Temperature Variation in the Urban Canopy with Anthropogenic Energy Use

Abstract

One of the detrimental effects caused by the urban warming is the increase of energy consumption due to the air conditioning of buildings in summer. In the cities of United States, the urban warming is surmised to increase the peak electric energy demand by 3 to 6% with 1.0 °C temperature rise (BRETZet al.,1998). This increased rate of demand is estimated up to 3%/°C in recent years in Tokyo, and about 1.6 GW of new demand is required as the daily maximum temperature increases by 1.0 °C in the greater Tokyo area (SAKAI and NAKAMURA, 1999). Most of this huge demand of summer electricity is caused by the air-conditioning systems, and is considered to be one of the common characteristics in big cities of Asian countries. From the viewpoint of the reduction of CO2emission to mitigate the global warming, this huge demand should be reduced through the control of the urban warming There were model results that analysed the relation between anthropogenic heat and temperature increase in Tokyo (URANOet al.,(1999), ICHINOSEet al.,(1999) etc.). However, they used mesoscale model only with static data of anthropogenic heat. Their results are too coarse, because the temperature in the city block highly depends on its structure (MURAKAMIet al.,2000) and the anthropogenic heat release dynamically depends on the ambient temperature. In the present study, a multi-scale numerical simulation system is developed to evaluate dynamically the increase of energy demands caused by the urban warming, and a case study is carried out for an urban canopy over a densely urbanized area in Tokyo.