Thermal insulation effect of green façades based on calculation of heat transfer and long wave infrared radiative exchange

Abstract

Vertical greenery systems offer an alternative method to reduce heat transfer through building envelope. This study conducted three experiments of green façades with different leaf coverage areas i.e. Bare Wall (BW) model, 50% leaf coverage area (GF-50%), and 90% leaf coverage area (GF-90%) to investigate its effect to overall heat transfer, radiative heat transfer, and Long Wave Infrared Radiative (LWIR) exchange on the wall. Calculation on the average of overall heat transfer showed BW model gained 2.10 W/m2 heat from outdoor environment. While GF-50% and GF-90% received 1.81 W/m2 and 1.46 W/m2, respectively. The contribution of leaf coverage area indicated BW absorbed 4% and 7% radiation heat transfer higher than GF-50% and GF-90%, respectively. The LWIR exchange of GF-90% was 6.76 W/m2 and 10.18 W/m2 lower than other. The findings lead to conclusion that increasing leaf coverage area of green façade can improve thermal insulation capacity of building wall.