Green Walls as Retrofitting Measure: Influence on Energy Performance of Existing Industrial Buildings in Central Italy

Industrial buildings in Italy are currently highly energy intensive. Their old age prevents them from complying with current environmental and energy requirements; consequently, redevelopment initiatives should therefore be considered in order to improve the overall performances of these facilities. Within this framework, this research aims to evaluate the results achievable by introducing indirect green façades as retrofitting solutions. Starting from a real case study building located in central Italy, energy simulations were carried out using DesignBuilder, varying buildings’ geometry, dimensions and windows-to-wall ratios as well as greenery coverage percentage. The evidence shows an appreciable potential for green walls to improve the summer performance of industrial buildings, as they resulted in a reduction in cooling energy demand during the summer season of about 14%. Moreover, external surface temperature was reduced by 8°C during the hottest days, ensuring higher durability in building components. Furthermore, indoor air temperature during the summer design week decreased by 0.6 °C. During the winter season, the green façades avoid exploiting free solar gains due to incident solar radiation, and a slight increase of about 4% occurred in heating energy needs. For this reason, the implementation of deciduous vegetation species should be evaluated for industrial buildings located in Mediterranean latitudes.