城市热岛效应对天津市居住建筑供暖和制冷负荷的影响

城市热岛效应已对建筑能源需求产生了重要影响,评估城市热岛效应影响下建筑的真实能耗需求及城乡差异对既有建筑的节能调控和未来建筑的方案设计都具有重要意义。论文以天津自动气象站2009—2017年逐时观测数据为基础,应用卫星遥感选站方法,选取天津市区周围4个有代表性的乡村参考气象站,对典型居住建筑全年逐时负荷进行了动态模拟,定量评估了城市热岛强度对不同时间尺度(年、日和小时)建筑负荷的影响。结果表明：① 随着城市热岛强度(I_UHI)的增强,城市居住建筑供暖负荷减少、制冷负荷增加,且年平均供暖负荷的减小幅度大于年平均制冷负荷的增加幅度。I_UHI每上升1 ℃,城市年平均供暖负荷较乡村减少4.01 kWh/m²、年平均制冷负荷增加1.05 kWh/m²。② 冬季供暖期和夏季制冷期逐日负荷变化表现为：供暖期的高负荷时段主要集中在12月下旬至翌年1月下旬、制冷期为7月下旬至8月上旬,高负荷时段城市日平均供暖和制冷负荷分别较乡村约减少10%、增加6%。③ 日内供暖负荷和制冷负荷小时变化均表现为夜间强于白天。在供暖期和制冷期,北京时间18:00至次日07:00时段无论在城市或是乡村都是高负荷时段;11:00至15:00时段在供暖期是低负荷时段,而在制冷期是高负荷时段,这可能与气温和供暖制冷需求有关。研究表明,应充分考虑小时、日尺度热岛强度对用能的影响,提高供暖和空调运行调控的精细化水平,以期达到降低供暖和制冷能耗的目的。

Impact of urban heat island effect on the heating and cooling loads of residential buildings in Tianjin City,China

The urban heat island (UHI) effect has had an important impact on building energy demand in big cities. It is of great significance, therefore, to evaluate the impact of the UHI on building energy demand in a metropolis in order to save energy for existing buildings and to better design for future buildings. Based on the hourly data from automatic weather stations and four representative rural weather stations selected by satellite remote-sensing method, the impacts of urban heat island intensity (I_UHI) on building heating and cooling loads of different time scales (annual, daily, and hourly) in Tianjing City were evaluated by simulating hour-by-hour loads of the typical residential buildings. The results show that: 1) The heating loads decreased and the cooling loads increased with the increase of the I_UHI in the past nine years. The decreased magnitude of the yearly heating load was larger than the increased magnitude of the yearly cooling load. When the I_UHI increased by 1 ℃, the annual mean heating loads decreased by 4.01 kWh/m² and the annual mean cooling loads increased by 1.05 kWh/m² in the urban areas compared to the rural areas. 2) The heating loads were the highest in the period from late December to late January of the following year, and the daily mean loads in the urban areas were about 10% lower than that in the rural areas. The cooling loads were the highest from late July to early August, and the daily mean loads in urban areas were about 6% higher than that in the rural areas. 3) Both heating and cooling loads were higher during the nighttime than daytime. The period from 18:00 to 07:00 Beijing Time was the high load stage in the urban and rural areas, regardless of heating period or cooling period. From 11:00 to 15:00 Beijing Time, however, the loads were low in the heating period but high in the cooling period, which may have been caused by changing temperature and the different heating or cooling demand of the urban residents. Therefore, the impact of UHI on hourly and daily building loads should be fully considered to promote the effective management of urban heating and cooling operation for reducing building energy consumption in big cities of northern China like Tianjin.