Systematic review of the climatic and non-climatic benefits of green roofs in urban areas

The concentration of human activity and buildings in cities, combined with the general lack of green spaces, give rise to multiple sustainability challenges. At the same time, cities have become important arenas for decarbonization efforts. Green roofs have emerged as a promising option to alleviate this multitude of sustainability challenges though the diverse benefits they can provide. This study systematically reviews 386 peer-reviewed studies across eleven benefit categories, spanning climatic benefits (e.g. energy and greenhouse gases emissions savings, carbon sequestration and storage), as well as non-climatic benefits such as noise and air pollution mitigation, stormwater retention, and improved biodiversity and human wellbeing. The literature shows that green roofs can provide all of these benefits through different mechanisms, but that the actual magnitude of benefits depends on various factors. Although intensive green roofs generally perform better across almost all benefit categories, the available evidence is currently dominated by literature on extensive green roofs (80 % of reviewed articles). Similarly, for most benefit categories the bulk of the evidence comes from modeling and simulations, rather than experimental studies in real-world conditions. There are notable research gaps in terms of long-term studies that explore benefit delivery over long periods of time, and case studies from the global South.