Impact of Incorporating NIR Reflective Pigments in Finishing Coatings of ETICS
Impact of Incorporating NIR Reflective Pigments in Finishing Coatings of ETICS
Ramos, Nuno M. M.;Maia, Joana;Souza, Andrea R.;Almeida, Ricardo M. S. F.;Silva, Luís
2021-05-25 00:00:00
infrastructures Article Impact of Incorporating NIR Reflective Pigments in Finishing Coatings of ETICS 1 , 1 1 2 3 Nuno M. M. Ramos * , Joana Maia , Andrea R. Souza , Ricardo M. S. F. Almeida and Luís Silva CONSTRUCT—LFC, Faculty of Engineering, University of Porto, 4200-465 Porto, Portugal; joanamaia@fe.up.pt (J.M.); andrea.souza@fe.up.pt (A.R.S.) Department of Civil Engineering, Polytechnic Institute of Viseu, 3504-510 Viseu, Portugal; ralmeida@estgv.ipv.pt Saint-Gobain Weber, Zona Industrial da Taboeira-Esgueira, 3800-055 Aveiro, Portugal; luis.silva@saint-gobain.com * Correspondence: nmmr@fe.up.pt Abstract: Near-infrared (NIR) reflective materials are being developed for mitigating building cooling needs. Their use contributes to broadening the range of colours, responding to the urban aesthetic demand without compromising the building performance. Despite the increase in NIR reflective pigments investigation, there is still a knowledge gap in their applicability, impact, and durability in multilayer finishing coatings of External Thermal Insulation Composite Systems (ETICS). Hence, the main goal of this work consists of evaluating the impact of incorporating NIR reflective pigments (NRP) in the solar reflectance of the surface layer of ETICS, without affecting the colour perception, as well as their influence on the colour durability and surface temperature. As such, colour, solar reflectance, and surface temperature were monitored for 2 years in dark-coloured specimens of ETICS, with and without NRP and a primer layer. It was confirmed that the main contribution of NRP is Citation: Ramos, N.M.M.; Maia, J.; the increase of solar reflectance and, consequently, the decrease in surface temperature, especially Souza, A.R.; Almeida, R.M.S.F.; Silva, for high exterior temperatures (around 30 C). Moreover, these pigments highly increase the NIR L. Impact of Incorporating NIR reflectance without affecting the visible colour. In addition, they contribute to maintaining the colour Reflective Pigments in Finishing characteristics. The application of primer increased the surface temperature, especially for higher Coatings of ETICS. Infrastructures 2021, 6, 79. https://doi.org/ exterior temperatures. However, it contributes to a lower colour difference and solar reflectance 10.3390/infrastructures6060079 variation, which is an important achievement for durability purposes. Academic Editor: Maria do Keywords: solar reflectance; surface temperature; colour; ETICS; NIR reflective pigments Rosário Veiga Received: 30 April 2021 Accepted: 23 May 2021 1. Introduction Published: 25 May 2021 The use of thermal insulation materials is an effective way of reducing heat losses in buildings by decreasing the thermal transmittance through the envelope [1]. In addition, Publisher’s Note: MDPI stays neutral new eco-efficient materials and technologies are being developed to mitigate buildings’ with regard to jurisdictional claims in cooling demand [2–4]. published maps and institutional affil- The ETICS (External Thermal Insulation Composite System) is one of the most widely iations. used thermal façade systems, and its performance has been studied by different au- thors [5–7]. This technology is quite popular in the building industry, presenting posi- tive aspects such as the reduction of thermal bridges and the ability to be easily applied in façade refurbishment. However, pathologies related to finishing coatings, especially Copyright: © 2021 by the authors. microcracking and algae growth, can occur and were observed in various studies [8–10]. Licensee MDPI, Basel, Switzerland. The degradation agents, which affect the ETICS coating, include solar radiation, tempera- This article is an open access article ture and relative humidity fluctuations, and the action of rain. These agents can produce distributed under the terms and colour changes, staining, and cracking [11,12]. To prevent part of these pathologies, the conditions of the Creative Commons old guideline ETAG 004 [13] defines 80 C as the maximum temperature recommended for Attribution (CC BY) license (https:// the ETICS surface. However, the new European Assessment Document EAD 040083-00- creativecommons.org/licenses/by/ 0404 [14], which replaces the ETAG 004, did not refer to this recommendation. In addition, 4.0/). Infrastructures 2021, 6, 79. https://doi.org/10.3390/infrastructures6060079 https://www.mdpi.com/journal/infrastructures Infrastructures 2021, 6, 79 2 of 15 the European Guideline for the application of ETICS [15] recommends a minimum solar reflectance between 0.2 and 0.3 (depending on the climatic conditions). These restrictions have led to the frequent use of light colours in façades with ETICS. Daniotti et al. [16] evaluated the effect of thermal shock through the analysis of the number of events that occur in a certain period in which there is a variation of the surface temperature between 4 C, 5 C, and 10 C in one hour. It was found that ETICS with solar absorption values of 0.80 had an occurrence of 2000 events per year, for a surface temperature variation of 4 C/h, and 300 events/year for a surface temperature variation of 10 C in one hour. While considering a solar absorption of 0.60, the number of events is considerably lower (more than 500 events). It is considered that approximately 99% of solar radiation comprises wavelengths between 300 and 2500 nm, which is called the solar spectrum [17]. Therefore, it is important to measure the reflectance of the surfaces over the entire solar spectrum, as this is a function of the wavelength of the incident radiation, also depending on other factors such as the angle of the incident radiation, the colour, and the roughness of the surfaces, among others [18]. As the solar spectrum includes visible light (Vis), ultraviolet (UV) and infrared (IR) radiation, different possibilities of reducing solar absorption by building surfaces can be explored by the industry. Cool materials are defined as having high solar reflectance and high infrared emit- tance [19]. Various scientific contributions that have been developed since the 1970s demon- strated that cool coatings can significantly improve indoor and outdoor thermal comfort while reducing the buildings’ energy consumption [20]. A technology that is already being commercially applied is the introduction of near-infrared reflective (NIR) pigments that reduce the overall solar absorption of the surface [2,21,22]. If this type of cool pigments can be used in ETICS as part of its multilayer finishing system, the range of colours could be broadened, providing a positive answer to the urban aesthetic request for darker colours and complementing the current white-cool solutions. The incorporation of high reflectance pigments in the finishing coatings of ETICS can produce impacts on its solar reflectance, surface temperature, and colour degradation. The ETICS finishing will usually correspond to a rough surface between 0.4 and 1 mm [23] that in practical applications may present a sensitive heterogeneity regarding optical and thermal properties. It is widely accepted [24–26] that the optical properties and the scattering ability of the cool coated surface is mainly affected by the particle size and the refractive index of the oxides combined on layers coating [27,28]. Therefore, several studies were carried out to optimize the use of nanoparticles in cool coatings. The properties of powder cool pigments were evaluated on Levinson et al. [24] and Jose et al. [29] for different colours and oxides particles. Paints based on acrylonitrile styrene acrylate (ASA) doped with barium titanate (BaTiO ), calcium molybdate (CaMoO ), yttrium oxide (Y