Effects of Interior and Exterior Shading Elements on the Indoor Thermal Environment for Buildings in a Semiarid Climate

In semiarid climates, buildings with extensive glazing often become overheated by direct solar radiation in the summer. Careful selection of shading devices (SDs) is crucial to mitigate this issue. This study is a comprehensive evaluation of the indoor thermal performance of various internal and external SDs in a semiarid Indian city. A total of 150 simulations using EnergyPlus were conducted for windows with no shading (NS), fixed shading elements [egg-crates (ECs) and overhangs (OVs)], and movable SDs [louvers (LVs) and internal blinds (BLs)]. Such parameters as the window/wall ratio (WWR), the window facade direction, the slat angle of LVs and BLs, and the OV depth were varied. Indoor thermal performance was assessed for windows facing south and west before the monsoon (May) and in winter (December). Results indicated that LVs and BLs with a 45° slat angle offered superior thermal conditions, reducing mean radiant temperature (MRT) and indoor air temperature by up to 3.0°C and 1.5°C, respectively, for west-facing windows with larger WWRs in summer. Moreover, LVs at 45° showed better reduction in cooling energy consumption than NS conditions (from 7.5% to 16.8% for west-facing windows) at varied WWRs compared with other SDs. Increasing the OV depth to 1 m reduced window heat gain rates but had minimal impact on indoor air temperature and MRT. This study has implications for buildings in similar climates, where summers are hot and winters are mild.