Estimation of regional anthropogenic heat from air conditioning systems and related devices in metropolitan commercial districts of Japan

Abstract

With the expanding urban areas and increasing elderly population in Japan, anthropogenic heat poses substantial threat to human health. Air conditioning systems contribute to the anthropogenic heat from buildings. However, information regarding the heat characteristics of these systems is inadequate. In the present study, we developed a method for estimating anthropogenic heat from air conditioning, which accounts for most of the artificial heat from buildings during summer, to include artificial anthropogenic heat from surrounding buildings in the local heat risk assessment. The estimation results for commercial areas in Japan using the developed method showed that latent heat from air conditioning is substantially higher than sensible heat, and there was a difference in heat emissions between daytime and nighttime and between weekdays and holidays. A comparison of the calculation results of our method and those of previous studies showed no major differences in the orders of magnitude. With regard to the change in the amount of air-conditioning anthropogenic heat in the region, a directly proportional relationship was found between the outdoor temperature and the amount of air-conditioning anthropogenic heat. These results are useful for assessing the summer heat risk in urban areas and developing methods to mitigate the risks posed by urban heat.