Effects of Green Roof in Reducing Surface Temperature and Addressing Urban Heat Island in Tropical Climate of Malaysia

Urban heat island (UHI) in cities across Malaysia has worsened due to rapid development and construction. Previous research highlight temperature difference between Putrajaya and its suburban neighbouring area is as high as 5˚C. Green roofs in urban areas can be used as a green intervention strategy to reduce UHI impact by increasing air moisture and surface wetness through its plants, which consequently decreases surrounding air and surface temperature. Green roofs also provide additional insulation that reduces heat transfer into buildings, therefore reducing cooling demand and operational energy in buildings. Conventional building roofs in tropical climate have measured surface temperature up to 60˚C, compared to surrounding irrigated grass and water bodies that are measured as low as 15˚C. This paper compared surface temperatures of green roof and conventional non-green roof case studies in a tropical climate setting, to combat urban heat island effect. A triangulation technique was adopted, using a case study analysis with an in-depth structured interview and physical fieldwork investigation. The findings concluded that green roofs had significantly lower surface temperature compared to non-green flat roof. This paper provides evidence that supports green roof as a green intervention strategy in reducing urban heat island and encourage building designers to maximize under-utilized spaces of roofs to increase urban greenery coverage.