Examples by country
Switzerland has one of Europe’s oldest green roofs, created in 1914 at the Moos lake water-treatment plant, Wollishofen, Zürich. Its filter-tanks have 30,000 square metres (320,000 sq ft) of flat concrete roofs. To keep the interior cool and prevent bacterial growth in the filtration beds, a drainage layer of gravel and a 15 cm (6 in) layer of soil was spread over the roofs, which had been waterproofed with asphalt. A meadow developed from seeds already present in the soil; it is now a haven for many plant species, some of which are now otherwise extinct in the district, most notably 6,000 Orchis morio (green-winged orchid). More recent Swiss examples can be found at Klinikum 1 and Klinikum 2, the Cantonal Hospitals of Basel, and the Sihlpost platform at Zürich’s main railway station.Sweden
What is claimed to be the world’s first green roof botanical garden was set up in Augustenborg, a suburb of Malmö, in May 1999. The International Green Roof Institute (IGRI) opened to the public in April 2001 as a research station and educational facility. (It has since been renamed the Scandinavian Green Roof Institute (SGRI), in view of the increasing number of similar organisations around the world.) Green roofs are well-established in Malmö: the Augustenborg housing development near the SGRI botanical garden incorporates green roofs and extensive landscaping of streams, ponds and soakaways between the buildings to deal with storm water run-off.
The new Bo01 urban residential development (in the Västra Hamnen (Western Harbour) close to the foot of the Turning Torso office and apartment block, designed by Santiago Calatrava) is built on the site of old shipyards and industrial areas, and incorporates many green roofs.
Long-held green roof traditions since the early industrialization about 100 years ago exist in Germany. Since the 1970s, a vibrant green roof industry also exists. Building codes developed by the Fachvereinigung Bauwerksbegrünung, have existed since the 1980s. The current issue was published in 2008. Since the 1980s, environmental mitigation regulations have helped to push green roofs to reduce the ecological footprint of buildings. Now, about 10,000,000 m² of new green roofs are be constructed each year. About 3/4 of these are extensive, the last 1/4 are roof gardens. The two cities with the most green roofs in Germany are Berlin and Stuttgart. Surveys about the status of regulation are done by the FBB (Fachvereinigung Bauwerksbegrünung = German organization for green building technologies). Nearly one third of all cities have regulations to support green roof and rain water technology. Green roof research institutions in Germany are located in several cities as including Hannover, Berlin, Geisenheim and Neubrandenburg.
Sod roofs are frequently found on traditional farmhouses and farm buildings in Iceland.
British examples can be found at the University of Nottingham Library, and in London at the Horniman Museum and Canary Wharf. The Ethelred Estate, close to the River Thames in central London, is the British capital’s largest roof-greening project to date. Toxteth in Liverpool is also a candidate for a major roof-greening project.
In the United Kingdom, green roofs are often used in built-up city areas where residents and workers often do not have access to gardens or local parks. They have also been used by companies such as Rolls-Royce Motor Cars, who have one of the biggest green roofs in Europe (covering more than 32,000m² to help their factory, at Goodwood, West Sussex, blend into its rural surroundings.
The city of Toronto approved a by-law in May 2009, mandating green roofs on residential and industrial buildings. There is criticism from Green Roofs for Healthy Cities that the new laws are not stringent enough, since they will only apply to residential building that are a minimum of six storeys high. By 31 January 2011, industrial buildings will be required to render 10% or 2,000m² of their roofs green.In 2008, the Vancouver Convention Centre installed a six-acre living roof of indigenous plants and grasses on its West building, making it the largest green roof in Canada.
In France, a huge green roof of roughly 8,000 square metres (86,000 sq ft) has been incorporated into the new museum L’Historial de la Vendée which opened in June 2006 at Les Lucs-sur-Boulogne.
The Greek Ministry of Finance has now installed a green roof on the Treasury in Constitution Square in Athens. The so called “oikostegi” (Greek – oiko, pronounced eeko, meaning building-ecological, and stegi, pronounced staygee, meaning roof-abode-shelter) was inaugurated in September, 2008. Studies of the thermodynamics of the roof in September 2008 concluded that the thermal performance of the building was significantly affected by the installation. In further studies, in August 2009, energy savings of 50% were observed for air conditioning in the floor directly below the installation. The ten-floor building has a total floor space of 1.4 hectares. The oikostegi covers 650m², equalling 52% of the roof space and 8% of the total floor space. Despite this, energy savings totalling €5,630 per annum were recorded, which translates to a 9% saving in air conditioning and a 4% saving in heating bills for the whole building.An additional observation and conclusion of the study was that the thermodynamic performance of the oikostegi had improved as biomass was added over the 12 months between the first and second study. This suggests that further improvements will be observed as the biomass increases still further. The study also stated that while measurements were being made by thermal cameras, a plethora of beneficial insects were observed on the roof, such as butterflies, honey bees and ladybirds. Obviously this was not the case before installation. Finally, the study suggested that both the micro-climate and biodiversity of Constitution Square, in Athens, Greece had been improved by the oikostegi.
