external facades, entering indoors that may affect the indoor ’ spaces, are minimized since the windows remain closed and the spaces by fenestrations that exist on the window’s panel (Figure 6). For the LIHe typol- winds basically remove heat from external facades, entering indoors spaces by fenestrations ogy, the worst average performance is observed when walls are oriented to the north that exist on the window’s panel (Figure 6). For the LIHe typology, the worst average (10,269 °Ch). In contrast, the best average performance is obtained when the walls are performance is observed when walls are oriented to the north (10,269 Ch). In contrast, the oriented west (9,339 °Ch). In this case, a 9% reduction in the CDH is achieved, being the best average performance is obtained when the walls are oriented west (9339 Ch). In this best orientation for the building without the bermed earth-sheltered wall. Similar to the case, a 9% reduction in the CDH is achieved, being the best orientation for the building cooling energy demand, the incorporation of the thermal mass strategy with bermed without the bermed earth-sheltered wall. Similar to the cooling energy demand, the earth-sheltered walls provides a CDH reduction in bedrooms for all orientations (Figure incorporation of the thermal mass strategy with bermed earth-sheltered walls provides a 6). For LIHb, the worst performance is seen when the bermed earth-sheltered walls are CDH reduction in bedrooms for all orientations (Figure 6). For LIHb, the worst performance oriented to the north (7585 °Ch), and the best performance when the walls are oriented to is seen when the bermed earth-sheltered walls are oriented to the north (7585 Ch), and t the he west best performance (5810 °Ch, 23when .4% reduct the walls ion).ar e oriented to the west (5810 Ch, 23.4% reduction). Figure 6. Weighted annual average cooling-degree hours (CDH) indicator in baseline and future Figure 6. Weighted annual average cooling-degree hours (CDH) indicator in baseline and fu- ture scenarios ( scenarios (colors colors in we in west orientation st orientation for for LIHb LIHb in in the 20 the 2050s 50s was changed to was changed to match match with the with the colors colors established in the RTQ-R). established in the RTQ-R). Regarding the performance of the CDH, the same design recommendation for the Regarding the performance of the CDH, the same design recommendation for the orientation of the thermal mass strategy for buildings without the tested strategy should orientation of the thermal mass strategy for buildings without the tested strategy should be followed for the building with the bermed earth-sheltered wall. CDH reduction is be followed for the building with the bermed earth-sheltered wall. CDH reduction is expressive, varying from 26% to 38%, as much as those observed in the previous cool- expressive, varying from 26% to 38%, as much as those observed in the previous cooling ing demand analysis. For the LIH implanted in Salvador city, the combined adaptation demand analysis. For the LIH implanted in Salvador city, the combined adaptation measures in the current climate resulted in decreasing in cooling degree-hours ranging measures in the current climate resulted in decreasing in cooling degree-hours ranging between 33% to 68%, compared to the standard LIH, reaching CDH varying between between 33% to 68%, compared to the standard LIH, reaching CDH varying between higher than 5000 Ch and lower than 12,000 Ch [12]. Notice that LIHe typology presented higher than 5,000 °Ch and lower than 12,000 °Ch [12]. Notice that LIHe typology pre- level “A” energy efficiency rating (CDH  12,566 Ch) in all orientations evaluated in the sented level “A” energy efficiency rating (CDH ≤ 12,566 °Ch) in all orientations evaluated base scenario, as well as LIHb which had its envelope improved with the implementation in the base scenario, as well as LIHb which had its envelope improved with the imple- of the partially-bermed earth-sheltered walls. mentation of the partially-bermed earth-sheltered walls. The raising of the air temperature, due to climatic conditions that may prevail in future periods due to climate change, will progressively impact the possibility of transferring heat Appl. Sci. 2021, 11, 420 15 of 22 from the indoors to the outdoors environments, reducing the potential use of naturally ventilated strategy in the residential buildings. In the 2020 scenario, an increase in the CDH inside LIHe rooms (18% to 30%) was observed, with the best performance strategy orientation (west) in the base scenario being the most impacted due to global warming effects. In the LIHb, the scenario was even more drastic, with CDH doubling (reduction from 61% to 