A green wall is a wall partially or completely covered with greenery that includes a growing medium, such as soil or a substrate. Most green walls also feature an integrated water delivery system. A green wall is also known as a living wall or vertical garden. It provides insulation to keep the building's inside temperature consistent.
It is useful to distinguish green walls from green facades. Green walls have growing media supported on the face of the wall (as described below), while green facades have soil only at the base of the wall (in a container or in ground) and support climbing plants on the face of the wall to create the green, or vegetated, facade.
Green walls may be indoors or outside, freestanding or attached to an existing wall, and come in a great variety of sizes.
Stanley Hart White, a Professor of Landscape Architecture at the University of Illinois patented a "vegetation-Bearing Architectonic Structure and System" in 1938, though his invention did not progress beyond prototypes in his backyard in Urbana, Illinois.
Patrick Blanc, a botanist specialized in tropical forest undergrowth, worked with architect Adrien Fainsilber and engineer Peter Rice implementing the first successful large indoors green wall in 1986 at the Cité des Sciences et de l'Industrie in Paris. In 2005, he created the landmark vegetal exterior wall of the administrative building of the Musée du quai Branly with architect Jean Nouvel.
Green walls subsequently saw a rapid surge in popularity. Of the 61 large-scale outdoor green walls listed in an online database provided by greenroof.com, 80% were constructed in or after 2009 and 93% in or after 2007. Many iconic green walls have been constructed by institutions and in public places such as airports and are now becoming common.
As of 2015, the largest green wall covers 2,700 square meters (29,063 square feet or more than half an acre) and is located at the Los Cabos International Convention Center).