Urban form, building characteristics, and residential electricity consumption: A case study in Tainan City

Which urban form factor most affects household electricity consumption? This study investigated the relationships between urban density, community layout, and land use factors and household electricity consumption simultaneously, along with building characteristics and demographic indicators. The study site involved 231 communities located in the former provincial area of Tainan City, Taiwan. Due to the area's subtropical climate, air conditioning accounts for approximately 40% of the total yearly household electricity consumption. Of the urban form factors examined, greater population density was most strongly associated with lower household electricity consumption, followed respectively by greater urban canyon narrowness, or higher height to width ratios, and greater percentages of vacant space and building land use. Notably, both urban canyons and building land use percentages were associated with decreased consumption only after increasing past threshold levels, specifically a 1.5 height to width ratio and 40.7%, respectively. In addition, building characteristics, namely smaller household living areas and greater building age, were most strongly connected with lower household electricity consumption. In contrast, larger household living areas were linked with decreased household electricity consumption/floor area, revealing the importance of lower energy intensities of sizable scales. Of the demographic indicators studied, higher percentages of older adults were associated with lower household electricity consumption. Concerning urban form, the findings suggest that to reduce residential energy usage in a subtropical climate, buildings should be clustered to maximize the inter-building shadows resulting from narrower urban canyons, while simultaneously increasing non-built land use percentages in the adjacent areas.