Naturally everything heats up when exposed to solar radiation. A building is no different. During the summer it leads to an increased demand on cooling systems and the energy they require. Studies have shown that the surface of an exterior green wall is up to 10°C cooler than an exposed wall, therefore considerably less heat is radiated inward. Not only do green walls reduce cooling requirements but they also help to mitigate the urban heat island effect. The Sustainability and LEED® Credits sections go into greater detail about this effect and how green walls or living walls help.
Interior green walls also help to save energy during the summer. Through the process known as transpiration plants actually cool their surrounding environment slightly. With each additional plant this increases and therefore a green wall, with hundreds of plants, can reduce the temperature of a room by anywhere from 3 to 7°C. Some studies have shown that interior green walls can cut electricity bills by up to 20%!
During winter the dot-pot living wall system acts as extra insulation. There is an additional layer of air between it and the wall which reduces the amount of heat escaping and cool air coming in.