Contribution of green walls to building microclimate control

The Urban Heat Island (UHI) effect induces an excessive use of building cooling systems, increasing the energy consumption, airborne pollution concentration and greenhouse gas emissions into the atmosphere. The Green Walls can be used as passive energy savings systems for controlling the solar heat gain for the buildings in summer and for increasing their thermal insulation in winter, contributing to the UHI effect mitigation. Experimental tests were carried out at the University of Bari (Italy), from August 2014 to February 2015, aimed to analyze the contribution of green walls with two different plant species (Pandorea jasminoides variegated and Rhyncospermum jasminoides) to the building thermal performance. Three prototypes of building vertical wall were built; two walls were covered with plants and the third was kept uncovered for control. The collected data analysis pointed out that in warm days the maximum daylight temperatures observed on the external surface of the walls covered with plants were lower up to 4 °C than the respective temperatures measured on the control wall and during the nighttime of cold days the minimum temperatures measured on the external surface of the walls covered with plants were higher up to 2°C than the ones of the control wall.