Impact of forms in balcony designs on the indoor thermal environment and energy efficiency of residential building at Dhaka

The designs of open and closed balconies significantly impact the thermal performance and energy efficiency of residential buildings in Dhaka City by influencing indoor temperature regulation and energy consumption. Closed balconies, with better insulation and strategic placement, enhance energy efficiency and thermal comfort compared to open balconies. This study investigates the impact of balcony design on the thermal performance and energy efficiency of residential buildings in Dhaka, Bangladesh, a tropical wet and dry climate zone. The research employs both experimental and comparative methodologies, focusing on real-time measurements of indoor air temperature and relative humidity (RH) across different balcony configurations, including open and closed balconies. The study examines the effects of balcony orientation, window-to-wall ratio, and insulation on indoor thermal comfort and energy consumption. Data were collected during both heating and non-heating days from three residential buildings: one with an open balcony and two with closed balconies. The results underscore the critical role of closed balconies in reducing temperature fluctuations and enhancing indoor comfort, acting as effective thermal buffers. Notably, south-facing closed balconies, especially those with smaller windows and improved insulation, demonstrated the greatest energy savings, reducing cooling loads by 5%–12% and up to 27% with insulation. Moreover, closed balconies with high thermal insulation were found to be more energy-efficient than open balconies, irrespective of their insulation status. These findings emphasize the importance of balcony design in optimizing thermal comfort and energy efficiency in residential buildings, particularly in tropical climates. Properly designed closed balconies, with attention to their orientation and insulation, provide significant benefits in reducing energy consumption while maintaining a comfortable indoor environment. The results offer valuable insights for improving residential building designs in Dhaka and similar climates, contributing to energy-efficient building practices that could be applied globally.