Sports facilities, paths and urban farming are common features of today’s towns and cities. And green roofs in urban spaces are becoming an increasingly remarkable and widespread development, which is garnering greater support too. According to market research company Technavio, the green roof market will see an annual rise of approx. 14% by 2025. Particularly over the past few years, green frontrunners like Singapore, Hong Kong, Japan, Canada, the United States and Germany have taken steps to incentivise the development and provide the relevant legal framework. This post will deal with whether debates are merely being conducted on what demands will actually be met. It will also look at the status quo of the countries or towns and cities in general.
When it comes to green roofs, everyone’s talking about the Asian city-state. With five million people over an area of approx. 712 km², it’s not just the population density that’s noteworthy. The solutions and vast sums of money required to support Singaporeans are equally so. The Housing Development Board (HDB) manages the public housing where the majority of the population lives. What’s more, it kick-started research into green roofs and buildings, which was then turned into reality.
The Center of Greenery and Ecology (CUGE) backs this trend. It’s responsible for public parks and green spaces and paves the way for a greener city through research projects and demos. Some of the issues in the guidelines, such as a standard for green roofs, have not yet been resolved. Basic legal minimum requirements for new buildings are still lacking. Nevertheless, the appeal of more green roofs alone seems to be enough.
In Hong Kong, buildings are between 25 and 50 storeys high on average and usually have flat roofs. As long as a green roof doesn’t prevent evacuation of a building, it’s permitted and a preferred option. The idea of green roofs was born in 2005 and has since been adopted by the University of Hong Kong and underpinned via the creation of research roofs. In 2006, the city council joined in and published a feasibility study for appropriate constructions. Green roofs on public buildings and schools are now commonplace. However, the lack of subsidies for private owners is criticised.
Because green roofs in Japan are lacking, it’s difficult to say what the modus operandi and regulations are. However, it’s clear that Japan is trying to encourage the shift towards more green roofs in urban spaces. For instance, Hajime Koshimizu founded a national organisation called Sky Front in 2007. This group now has 200 members and is called the Organization for Landscape and Urban Green Infrastructure. It deals with issues such as photovoltaics, vegetable cultivation and biodiversity on green roofs.
Over the past few years, Canadian towns and cities have ever frequently been in the spotlight due to their green urban design. As early as 2009, legislation came into force in Toronto requiring a minimum of 20% planted roof surface on new builds totalling 2000 sq m or more. This figure rises to at least 60% for buildings covering 20,000 sq m or more.
Vancouver Convention Centre stands apart for its LEED® Platinum certification. This makes the building the most sustainable trade fair complex worldwide and it’s a flagship public building. In terms of legal regulations, Vancouver is proving to be somewhat sluggish. In 2018, a demand was made for minimum green roof requirements for new builds, but it was rejected.
In the US, the growth of green roofs is progressing at different speeds. For instance, San Francisco requires between 15 and 30% of the roof space on new buildings to incorporate solar panels, green roofs or both.
Philadelphia uses tax breaks as incentives and in Washington the issue is governed by stormwater regulations. Portland offers subsidies of $5 per square foot for what are known as eco roofs. In Portland, the underlying idea was to tackle the problems with stormwater runoff in this way. Chicago got the ball rolling by adding the first green roof to City Hall in 2001. There is no support from the state or elsewhere, but the number of green roofs is rising every year.
In Germany, incentives, support and regulations regarding green roofs also vary. Hamburg advertises subsidies of up to €100,000. In Düsseldorf and Stuttgart, housing cooperatives and charitable organisations were already trying to boost the importance of green roofs in Germany 40 years ago. Some 30 towns and cities are now heading in the same direction by providing consultation and subsidies. According to the Bundesverband GebäudeGrün e. V. (BuGG), at 4.1 km² per person, Stuttgart has the most green roof space of any German city. At over 3 million km², Munich comes first place in terms of area and accounts for a lot of Germany’s green roof space at 7.2 million km². Unfortunately, neither towns nor cities nor the federal government have specified minimum legal requirements regarding green roofs on new builds yet.
In many respects, the Danish capital is Europe’s poster child when it comes to urban adaptation to climate change. This includes the first law requiring a green roof for most new builds. This act has been in force since 2010 and applies to large building complexes in particular. The proportion of green spaces they need to incorporate depends on lots of factors. In Copenhagen, this decision was also taken to improve the city’s water management. In addition to new builds, all public buildings are required to have green roofs.
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