111%). In the 2050 scenario, the CDH exceeded double in some orientations, when compared to the base scenario, for both LIHe (148% to 173%) and LIHb (227% to 327%) (Figure 6). The impact in the CDH may be assigned to the predicted increasing of the outdoor air environment (projected rising of 1.5 C and 3.3 C for 2020 and 2050, respectively) and reduction in the humidity, but also due to the elevation of global hori- zontal radiation. In turn, the rising in ground temperature (see Table 4) also corroborates degeneration of the building’s thermal performance [9,13]. Despite the observed impacts, LIHb typology is proposed as a climate-responsive design strategy to counterbalance the effects caused by climate change in a situation where natural ventilation occurs 24 h per day, However, its impact is lower than that observed in cooling energy demand, in which the HVAC system is switched on at night when the indoor temperature is above the thermostat temperature, defined as a baseline thermal comfort temperature in the RTQ-R [23]. In the 2020 scenario, the reduction provided by the implementation of the strategy varies from 11% to 16%, depending on the orientation, when compared to the thermal performance of the building without the strategy. The same occurs in the 2050 scenario, with a variation between 9% and 12%. The highest reduction in the thermal performance was shown when the thermal mass strategy was oriented to the west, with a 13.9% average reduction, even so, less expressive than that shown for energy consumption. These projections corroborate the previous study conducted with the same low-income house, but with different types of passive strategies used in building envelopes and without the bermed earth-sheltered wall. Projections in the CDH indicator are expected to increase 31.3% and 28.6% in 2020 and 2050 scenarios [13]. However, in the standard LIH without any adaptation measures and with the use of bermed earth walls, the reduction in CDH is similar to that observed in this research [45]. The bermed earth-sheltered wall strategy, when compared with other isolated mea- sures, displays a lower reduction in terms of percentage [12]: the wall with solar absorp- tance 0.3 (base scenario reduction: 34.28%|2050 Scenario reduction: 25.97%), concrete wall with insulation (55.55%|37.14%), and clay roof replaced by a metal roof with 0.07 m of insulation and solar absorptance 0.3 (57.87%|39.88%). Thus, in terms of CDH, the bermed earth-sheltered strategy in this study is less expressive when compared to the isolated measures tested in the previous study. One may note CDH is weighted by the areas of the long permanence rooms, including the living room/kitchen, which has the same area as the sum of the bedrooms area and is not in contact with the bermed earth-sheltered walls. Thus, this room reduced the potential strategy impact (by at least half) due to its lower performance than the ones in contact with the ground. Yet, this behavior may be attributed to the fact that before simulations, LIH was redesigned to improve original buildings’ thermal and energy performance, which makes it difficult to improve its envelope due to its already high thermal insulation. Due to the future trend of air temperature raising, foreseen in the future climate change scenarios, the building efficiency level, which is “A” for LIHe and LIHb in the base scenario, decreases when the future potential impacts of climate change are incorporated into the weather data. In the 2020 scenario, the building energy efficiency is reduced to level “C”, with an exception in LIHb for west orientation, where level “B” is reached. In the 2050 scenario, all orientation became level “E”, again with an exception in LIHb for west orientation, with level “D”. Thus, this orientation must be preferred to achieve the best energy and thermal performance. Similar decreasing in building energy efficiency is also reported for five-star buildings analyzed in Darwin, Australia, and in Guangdong Province, South China, due to the raising of the energy requirement in the 2050 scenario [7,10]. This Appl. Sci. 2021, 11, 420 16 of 22 fact indicates the need to establish specific design guidelines in the building environmental certification codes to deal with this potential issue. 