The surface composition of cities has been modified leaving cities with less shading, evaporative cooling, less rain water storage and infiltration. Climate change is already affecting cities all over the world including London. The intensity of the urban heat island (UHI) effect in London varies from temperatures that range 5–6°C higher but it has been recorded to be up to 9°C. Moreover, the Urban Heat Island effect in London has caused energy for cooling to be 25% higher than in rural. Shifting the thermal properties of surfaces in cities through the use of vegetation is an effective way to reduce the urban heat island effect Furthermore, greenery integrated in buildings has the capability to absorb shortwave radiation, increase the albedo of surfaces and cool ambient air through evapo-transpiration.
The increase of highly urbanised areas not only disconnects its users with the natural world but creates additional environmental and social risks. Vegetation is associated with improved health and well-being and numerous environmental benefits. Biophilia research has focused on understanding the relationship people have with nature and explaining the necessity of people to connect with nature and other forms of life. Furthermore, research has acknowledged that human beings have a necessity to be in contact with nature to be healthy productive individuals.
Green walls have numerous positive environmental benefits and can function as a sustainable approach in already built and new buildings. Green walls can act as a thermal barrier and provide insulation contributing to both heat and cooling loads reduction. To illustrate this, an experiment conducted in Manchester during winter with ivy covered walls registered an air temperature of 0.5°C warmer which translated to 8% energy savings. The energy consumption of a building can also be decreased by vegetated facades through its ability to decrease ambient and surface temperatures. Wall shrubs and climbing plants can regulate temperatures around brick walls playing an important role for retrofitting houses in temperate climates Implementing vegetation on facades is a simple passive strategy to adapt to climate change, regulate urban air temperatures, create constant micro climates, reduce streets’ canyon temperature and mitigate the Heat Island Urban Effect.