O ), and antimony oxide (Sb O ) 3 4 2 3 2 3 were studied by Xiang et al. [30] and Xiang and Zhang [31]. Acrylic latex-based incorpo- rated by TiO was developed by several authors [32–34], and the cool properties of acrylic paints incorporated with cool commercial pigments were evaluated by Uemoto et al. [35]. Another variety of coatings as cement-based materials [36], hydrophobic products [37], and polyester [38], doped with TiO , are also being developed and investigated. The durability and life-cycle of buildings highly depend on the material properties and environmental conditions regarding their long-term performance [39]. This takes even more importance when observing the climate changes and their impact on the built environment [40,41]. Several studies already focus on the effect of these materials on the surface temperature of buildings envelopes, especially in the summer season where their positive effect is more obvious. The life-cycle [42,43] and durability performance [44,45] of cool coatings have been studied by many authors with a focus on roofs, which together produced the fundamental results of an international standard elaboration such as the ASTM D 7897 [46]. Infrastructures 2021, 6, 79 3 of 15 Infrastructures 2021, 6, 79 3 of 15 produced the fundamental results of an international standard elaboration such as the ASTM D 7897 [46]. As analysed in Pisello [20], cool coating investigation is rapidly increasing its impact within the scientific community. Nevertheless, there is still a knowledge gap in the ap- As analysed in Pisello [20], cool coating investigation is rapidly increasing its im- plicability of cool materials and their durability when applied to building components. pact within the scientific community. Nevertheless, there is still a knowledge gap in the This gap is even more evident when considering the multilayer finishing coating applicability of cool materials and their durability when applied to building components. adopted in ETICS. Hence, the main goal of this work consists of evaluating the impact of This gap is even more evident when considering the multilayer finishing coating adopted incorporating NIR reflective pigments (NRP) in the solar reflectance, without affecting the in ETICS. Hence, the main goal of this work consists of evaluating the impact of incorporating colour perception, as well as their influence on the colour durability and surface temper- NIR reflective pigments (NRP) in the solar reflectance, without affecting the colour perception, ature. as well as their influence on the colour durability and surface temperature. 2. Methodology 2. Methodology 2.1. 2.1. Ex Experimental perimental Pr Proce ocedur duree This This study is focused on the evaluat study is focused on the evaluation ion of of t the he impac impactt of t of the he incorporat incorporation ion of of NIR NIR Reflective Pigments (NRP) in finishing coatings of ETICS. To that end, measurements of Reflective Pigments (NRP) in finishing coatings of ETICS. To that end, measurements of colour colour,, solar solar rreflectance, eflectance, and and surface surface te temperatur mperature e w wer ere c e carried arried o out ut between between May May o off 2017 2017 and May of 2019 (Month 0 to Month 24). Except for the surface temperature, which was and May of 2019 (Month 0 to Month 24). Except for the surface temperature, which was monitored continuously, the remaining properties were measured once a year in May. The monitored continuously, the remaining properties were measured once a year in May. tests were carried out on a roof of the Civil Engineering Department of the University of The tests were carried out on a roof of the Civil Engineering Department of the University Porto. Figure 1 presents the main climatic conditions during the experimental procedure of Porto. Figure 1 presents the main climatic conditions during the experimental proce- as well as the timeline of measurements. The air temperature distribution is shown using dure as well as the timeline of measurements. The air temperature distribution is shown box-plot charts, while the global solar radiation is represented by the monthly average using box-plot charts, while the global solar radiation is represented by the monthly av- values and the precipitation by monthly accumulated values. These data values were erage values and the precipitation by monthly accumulated values. These data values provided by IPMA (Portuguese Institute for Sea and Atmosphere) from a weather station were provided by IPMA (Portuguese Institute for Sea and Atmosphere) from a weather located nearby the experiment. station located nearby the experiment. Figure 1. Timeline of the experimental procedure and climatic conditions (source: IPMA). Figure 1. Timeline of the experimental procedure and climatic conditions (source: IPMA). The evaluation of solar reflectance was carried out using two methods and equipment: a pyranometer (method E 1918A) and a spectrophotometer. The method E 1918A, proposed by Akbari and Levinson [47], consists of an adaptation of the ASTM E1918 Standard Test Method for Measuring Solar Reflectance of Horizontal and Low-sloped Surfaces in the Field [18]. The E 1918A method uses a pyranometer to measure the radiant solar energy that is incident and the energy that is reflected at the surface per unit time and unit area. However, unlike the original procedure that is indicated for large surfaces, this method allows the measurement of square surfaces with an area of 1 m . Different authors Infrastructures 2021, 6, 79 4 of 15 compared distinct methods of solar reflection measurement, and the E 1918A method showed reliable results [48,49]. In the tests carried out in this work, an SR05 Hukseflux Thermal Sensors pyranometer was used, which presents an estimated precision of 4.4% [50]. This pyranometer meets the requirements of the second class of ISO 9060 [51]. Complementary to the measurement of total solar reflectance with the pyranometer, a spectrophotometer was used to evaluate the spectral reflection (UV-Vis and NIR spec- trum regions). The diffuse solar reflectance was measured using a modular UV-Vis/NIR spectrophotometer: FLAME-T and FLAME-NIR Ocean Optics. This modular spectropho- tometer combines a light source of tungsten-halogen and deuterium lamps (DH-200 Ocean Optics) delivered to a 4.5 mm fibber diameter port. The optical fibre emits a beam to the specimen, and the reflected light beam is read. The output of the test is the diffuse reflectance spectrum, which is measured at 10 nm wavelength intervals ranging from 190 to 1650 nm. The result of spectral reflection is expressed with the solar reflectance (SR) calculated by Equation (1) [52]. R(l )E Dl i li i i=1 SR = (1) å E Dl li i i=1 where R is the measured diffuse spectral reflectivity, l is the wavelength (nm) and E is the spectral irradiance of the sun at the earth surface (W/(m nm)), according to the ASTM Standard G-173 [17]. The reflectance regions are defined by Equation (2). SR = 0.05UV + 0.42Vis + 0.53NIR (2) The surface temperature was measured using T-type thermocouples with a standard metal combination (Copper Alloys and Constantan Alloys), connected to a Technetics Mikromec Logger Multisens. The measuring accuracy is 0.2 C. The colour was evaluated using the CIELab coordinate system (L*, a* and b*) according to ISO 1164-4 [53]. The CIELab coordinate system can be used to describe the colour and lightness of a reflecting surface normalised to the colour of the light source (if the reflecting surface has the same colour as the light source then a* and b* are zero) [54]. The coordinates of contours a* and b* correspond to the chroma and hue, and the L* represents the lightness. The lightness coordinate varies between 0 and 100, where zero is black and 100 is white. The contours vary from - a*b* to + a*b*, where a negative a* corresponds to green and positive to red tones, and the negative b* corresponds to blue and the positive corresponds to yellow tones [55]. The CIELAB parameters also allow the calculation of colour differences [56–58]. This colour difference—DE—reflects how the human eye perceives the colour difference, and it is calculated using the geometric coordinates L*a*b*. The colour was analysed using a Konica Minolta’s CR-10 Tristimulus portable Col- orimeter. The equipment measures the L*, a*, b*, and dE* in an area of 8 mm. All colour measurements are taken using conditions of the standard illuminant D65 and 10 degrees observer. The measuring range is L* 10 to 100 with a standard deviation within DE*ab 0.1 and operates between 0 and 40 C of temperature and 85% or less of relative humidity (at 35 C) with no condensation. 