3.3. Indoor Operative Temperatures and Thermal Comfort Conditions The raising in energy consumption and the reduction in the thermal performance previously discussed is related to the tendency of the outdoor air temperature observed in the future scenarios generated by the tool CCWorldWeatherGen (Figure 7). In the base scenario, the annual average air temperature is 26.7 C and in the futures, a gradual increase is caused due to global warming projections, reaching 28.5 C and 29.9 C in the 2020s and the 2050s, respectively. In this sense, an increase of 3.2 C is predicted until the 2050s, as mentioned previously. The highest increase is observed in the dry season in September (1.9 C and 4 C in the 2020s and 2050s, respectively) and the lowest in the wet season in January (1.2 C and 2.3 C in the 2020s and 2050s, respectively). The potential global warming is more pronounced in the research region than those observed in other Brazilian cities characterized by different climates [9,12]. This is an important issue, as dwellings in the region usually operate predominantly with natural ventilation, compromising the possibility to maintain adequate indoors thermal comfort in the warming predicted context, as is described below. The indoors operative temperatures in the house’s rooms accompany the observed rise in the outdoor air temperature, progressively moving upwards in each time-slice. In the LIHe, the integrated living room/kitchen operative temperatures related to the building orientations are higher than in the bedrooms, but the differences are small, causing the curves to overlap each other (Figure 7a). This is not happening in the LIHb, where the introduction of bermed earth-sheltering walls caused thermal damping inside the bedrooms (Figure 7b). The observed modulation is an effective measure to reduce temperature fluctuations during the day; however, it can also lead to a slower reduction of the operative temperature during the night, which makes important the use of natural ventilation through the window openings during this period [8]. It is possible to notice that thermal damp is progressively reduced, due to the outdoors air temperature warming and also the raising on the ground temperature, compromising the tested measure effectiveness. Thus, for this reason, thermal comfort conditions inside the building are accessed in the sequence. The adaptation measure implemented in the LIHb is effective in improving the build- ing thermal performance in the base scenario, increasing the comfort, and reducing hot discomfort hours inside the building (Figure 8). The west orientation is the most effective in providing the highest thermal comfort hours (82%), 12% higher than the LIHe for the same orientation. Therefore, a properly designed bioclimatic passive measure may become an alternative to improve the building’s habitability for the researched location, also, in the current weather conditions. In future scenarios, thermal comfort levels have progressively deteriorated inside the houses, and the raise in the hot discomfort hours is observed in both typologies with the projections established by the IPCC. The small number of cold discomfort hours almost vanishes, due to the forecast outdoor air temperature elevation. Despite that, in the 2020 scenario, the typologies are still capable of providing more hours of thermal comfort than discomfort. Note that LIHb, on average, provides better thermal habitability for the users (59%), when compared to LIHe (51%), which is near the borderline to have a warm environment inside its rooms. The LIHe oriented to the north has higher hot discomfort hours than comfort (49%). In this sense, the impact of climate change is more pronounced in LIHe than in LIHb. Therefore, bermed earth-sheltering walls are a climate- responsive alternative design to help to improve the building’s habitability. In turn, in the 2050 scenario, thermal comfort hours are below 50% in both typologies and orientations, with a hot environment predominating within the buildings. In the LIHb, this behavior is attributed to the fact that thermal comfort has been assessed considering all the long permanence rooms, including the living room/kitchen that does not have the researched strategy deployed. This room has a hotter environment than the bedrooms, as described Appl. Sci. 2021, 11, 420 17 of 22 above. This way, it requires a more detailed analysis of the bedrooms without a living room/kitchen thermal influence. (a) LIHe (b) LIHb Base Scenario Figure 7. Annual diary course of outdoor air temperature and indoor long permanence rooms operative temperatures for the base and future scenarios in (a) LIHe and (b) LIHb. Appl. Sci. 2021, 11, x FOR PEER REVIEW 18 of 23 The adaptation measure implemented in the LIHb is effective in improving the building thermal performance in the base scenario, increasing the comfort, and reducing hot discomfort hours inside the building (Figure 8). The west orientation is the most ef- fective in providing the highest thermal comfort hours (82%), 12% higher than the LIHe for the same orientation. Therefore, a properly designed bioclimatic passive measure may become an alternative