Abstract
Many studies have been conducted to ascertain the implementation of green roofs provides many advantages including extended roof life, increase of water run off quality and mitigation of urban heat island effect. Green roofs also have a carbon reducing benefits as they have the capacity to sequester carbon dioxide (CO2) in different part such as plant biomass and substrate. However, the lack of experimental data for tropical climate makes it difficult to evaluate eventually the suitability of green roofs as a heat mitigation and carbon emission reduction strategy in Malaysia. To explore the thermal performance of green roof, field measurement was carried out in Heriot-watt university the Malaysia’s first purpose – built green campus in Putrajaya.
The study measured solar radiation, outdoor and surface air temperature to determine the thermal performance of the green roof growing media (soil). Moreover, the empirical tests were compared between bare roof and two different soil thicknesses green roof (12 cm and 28 cm) to find out the effectiveness of green roof on heat transfer and carbon emission reduction with regard to surface and ambient air temperature and relative humidity. The temperature and relative humidity sensors were installed from 1m above the green roof surface to green roof layers.
The results showed that green roof influenced on surface and ambient air temperature reduction significantlywhere the ambient air temperature above green roof (12 and 28 cm depth) was between 1-2 °C lower than that for the bare roof. As a result, the findings showed that vegetation was more effective in reducing indoor airtemperature where the more thickness was applied in the green roof. Thus, the study strongly suggests that green roofs are beneficial to moderate the air temperature in hot and humid climate.
