While considering a solar absorption of 0.60, the number of events is considerably lower (more than 500 events).Ĭool materials are defined as having high solar reflectance and high infrared emittance. 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 ☌/h, and 300 events/year for a surface temperature variation of 10 ☌ in one hour. 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 ☌, 5 ☌, and 10 ☌ in one hour. These restrictions have led to the frequent use of light colours in façades with ETICS. In addition, the European Guideline for the application of ETICS recommends a minimum solar reflectance between 0.2 and 0.3 (depending on the climatic conditions). However, the new European Assessment Document EAD 0404, which replaces the ETAG 004, did not refer to this recommendation. To prevent part of these pathologies, the old guideline ETAG 004 defines 80 ☌ as the maximum temperature recommended for the ETICS surface. These agents can produce colour changes, staining, and cracking. The degradation agents, which affect the ETICS coating, include solar radiation, temperature and relative humidity fluctuations, and the action of rain. However, pathologies related to finishing coatings, especially microcracking and algae growth, can occur and were observed in various studies. This technology is quite popular in the building industry, presenting positive aspects such as the reduction of thermal bridges and the ability to be easily applied in façade refurbishment.
The ETICS (External Thermal Insulation Composite System) is one of the most widely used thermal façade systems, and its performance has been studied by different authors. However, it contributes to a lower colour difference and solar reflectance variation, which is an important achievement for durability purposes. The application of primer increased the surface temperature, especially for higher exterior temperatures. In addition, they contribute to maintaining the colour characteristics. Moreover, these pigments highly increase the NIR reflectance without affecting the visible colour. It was confirmed that the main contribution of NRP is the increase of solar reflectance and, consequently, the decrease in surface temperature, especially for high exterior temperatures (around 30 ☌). 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. 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. 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). Their use contributes to broadening the range of colours, responding to the urban aesthetic demand without compromising the building performance. Near-infrared (NIR) reflective materials are being developed for mitigating building cooling needs.
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