to improve the building’s habitability for the researched lo- Appl. Sci. 2021, 11, 420 18 of 22 cation, also, in the current weather conditions. Figure 8. Weighted percentage of comfort and discomfort hours inside the LIHe and LIHb in the Figure 8. Weighted percentage of comfort and discomfort hours inside the LIHe and LIHb in base and future scenarios. the base and future scenarios. Figure 9 depicts thermal comfort conditions inside the bedrooms where the strategy In future scenarios, thermal comfort levels have progressively deteriorated inside was implemented. Notice that behavior is similar to that displayed in Figure 8; however, the houses, and the raise in the hot discomfort hours is observed in both typologies with thermal comfort conditions preponderates in most orientations and time-slices. All building the projections established by the IPCC. The small number of cold discomfort hours al- orientations present the highest percentage of comfort hours than discomfort in the base Appl. Sci. 2021, 11, x FOR PEER REVIEW 19 of 23 most vanishes, due to the forecast outdoor air temperature elevation. Despite that, in the and 2020 scenario. However, the west orientation is the only one that provides more hours 2020 scenario, the typologies are still capable of providing more hours of thermal comfort of thermal comfort conditions (51%) in the 2050s. than discomfort. Note that LIHb, on average, provides better thermal habitability for the users (59%), when compared to LIHe (51%), which is near the borderline to have a warm environment inside its rooms. The LIHe oriented to the north has higher hot discomfort hours than comfort (49%). In this sense, the impact of climate change is more pronounced in LIHe than in LIHb. Therefore, bermed earth-sheltering walls are a climate-responsive alternative design to help to improve the building’s habitability. In turn, in the 2050 sce- nario, thermal comfort hours are below 50% in both typologies and orientations, with a hot environment predominating within the buildings. In the LIHb, this behavior is at- tributed to the fact that thermal comfort has been assessed considering all the long per- manence rooms, including the living room/kitchen that does not have the researched strategy deployed. This room has a hotter environment than the bedrooms, as described above. This way, it requires a more detailed analysis of the bedrooms without a living room/kitchen thermal influence. Figure 9 depicts thermal comfort conditions inside the bedrooms where the strategy Figure 9. Weighted percentage of comfort and discomfort hours for the bedrooms inside the LIHb Figure 9. Weighted percentage of comfort and discomfort hours for the bedrooms inside the LIHb in was in the base and future scenarios. implemented. Notice that behavior is similar to that displayed in Figure 8; however, the base and future scenarios. thermal comfort conditions preponderates in most orientations and time-slices. All build 4. Con 4. Conclusions ing or clusie io nt ns ations present the highest percentage of comfort hours than discomfort in the base and 2020 scenario. However, the west orientation is the only one that provides The ener The energy gy consu consumption mption and and ther thermal mal analysis analysindicated is indicated thattha thet use the use of of bermed beearth- rmed more hours of thermal comfort conditions (51%) in the 2050s. sheltered walls as a thermal mass for the bedrooms is a successful measure to improve earth-sheltered walls as a thermal mass for the bedrooms is a successful measure to improve buil building ding pe performance rformance an and d hhabitability abitability, ac , acting ting as asa pot a potential ential cli climate-r mate-responsi esponsive ve stra strategy tegy to to adapt buildings to face and counterbalance global warming effects that might prevail adapt buildings to face and counterbalance global warming effects that might prevail in in tropical climate regions. Higher impacts are observed in cooling energy demand than tropical climate regions. Higher impacts are observed in cooling energy demand than in the in the thermal performance, once the spaces in the former are not exposed to the thermal thermal performance, once the spaces in the former are not exposed to the thermal exchanges exchanges resulting from natural ventilation, since the windows remain closed when resulting from natural ventilation, since the windows remain closed when the HVAC system the HVAC system is operating. Due to the expected increase in air temperature in the is operating. Due to the expected increase in air temperature in the region (1.5 °C and 3.3 °C region (1.5 C and 3.3 C for 2020 and 2050, respectively), the potential use of naturally