The Impact of Orientation on Indoor Thermal Performance in Curtain-Walled Office Rooms : In The Case Of Adama, Ethiopia

Abstract

The trend of constructing a curtain-facade buildings is increasingly common in modern days due to their modern aesthetic and ability to maximize natural daylight. This makes maintaining indoor thermal comfort become even more challenging for cities like Adama which have a hot climates. These buildings have high solar heat gain because of the low insulation and high solar transmittance behaviour of the materials this makes their thermal performance affected by room orientation difference. However, there have been limited studies conducted in Ethiopia to explore how room orientation affects thermal performance. This study investigated the impact of room orientation on indoor thermal performance of selected curtain-walled office buildings in Adama, by analyzing 24 orientation (00 and 3600 have same value) and then giving more focus on the Northwest (NW) and Southeast (SE) orientation based on optimum chart. It uses a mixed-method approach combining physical measurement, occupant survey and computer simulation. Field measurements were carried out during working hours from April to May 2025 twice a day. The results shows that specially in afternoon period SE-facing rooms has a higher air temperature and relative humidity value when compared to NW-facing room. The simulation analysis also confirmed that NW-facing rooms have a higher comfort hours the SE-facing rooms. Also the respondents of the occupant thermal comfort survey revealed that they prefer a cooler condition and they don’t feel comfortable especially in the afternoon. Based on the obtained results, it can be concluded that Northwest (NW)-facing rooms provide better thermal performance and longer comfort hours compared to Southeast (SE)-facing rooms. Therefore, to optimize indoor thermal comfort in curtain walled office buildings in Adama, it is recommended that future office buildings should be oriented along South-north axis (curtain-wall should be in the north side), while for existing buildings southeast-facing facades should use a proper external shading devices and low emission glass, and adapting an orientation-based design strategies can improve the thermal comfort in this climate context.