Assessing the Influence of Urban Form on the Cooling Impacts of Urban Parks : A Case Study in Glasgow

Abstract

Urban Heat Island (UHI) effect has been a growing concern in the UK; therefore, the mitigation of such effects would contribute to sustainable urban development. A review of literature indicates that green infrastructure such as urban parks have proven to effectively regulate thermal comfort and aid in mitigating UHI effects. Parks cool their surroundings through heat exchange and shading. Several studies have explored the cooling effect of urban parks independently using various quantification methods without considering its surrounding spatial form. However, it is necessary to gain a comprehensive understanding of how the park cooling effect mechanism works on its surrounding built up area.

Using Remote Sensing, GIS, and Statistical analysis, 30 urban parks in Glasgow city were examined using buffer rings of 150 m and 300 m to investigate the influence of surrounding urban form to the park cooling effect (PCE). Park cooling effect (PCE) which is referred to as the cooling influence of parks on their surrounding built up areas, can be influenced by both park characteristics and their surrounding built up area. To understand the magnitude of cooling intensity of urban parks to their surrounding urban form, two parameters such as Park Cooling Intensity (PCI) and Park Cooling Distance (PCD) were used in this study. Landsat 8 TIR images were used to examine the Land Surface Temperature (LST) within the buffer zones to obtain PCI and PCD.

Park characteristics includes the area, perimeter, shape index and canopy cover were important factors used to determine the magnitude of cooling intensity of urban parks. Simultaneously, urban form parameters such as Mean Building Height (MBH), Floor Area Ratio (FAR), Canyon Aspect Ratio (H/W) and Sky View Factor (SVF) of the parks surrounding built up area were used to determine its influence on the potential cooling effect. The results found the average cooling intensity of the urban parks of sizes between 1.7 ha and 6.9 ha was 1.6°C while the cooling range was 252.7 m. Additionally, the relationship between the park characteristics and PCI including area, perimeter and NDVI showed a positive correlation except the shape index which negatively correlated with PCI. This suggest that with the increase in area, perimeter and vegetation in parks, there is an increase in PCE, while the decrease in shape complexity can enhance PCE. Urban form parameters however, showed negative correlation with PCI except the FAR which was positive correlated with PCI indicating that the increase in MBH, AR, SVF can decrease the cooling intensity of parks.

The results achieved in this study may contribute to the existing knowledge of park cooling effect and can provide guidance to policy makers on a more equitable urban park planning for climate adaptation on a local scale.