Experimental approach to the contribution of plant-covered walls to the thermal behaviour of building envelopes

The use of vegetation has an important impact on the thermal performance of buildings and on the modification of the urban climate as well, both in winter and summer. Plants absorb a significant amount of solar radiation for their growth and biological functions, functioning as a solar barrier that prevents solar radiation absorption extensively. Their utilization is essential and can considerably improve the microclimate of the built environment. Vegetation planted to cover the external surface of a building is common practice in urban areas. However, up to now, it has not been fully approved as an energy-saving method. Climbers can provide a cooling potential on the building surface, which is very important during the hot periods of the year, especially in warm climates. Hence, the peak temperatures that appear are essentially lower, in addition to the decrease of heat flow losses. In this study the thermal analysis concerns two equivalent building floors that incorporate non-covered and covered with plants wall sections (insulated wall surfaces), respectively. The investigation is carried out during the cooling period in the Greek region. A comparison between the bare and plant-covered surface sections of the walls is conducted via an experimental setup (stationary method). Results are focused on the developed temperature variations and dynamic thermal characteristics of wall surfaces for both cases under investigation. As it is shown, the contribution of plant-covered wall sections is important so that the thermal behaviour of the building envelope can be improved.