Urban areas have been suffering with climate change phenomena of urban heat islands. As a consequence, there is an increase in energy peak demand for thermal conditioning, besides high temperature cause discomfort in houses that cannot afford for air conditioning. Cool coatings are an alternative that could help to minimize the effects of urban heat islands. Those coatings have the ability to reflect incident sunlight as well reemit absorbed heat back to the environment. Traditionally, white surfaces are responsible for high reflecting power. Based on this concept, this study measured the reflectance properties and thermal emissivity on different types of substrate painted with lime coating, using different numbers of coats. Besides these properties, an analysis of the coverage capacity of the samples in wet and dry conditions was made. The results of reflectance ranged from 0.56 to 0.83 depending on the number of coats and type of substrate. The thermal emissivity remained with almost the same index, on average, 0.97, regardless of the type of substrate and coats of paint. Finally, it was noticed a significant contrast between the surfaces under wet and dry conditions. The results demonstrate that the lime coating meets the requirements of reflectance and thermal emissivity for a cool coating.
Lime; Coating; Reflectance; Cool coating