for 2020 and 2050, respectively), the potential use of naturally ventilated strategy in the resi- ventilated strategy in the residential buildings is affected, restricting the possibility to dential buildings is affected, restricting the possibility to transfer heat from the indoors to the transfer heat from the indoors to the outdoors environments, compromising building outdoors environments, compromising building thermal performance. thermal performance. The reduction in cooling energy consumption varied from 34% to 38% between the base and future scenarios, being more relevant when the bermed earth-sheltered walls are oriented to the west, that is, the main façade of the building is oriented to the east. Similar reductions for cooling degree-hours, evaluated when the building is in a natu- rally ventilated mode, are observed, ranging from 26% to 38%, with better performance also following the previous results, i.e., the main façade of the building oriented to the east. The effects of climate change impact on both operating modes idealized for the building long permanence rooms, i.e., when the building environments are operating naturally ventilated and with the use of HVAC. In the 2020 scenario, the increase in cooling energy consumption is over 28% for LIH, with and without the implementation of the bioclimatic strategy of bermed earth-sheltered walls, while in the 2050 scenario, it exceeds 64%. In the thermal performance, the projected increase in cooling degree-hours is more drastic, reaching 111% and 327% in the 2020 and 2050 scenarios, respectively. In these future scenarios, the reduction provided by the implemented measure depends on its orientation and varied between 32% to 36%, compared to the energy consumption of the building without this passive strategy. Again, the highest reduction in cooling energy consumption was shown when the thermal mass strategy was oriented to the west, with a 36% reduction, on average. Thus, because of future potential impacts of climate change, building efficiency level, which is “A” in the base scenario, decreases to level “E” in the 2050 scenario, an exception in LIHb for west orientation, in which level remains “D”. However, it should be pointed out that, for a fair judgment, the energy efficiency benchmarks should also be corrected for the climate change effects. Based on these po- tential impacts, specific design guidelines should be established by the international sustainable building organizations to enable designers, builders, and stakeholders to an- Appl. Sci. 2021, 11, 420 19 of 22 The reduction in cooling energy consumption varied from 34% to 38% between the base and future scenarios, being more relevant when the bermed earth-sheltered walls are oriented to the west, that is, the main façade of the building is oriented to the east. Similar reductions for cooling degree-hours, evaluated when the building is in a naturally ventilated mode, are observed, ranging from 26% to 38%, with better performance also following the previous results, i.e., the main façade of the building oriented to the east. The effects of climate change impact on both operating modes idealized for the building long permanence rooms, i.e., when the building environments are operating naturally ventilated and with the use of HVAC. In the 2020 scenario, the increase in cooling energy consumption is over 28% for LIH, with and without the implementation of the bioclimatic strategy of bermed earth-sheltered walls, while in the 2050 scenario, it exceeds 64%. In the thermal performance, the projected increase in cooling degree-hours is more drastic, reaching 111% and 327% in the 2020 and 2050 scenarios, respectively. In these future scenarios, the reduction provided by the implemented measure depends on its orientation and varied between 32% to 36%, compared to the energy consumption of the building without this passive strategy. Again, the highest reduction in cooling energy consumption was shown when the thermal mass strategy was oriented to the west, with a 36% reduction, on average. Thus, because of future potential impacts of climate change, building efficiency level, which is “A” in the base scenario, decreases to level “E” in the 2050 scenario, an exception in LIHb for west orientation, in which level remains “D”. However, it should be pointed out that, for a fair judgment, the energy efficiency benchmarks should also be corrected for the climate change effects. Based on these potential impacts, specific design guidelines should be established by the international sustainable building organizations to enable designers, builders, and stakeholders to anticipate the behavior of the built environment under the potential future global