Soil Matters 4 - Our rooftops are getting greener

Green roofs are an excellent example of how a visually arresting addition to a building can also perform a functional role. In this case; managing rainwater, providing natural insulation and absorbing carbon dioxide.

The benefits

The more we understand the variety of benefits green roofs offer, the more popular they become. In some cases, major local authorities such as those in London and Sheffield have already provided supplementary planning guidance which asks developers to make use of green roofs on their projects where it is possible and applicable.

The London Plan, for example, encourages developers to include green roofs in all new developments ‘wherever appropriate’ and from 2011, developers in Sheffield will be required to include 80 per cent vegetative cover - on a base of 80mm - on any building with a footprint over 1,000 square metres or in a development with more than 10 dwellings. These policy changes highlight just how seriously some authorities are now taking the use of green roofs and pave the way for them to become much more common in the UK.

Guidance

While this is encouraging news for those of us who have long appreciated the beauty and benefits of green roofs, there is still a big issue to overcome; primarily that there is no single UK specification on how best to develop a green roof. Fortunately, work being done by the Sheffield Green Roof Centre should help us to establish a set of clear guidelines and a picture of good practice.

The guidance document, currently being drafted, will help designers and contractors improve the way they work with green roofs in the UK. Industry currently works to guidance laid out in the German FLL guidelines, which form the basis of similar green roof specifications in Switzerland, Austria and Holland. However, the need for a UK specification is paramount. With different planning requirements, diverse customer needs and varying rules and regulations regarding material use and flood management criteria, the work being done by the Green Roof Centre will underpin the science of green roof design and turn the market into a standardised and highly successful industry.

Training

Training and education also needs to be in place to improve knowledge and skills in this area. Non-government organisations such as Livingroofs.org are now looking to establish training criteria which will complement the work being done by the Green Roof Centre and boost the confidence of designers and contractors looking to install green roofs. WRAP too has a role to play, and the work currently being conducted by the Royal Horticultural Society and Vital Earth, for example, is helping to prove how the use of BSI PAS 100 compost can deliver practical technical benefits when used in the creation of a sustainable green roof substrate. 

The UK is now Europe’s largest market for green roofs, both in terms of new build but also in retro-fitting. The installation of ‘green pathways’ in our towns and cities is likely to become a commonplace addition over the next decade. And with major backers such as the Mayor of London, Sheffield City Council and Manchester City Council, the future of green roofs looks assured.

Where can I find BSI PAS 100 compost?

To find your nearest BSI PAS 100 compost supplier visit compostsuppliers.wrap.org.uk.

More information on green roofs can be found at www.livingroofs.org.