Vertical greenery systems for the energy retrofitting of buildings in Mediterranean climate: a case study in Catania, Italy

The increasing awareness of issues like climate change and reduction of available fossil resources moves scientific research into the development of new technological solutions in order to reduce the energy and environmental impact of buildings. Hence, in recent years, key concepts such as energy saving and environmental sustainability affected both the design of new buildings and the retrofitting of existing buildings. The present study aims to evaluate the energy behavior of an existing building in Mediterranean area, and to quantify the potential contribution provided by retrofitting solutions implying the adoption of green roofs and green façades. Dynamic simulations, validated by comparison with experimental results, show that a green façade with dense foliage allows a reduction by 1.7 °C in the indoor air temperature and by 1.5 °C in the inside surface temperature, if compared to a traditional retrofit solution for the envelope. Furthermore, the outside surface temperature is reduced by 2.9 °C, and the cooling load is reduced by 32%. These results suggest that green façades are a viable solution to mitigate current environmental issues in buildings. Lower energy consumption corresponds to lower pollutants emissions and to economic savings in the use of the building.