Hygrothermal potential of applying green screen façades in warm-dry summer mediterranean climates

Abstract

Green screen façades (GSF) remain an unexplored field of study in warm-summer climates with Mediterranean conditions. This research aims to establish whether or not these thermal comfort façade systems are worth developing in cities with dry summers and a high range of thermal oscillation. A comparative study of four buildings´ green screen façades in Santiago de Chile was carried out, with different orientations and plant species, both in type and state of maturity. Temperature and relative humidity outside and inside the cavity were measured during summer days. It was observed that, during the day, interior relative humidity was higher while the temperature was lower, reverting this behaviour during the afternoon and night. This result accounts for the existence of two different daily periods: passive cooling through evapotranspiration in the presence of solar radiation - reaching up to an 8°C temperature reduction and a 30% increase of the relative humidity - and passive heating in its absence. The results show that the determining parameters in the behaviour of a green screen façade in a temperate-warm climate are, first, the orientation of the façade, and second, the density of foliage. Regarding orientation, it was also found that the sun exposure was directly proportional to the performance of a green screen façade.