Value can be added to the installation of green walls by designing for a variety of specific benefits. Most green facades are implemented to create an element of aesthetic diversity that adds to the palette of building materials and the surfaces created. Designers of green walls can work at a great range of scales, from the creation of small private space interactions like intimate garden settings, to the monumental scale of a multistory project. Green walls can also be integrated into the entire building site design and utilize multiple systems and forms. Specific benefits can include security, privacy screening, shade, biodiversity, habitat, and even urban agriculture. These design specific benefits are not mutually exclusive.
The greening and preservation of urban space has become an important consideration for cities, municipalities and communities, mostly based on the pressure from increased population density on existing infrastructure. As impervious surface area and building sizes increase to meet demand, water quality, storm water management and Urban Heat Island (UHI) effect have become primary challenges for designers and policy makers.
Urban Heat Island Effect (UHI)
As urban centers grow, ecosystem services become altered and even replaced. Roofs and pavement comprise over 60% of surface area in some cities. These surfaces absorb the sun’s energy and cause urban regions to become warmer than their rural surroundings, forming an “island” of higher temperatures in the landscape known as the Urban Heat Island (UHI). Urban Heat Island effects lead to increased air conditioning costs, air pollution levels, heat and pollution-related illnesses and even death. Natural, pervious surfaces and vegetation can play an important role in the mitigation of UHI effects. According to the EPA, trees and vegetation lower surface and air temperatures by providing shade, and through evapotranspiration. Shaded surfaces, for example, may be 20–45°F (11–25°C) cooler than the peak temperatures of unshaded materials.
Shading and Light Control
Creating shade can be a clear benefit for areas in the public domain like transportation waiting nodes, waiting areas and parks. The combined effects of UHI also apply to these pedestrian areas and not only to building surfaces. Balconies, rooftops, community gardens and patios can all benefit from elements of a vertical green facade or horizontal adaptation. With increasing urban density the control of light pollution becomes an important strategy for mixed use environments and integrated structured parking.