Evaluation of green roof performances for urban stormwater quantity and quality controls

ABSTRACT

Rapid urbanization in the recent decades has quickly fuelled up the process of global warming. Many mitigation measures have been formulated and implemented in order to tackle the effect of global warming. Green roofs (roof with vegetated cover) have been proposed and implemented by various countries as one of the new environmentally friendly innovation. This paper evaluates the qualitative and quantitative performances of an extensive green roof system under tropical climate. Simulations showed that the peak discharge of stormwater run-off was reduced up to 26% in relation to concrete tile roof. Its reduction ability was decreased for storms with intense rainfall. Increment of pH was observed for the green roof run-off, and the run-off quality ranged between class I and II under Malaysia National Water Quality Index (WQI). High concentrations of phosphate were observed in the run-off samples, which showed that substrates (fertilized planting soil) might be the potential contributor. Findings indicated that there was a reduction up to around 5% for indoor temperature of the building after installation of the extensive green roof system.

Keywords:

• Green roof
• peak discharge
• run-off quality
• tropical climate
• Water Quality Index

Acknowledgements

The authors acknowledge Humid Tropics Centre (HTC), Kuala Lumpur and Department of Irrigation and Drainage of Malaysia (DID) for their financial support and collaboration in succeeding this green roof demonstration project. Besides, technical guidance and advice from ZHL Engineers Sdn. Bhd are highly appreciated.

Disclosure statement

No potential conflict of interest was reported by the authors.