A PILOT GREEN ROOF RESEARCH PROJECT IN SINGAPORE

In an effort to promote green roofs in Singapore, the National Parks Board and the Housing Development Board of Singapore jointly embarked on a pilot project to install a green roof on the existing roof of a multi-storey carpark in a public housing estate. Serving as a demonstration and research site, this is also the first significant green roof installation in Singapore. This paper describes four distinct green roof systems used in the installation, and the results of various studies conducted in conjunction with the project. The studies focused on the evaluation of suitable plants, the associated thermal benefits, and air quality changes arising from the installation. For the study on suitable plants, the estimated daily atmospheric water deficit experienced showed that plants experienced irregular periods of depleted water in the root zone, hence pointing to the need to use drought tolerant plants even under humid tropical conditions. The evaluation of environmental benefits compared conditions on the roof before and after the installation of the green roofs. The green roofs installed significantly reduced the amount of visible radiation recorded on the facades of residential apartment blocks directly facing the multi-storey carpark, thereby reducing glare and improving visual comfort of the occupants. The use of infrared thermal imagery and thermocouple temperature sensors showed significant differences in surface temperatures between greenery-covered, or exposed surfaces. Marginal differences in ambient air temperature were recorded. The evaluation of air quality changes, looking at concentrations of acidic gaseous pollutants and particulate matter, showed variable results. The acidic gaseous pollutants sulphur dioxide and oxides of nitrogen showed marginal reduction following installations. The mass concentration of particulate matter, PM10 and PM2.5 increased significantly after installation, but number concentration had decreased marginally