Thermoenergetic analysis with an emphasis on the roofing of a single-family building located in bioclimatic zones 01 and 08

Abstract

Buildings designed to have good thermal energy performance can reduce energy consumption, make a more thermally pleasant environment, and help mitigate the effects of urban heat islands. In addition to the climate in which the dwelling is located, the solar reflectance and thermal emittance of the materials that constitute the envelope components can influence the heat exchanges between the building and the external environment. In this regard, the present study aims to comparatively analyze the thermal energy behavior of roofs with conventional low solar reflectance tiles and cool roofs with high solar reflectance tiles, with and without resistive thermal insulation, in a single-family dwelling, considering two Brazilian bioclimatic zones (ZB 01 and ZB 08). The adopted methodology was based on computational simulations carried out using the EnergyPlus software, which provides output data necessary for calculating the following indicators: percentage of occupied hours within an operative temperature range (PHFT), thermal load consumption, roof surface temperature, and heat flux in the roof. Regarding thermal performance, in the colder climate (ZB 01), roofs with resistive thermal insulation obtained better PHFT and thermal load results, particularly those with low solar reflectance tiles. On the other hand, in the hot climate (ZB 08), cool roofs without resistive thermal insulation achieved better thermal performance indices. As for the reduction in external surface temperature and heat emissions, it was observed that the use of cool roofs led to the greatest reductions in these parameters in both bioclimatic zones.