Zoysia Soil-Less Green Roof’s Performance: A Life Cycle Assessment

The use of green roofs is demonstrated to improve the energy performance ofbuildings, increase biodiversity, reduce environmental impacts of urban areas, and mitigateclimate change phenomena. T heir use on a large scale is desirable in the coming years.Still, the choice of the most suitable green roof design solution should also consider theimpacts of their production. Within this study, the Life Cycle Assessment methodology wasused to evaluate the environmental impact of a particular typology of soil-less green roofsideated by an Italian company. In this lightweight green roof, the growing medium is replacedby recycled felt layers, filtration is guaranteed by geotextile, and a closed-loop sub-irrigationsystem fertilises the pre-growth lawn placed on the top. The extremely low weight of thissystem suggests an optimal use in building retrofitting scenarios, but its environmentalimplication was not known. The environmental impact of this product has been assessed withan attributional cradle-to-gate approach through four different methodologies (ReCiPemidpoint and endpoint H V1.1, Ecological footprint V1.01, and IPCC 2013 GWP 100y V1.0)using the ecoinvent v3, Agri-footprint 1.0, and ELCD database on the SimaPro 8.4.4.0software. The IPCC method has shown a Global Warming Potential of 7.66 kg of CO2 eq. for1 m2 of Pratotetto® green roof; however, the reuse of waste materials from the textile industrymust be considered.