Effects of green spaces on urban microclimate in residential areas in hot and humid climates

Abstract

Urbanization diminishes and fragments green spaces. Thus, it contributes to the degradation of the environment. Urbanization also contributes to the creation of urban heat islands. Housing schemes should have green spaces that are capable of mitigating urban heat islands. Nowadays, a terraced housing neighbourhood is the major type of housing scheme in Malaysia. However, the measurable influence of green spaces is hard to quantify. The aim of the research is to quantify the cooling effects of urban green spaces in a residential area in a tropical region. In consideration of a location, layout, landscape component and built year, Bukit Indah, Johor is chosen as a study area. The study focuses on the layout, land use coverage ratio, and cooling intensity of green spaces by using the three-dimensional microclimate model ENVI-met. A review of the literature in this field identified basic information about urban heat islands and mitigation methods and tools. Three focus areas with a dimension of 240 x 240 metre are chosen for detail comparison analysis in a neighbourhood scale within the study area. Those three areas contain different types of green space layout and coverage ratio, specifically, neighbourhood park, play field, play lot, recreational yard, and road side plantings as a parameter. Through the comparative study based on the different combination of parameters, it is concluded that urban green spaces in the study area mitigate urban heat islands by 1◦C. In this case, a better cooling effect is found with interconnected green spaces, and terraced housing blocks should be aligned parallel with the prevailing wind. This is because the cooling effectiveness is limited beyond the boundary of the green spaces but the wind can cool the area approximately 1◦C. The result can contribute to zoning, building and landscape law where urban planners, architects, and landscape architects use climatological data as a basis for landscape design in a residential area.