2.2. Materials The proposed methodology was applied to 5 ETICS specimens with 1 m : 3 constituted by 3 layers, and 2 constituted by 4 layers. The difference between the two sets is that primer was only applied in 2 specimens. Figure 2 shows a schematic representation of the constitution of the specimens and their placement. Infrastructures 2021, 6, 79 5 of 15 2.2. Materials The proposed methodology was applied to 5 ETICS specimens with 1 m : 3 consti- tuted by 3 layers, and 2 constituted by 4 layers. The difference between the two sets is that Infrastructures 2021, 6, 79 5 of 15 primer was only applied in 2 specimens. Figure 2 shows a schematic representation of the constitution of the specimens and their placement. 1.Finishing coating: organic coating composed of mineral fillers, resins in aqueous dis- persion, pigments and specific additives (antifungals and oth- ers) (1700–1800 kg(m ); 2. Base coating: cement, min- eral fillers, resins, synthetic fi- bres and special additives (1400 kg/m ), reinforced with glass fi- bre mesh; 3. Insulation: EPS slab (20 kg/m ). 4. Primer: mineral fillers, acrylic copolymers in aqueous dispersion and specific addi- tives. Figure 2. Constitution of the specimens and placement “in situ” (only specimens with primer have Figure 2. Constitution of the specimens and placement “in situ” (only specimens with primer have layer 4). layer 4). The finishing coating consists of a thin layer of a commercial material of approxi- The finishing coating consists of a thin layer of a commercial material of approximately mately 2 mm, with 3% of TiO2 incorporation. The primer is a thin black layer (between 0.1 2 mm, with 3% of TiO incorporation. The primer is a thin black layer (between 0.1 and and 0.15 mm) with the incorporation of TiO2. The base coating is applied in two layers of 0.15 mm) with the incorporation of TiO . The base coating is applied in two layers of 1.5 mm with a glass fibre mesh between them. The EPS insulation slab layer has a thick- 1.5 mm with a glass fibre mesh between them. The EPS insulation slab layer has a thickness ness of 4 cm. of 4 cm. Table 1 includes a detailed description of the constitution of the 5 specimens. Regard- Table 1 includes a detailed description of the constitution of the 5 specimens. Regard- ing the designation of the specimens, “P” stands for primer, “W” stands for the white ing the designation of the specimens, “P” stands for primer, “W” stands for the white colour, and “NR” stands for the incorporation of NIR Reflective Pigments (NRP). Only colour, and “NR” stands for the incorporation of NIR Reflective Pigments (NRP). Only one one specimen specimen is white, is whit and e, and the t remaining he remain ar in eg are bl black. ac The k. T white he whit (W) e (W and) black and bl (S) ack ar(S e r ) efer are re ence f- erence spec specimens, imens, witho without NIR u reflective t NIR reflective pi pigments gments and primer and pr . These imer. T specimens hese spec arime e important ns are im- to porta establish nt to esta benchmarks blish benchma in the colour rks in the range colo comparison. ur range comparison. Table 1. Constitution of the specimens. Table 1. Constitution of the specimens. Specimen Primer NIR Finishing Coating Description Specimen Primer NIR Finishing Coating Description S Standard black (reference) S Standard black (reference) PS ● Standard black with primer PS Standard black with primer NR ● NIR Black NR NIR Black PNR ● ● NIR Black with primer PNR NIR Black with primer W White (reference) W White (reference) To evaluate the effect of the NIR reflective pigments, the black specimens have two different constitutions regarding the pigment incorporated in the finishing coating. Spec- To evaluate the effect of the NIR reflective pigments, the black specimens have imen “S” includes a standard colourant—ferroso-ferric oxide dispersion, colour index two different constitutions regarding the pigment incorporated in the finishing coating. PBk11, with 48% pigment content—and specimen NR incorporates a NIR reflective col- Specimen “S” includes a standard colourant—ferroso-ferric oxide dispersion, colour in- ourant—chrome iron oxide dispersion, colour index PBr29, with 74% pigment content. dex PBk11, with 48% pigment content—and specimen NR incorporates a NIR reflective The colourants were incorporated in 6% of volume in addition to the finishing coating. colourant—chrome iron oxide dispersion, colour index PBr29, with 74% pigment content. The colourants were incorporated in 6% of volume in addition to the finishing coating. 3. Results and Discussion 3.1. Colour The CIELab colour coordinates were determined following the previously explained procedure. Table 2 presents the results obtained in each specimen. Infrastructures 2021, 6, 79 6 of 15 3. Results and Discussion 3.1. Colour The CIELab colour coordinates were determined following the previously explained procedure. Table 2 presents the results obtained in each specimen. Table 2. CIELab colour coordinates. Infrastructures 2021, 6, 79 6 of 15 Initial CIELab Coordinates ** Specimen Month Colour L* a* b* 0 34.0 ± 0.17 −0.2 ± 0.10 −1.5 ± 0.25 Table 2. CIELab colour coordinates. S 12 33.9 ± 0.10 −0.1 ± 0.10 0.0 ± 0.10 CIELab Coordinates ** Initial 24 35.9 ± 0.45 −0.5 ± 0.10 0.4 ± 0.50 Specimen Month Colour L* a* b* 0 33.4 ± 0.36 0.1 ± 0.15 −1.0 ± 0.53 0 34.0 0.17 0.2 0.10 1.5 0.25 PS 12 33.3 ± 0.71 −0.2 ± 0.06 0.0 ± 0.06 S 12 33.9 0.10 0.1 0.10 0.0 0.10 24 34.5 ± 0.12 0.4±0.31 1.1 ± 0.15 24 35.9 0.45 0.5 0.10 0.4 0.50 0 34.8 ± 0.62 0.4 ± 0.06 −2.3 ± 0.36 0 33.4 0.36 0.1 0.15 1.0 0.53 NR 12 12 33.3 34.7 ± 0.71 0.84 0.2 0.1 0.06 ± 0.15 0.0 0.06 −1.0 ± 0.67 PS 24 34.5 0.12 0.4 0.31 1.1 0.15 24 36.3 ± 0.21 −0.5 ± 0.17 −1.2 ± 0.06 0 34.8 0.62 0.4 0.06 2.3 0.36 0 34.1 ± 0.60 0.7 ± 0.10 −2.0 ± 0.31 12 34.7 0.84 0.1 0.15 1.0 0.67 NR PNR 12 33.5 ± 0.21 0.5 ± 0.15 −1.4 ± 0.30 24 36.3 0.21 0.5 0.17 1.2 0.06 24 35.5 ± 0.06 0.3 ± 0.10 −1.3 ± 0.26 0 34.1 0.60 0.7 0.10 2.0 0.31 ** Average and standard deviation (3 measurements). PNR 12 33.5 0.21 0.5 0.15 1.4 0.30 24 35.5 0.06 0.3 0.10 1.3 0.26 ** Average and standard deviation (3 measurements). The lightness indicates the brightness or the tone of the initial colour (Month 0) and can be used to compare specimens of the same colour. It is possible to verify that the The lightness indicates the brightness or the tone of the initial colour (Month 0) and standard (S) and NIR reflective pigment (NR) specimens have the same brightness, with can be used to compare specimens of the same colour. It is possible to verify that the a maximum difference of 4.8% between the PS and NR specimens. The primer application standard (S) and NIR reflective pigment (NR) specimens have the same brightness, with a (PS and PNR) resulted in lower L* in comparison with the specimens without primer, maximum difference of 4.8% between the PS and NR specimens. The primer application which can be explained by the colour of this layer being darker than the base coat. As (PS and PNR) resulted in lower L* in comparison with the specimens without primer, reported by which can beRevel et explained al. [59], Coser by the colour et of al. [60] this layer , and Ross being