Improving urban thermal environments by analysing sensible heat flux patterns in zoning districts

This study developed a method of improving Seoul's thermal environment by focusing on sensible heat flux and types of land-use and cover to mitigate the urban heat island (UHI) effect. First, the relationships between the sensible heat flux in summer and (a) the land cover ratio, and (b) the heights and densities of buildings in different land-use zoning districts were identified and analysed. The rationale for improving the thermal environment was then considered based on the physical relationships among heat, space, and the thermal-environment type. Energy budget distribution data were then used to identify an optimised land-use plan to mitigate the UHI effect. Spatial data describing the physical elements in land-use zoning were then generated using high-resolution images of the sensible heat flux distribution and directly correlated to existing land-use and thermal comfort. Finally, a K-means clustering analysis was employed to determine the unfavourable and favourable thermal areas in each zoning district based on correlated sensible heat flux data. The results indicate that the highest concentration of unfavourable thermal areas of all studied zoning districts was neighbourhood commercial districts, which accounted for 9.9% of the total identified unfavourable thermal areas, whereas the lowest level of sensible heat flux was observed in single-family residential areas. This study thus developed a basis for a spatial planning framework that can be used to improve the thermal conditions of cities and encourage summer energy savings using zoning-based requirements. •Seoul's current land use zoning districts do not reflect their thermal environment.•We suggest a way to improve urban thermal environment in terms of sensible heat flux and land use zoning districts.•We extract the unfavourable and favourable thermal areas for thermal zoning map.•Green and residential areas with lower building heights and density have lower sensible heat flux levels.•Thermal zoning can contribute to improving residents' thermal comfort and reduce UHIE, being out of only land use efficiency.