Embedding "substrate" in environmental assessment of green roofs life cycle: evidences from an application to the whole chain in a Mediterranean site.

A classical LCA methodology is here applied to green roofs including in this analysis also the whole life cycle of the substrate, that represented a lack of previous LCA studies on green roofs. This inclusion will allow a complete and proper application of the LCA methodology to achieve an environmental accounting of the “green roof” performance. We have here chosen to approach the problem by analysing a specific substrate, that is used within an actual extensive green roof. Afterwards, we have applied the LCA methodology to the whole actual extensive green roof whose substrate under analysis is part of. In this manner, we achieved an environmental accounting of the “green roof” performance. In this study the contribution of production, maintenance and end of life to the whole environmental burden of extensive green roofs has been illustrated as well. Furthermore, in the present work we have speculated about the required level of data for allowing a complete LCA analysis of a green roof. Particularly, we have focused here our attention on the role of fertilizers used for the green roof maintenance and on the disposal of substrate, which seem to play a significant role in the whole LCA balance.