Green roofs are simply intentionally vegetated roof surfaces. Designed to replace or augment the ‘traditionally’ engineered roof design, the principle lies in the numerous benefits that a green roof provides and the utilisation of the large space available on many roofs for environmentally sound projects.
Green roofs can provide positive benefits over traditional builds, a very topical example is the reduction in surface run-off from the roof helping to prevent flash flooding and other problems associated with intense rainfall. This will become especially important as climate change creates weather patterns outside the current norm. By allowing the water to soak through the green roof the quality of the water is improved, and you could harvest the rainwater that has fallen on a green roof for watering the vegetable patch, washing the car and so on.
At the time of writing there is no U Value for thermal performance of green roofs, but research by Nottingham Trent University amongst other international research on green roofs have shown that they significantly reduce the need for air conditioning in the summer and provide a good degree of insulation in the winter.
The soil, plants and trapped layers of air within green roof systems act as a sound insulation barrier, sound waves are reflected, absorbed or deflected because the growing medium tends to block lower sound frequencies while the plants block the higher sound frequencies. The vegetation and substrates on a green roof can improve air quality as airborne particles and pollutants from the atmosphere are filtered, and plants naturally absorb CO2 and produce oxygen as a result of photosynthesis.
They aren’t just great for domestic environments or blending with rural areas. Beyond purely scientific reasons the increase in amenity space and room for urban agriculture are two important benefits of a green roof build. Dense urban areas suffer from low amounts of green space, so allowing residents to enjoy roof top parks and roof gardens provides important green spaces to improve residents’ quality of life as well as the practical effects of reducing carbon. Roofs which are strong enough to support urban agriculture allow food growing within an urban environment, meaning you could enjoy the benefits of an allotment on your own roof if other space is limited! Bees and other beneficial insect life are also attracted, whether you have a wildflower or sedum type of roof or you grow vegetables. Biodiversity is one more great reason for having a green roof.
The rapid change in urban development and the use of materials that absorb and/or reflect heat has given rise to a phenomenon known as Urban Heat Island Effect (UHIE). These higher ambient temperatures in urban areas can be mitigated by using green roofs or green walls on buildings (commercial and private dwellings) as research in cities all over the world looking for savings and reductions in their carbon emissions identify a positive impact on reducing the UHIE.
More information about green roof builds, sustainable construction and the green roof process can be found on Ledbury-based greenroofoptions.com. It is run by Robin Oakey, a man with a passion for green roofs and cutting edge ideas on the materials used to make them as carbon neutral as possible. He also happens to have helped us when we moved into our new office & warehouse! Using his advice we have built the interior with recycled and re-used materials as far as possible to minimise our carbon footprint. Robin’s website allows anyone with interest in green roofs to read more information and get in touch to discuss their requirements. He works on domestic and very large urban green roof projects, and has a wealth of knowledge and ideas about general green building as well.
Dusty Gedge, the renowned TV presenter and big proponent of green roofs is another passionate innovator, he is one of the team behind a useful website for urban environmental regeneration and information, livingroofs.org, which provides more information on green roofs and covers the numerous benefits green roofs provide.