darker i et al. [ than 61] the , the incorp base coat. oration As of reported by Revel et al. [59], Coser et al. [60], and Rossi et al. [61], the incorporation of some types of NIR reflective pigments can lead to an increase of L*. However, in this some types of NIR reflective pigments can lead to an increase of L*. However, in this study, study, a black-based coloured pigment was used, which explains the lower lightness dif- a black-based coloured pigment was used, which explains the lower lightness difference. ference. Similar results were also found by Cozza et al. [62]. Similar results were also found by Cozza et al. [62]. Regarding black colour, a* and b* coordinates are expected to be around zero and not Regarding black colour, a* and b* coordinates are expected to be around zero and presenting a large difference between them (achromatic aspect) [55]. Figure 3 presents the not presenting a large difference between them (achromatic aspect) [55]. Figure 3 presents chroma coordinates of the analysed specimens in M0, M12, and M24, considering the spec- the chroma coordinates of the analysed specimens in M0, M12, and M24, considering imens with and without (standard) NIR reflective pigments (with and without primer ap- the specimens with and without (standard) NIR reflective pigments (with and without plic primer ation) application). . Figure 3. Chroma coordinates. Figure 3. Chroma coordinates. It is possible to observe in Figure 3 the impact of NIR reflective pigments (NR and PNR) in the colour aesthetic since a* and b* values and the difference between them are higher for the specimens without NIR reflective pigments (S and PS). In addition, the incorporation of NRP leads to a lower variation of the chroma coordinates, which contributes to colour durability. Infrastructures 2021, 6, 79 7 of 15 It is possible to observe in Figure 3 the impact of NIR reflective pigments (NR and PNR) in the colour aesthetic since a* and b* values and the difference between them are higher for the specimens without NIR reflective pigments (S and PS). In addition, the in- Infrastructures 2021, 6, 79 7 of 15 corporation of NRP leads to a lower variation of the chroma coordinates, which contrib- utes to colour durability. The total colour difference (∆E) and the lightness difference (∆L), calculated for the The total colour difference (DE) and the lightness difference (DL), calculated for the whole period of analyses (Month 0 to Month 24), are shown in Figure 4. whole period of analyses (Month 0 to Month 24), are shown in Figure 4. Figure 4. Colour difference between M0 and M24. Figure 4. Colour difference between M0 and M24. The smallest colour difference detectable by the human eye is usually considered as The smallest colour difference detectable by the human eye is usually considered as DE = 1, but a limit value of 3 was considered, following Cozza et al. [62] and Mokrzycki and ∆E=1, but a limit value of 3 was considered, following Cozza et al. [62] and Mokrzycki and Tatol [63]. According to the studies performed by Ihara et al. [64] and Uemoto et al. [35], Tatol [63]. According to the studies performed by Ihara et al. [64] and Uemoto et al. [35], it was expected that colours with cool properties presented a higher colour degradation it w in the as expect early years ed that (befor colo e thr urs w ee years ith coo of exposur l proper e). ties pr Regar esented dless of that, a higas her co can be lour seen dein gradation Figure 4, no specimen achieved the critical value of DE, which could be explained by the in the early years (before three years of exposure). Regardless of that, as can be seen in incorporation of TiO in the formulation of the finishing coating. TiO is frequently used 2 2 Figure 4, no specimen achieved the critical value of ∆E, which could be explained by the as an additive to improve the weathering resistance of polymeric coatings [60,65,66]. In incorporation of TiO2 in the formulation of the finishing coating. TiO2 is frequently used addition, the influence of the primer application (PS and PNR) was identified, since a lower as an additive to improve the weathering resistance of polymeric coatings [60,65,66]. In colour variation, compared with the specimens without primer (S and NR), was obtained. addition, the influence of the primer application (PS and PNR) was identified, since a It was expected that darker colours presented a fast degradation due to thermal stress lower colour variation, compared with the specimens without primer (S and NR), was and UV degradation regarding high solar absorption [64]. However, as verified in Figure 4, obtained. the PNR specimen presented a reduction of 15% on the DE compared to the PS, even having It was expected that darker colours presented a fast degradation due to thermal stress a superior lightness variance. and UV degradation regarding high solar absorption [64]. However, as verified in Figure 3.2. Solar Reflectance 4, the PNR specimen presented a reduction of 15% on the ∆E compared to the PS, even The results of the solar reflectance (SR) obtained by the pyranometer method are having a superior lightness variance. presented in Table 3, where the effect of the incorporation of NRP can be identified. 3.2. Solar Reflectance Table 3. Solar reflectance. The results of the solar reflectance (SR) obtained by the pyranometer method are pre- SR (-) * sented in Table 3, where the effect of the incorporation of NRP can be identified. Specimen Month 0 Month 12 Month 24 Table 3. Solar reflectance. S 0.12 0.007 0.12 0.009 0.08 0.011 PS 0.11 0.002 0.12 0.008 0.08 0.007 NR 0.25 0.003 0.25 0.006 SR (-) * 0.19 0.008 Specimen PNR 0.25 0.006 0.23 0.010 0.22 0.007 Month 0 Month 12 Month 24 W 0.62 0.003 0.61 0.008 0.47 0.009 S 0.12 ± 0.007 0.12 ± 0.009 0.08 ± 0.011 * Average and standard deviation (3 measurements). PS 0.11 ± 0.002 0.12 ± 0.008 0.08 ± 0.007 Specimens NR and PNR (with NIR reflective pigments) had an increase of 118% in NR 0.25 ± 0.003 0.25 ± 0.006 0.19 ± 0.008 comparison to the standard black (S and PS). The improvement resulting from the incorpo- PNR 0.25 ± 0.006 0.23 ± 0.010 0.22 ± 0.007 ration of NIR reflective pigments was also stated in several previous studies [60,65,67,68]. W 0.62 ± 0.003 0.61 ± 0.008 0.47 ± 0.009 Generally, the specimens presented a reduction of solar reflectance throughout the exposi- * Average and standard deviation (3 measurements). tion period. Figure 5 shows the solar reflectance of the black-coloured specimens regarding the entire period of ageing (Month 0 to Month 24). Infrastructures 2021, 6, 79 8 of 15 Specimens NR and PNR (with NIR reflective pigments) had an increase of 118% in comparison to the standard black (S and PS). The improvement resulting from the incor- poration of NIR reflective pigments was also stated in several previous studies [60,65,67,68]. Generally, the specimens presented a reduction of solar reflectance through- Infrastructures 2021, 6, 79 8 of 15 out the exposition period. Figure 5 shows the solar reflectance of the black-coloured spec- imens regarding the entire period of ageing (Month 0 to Month 24). Figure 5. Solar reflectance of the black-coloured specimens in months M0, M12, and M24. Figure 5. Solar reflectance of the black-coloured specimens in months M0, M12, and M24. The standard black (S) showed a reduction of 33% in the solar reflectance, between M0 and The stand M24, whil ard e black for NR (S) was sho 25%. wed a Considering reduction of the specimens 33% in the solar re with primer flectance, betw layer, the een difference between M0 and M24 was 25% and 13% for PS and PNR, respectively. In M0 and M24, while for NR was 25%. Considering the specimens with primer layer, the both cases, the incorporation of NIR reflective pigments had a positive effect to keep the difference between M0 and M24 was 25% and 13% for PS and PNR, respectively. In both solar reflectance values. These results are in line with previous studies developed by