warming scenarios. The increase in cooling energy consumption, as well as in the cooling degree-hours, can be easily seen when the effects of climate change are incorporated into the weather data and thermos-energetic simulation is performed. However, the building with bermed earth-sheltered walls (LIHb) always presents better performance than the building without it (LIHe) in all orientations, demonstrating the positive impact of this measure. It can be considered as a climate-responsive design strategy because of the improvement in the housing resilience when facing the global warming impacts, since the cooling energy consumption in the 2020s on LIHb is on average 12.3% lower than in the base scenario, compared to LIHe, almost being able to provide full demand in the 2050s (consumption of LIHb surpassed the LIHe in base scenario only by 10.7%). The same behavior is not observed for CDH, due to the way this indicator is calculated, weighing the areas of the long permanence building rooms, including living room/kitchen, which is not in contact with the bermed earth-sheltered walls. This room, considered in the CDH calculation, presents lower thermal performance than the bedrooms, which influenced the final performance, reducing the positive impact of the implementation of the earth-sheltered wall. LIHb provides better thermal habitability for the users, when compared to LIHe, in all time-slices researched. Despite the progressive deterioration of thermal comfort conditions within the building rooms, the bermed earth-sheltered walls are an alternative to partially neutralize the global warming effects. When its impact, together with environments that do not have the measure deployed (which reduce the positive impact as described above), is analyzed, more hours of thermal comfort conditions may be achieved only until the 2020 scenario. However, considering only the rooms where the strategy is deployed, this condition may be guaranteed until the 2050 scenario by the building’s west orientation. Thus, given the impacts presented, it is possible to verify that bermed earth-sheltered walls correspond to an alternative strategy for the adaptation effects of climate change and should be thought of as an adaptive measure to promote building sustainability, in terms of cooling energy consumption. Therefore, the use of the thermal mass, combined with other passive adaptation strategies, may help to counterattack the climatic conditions that may prevail in future periods due to global warming on tropical climates. A cost–benefit analysis Appl. Sci. 2021, 11, 420 20 of 22 between the studied climate change adaptation measure investment and the energy-saving should be assessed in future work, aiming to evaluate the payback period. The thermal and energy analysis conducted in this study deals with uncertainties regarding the internal climate variability related to the climate model and premises adopted for future scenario definitions. The latter are based on economic growth, social trends, adaptation/ mitigation policies, technological development, and demographic factors. Therefore, the evaluation conducted in this study for the future scenarios should be treated as a possible trend, rather than as absolute values. However, the potential uncertainties in the future climate data do not invalidate the predictions made by the CCWorldWeatherGen tool, which can confidently be used to anticipate the behavior of the built environment in the potential future global warming scenarios. Author Contributions: Conception and execution of the building simulation—I.J.A.C., R.M.A. and E.L.A.d.G.; methodology—I.J.A.C., R.M.A. and E.L.A.d.G.; formal analysis—I.J.A.C. and L.C.D.; writing—I.J.A.C. and R.M.A.; reviewing and editing—L.C.D. and R.M.A.; visualization—F.R., K.d.A.C.R. and L.M.d.A. All authors have read and agreed to the published version of the manuscript. Funding: This research was funded by the Federal University of Mato Grosso (UFMT) (Edict number 01/2020, Process N. 23108.066371/2020-11) and by the Mato Grosso State Research Support Foundation (FAPEMAT) by a master contract granted (Edict number 017/2015). Institutional Review Board Statement: This study did not require ethical approval. Informed Consent Statement: Informed consent was obtained from all subjects involved in the study. Data Availability Statement: Data sharing is not applicable to this article. Acknowledgments: The authors would like to thank the Federal University of Mato Grosso/ Brazil and the Mato Grosso State Research Support Foundation (FAPEMAT) to support this research. Conflicts of Interest: The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results. 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