Heat transfer reduction in building envelope with green façade system: A year-round balance in Mediterranean climate conditions

This study focuses on the thermal behaviour of a building prototype equipped with an evergreen green façade. The results of a two-year experimental campaign carried out under Mediterranean climate conditions are presented. Heat fluxes in the green covered wall and in the bare wall were analysed. Their comparison allowed finding out the energy saving, in terms of heat flux reduction through the wall, obtained through the use of the green façade. The energy benefit was evaluated throughout the year, differences between warm and cold periods and between times of day were pointed out. In the warm periods, energy saving was recorded mainly at daytime, while in the cold periods at night-time. The evergreen green façade allowed remarkable energy saving in wintertime as well. The monthly mean energy saving resulted equal to 8.19 MJ m−2. The maximum benefit was achieved in July, 17.24 MJ m−2, while the minimum in January, 2.33 MJ m−2. The green façade provided an annual energy saving equal to 28.5 % compared to the un-vegetated wall.