cases, the incorporation of NIR reflective pigments had a positive effect to keep the solar Paolini et al. [65] and Rosso et al. [69], where a loss of reflectance with the ageing effect was reflectance values. These results are in line with previous studies developed by Paolini et also observed. al. [65] and Rosso et al. [69], where a loss of reflectance with the ageing effect was also A standard black colour should have a spectral reflectance curve, on the Vis region, observed. near to 20%, and colours with NIR reflective pigments should be focussed on the NIR A standard black colour should have a spectral reflectance curve, on the Vis region, region since it is where their performance is enhanced. The colour variation can affect the rnear to 20% eflectance in ,the and colour visible range s with NIR r of the solare spectr flective pigme um, whichn contributes ts should be to 42% focussed on of the solarthe NIR Infrastructures 2021, 6, 79 9 of 15 reflectance, according to Equation (2). To evaluate this effect, the contribution of NRP in region since it is where their performance is enhanced. The colour variation can affect the the different regions was analysed in Month 24 with the aid of a spectrophotometer (see reflectance in the visible range of the solar spectrum, which contributes to 42% of the solar Figure 6). reflectance, according to Equation (2). To evaluate this effect, the contribution of NRP in the different regions was analysed in Month 24 with the aid of a spectrophotometer (see Figure 6). Figure 6. Spectral reflectance. Figure 6. Spectral reflectance. Observing the UV-Vis region (small square) is possible to detect a similar behaviour between the specimens, which can indicate that the incorporation of the NRP (blue line) does not affect these reflectance values, lower than 20%, and also the colour (see Table 2). The specimens with NRP (blue line) had higher NIR reflectance than the standard speci- mens (red line). The primer (dash line) also positively influenced the NIR reflectance. The diffuse solar reflectance in the solar spectrum regions (UV/Vis/NIR) was calcu- lated according to Equation (1) and Equation (2), and the results are presented in Figure Figure 7. UV-Vis-NIR reflectance. Since the finishing coating and primer layer incorporate TiO2 particles, which con- tribute to a lower degradation of polymeric-based materials due to UV radiation [65,66], low values of UV reflectance were observed. These results and the colour parameters (in Table 2) confirmed this effect. The Vis reflectance is related to the visible colour of the finishing coating. Conse- quently, light colours will have a higher reflectance in this region at the same time that the NIR reflectance will significantly affect the absorbed solar energy. Several studies stated Infrastructures 2021, 6, 79 9 of 15 Figure 6. Spectral reflectance. Infrastructures 2021, 6, 79 9 of 15 Observing the UV-Vis region (small square) is possible to detect a similar behaviour between the specimens, which can indicate that the incorporation of the NRP (blue line) does not affect these reflectance values, lower than 20%, and also the colour (see Table 2). Observing the UV-Vis region (small square) is possible to detect a similar behaviour be- tween the specimens, which can indicate that the incorporation of the NRP (blue line) does The specimens with NRP (blue line) had higher NIR reflectance than the standard speci- not affect these reflectance values, lower than 20%, and also the colour (see Table 2). The mens (red line). The primer (dash line) also positively influenced the NIR reflectance. specimens with NRP (blue line) had higher NIR reflectance than the standard specimens The diffuse solar reflectance in the solar spectrum regions (UV/Vis/NIR) was calcu- (red line). The primer (dash line) also positively influenced the NIR reflectance. lated according to Equation (1) and Equation (2), and the results are presented in Figure The diffuse solar reflectance in the solar spectrum regions (UV/Vis/NIR) was calcu- lated according to Equations (1) and (2), and the results are presented in Figure 7. Figure 7. UV-Vis-NIR reflectance. Figure 7. UV-Vis-NIR reflectance. Since the finishing coating and primer layer incorporate TiO particles, which con- Since the finishing coating and primer layer incorporate TiO2 particles, which con- tribute to a lower degradation of polymeric-based materials due to UV radiation [65,66], tribute to a lower degradation of polymeric-based materials due to UV radiation [65,66], low values of UV reflectance were observed. These results and the colour parameters (in Table 2) confirmed this effect. low values of UV reflectance were observed. These results and the colour parameters (in The Vis reflectance is related to the visible colour of the finishing coating. Conse- Table 2) confirmed this effect. quently, light colours will have a higher reflectance in this region at the same time that The Vis reflectance is related to the visible colour of the finishing coating. Conse- the NIR reflectance will significantly affect the absorbed solar energy. Several studies quently, light colours will have a higher reflectance in this region at the same time that the stated that black colours should present a Vis reflectance near to 0.2 [62,70–72]. It could be NIR reflectance will significantly affect the absorbed solar energy. Several studies stated observed that the specimens with NIR reflective pigments (NR and PNR) presented Vis reflectance 0.1, confirming that the colour does not change due to the pigment incorpora- tion. Analysing the spectral behaviour, a higher variation of NIR reflectance was expected, comparing to the Vis region: an increment of 91% in NR, comparing to S, and 73% between PS and PNR. The correlation between the diffuse reflectance (spectrophotometer) and solar re- flectance (pyranometer) is shown in Figure 8. The good correlation between the results (R > 0.9) confirmed that the diffuse re- flectance of rough coatings contributes to practically all solar reflectance, which was also verified by Zinzi et al. [73] and Meola et al. [74]. Infrastructures 2021, 6, 79 10 of 15 that black colours should present a Vis reflectance near to 0.2 [62,70–72]. It could be ob- served that the specimens with NIR reflective pigments (NR and PNR) presented Vis re- flectance ≈0.1, confirming that the colour does not change due to the pigment incorpora- tion. Analysing the spectral behaviour, a higher variation of NIR reflectance was expected, comparing to the Vis region: an increment of 91% in NR, comparing to S, and 73% between PS and PNR. Infrastructures 2021, 6, 79 10 of 15 The correlation between the diffuse reflectance (spectrophotometer) and solar reflec- tance (pyranometer) is shown in Figure 8. Figure 8. Correlation between spectrophotometer and pyranometer measured reflectance. Figure 8. Correlation between spectrophotometer and pyranometer measured reflectance. 3.3. Surface Temperature The good correlation between the results (R > 0.9) confirmed that the diffuse reflec- The surface temperature of each specimen and the exterior temperature (Te) were tance of rough coatings contributes to practically all solar reflectance, which was also ver- analysed. Since the NRP impact is enhanced with high temperatures, two distinct and ified by Zinzi et al. [73] and Meola et al. [74]. representative (of the most usual behaviour) periods were considered: mild (during M12) and high temperatures (M13). 