EFFECT OF ROOFTOP GREENERY ON OUTDOOR MEAN RADIANT TEMPERATURE IN THE TROPICAL URBAN ENVIRONMENT

Abstract

Field measurement was conducted to collect plant and meteorological data on a rooftop in Singapore. Three roof garden plots were set up. Concurrent measurements of plant evapotranspiration rate (ET) and shrub albedo (SA) were made from May 2014 to December 2014. Results show that significant reductions in air, surface and mean radiant temperature (Tmrt) can be observed in the presence of rooftop greenery. An empirically derived model was developed to establish the relationship between Tmrt reduction and plant traits such as ET and SA during periods of high solar irradiance (R2 = 0.851). The Tmrt prediction model was validated with 150 data points and was able to estimate Tmrt with reasonable accuracy. A plant selection chart based on the regression model was developed to enable plant selection by referencing ET and SA traits and their resultant Tmrt reduction potential.