Green facade definition

A green facade is created by growing climbing plants up and across the facade of a building, either from plants grown in garden beds at its base, or by container planting installed at different levels across the building.

Climbing plants can attach directly to the surface of a building, or they can be supported on a structure independent of the building. The use of climbers that anchor themselves to a structure by twining stems or twining tendrils enables a green facade to be installed in front of solid walls or some other structure, to create a partition, privacy screen or sunshade. The degree of density of the facade coverage can be managed to suit the required function. For example, a facade designed to shade a building wall would ideally have greater foliage density than a screen installed near a window that is designed to allow at least partial views to the environment beyond the facade.

CH2-roof-facade.jpgGreen facades are often installed because they provide an attractive look to a building wall, or they may be used to block out a view, or to provide shade for a building. Green facades can create a cooler microclimate immediately adjacent to a building, primarily through direct shading of the building facade, but also from cooling from plant foliage (transpiration of water through the leaves), and evaporative loss of water from the growing medium. All climbing plants will provide some retention of stormwater, shading of the building, protection of its surface, and capture of airborne particulate matter and volatile gaseous pollutants. These benefits will be greater for evergreen species that retain foliage cover year-round.

For multi-level facades, particularly at height, wind can create significant problems for plant attachment. In these settings, twining climbers are preferred over plants that adhere directly to the building facade as the twining stems attach strongly around vertical and horizontal supports. Foliage may still be stripped under extreme wind conditions, so foliage type and size should be matched to the level of exposure and likely wind strengths at the site. In general, the higher the planting on a building, the more extreme the growing conditions are likely to be. Other factors of importance in multi-level facade design include planter box design (volume, substrate, drainage), maintenance access and irrigation system design.

The distinction between green walls and green facades is not always clear. As the design and use of plants on vertical surfaces expands, systems become harder to define. For instance, a ‘hybrid living wall’ system has been created in Adelaide that uses both green wall and green facade technologies. This blurring of definitions is akin to the already acknowledged difficulties in classifying green roof types, where new designs merge what were previously considered different categories.