Towards green roof implementation: Drivers, motivations, barriers and recommendations

The environmental challenges in cities urge people to explore feasible strategies for resilient, sustainable, healthy and livable built environments, of which designing and building green roof (GR) is an important approach. Whilst extensive studies have been proving GR benefits in energy, environmental and ecological aspects, GR implementation (GRI) for achieving such multi-benefits has received limited attention. In order to facilitate GRI, therefore, this paper aims to delineate factors that can affect GRI. This study conducted a systematic review of 186 published papers from 2000 to 2019, for the identification of drivers, motivations and barriers to the GRI. The results indicate that the drivers to GRI include policy pressure, market pressure, and innovation and technology advancement. Besides, GRI can be potentially motivated by multiple factors including energy efficiency, urban heat island mitigation, roof longevity prolongation, air purification, runoff control, water purification, urban infrastructure improvement, sound insulation and noise reduction, biodiversity increase, recreation and aesthetics, property value enhancement and employment improvement. Nevertheless, GRI can be constrained by several barriers such as a lack of government policy, unsound technological level, unsound economic benefit assessment and individual unwillingness. According, this study proposed strategic recommendations in policy, technical, economic and social aspects, with the considerations of various GRI stakeholders (e.g. designer, engineer, constructor and builder, contractor, building operator, owner, end-user, government agent), to strengthen GRI drivers, foster GRI motivations and overcome GRI barriers. Overall, this study is of significance to inform the people with knowledge of factors affecting GRI, which can further promote researchers to explore interrelationships among multiple factors on the one hand and can further promote decision-makers to develop sound policies on the other for GR adoption.