Go Green! Green Roofs
A green roof or living roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It also include additional layers such as a root barrier and drainage and irrigation systems. Container gardens on roofs, where plants are maintained in pots, are not generally considered to be true green roofs. The word “green” refers to environmentalism and not the color green.
The new California Academy of Sciences building in San Francisco by Italian architect Renzo Piano. Photographs: © Tim Griffith via archdaily2 Bar House in Menlo Park, California by Feldman Architecture. Photograph: Joe Fletcher PhotographyGreen roofs absorb rainwater and protect the roofs of the buildings from sunlight. They are also helping to lower urban air temperatures and reduce the heat-island effect (An urban heat island is a metropolitan area which is significantly warmer than its surrounding rural areas). Green roofs filter pollutants and carbon dioxide out of the air and pollutants and heavy metals out of rainwater. They also provide a habitat for many creatures.
Mill Valley Cabins by Feldman Architecture. Photographs: Joe Fletcher PhotographySchool of Art, Design and Media at Nanyang Technological University in Singapore by CPG Consultants via archdaily
There are also some financial benefits of green roofs: increase roof life span dramatically, increase real estate value, reduction in energy usage, federal and local tax incentives – for example, a one-year property tax credit is available in New York City, since 2009, for property owners who green at least 50% of their roof area.
L’Historial de la Vendée, a new museum in western France by Plan 01. Photographs: Plan 01
Green roofs are also becoming increasingly popular in the United States, although they are not as common as in Europe.
City Hall in Chicago, Illinois. Photograph: Diane Cook and Len Jenshel
A bus shelter in San Francisco, CA. Photograph: triplepunditToday, it is estimated that about 10% of all German roofs have been “greened”, which makes Germany the leader in this area (Austria and Switzerland come on the second place). Since 1989 municipal regulations in Stuttgart, Germany have required all new, flat-roof buildings to have green roofs.
Aerial views from Stuttgart, Germany. Photographs: 1.howtobuildahouseblog 2.Peter PhilippiA number of European Countries have very active associations promoting green roofs. The City of Linz in Austria has been paying developers to install green roofs since 1983, and in Switzerland it has been a federal law since the late 90s. In the UK, their uptake has been slow, but a number of cities have developed policies to encourage their use, notably London and Sheffield.
Therme Vals Spa by Peter Zumthor in Switzerland. Photographs: thelifeisalostdream