Cooling-related energy uses and adaptive behaviors in high-rise residential buildings in the subtropical climate: A case study in Hong Kong

Abstract

The growing urban population has accelerated the development of high-density cities and high-rise buildings. Meanwhile, cooling energy use is expected to increase, especially in (sub)tropical areas, due to climate change, the rising ownership rate of air-conditioners, and working-from-home during the Covid-19 pandemic. Thus, reducing cooling energy use in high-rise residential buildings is essential for achieving net zero by 2050. However, limited empirical studies are available on cooling energy use of high-rise residential buildings. This study aims to investigate cooling-related energy uses and adaptive behaviors in high-rise residential buildings, particularly, the vertical variation of energy uses and relevant factors. A high-rise student residence in Hong Kong was examined. Four-year electricity meter records in 716 rooms were analyzed to check the statistical significance of the vertical cooling electricity use difference. Long-term in-situ monitoring was applied to obtain environmental and behavioral data with twenty-one residents. A validated building energy model was used to explain the vertical cooling energy use difference. Results show that the annual cooling electricity use declined averagely by 0.8% per floor, which could be mainly explained by the environmental and behavioral factors that changed with building height. The findings will facilitate decision-making on energy efficiency in high-rise residential buildings. • The monitored annual cooling electricity use declined vertically by 0.8% per floor. • The measured outdoor temperature lapse rate ranged from 1.5 to 11.7 K/km. • Fewer extremely hot hours were experienced by residents on higher floors in summer. • Residents on higher floors opened windows more often during the cooling season. • Behavior modes moderated the impact of environmental factors on cooling energy use.