Potential for improving green roof performance through artificial irrigation

Historically extensive green roofs were designed for natural precipitation with a plant selection focusing on hardy succulents such as sedums that can survive harsh, water stressed conditions. Although this seems a convenient solution to establish and maintain a green roof system, at a much broader level this does not optimize the functions and performance of the green roof. In this paper the influence of irrigation on green roof functions and performance is presented for an extensive green roof by an extensive literature study. Green roof energy saving potential under Sri Lankan climatic conditions is significant. The average water retention of green roof substrate under different climatic zone conditions in Sri Lankan context is simulated with hypothetical twelve extensive green roof types. Results justify the artificial irrigation requirement and provide key directions to develop water balance model considering locational factors to maintain set soil moisture target.