Living roofs, green roofs, high rise harvest, sky gardens call them what you may but bringing back vegetation and soil to buildings has been just below the radar screen of planners, consultants and architects for a number of years. However living roofs are now entering mainstream. The recent Ecobuild exhibition demonstrated this yet again with the number of companies displaying green roofs system increasing.
It has been a long haul for many of us in the green roof movement. The use of vegetation on buildings had all to often been perceived as belonging only in the realm of the margins – the ‘hippy’ alternative brigade intent on some pre modern response to the world.
However over the last five years an increasing awareness that climate change is here, is real and is something that needs to be tackled has raised the profile of a number of technologies already widely used in more enlightened countries, namely the German speaking countries of Austria, Switzerland and Germany. In these countries there have been policies in place to drive the uptake of green roofs and therefore the market. And in the main the technology is delivered by the landscaping contracting world not the traditional roofing world of waterproofing manufacturers and roofing contractors.
In 2008 the first distinct policies on green roofs appeared. Firstly the New London Plan published in 2008 included a the first such policy in the UK stating in brief that all new major developments should include green roofs within their design and that smaller green roof projects should be encouraged by the 32 London Boroughs. Later in June Sheffield included green roofs as a distinct approach in the supplementary planning guidance. The Environment Agency a key player in terms of green roofs produced a pre application design toolkit for developers to provide a systemic approach to how green roofs should be delivered in new developments.
The Agency is important, as it is responsible for flood defense. One of the successes of the German market has been the use of green roofs as a source control mechanism in the sustainable urban drainage system. By accepting that water can be retained at roof level this should see green roofs being more widely used to meet sustainable urban drainage requirements. In the light of this, there is growing interest north of the border in Scotland. A Scottish Green Roof Forum has been established to promote the use of green roofs, especially in terms of water – both run off and quality of run off and of course biodiversity and it is hoped that the Scottish Government will take a proactive view of green roofs as they have done in the past with other forms of sustainable urban drainage.
Other areas are in the process of addressing how they may develop distinct approaches to green roofs such as Manchester, Bristol and Swindon are a few that the author is aware of.
But what do green roofs do’ Cities are generally dry, impoverished of soil, impermeable and hot. Increasing the soil and vegetation in the urban realm returns elements of the natural world and the distinct ecosystem service nature provides to us free of charge. Vegetation and soil retain water, which has already been mentioned above, but also through the process of evapo-transpiration return the water back to the atmosphere. This process takes heat away from buildings providing both significant savings to the buildings in terms of air conditioning costs whilst at the same time helping to combat the negative effects of the Urban Heat Island. It is predicted that climate change is likely to lead to an increase in summer urban temperatures and an increase in short sharp heavy rainstorms in summer. Green roofs address both of these issues.
Vegetation and soil ensures that nature can move back into the city, acting as a filter for air pollutants, adding additional noise insulation and protecting waterproofing membranes from the effects of UV and frost. It is strange how certain themes appear. At present there is a real interest in food growing and although the author is skeptical about mass food production at roof level, the interest in honey and bees is certainly one that could be addressed at roof level. The some of the best honey in the UK is produced in London, which also produces more pounds per acre than in the wider countryside. Greening the roofs of our cities could potentially lead to potential for a small industry producing honey. Already there are a number of hives that have been established on roofs in the Capital and this could be replicated across the country.
Guidelines
As the green roof industry evolves from an immature market to a mature one there are increasing calls for the introduction of a distinct British Guideline on how to install green roofs. Currently the de facto international guideline is the German FLL. The latest FLL has been translated into English and is available from www.fll.de. Most other European Guidelines [Austrian, Swiss, Dutch, Hungarian and Italian] are based on the original German guideline. To address the issue in the UK, GRO [the green roof organization] has been formed including major stakeholders from industry and other organizations [including livingroofs.org Ltd and the Green Roof Centre] in Sheffield to arrive at a UK code of practice. GRO has produced an interim guidance document [www.livingroofs.org/guidance] and will be working towards a further more detailed guidance note in the near future.
Training
As the industry expands there will be a need for specialist companies or parts of companies to provide the expertise to install good green roofs. Currently simple single layer sedum blankets systems are the main systems being used in the UK. However the market is moving towards a more substrate based approach to green roofs with a greater range of planting options. This in part will be driven by the need to meet biodiversity action plans and to provide greater water holding capacity at roof level.
GRO is currently working on a training programme but at present there are a number of organizations that can provide training. The Green Roof Centre in Sheffield runs regular training programmes, as do CIRIA. The author is running a series of training programmes with his colleague John Little of the grass roof company [see below]. These training programmes aim to increase the knowledge and expertise in green roof applications in the UK.
The Small Scale
Other the years since establishing Livingroofs.org Ltd [www.livingroofs.org] the author has witness an increasing interest from the public in how to do small-scale projects in gardens or on extensions. This is an area all to often ignored by many in the industry. The number of people unable to find a local small-scale contractor with the knowledge and the willingness to install a green roof means that there is definitely a market for many landscaping contractors at a local or regional level to provide a distinct service.
To this effect the author and John Little have produced an e –guide for small-scale contractors and the self-build enthusiasts outlining how to convert a shed or build a small green roof building from scratch. The guide is based on over 15 years of installing green roofs in London and Essex, from garden out houses, to outdoor classrooms and small extensions. It is hoped that the guide will be updated and be published as book later in the year.
Diversity is best
Having traveled widely in Europe looking at green roofs, there is a need as the market matures to understand the full range of possible green roof solutions that are available. Sedum blanket systems are on one element of the green roof market on the continent and in fact a relative small element. Through out Germany, Switzerland and Austria most systems are based on a substrate approach with a range of planting including both sedums and herbs. This approach has a number of benefits increasing the amount of water that is stored and increasing the thermal barrier. An increase in the range of plants that are used provides a greater benefit as a local nature refuge. And as policy is refined and a greater understanding of the range of green roofs that are possible it is likely that customers and policy makers are going to more demanding about the types of green roofs that are desired.
The Future
The green roof market, even in these current times of tightening belts, is still on the increase. And as soon as things begin to pick the industry is surely going to continue to grow exponentially. As regional and local authorities rise to the challenge of climate change and the green agenda, green roofs will be increasingly common sight in our cities. Not on new developments but also on existing buildings. Our cities will change form the hot impermeable grey concrete jungles to flourishing cool permeable green cities – and vegetation at roof level will be key to achieving this vision.
www.livingroofs.org
training@livingroofs.org
info@greenrooftraining.co.uk
www.greenroofdirectory.com