Dependence of Cool Roof Paint Colors on Household Cooling Load and Analysis of Roof Paint Deterioration

Abstract

Nowadays, a cool roof, composed of highly reflective paint, plays a vital role in reducing cooling energy consumption and saving electricity supply on residential and commercial buildings. As a tactic to combat global warming, particularly the urban heat island effect, the development of surface coatings and their compositions that reduce solar absorption while increasing thermal emittance is becoming more prominent. Thus, this work aims to investigate the importance of color shades and coating deterioration of roof paint on solar reflectance and thermal emittance, in accordance with the standard test method (ASTM E903-12). Samples of cool roof paints with three distinct shades were collected from two well-known commercial brands (Brand A and Brand B). which consists of three colors are white and black for reference colors and red for the popular color. Meanwhile, for the study of the coating deterioration on the aging of solar reflectance of cool roof paint, the accelerated weathering testing instrument needs to be applied to simulate the long-term operation of outdoor exposure. The result showed that as the heat conductivity of the white-painted roof rose via the housing over time, the solar reflectance index (SRI) of white shade was greatly reduced by 4.45 %. The RSI value of the black shade, on the other hand, increased by 29.14 % as the heat transfer coefficient of the black-painted roof decreased with time, as evidenced by the roof thermal transfer value (RTTV). By considering the red shade, its RSI and RTTV values do not change much, indicating that the rate of heat transfer going through the buildings remains constant. Based on these basic findings, it could lead to the formulation of a massive range of high solar-reflective pigments, designed to aid UV protection and thermal resistance on buildings.