Impact of urban heat island on the variation of heating loads in residential and office buildings in Tianjin

Urban heat island (UHI) significantly affects the energy demand of buildings. Therefore, it is important to consider UHI effect when evaluating the real energy demand of buildings in urban and rural areas. Based on hourly data observed over the past ten years from automatic weather stations and four representative rural weather stations selected by remote sensing method, the impact of the UHI intensity (UHII) on the building loads at fine time scales (i.e. day and hour) were evaluated by simulating the hourly loads during whole year of the typical residential and office buildings in urban and rural areas. UHII was found to be the main climatic factor affecting the variations in heating load in both residential and office buildings. With a heating-period mean UHII of 2.1 degrees C in the ten years, the daily heating load in urban areas is significantly lower than that in rural areas, which is 10.1 and 7.5% less for residential and office buildings, respectively. For residential and office buildings, the daily heating load has decreased by 34.2 x 10(-3) and 27.7 x 10(-3) kWh/m(2), respectively, for every 1 degrees C increase in UHII. For both types of buildings, the period of high energy consumption in both urban and rural areas was from late December to late January of the following year. The hourly load in residential buildings was high at night and low during the daytime, and the opposite was founded in office buildings. For residential buildings, the period from 18:00 one day to 07:00 the next day was the high load period in both urban and rural areas, whereas the high load period in office buildings was from 07:00 to 19:00. The peak load in residential and office buildings was founded from 05:00 to 07:00 and from 07:00 to 11:00, respectively. Overall, the daily and hourly heating load variations in residential and office buildings response to UHI should be fully considered to improve the fine-level of heating operation regulations, especially in urban areas, to reduce the energy consumption of buildings. (C) 2020 Elsevier B.V. All rights reserved.