NAME OF PRESENTER: KINGA OWCZAREK (SRI) TITLE Study on Rainwater Retention Effect of Extensive Green Roofs KEY WORDS Green roof, Stormwater management, Retention, Runoff 1.1 INTRODUCTION Green roofs are roofs on which vegetation is intentionally grown. The installation of a green roof has the potential to bring environmental, economical and aesthetical benefits such as reduction and delay of storm water runoff, improvement of the storm water runoff quality, mitigation of the heat island effect, air quality improvement, enhancement of biodiversity, energy savings, and provision of recreational and agricultural spaces, if carefully designed to specific climate conditions. This work concentrates on reduction of the storm water runoff (rainwater retention) effect of extensive green roofs. 1.2 OVERVIEW OF METHODOLOGY The investigation of the retention effect is based on continuous monitoring program of nine different green roof configurations (on site experiment) and five different green roof designs (laboratory experiment). Researched green roofs are constructed varying parameters such as depth of the substrate and drainage layer as well as vegetation and material type. 1.3 PRELIMINARY FINDINGS The results show that the extensive green roofs can reduce runoff by retaining more rainwater daily, monthly, yearly or per an individual rain event in comparison to conventional roof. Rainfall time and intensity as well as substrate moisture content influence significantly rainwater retention. Storm water runoff reduction is greater for the roofs of greater substrate depth. Further analyses of data series are in progress.