3.3. Surface Temperature As expected, the higher the exterior temperature, the higher the surface temperatures and the The surface t differences between emperature the dif ofer f eent ach specimen specimen s (see and Figur the eexterior temp 9). In both mild erature and hot (Te) were Infrastructures 2021, 6, 79 11 of 15 periods, the benefits of raising the solar reflection, even when it is done mainly in the NIR analysed. Since the NRP impact is enhanced with high temperatures, two distinct and region, could be observed by the reduction of the surface temperature (during the day), representative (of the most usual behaviour) periods were considered: mild (during M12) which is in line with the results obtained by Krimpalis and Karamanis [75] and Li et al. [76]. and high temperatures (M13). As expected, the higher the exterior temperature, the higher the surface temperatures 80 80 and the differences between the different specimens (see Figure 9). In both mild and hot PS PS 70 70 NR NR PNR periods, the benefits of raising the solar reflection, even when it is done mainly in the NIR PNR 60 60 W Te region, could be observed Te by the reduction of the surface temperature (during the day), which is in line with the results obtained by Krimpalis and Karamanis [75] and Li et al. 40 40 [76]. 30 30 20 20 10 10 0 0 Time (h) Time (h) (a) (b) Figure 9. Surface temperature in: (a) Day of lower temperatures (M12); (b) Day of high temperatures (M13). Figure 9. Surface temperature in: (a) Day of lower temperatures (M12); (b) Day of high temperatures (M13). A statistical analysis of a representative week of each period (mild and hot) is shown A statistical analysis of a representative week of each period (mild and hot) is shown i in n Fi Figur gures 10 es 10 a and nd 11 11,, r respecti espectively vely.. 100% 80% 60% 40% PS NR PNR 20% 0% 0 1020 304050607080 Temperature (ºC) (a) (b) Figure 10. Surface temperature during a mild week (M12): (a) Box-plots; (b) Cumulative frequencies. 100% 80% 60% 40% PS NR PNR 20% 0% 0 1020304050607080 Tempe rature (ºC) (a) (b) Figure 11. Surface temperature during a hot week (M13): (a) Box-plots; (b) Cumulative frequencies. Temperature (ºC) Temperature (ºC) Cumulative Frequency Cumulative Frequency Infrastructures 2021, 6, 79 11 of 15 Infrastructures 2021, 6, 79 11 of 15 80 80 80 80 PS PS PS 70 PS NR 70 70 NR NR NR PNR PNR PNR PNR 60 60 60 W 60 W Te Te Te Te 50 50 50 50 40 40 40 40 30 30 20 20 20 20 10 10 10 10 0 0 Time (h) Time (h) Time (h) Time (h) (a) (b) (a) (b) Figure 9. Surface temperature in: (a) Day of lower temperatures (M12); (b) Day of high temperatures (M13). Figure 9. Surface temperature in: (a) Day of lower temperatures (M12); (b) Day of high temperatures (M13). A statistical analysis of a representative week of each period (mild and hot) is shown A statistical analysis of a representative week of each period (mild and hot) is shown Infrastructures 2021, 6, 79 11 of 15 in Figures 10 and 11, respectively. in Figures 10 and 11, respectively. 100% 100% 80% 80% 60% 60% 40% 40% PS PS NR NR PNR 20% PNR 20% 0% 0% 0 1020 304050607080 0 1020 304050607080 Temperature (ºC) Temperature (ºC) (a) (b) (a) (b) Figure 10. Surface temperature during a mild week (M12): (a) Box-plots; (b) Cumulative frequencies. Figure 10. Surface temperature during a mild week (M12): (a) Box-plots; (b) Cumulative frequencies. Figure 10. Surface temperature during a mild week (M12): (a) Box-plots; (b) Cumulative frequencies. 100% 100% 80% 80% 60% 60% 40% 40% PS PS NR NR PNR 20% PNR 20% 0% 0% 0 1020304050607080 0 1020304050607080 Tempe rature (ºC) Tempe rature (ºC) (a) (b) (a) (b) Figure 11. Surface temperature during a hot week (M13): (a) Box-plots; (b) Cumulative frequencies. Figure 11. Surface temperature during a hot week (M13): (a) Box-plots; (b) Cumulative frequencies. Figure 11. Surface temperature during a hot week (M13): (a) Box-plots; (b) Cumulative frequencies. The incorporation of NRP (NR and PNR specimens) promoted, as expected and previously observed, a reduction of the surface temperature, especially for exterior air temperature above 25 C. Comparing the two analysed weeks, the hot period promoted a greater occurrence of higher surface temperatures, as shown in the cumulative frequencies charts). In addition, specimens with the primer layer (PS and PNR) presented higher temperature compared with the ones without primer. The primer layer reduced the effect of NRP (PNR specimen) since similar behaviour to the standard specimen (S) is observed. As long as the lightness and solar reflectance measured in M12 is similar between the specimens with and without primer, this difference could be related to the internal reflection due to the white primer layer with the NRP and TiO particles [34]. Despite the reduction of the surface temperature through the incorporation of NRP in black finishing coatings, the maximum surface temperature is still 15 C higher than the white coating due to the much higher solar reflectance. This fact is related to solar energy in the different spectrum regions. As referred in Equation (2), 53% of the total solar energy occurs in the NIR region of the solar spectrum. As such, the incorporation of NIR reflective pigments, in this specific region, is responsible for the reduction of a part of the absorbed energy, while the great remaining part is in the visible region (42%) where the colour is determinant. In addition, all the specimens presented maximum surface temperature under 80 C, which meets the ETAG 004 recommendation [13]. 4. Conclusions In façade systems, such as ETICS, the final layer properties present a very important role in the overall performance. Solar reflectance is particularly determinant for the thermal Temperature (ºC) Temperature (ºC) Temperature (ºC) Temperature (ºC) Cumulative Frequency Cumulative Frequency Cumulative Frequency Cumulative Frequency Infrastructures 2021, 6, 79 12 of 15 performance of these systems and contributes decisively to their durability. Taking into account that they are constituted by different materials/layers and, consequently, different thermo-mechanical properties, these systems are subjected to cracking, especially with a high-temperature variation. This fact contributes to compromising the stability and integrity of the different layers and the durability of the entire system. The incorporation of NIR reflective pigments contributed to maintaining the colour characteristics, such as lightness and chroma, even in dark coatings. In addition, the colour difference after 2 years of ageing in NIR reflective pigments was lower when NRP were incorporated. The main contribution of NIR reflective pigments is the increase of the solar reflectance and consequently the decrease of surface temperature, even in dark colours, especially for high temperatures (above 25 C). These pigments highly increase the NIR reflectance without affecting the colour (in the visible region). The application of primer, under the finishing coating, increased the surface tempera- ture, especially for higher exterior temperatures. However, the primer layer contributes to a lower colour difference and solar reflectance variation, which is an important achievement for durability. A good correlation between the diffuse reflectance (measured with the spectropho- tometer) and solar reflectance (measured with the pyranometer) confirmed that the diffuse reflectance of rough coatings contributes to practically all solar reflectance. Author Contributions: Conceptualization, N.M.M.R., J.M., A.R.S. and R.M.S.F.A.; methodology, J.M., A.R.S. and L.S.; formal analysis, J.M. and A.R.S.; investigation, J.M. and A.R.S.; data curation J.M. and A.R.S.; writing—original draft preparation, J.M. and A.R.S.; writing—review and editing, N.M.M.R., J.M., A.R.S. and R.M.S.F.A.; visualization, N.M.M.R., J.M., A.R.S., R.M.S.F.A. and L.S.; supervision, N.M.M.R. All authors have read and agreed to the published version of the manuscript. Funding: This research was financially supported by: Base Funding - UIDB/04708/2020 of the CONSTRUCT - Instituto de I&D em Estruturas e Construções - funded by national funds through the FCT/MCTES (PIDDAC) and by Project PTDC/ECI-CON/28766/2017 - POCI-01-0145-FEDER- 028766 funded by FEDER funds through COMPETE2020 -Programa Operacional Competitividade e Internacionalização (POCI) and by national funds (PIDDAC) through FCT/MCTES. