Impact of urban heat island on high-rise residential building cooling energy demand in Hong Kong

This study aims to investigate the impact of urban heat island (UHI) on cooling energy demand in high-rise residential buildings, with a primary focus on cooling -dominated regions. We take Hong Kong, a typical highly urbanised city with a humid subtropical climate, as a representative case. Multiple year -by -year EnergyPlus simulations were conducted using 20 years of actual meteorological data (1999 - 2018) from one urban site and one rural site for a typical 40 -storey residential building. Cross-sectional analyses were performed in interannual, seasonal, and diurnal scales to comprehensively examine the temporal dynamics of cooling -relevant energy impacts of UHI. Regression analyses were conducted to reveal the relationship between UHI ' s energy impact and UHI intensity (UHII). Results show that UHI causes an increase of 6.0% in cooling energy demand for high-rise residential buildings in Hong Kong. Such impact reaches a daily (intra-annual) minimum/maximum of -1.4%/+21.8% (+3.5%/+28.3%) at 5 pm/6 am (in summer/winter) and diminishes by an average rate of 1.7% per decade likely due to the urbanisation in rural regions. Each 1 degrees C increase in UHII causes an increase of 7.9%/ 16.1%/36.9% in seasonal cooling energy demand for summer/transitional seasons/winter, respectively. This study reveals that UHI ' s intricate temporal dynamics can lead to heterogeneous effects on building energy performance. Besides, distinct patterns of UHI-driven cooling energy profiles between high-rise and low -/medium -rise buildings are identified. Moreover, this study underscores the importance of employing multiple yearby -year meteorological data and addressing season -specific nonlinearity in building energy research to ensure the reliability of findings against the backdrop of climate change.