Spatiotemporal variations in cold waves and the impacts of UHI on building loads during cold wave periods in Tianjin, China

The outbreak of cold waves often causes a rapid decrease in temperature and a sharp increase in the heating load demand of urban buildings, imposing enormous pressure on the energy and power systems of megacities. In this study, the spatiotemporal variations in cold waves were analyzed over a 30-year period (1991–2020) in Tianjin, China. Based on the above study, three typical cold wave (CW) events were selected, the rural weather stations were selected using satellite-based methodology, and the impacts of UHI effect on heating loads of residential buildings during CW periods were evaluated by simulating the hourly heating loads during CW and non-CW periods. The results show that the UHI intensity (UHII) was lower during CW periods than non-CW periods. The UHI effect reduced urban heating loads by 8.72% compared to rural areas during CW periods. During high-load periods (18:00 (Beijing time) to 07:00 the following day), urban heating loads were 10.24% lower than rural areas, while urban heating loads were 11.65–16.04% lower than rural areas during non-CW periods. Therefore, during CW periods, the UHII weakens, and its impacts on residential building loads are reduced. Practical application This study provides the variations of UHII during typical CW events in cold climates, and evaluates the impacts of UHI effect on residential heating loads. The response of the heating load variations in residential building to UHI effect during CW periods should be comprehensively considered to improve the fine-level of heating operation regulations, especially in urban areas in cold climates, to reduce the heating energy consumption and emission of buildings.