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: The data presented in this study are available on request from the corresponding author. Acknowledgments: The authors acknowledge Saint-Gobain Weber for the materials supply and IPMA (Portuguese Institute for Sea and Atmosphere) for the weather data sharing. Conflicts of Interest: The authors declare no conflict of interest. References 1. Kisilewicz, T.; Fedorczak-Cisak, M.; Barkanyi, T. Active thermal insulation as an element limiting heat loss through external walls. Energy Build. 2019, 205, 109541. [CrossRef] 2. Pacheco-Torgal, F. Eco-efficient construction and building materials research under the EU Framework Programme Horizon 2020. Constr. Build. Mater. 2014, 51, 151–162. [CrossRef] 3. Pedroso, M.; Flores-Colen, I.; Silvestre, J.; Gomes, M.; Silva, L.; Ilharco, L. Physical, mechanical, and microstructural characterisa- tion of an innovative thermal insulating render incorporating silica aerogel. Energy Build. 2020, 211, 109793. [CrossRef] 4. Vale, H.; Melo, H.; Soares, A.; Flores-Colen, I.; Gomes, M.G. Performance of Industrial Thermal Insulation Renders. In Proceedings of the 9th International Masonry Conference, Guimarães, Portugal, 7–9 July 2014; Lourenço, P.B., Haseltine, B.A., Vasconcelos, G., Eds.; International Masonry Society: Whyteleafe, UK, 2014. 5. Künzel, H.; Künzel, H.; Sedlbauer, K. Long-term performance of External Thermal Insulation Systems (ETICS). Architectura 2006, 5, 11–24. 6. Barreira, E.; de Freitas, V.P. Experimental study of the hygrothermal behaviour of External Thermal Insulation Composite Systems (ETICS). Build. Environ. 2013, 63, 31–39. [CrossRef] Infrastructures 2021, 6, 79 13 of 15 7. D’Orazio, M.; Cursio, G.; Graziani, L.; Aquilanti, L.; Osimani, A.; Clementi, F.; Yéprémian, C.; Lariccia, V.; Amoroso, S. Effects of water absorption and surface roughness on the bioreceptivity of ETICS compared to clay bricks. Build. Environ. 2014, 77, 20–28. [CrossRef] 8. Nilica, R.; Harmuth, H. Mechanical and fracture mechanical characterization of building materials used for external thermal insulation composite systems. Cem. Concr. Res. 2005, 35, 1641–1645. [CrossRef] 9. Daniotti, B.; Cecconi, F.R.; Paolini, R.; Galliano, R. Durability Evaluation of External Thermal Insulation Composite Systems: Frequency Assessment of Thermal Shocks. In Proceedings of the CIB World Building Congress 2013, Brisbane, QLD, Australia, 5–9 May 2013; Queensland University of Technology (QUT), Ed.; 10. Kvande, T.; Bakken, N.; Bergheim, E.; Thue, J.V. Durability of ETICS with Rendering in Norway—Experimental and Field Investigations. Buildings 2018, 8, 93. [CrossRef] 11. Daniotti, B.; Cecconi, F.R. CIB W080: WG3 Test Methods for Service Life Prediction; CIB Report: Publication 331; Politecnico di Milano: Milan, Italy, 2010; ISBN 978-90-6363-062-1. 12. Spagnolo, S.L.; Daniotti, B. Performance over Time and Durability Assessment of External Thermal Insulation Systems with Artificial Stone Cladding; Research for Development; Springer: Berlin/Heideberg, Germany, 2019; pp. 277–287. 13. EOTA. ETAG 004, Guideline for European Technical Approval of External Thermal Insulation Composite Systems with Rendering; European Organisation for Technical Approvals: Brussels, Belgium, 2013. 14. EOTA. EAD 040083-00-0404, External Thermal Insulation Composite Systems (ETICS) with Rendering; European Organisation for Technical Approvals: Brussels, Belgium, 2019. 15. EAE. European Guideline for the Application of ETICS; European Association for External Thermal Insulation Composite Systems: Baden-Baden, Germany, 2011. 16. Daniotti, B.; Cecconi, F.R.; Paolini, R.; Galliano, R.; Ferrer, J.; Battaglia, L. Durability evaluation of ETICS: Analysis of failures case studies and heat and moisture transfer simulations to assess the frequency of critical events. In Proceedings of the 4th Portuguese Conference on Mortars & ETICS, Coimbra, Portugal, 29–30 March 2012. 17. ASTM. Standard Tabels for Reference Solar Spectral Irradiances: Direct Normal and Hemispherical on 37 Tilted Surface; ASTM International: West Conshohocken, PA, USA, 2012. 18. ASTM. ASTM E1918-06 (2015): Standard Test Method for Measuring Solar Reflectance of Horizontal and Low-Sloped Surfaces in the Field; American Society for Testing and Materials: West Conshohocken, PA, USA, 2015. 19. Santamouris, M. Heat Island Research in Europe: The State of the Art. Adv. Build. Energy Res. 2007, 1, 123–150. [CrossRef] 20. Pisello, A.L. State of the art on the development of cool coatings for buildings and cities. Sol. Energy 2017, 144, 660–680. [CrossRef] 21. Mohelnikova, J. Materials for reflective coatings of window glass applications. Constr. Build. Mater. 2009, 23, 1993–1998. [CrossRef] 22. Pacheco-Torgal, F.; Jalali, S. Nanotechnology: Advantages and drawbacks in the field of construction and building materials. Constr. Build. Mater. 2011, 25, 582–590. [CrossRef] 23. Borsoi, G.; Parracha, J.; Caiado, P.; Flores-Colen, I.; Dionísio, A.; Veiga, R. Assessing Water Resistance and Surface Properties of ETICS. In Proceedings of the XV International Conference on Durability of Building Materials and Components (DBMC 2020), Barcelona, Spain, 20–23 October 2020; Serrat, C., Casas, J.R., Gibert, V., Eds.; 24. Levinson, R.; Berdahl, P.; Akbari, H. Solar spectral optical properties of pigments—Part II: Survey of common colorants. Sol. Energy Mater. Sol. Cells 2005, 89, 351–389. [CrossRef] 25. Baneshi, M.; Maruyama, S.; Komiya, A. The Effects of Using Some Common White Pigments on Thermal and Aesthetic Performances of Pigmented Coatings. J. Therm. Sci. Technol. 2009, 4, 131–145. [CrossRef] 26. Baneshi, M.; Gonome, H.; Komiya, A.; Maruyama, S. The effect of particles size distribution on aesthetic and thermal per- formances of polydisperse TiO pigmented coatings: Comparison between numerical and experimental results. J. Quant. Spectrosc. Radiat. Transf. 2012, 113, 594–606. [CrossRef] 27. Piri, N. Application of Multi Flux Model to Predict Optical Performance of Titanium Dioxide Nanopigments. Int. J. Nanosci. Nanotechnol. 2019, 15, 27–36. 28. Kinoshita, S.; Yoshida, A. Investigating performance prediction and optimization of spectral solar reflectance of cool painted layers. Energy Build. 2016, 114, 214–220. [CrossRef] 29. Jose, S.; Joshy, D.; Narendranath, S.B.; Periyat, P. Recent advances in infrared reflective inorganic pigments. Sol. Energy Mater. Sol. Cells 2019, 194, 7–27. [CrossRef] 30. Xiang, B.; Yin, X.; Zhang, J. A novel cool material: ASA (acrylonitrile-styrene-acrylate) matrix composites with solar reflective inorganic particles. Compos. Sci. Technol. 2017, 145, 149–156. [CrossRef] 31. Xiang, B.; Zhang, J. Effects of content and surface hydrophobic modification of BaTiO3 on the cooling properties of ASA (acrylonitrile-styrene-acrylate copolymer). Appl. Surf. Sci. 2018, 427, 654–661. [CrossRef] 32. Song, J.; Qin, J.; Qu, J.; Song, Z.; Zhang, W.; Xue, X.; Shi, Y.; Zhang, T.; Ji, W.; Zhang, R.; et al. The effects of particle size distribution on the optical properties of titanium dioxide rutile pigments and their applications in cool non-white coatings. Sol. Energy Mater. Sol. Cells 2014, 130, 42–50. [CrossRef] 33. Xie, N.; Li, H.; Abdelhady, A.; Harvey, J. Laboratorial investigation on optical and thermal properties of cool pavement nano- coatings for urban heat island mitigation. Build. Environ. 2019, 147, 231–240. [CrossRef] Infrastructures 2021, 6, 79 14 of 15 34. Zhou, A.; Yu, Z.; Chow, C.L.; Lau, D. Enhanced solar spectral reflectance of thermal coatings through inorganic additives. Energy Build. 2017, 138, 641–647. [CrossRef] 35. Uemoto, K.L.; Sato, N.M.; John, V.M. Estimating thermal performance of cool colored paints. Energy Build. 2010, 42, 17–22. [CrossRef] 36. Daniotti, B.; Diamanti, M.V.; Luongo, N.; Massari, S.; Pedeferri, M.P.; Spagnolo, S.L. Characterization of durability and photo- catalytic properties of TiO2 cement-based materials. In Materials for Energy, Efficiency and Sustainability: TechConnect Briefs 2018; TechConnect Briefs: Washington, DC, USA, 2018; Volume 2, pp. 203–206. ISBN 978-0-9975117-9-6. 