Seven Castles

Green Roof

                                      

December 29, 2007

 

A green roof is a roof of a building partially or completely covered with vegetation and soil, or a growing medium planted over a waterproofing membrane. It is designed to be environmentally and aesthetically pleasing. The term "green roof" may also be used to indicate roofs that utilize some form of "green" technology, such as solar panels or a photovoltaic module.

 

The concept is basically about growing plants on roofs, thus helping to replace the green footprint destroyed due to the construction of the building, and spread greenery in urban areas.

 

With the obvious psychological and aesthetic benefits of garden-like environments surrounding you, green roofs are used to provide amenity space for building users (in effect replacing a yard or patio); grow fruits, vegetables and flowers; reduce heating (by adding mass and thermal resistance value) and cooling (by evaporative cooling) loads on a building (especially if it is glassed in so as to act as a terrarium and passive solar heat reservoir); reduce the urban heat island effect: increase roof life span; reduce storm water run off; filter pollutants and carbon dioxide out of the air; filter pollutants and heavy metals out of rainwater; and increase wildlife habitat in built-up areas.

 

Some disadvantages that have been found in the use of green roofs include the need to strengthen the structural support of some existing roofs when retrofitted to accommodate the weight of a green roof.

 

Switzerland has one of Europe's oldest green roofs, created in 1914 at a lake water treatment plant in Zurich. Modern green roofs, made of a system of manufactured layers deliberately placed over roofs to support growing medium and vegetation, are a relatively new phenomenon. They were developed in Germany in the 1960s, and have since spread to many countries. Green roofs are the most prevalent in Germany, a country widely regarded as the leader in the research of the green roof concept, both the usage as well as the technology. According to estimations, it is thought that around 10 percent of the flat roofs in Germany are green. The world's first green roof botanic garden was set up in a suburb of Malmö, Sweden in May 1999.

 

Unfortunately, there are many barriers to this concept being accepted widely, like a general lack in the awareness about green roofs, the possible higher costs of installation, the lack of quantifiable data regarding their benefits, the lack of technical know-how of building them, and the paucity in the incentives from the government for installing them. 

【作者: zhangliping】【访问统计:】【2007年12月29日 星期六 05:35】【注册】【打印】