A Green Roof Test Bed for Stormwater Management and Reduction of Urban Heat Island Effect in Singapore

A green roof test bed, established at the Nanyang Technological University in Singapore, was used to investigate its benefit for storm water management and urban heat island effect mitigation. The system comprised 3 units, 2 in the form of vegetated roofs and the other a bare roof. The system was equipped with automatic monitoring devices for measuring the hydrological data. Continuous data monitoring on the roofs was conducted to evaluate the thermal and hydrological effects. The study shows that the green roof test bed can significantly reduce the roof surface temperature (by an average of 7.3ºC) and lower the ambient air temperature (by an average of 0.5ºC) when compared with a bare roof during day time hours (from 10:00 am to 4:00 pm). The ability to reduce and delay the peak runoff was demonstrated by using a typical rainfall event with 18 mm depth. The designed system is useful in evaluating both thermal and hydrological benefits of a green roof system in tropical areas and can offer guidance to local managers in mitigating the urban heat island effect and designing storm water management strategies.