37. Borsoi, G.; Esteves, C.; Flores-Colen, I.; Veiga, R. Effect of Hygrothermal Aging on Hydrophobic Treatments Applied to Building Exterior Claddings. Coatings 2020, 10, 363. [CrossRef] 38. Piri, N.; Shams-Nateri, A.; Mokhtari, J. Solar spectral performance of nanopigments. Sol. Energy Mater. Sol. Cells 2017, 162, 72–82. [CrossRef] 39. Daniotti, B.; Spagnolo, S.L. Service life prediction for buildings’ design to plan a sustainable building maintenance. In Proceedings of the Portugal SB 2007—Sustainable Construction, Materials and Practices: Challenge of the Industry for the New Millennium, Lisbon, Portugal, 12–14 September 2007; pp. 515–521. 40. Grynning, S.; Gradeci, K.; Gaarder, J.E.; Time, B.; Lohne, J.; Kvande, T. Climate Adaptation in Maintenance Operation and Management of Buildings. Buildings 2020, 10, 107. [CrossRef] 41. Stagrum, A.E.; Andenæs, E.; Kvande, T.; Lohne, J. Climate Change Adaptation Measures for Buildings—A Scoping Review. Sustainabiliy 2020, 12, 1721. [CrossRef] 42. Berdahl, P.; Akbari, H.; Levinson, R.; Miller, W.A. Weathering of roofing materials—An overview. Constr. Build. Mater. 2008, 22, 423–433. [CrossRef] 43. Susca, T. Enhancement of life cycle assessment (LCA) methodology to include the effect of surface albedo on climate change: Comparing black and white roofs. Environ. Pollut. 2012, 163, 48–54. [CrossRef] [PubMed] 44. Sleiman, M.; Chen, S.; Gilbert, H.E.; Kirchstetter, T.W.; Berdahl, P.; Bibian, E.; Bruckman, L.S.; Cremona, D.; French, R.H.; Gordon, D.A.; et al. Soiling of building envelope surfaces and its effect on solar reflectance—Part III: Interlaboratory study of an accelerated aging method for roofing materials. Sol. Energy Mater. Sol. Cells 2015, 143, 581–590. [CrossRef] 45. Ferrari, C.; Touchaei, A.G.; Sleiman, M.; Libbra, A.; Muscio, A.; Siligardi, C.; Akbari, H. Effect of aging processes on solar reflectivity of clay roof tiles. Adv. Build. Energy Res. 2014, 8, 28–40. [CrossRef] 46. ASTM. Standard Practice for Laboratory Soiling and Weathering of Roofing Materials to Simulate Effects of Natural Exposure on Solar Reflectance and Thermal Emittance; ASTM International: West Conshohocken, PA, USA, 2018. 47. Akbari, H.; Levinson, R.; Stern, S. Procedure for measuring the solar reflectance of flat or curved roofing assemblies. Sol. Energy 2008, 82, 648–655. [CrossRef] 48. Levinson, R.; Akbari, H.; Berdahl, P. Measuring solar reflectance—Part II: Review of practical methods. Sol. Energy 2010, 84, 1745–1759. [CrossRef] 49. Levinson, R.; Egolf, M.; Chen, S.; Berdahl, P. Experimental comparison of pyranometer, reflectometer, and spectropho-tometer methods for the measurement of roofing product albedo. Sol. Energy 2020, 206, 826–847. [CrossRef] 50. Hukseflux, T.S. Pyranometer Products. Available online: http://www.hukseflux.com/product_group/pyranometer (accessed on 22 April 2016). 51. ISO. ISO 9060:2018—Solar Energy—Specification and Classification of Instruments for Measuring Hemispherical Solar and Direct Solar Radiation; International Organization for Standardization: Geneva, Switzerland, 2018. 52. ASTM. Standard Test Method for Solar Absorptance, Reflectance, and Transmittance of Materials Using Integrating Spheres; ASTM International: West Conshohocken, PA, USA, 2020. 53. ISO. EN ISO/CIE 11644: Colorimetry Part 3: CIE Tristimulus Values; CIE International Commission on Illumination: Geneva, Switzerland, 2019. 54. Hanson, A.R. 1—What is colour? In Colour Design, 2nd ed.; Best, J., Ed.; Woodhead Publishing: Cambridge, UK, 2012; pp. 3–21. 55. Sattar, S. Characterizing Color with Reflectance. J. Chem. Educ. 2019, 96, 1124–1128. [CrossRef] 56. Sharma, G.; Wu, W.; Dalal, E.N. The CIEDE2000 color-difference formula: Implementation notes, supplementary test data, and mathematical observations. Color Res. Appl. 2004, 30, 21–30. [CrossRef] 57. Brainard, D.H. Color Appearance and Color Difference Specification. Sci. Color 2003, 191–216. [CrossRef] 58. Weatherall, I.L.; Coombs, B.D. Skin Color Measurements in Terms of CIELAB Color Space Values. J. Investig. Dermatol. 1992, 99, 468–473. [CrossRef] 59. Revel, G.M.; Martarelli, M.; Emiliani, M.; Gozalbo, A.; Orts, M.J.; Bengochea, M.Á.; Delgado, L.G.; Gaki, A.; Katsiapi, A.; Taxiarchou, M.; et al. Cool products for building envelope—Part I: Development and lab scale testing. Sol. Energy 2014, 105, 770–779. [CrossRef] 60. Coser, E.; Moritz, V.F.; Krenzinger, A.; Ferreira, C.A. Development of paints with infrared radiation reflective properties. Polímeros 2015, 25, 305–310. [CrossRef] 61. Rossi, S.; Lindmark, H.; Fedel, M. Colored Paints Containing NIR-Reflective Pigments Exposed to Accelerated Ultraviolet Radiation Aging with Possible Application as Roof Coatings. Coatings 2020, 10, 1135. [CrossRef] 62. Cozza, E.; Alloisio, M.; Comite, A.; Di Tanna, G.; Vicini, S. NIR-reflecting properties of new paints for energy-efficient buildings. Sol. Energy 2015, 116, 108–116. [CrossRef] Infrastructures 2021, 6, 79 15 of 15 63. Mokrzycki, W.; Tatol, M. Color difference Delta E—A survey. Mach. Graph. Vis. 2011, 20, 383–411. 64. Ihara, T.; Jelle, B.P.; Gao, T.; Gustavsen, A. Accelerated aging of treated aluminum for use as a cool colored material for facades. Energy Build. 2016, 112, 184–197. [CrossRef] 65. Paolini, R.; Zani, A.; Poli, T.; Antretter, F.; Zinzi, M. Natural aging of cool walls: Impact on solar reflectance, sensitivity to thermal shocks and building energy needs. Energy Build. 2017, 153, 287–296. [CrossRef] 66. Pisello, A.L.; Fortunati, E.; Fabiani, C.; Mattioli, S.; Dominici, F.; Torre, L.; Cabeza, L.F.; Cotana, F. PCM for improving pol- yurethane-based cool roof membranes durability. Sol. Energy Mater. Sol. Cells 2017, 160, 34–42. [CrossRef] 67. Gobakis, K.; Kolokotsa, D.; Maravelaki-Kalaitzaki, N.; Perdikatsis, V.; Santamouris, M. Development and analysis of ad-vanced inorganic coatings for buildings and urban structures. Energy Build. 2015, 89, 196–205. [CrossRef] 68. Santamouris, M. Cooling the cities—A review of reflective and green roof mitigation technologies to fight heat island and improve comfort in urban environments. Sol. Energy 2014, 103, 682–703. [CrossRef] 69. Rosso, F.; Pisello, A.L.; Jin, W.; Ghandehari, M.; Cotana, F.; Ferrero, M. Cool Marble Building Envelopes: The Effect of Aging on Energy Performance and Aesthetics. Sustainability 2016, 8, 753. [CrossRef] 70. Vox, G.; Maneta, A.; Schettini, E. Evaluation of the radiometric properties of roofing materials for livestock buildings and their effect on the surface temperature. Biosyst. Eng. 2016, 144, 26–37. [CrossRef] 71. Gonome, H.; Baneshi, M.; Okajima, J.; Komiya, A.; Maruyama, S. Controlling the radiative properties of cool black-color coatings pigmented with CuO submicron particles. J. Quant. Spectrosc. Radiat. Transf. 2014, 132, 90–98. [CrossRef] 72. Ganguly, A.; Chowdhury, D.; Neogi, S. Performance of Building Roofs on Energy Efficiency—A Review. Energy Procedia 2016, 90, 200–208. [CrossRef] 73. Zinzi, M.; Carnielo, E.; Rossi, G. Directional and angular response of construction materials solar properties: Characteri-sation and assessment. Sol. Energy 2015, 115, 52–67. [CrossRef] 74. Meola, C.; Boccardi, S.; Carlomagno, G.M. (Eds.) Infrared Thermography in the Evaluation of Aerospace Composite Materials. In Infrared Thermography in the Evaluation of Aerospace Composite Materials; Woodhead Publishing: Cambridge, UK, 2017; pp. 57–83. 75. Krimpalis, S.; Karamanis, D. A novel approach to measuring the solar reflectance of conventional and innovative building components. Energy Build. 2015, 97, 137–145. [CrossRef] 76. Li, H.; Harvey, J.; Kendall, A. Field measurement of albedo for different land cover materials and effects on thermal performance. Build. Environ. 2013, 59, 536–546. [CrossRef]
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