In Egypt, soil-less agriculture is used to grow plants on the roofs of buildings. No soil is placed directly on the roof itself, thus eliminating the need for an insulating layer; instead, plants are grown on wooden tables. Vegetables and fruit are the most popular candidates, providing a fresh, healthy source of food that is free from pesticides.
A more advanced method (aquaponics), being used experimentally in Egypt, is farming fish next to plants in a closed cycle. This allows the plants to benefit from the ammonia excreted by the fish, helping the plants to grow better and at the same time eliminating the need for changing the water for the fish, because the plants help to keep it clean by absorbing the ammonia. The fish also get some nutrients from the roots of the plants.
United States of America
One of the largest expanses of extensive green roof is to be found in the US, at Ford Motor Company’s River Rouge Plant, Dearborn, Michigan, where 42,000 square metres (450,000 sq ft) of assembly plant roofs are covered with sedum and other plants, designed by William McDonough. Built over Millennium Park Garage, Chicago’s 24.5-acre (99,000 m2) Millennium Park is considered one of the largest intensive green roofs. Other well-known American examples include Chicago’s City Hall and the Gap headquarters in San Bruno, CA. Recently, the American Society of Landscape Architects retrofitted their existing headquarters building in Washington, D.C. with a green roof designed by landscape architect Michael Van Valkenburgh.
Another example of a green roof in the United States is the Ballard Library in Seattle. The landscape architect was Swift & Co. and the building architect was Bohlin Cywinski Jackson. This green roof has over 18,000 plants to help with insulation and reduce runoff. The plants used on the roof include Achillea tomentosa (woolly yarrow), Armeria maritima (sea pink, sea thrift), Carex inops pensylvanica (long-stoloned sedge), Eriophyllum lanatum (Oregon sunshine), Festuca rubra (red creeping fescue), Festuca idahoensis (Idaho fescue), Phlox subulata (creeping phlox), Saxifraga caespitosa (tufted saxifrage), Sedum oreganum (Oregon stonecrop), Sedum album (white stonecrop), Sedum spurium (two-row stonecrop), Sisyrinchium idahoense (blue-eyed grass), Thymus serpyllum (wild thyme), Triteleia hyacinthina (fool’s onion).
The new California Academy of Sciences building in San Francisco’s Golden Gate Park has a green roof that provides 2.5 acres (10,000 m2) of native vegetation designed as a habitat for indigenous species, including the threatened Bay checkerspot butterfly. According to the Academy’s fact sheet on the building, the building consumes 30-35% less energy than required by code.
An early green roofed building (completed in 1971) is the 358,000 sq ft (33,300 m2) Weyerhaeuser Corporate Headquarters building in Federal Way, Washington. Its 5 story office roof system comprises a series of stepped back terraces covered in greenery. From the air, the building blends into the landscape.
The first green roof in New York City was installed in midtown Manhattan atop the United States Postal Service’s Morgan Processing and Distribution Center. Construction on the 109,000 sq ft (10,100 m2) project began in September 2008, and was finished and dedicated in July 2009. Covered in native vegetation and having an expected lifetime of fifty years, this green roof will not only save the USPS approximately $30,000 a year in heating and cooling costs, but will also significantly reduce the amount of storm water contaminants entering the municipal water system.
Green roofs have been increasing in popularity in Australia over the past 10 years. Some of the early examples include the Freshwater Place residential tower in Melbourne (2002) with its Level 10 rooftop Half Acre Garden, CH2 building housing the Melbourne City Council (2006) – Australia’s first 6-star Green Star Design commercial office building as certified by the Green Building Council of Australia, and Condor Tower (2005) with a 75 square metre lawn on the 4th floor.
In 2010, the largest Australian green roof project was announced. The Victorian Desalination Project will have a “living tapestry” of 98,000 Australian indigenous plants over a roof area spanning more than 26,000 square metres. The roof will form part of the desalination plant’s sophisticated roof system, designed to blend the building into the landscape, provide acoustic protection, corrosion resistance, thermal control and reduced maintenance. The green roof will be installed by Fytogreen Australia.
Since 2008 City Councils and influential business groups in Australia have become active promoting the benefits of green roofs. “The Blueprint to Green Roof Melbourne” is one program being run by the Committee for Melbourne.