Life cycle benefits and challenges of large - Scale green roof implementation in a mediterranean compact city: The case of Thessaloniki

Abstract

Green roof installation is considered to be an effective practice in restoring green spaces to high - density urban areas, in an effort to mitigate environmental problems that arise from their growing expansion. The present study attempts to further investigate this claim by assessing the environmental and economic life cycle benefits and challenges of two extensive green roof large - scale implementation scenarios (on existing or on well - insulated roofs) in the compact mediterranean city of Thessaloniki, Greece. In both scenarios green roofs provided energy savings (13-19%), greenhouse gas emissions (22-29%) and waste production (57-60%) reductions but also led to a significant increase in water consumption (279-291%), with performance being better in the latter case. They also accrued significant public economic benefits in both a low and high discount rate scenario, although they were not an efficient choice for private owners in the second one. These results seem to imply that green roofs could potentially be a viable urban green infrastructure solution, if their water use is minimized in a sustainable way and additional state incentives are considered.