Vegetation as a passive system for enhancing building climate control

Abstract

Building indoor air temperature depends on several different parameters
\nrelated to the climate of the region, the building itself and its use. The main
\nparameters influencing the microclimate are: external air temperature and relative
\nhumidity, incident solar radiation, long wave radiation exchange between the building
\nsurfaces and its surroundings, incidence and speed of the wind, air exchanges,
\nphysical and thermal properties of the building’s envelope materials, design variables
\nsuch as building dimensions and orientation, presence of artificial light, electrical
\nequipment. A sustainable technology for improving the energy efficiency of buildings
\nand to mitigate urban heat island is the use of green roofs and walls. The green
\ntechnology can allow the physical shading of the building and promote
\nevapotranspiration in summer and increase the thermal insulation in winter. An
\nexperimental test was carried out at the University of Bari (Italy). Three vertical walls,
\nmade with perforated bricks, were tested: two were covered with plants (one with
\nPandorea jasminoides variegated, the second with Rhyncospermum jasminoides) while
\nthe third wall was kept uncovered and used as control. A system composed by a data
\nlogger and sensors was used to measure and record the following parameters:
\ntemperature of the wall surface under solar radiation and of the surface on the other
\nside of the wall, solar radiation falling on the wall, and external air temperature. The
\nuse of the green walls during cold months allowed increasing the thermal insulation
\nperformance of the walls by keeping the external surface temperature in nighttime
\nhours up to about 2.8°C over the surface temperature of the wall not covered with
\nplants.