SOMBREAMENTO X EXPOSIÇÃO AO SOL

ANÁLISE DO BALANÇO DA RADIAÇÃO SOLAR EM FORMAS INCLINADAS E DESLOCADAS

Abstract

This paper aims to evaluate if the reduction of thermal loads by self-shaded surfaces can overcome the increase of thermal loads by opposite facades with the same area exposed to the sun. From a prismatic base form of 1:1:2 (WxHxL), four different scenarios are created by adopting the design operations Shift and Skew and by alternating the shading between the largest and the smallest facades. Numerical simulations are carried out by means of Rhinoceros, Grasshopper and Ladybug to calculate solar radiation (kWh/m²) – total and by facade – on each form, considering four solar orientations and six different Brazilian climatic contexts. The results indicate that Fortaleza and Florianopolis present, respectively, the highest and the lowest total solar radiation for all orientations and scenarios. In general, the skewed forms present higher solar gains than shifted forms, due to the greater surface area exposed to the sun. Thermal loads are higher when self-shading is adopted on the largest façades. Furthermore, skewed and shifted forms present a remarkable increase of the solar gains compared to the base form. We conclude that the reduction of the thermal loads by self-shading is significantly inferior to the increase of the solar contribution due to the greater exposure to the sun in the opposite façade. Therefore, the adoption of the self-shading does not compensate in these cases.