Development and thermal-optical characterization of a cementitious plaster with phase change materials and thermochromic paint

Current climate challenges in urban areas require practical solutions to mitigate the negative environmental impacts attributed to cities such as the urban heat island (UHI) effect. Thermal stresses caused by high temperatures, temperature fluctuations, and UV radiation exposed to building surfaces negatively affect urban and indoor building thermal comfort, building energy use, and durability of the finish materials. Therefore, increasing the performance of exterior finish materials to mitigate the effects of environmental loads would have benefits on the material, building, and urban scales. This paper aims to characterize the optical and thermal properties of a novel cementitious plaster to control solar and thermal loads. The cement plaster developed for exterior façade applications was integrated with thermochromic paint (TC) and phase change materials (PCM) to dynamically control thermal stresses and solar radiation on the exterior surface of buildings. The solar reflectance, infrared emittance, and thermal conductivity of the samples were measured. The results showed that by applying the TC paint on the surface of the cement plaster, solar reflectance was increased by 23%. By combining the TC paint and the PCMs with the cement plaster, a higher rate of solar absorption in colder temperatures compared to a regular cement plaster was shown. The findings indicate the benefits of using such a plaster year around given the dynamic variation of solar reflectance and absorptance.