A lifecycle analysis approach to the impact of green roofs on the structural and thermal performances of buildings

Buildings account for more than 40% of global energy consumption and up to a third of global greenhouse gas emissions in developed and developing countries. Electricity is currently the primary energy used for cooling buildings and appliances, but most countries use fossil fuels for heating. Both energy sources cause significant CO2 emissions. Plants and vegetation improve air quality and reduce greenhouse gas emissions directly by absorbing greenhouse gases such as carbon dioxide from the atmosphere or indirectly by reducing energy use. Further, plants reduce the roof temperature by providing shade on roof surfaces. Large-scale implementation of rooftop gardens substantially reduces energy consumption and ultimately lowers energy costs but impact the overall weight of the building and require additional construction cost. Therefore, the impact of green roofs on various structural and thermal performances of buildings varies for extensive intensive or semi-intensive systems. These interacting impacts warrant a lifecycle analysis to optimize the extent of green roof applications concerning sustainability performance measures, including energy, emissions, water, and waste. This paper addresses the lifecycle analyses of green roofs in the hot summer Mediterranean climate like Rome in Italy or similar cities in the region. The target climate is essential to indicate the value of green roofs in warming climates around the globe. Moreover, results translate energy consumption to releasing greenhouse gas emissions and measures of water and waste related to structural or thermal operations. Conclusions enable building professionals to assess the challenges and opportunities of green roof applications on new and existing buildings.