Contribution of green roofs to energy savings in building renovations
Júlia G. Borràs, Carlos Lerma, Ángeles Más, Jose Vercher, Enrique Gil
Abstract
Reversing the consequences of climate change and achieving more resilient societies involves reducing CO2 emissions and energy consumption, especially in sectors as important as construction. Green roofs, due to their particularities, imply a series of benefits, among which energy saving stands out. This implies a reduction in the consumption of resources and in CO2 emissions, more evident in the case of the refurbishment of buildings. A comparison is proposed between the energy savings obtained by renovating only the roof and renovating the entire thermal envelope. This is done with three roof construction systems (including two green roofs) and in 6 Spanish cities that represent different climatic zones. The novelties provided by this research are based on the comparison of both renovation cases to obtain the influence of the roof with respect to the thermal improvement of the envelope. The energy savings obtained by renovating the roof are very similar in all cities, but after renovating the entire envelope, the savings increase as the climate gets colder. Determining the most influential variables in these savings, as well as the influence of the roof, allows choosing the most appropriate construction techniques to optimize the energy renovation of existing buildings.