S07 - Session P1 - Green roof thermal behaviour : a long term monitoring on an experimental green roof

Authors: Philippe Faucon *, Arnaud Fertet, Mayeul Duval

The thermal advantages of green roofs are commonly cited and have been widely studied in the past The results of the research show that extensives green roof can supply an insulation, and are interesting when they are coupled with low weight builidng (like wood constructions), by providing thermal inertia. But extensives green roofs are living component. On question remains : are the thermal advantages and performances the same years after the setting up ? To investigate this question, an experimental test plot where set up in Chatellerault (France) in 2013. This test plot reproduce on one single building 6 types of roofing (20 m² each) : EPDM waterproofing layer, EPDM + gravels, EPDM + extensive green roof substrate whithout vegetation, EPDM +extensive green roof substrate (mainly pouzzolane) planted with several sedum species, EPDM + extensive green roof substrate (mix pouzzolane + 2 type of reuse building materials). For each modality, thermal sensor were putted on the waterproofing layer, in the middle of the substrate, and in the canopy. A thermal flux sensor was added, in order to measure the heat flux. All mesurement were recorded every hours, with a datalogger. Eight years later, the results of typical days (hot summe days or cold winter days) shows that the diffrence between modalities are the same in 2021 than in 2013. Then it's possible to conclue that 8 years after building, the thermal behaviour is the same, and extensives green roof are still fitting the insulation role.