Thermal Analysis of a Concrete Roof with an Outdoor Reflective Surface

Abstract

The present research evaluates the thermal effectiveness of a reflective surface at the outdoor surface of a concrete roof. The objective of the reflective surface is to reduce the heat gain by reflecting most of the solar radiation in the daytime and emitting a large amount of radiation. A testing room was constructed and equipped with thermocouples, heat flux sensors, and a data acquisition module. The outdoor space is a real weather condition, whereas the indoor environment is controlled. A numerical method is employed to study the effect of the solar reflectivity of the roof and the operating month, and heat gain for all the case studies is determined. The numerical results are validated with the experimental results, which were conducted during August, and the roof with concrete and white color surfaces are tested. The results show a significant heat gain reduction when the solar reflectivity of the roof is increased, and the net heat gain through the roof can be reduced by 50%. However, the results indicate that the effectiveness of the solar radiation reflector is nearly independent of the operating month.