The Evolution of Green Roofs
Green roofs have come a long way since their inception hundreds of years ago. The first recorded green roofs used moss and grass to keep the structures warm in winter and cool during summer. Although these insulating properties remain in green roof systems today, the focal reasons for installing a living roof system are to replace naturally vegetated areas being lost through the construction of ever-growing urban areas; to benefit biodiversity and aid water retention.
London is an excellent example for the rate of urban growth. Everywhere you look there are cranes and new developments sprouting up around our capital city. The issue is the space lost due to this urbanisation. Many areas of development are replacing green areas that are habitats for local wildlife and species of various plants, flowers and grasses.
The ball is rolling to counter this through policies suggesting that developments are now expected to incorporate living roofs where possible. This is a step closer to the policies in Germany that have been in place for many years, and to the recent law passed in France, stating that rooftops on new buildings in commercial zones must be partially covered in plants or solar panels. The Flood and Water Management Act 2010 will bring us much closer to that situation. Hopefully similar laws will spread globally to combat problems that are being caused by this boom in construction.
As the rate of urban growth increases, so does the demand for space. For too long the rooftop has been wasted by the construction industry. It is no longer space just for plant rooms or air conditioning units. The landscape is changing.
Tom Wood, Sales Office Manager at Sky Garden Ltd, has noticed an increase in the demand for rooftops to be used as recreational space:
“Architects, planner and developers are beginning to utilise the roof space of buildings for recreational use.
“Green roofs are traditionally extensive sedum or wildflower blankets that look amazing, but cannot be fully utilised by the end user. We are now noticing a rise in landscaped roof gardens, where the space can be enjoyed for recreational use as well as helping to replace natural habitats that are lost through urbanisation. This makes sense in cities where space is sparse.”
Green Roof Benefits
Insulation, bio-diversity and recreation are three of the many benefits of living roof systems we have looked at so far. Although the benefits stay constant with a living roof, the importance of these benefits fluctuates depending on where the system is installed.
Tom goes on to say:
“The real benefits of a green roof depend on the location and type of development. For example, schools benefit from green roofs as they reduce noise; creating an environment for students to thrive in.
“Green roofs in London encourage bio-diversity; help reduce the Urban Heat Island Effect and aid storm water management. In rural areas, green roofs can assist the planning process by camouflaging the development; reducing the impact on the environment.”
As Tom touched on, The Urban Heat Island Effect (UHIE) is caused by darker surfaces in towns and cities absorbing the sun’s heat during the day and releasing it back slowly into the atmosphere in the evening. This keeps the temperature of the area unnaturally warm and leads to more energy being needed to cool the buildings internally. Green roofs prevent the UHIE by absorbing the sun’s heat and cooling the area through evaporation from the soil and vegetation.
In regards to storm water management, the drainage properties of green roofs allow the system to hold rainwater which is then taken up and used by the plants. This reduces the volume of water that drainage systems have to cope with; a major benefit in mitigating against storm flooding.
A key benefit of green roofs in rural areas is planning approval. New developments are required to meet predetermined BREEAM certification levels in order for the project to be approved. Living roof systems are often used to help reach that level.
Sky Garden’s M5 Gloucester Services is a fine example of a green roof being used for planning permission. Locally sourced vegetation and seed mixes were used in order to mimic the surrounding rolling hills of the Cotswolds. This was done in order to counter the loss of natural vegetation that was lost during construction of the services. The building is hardly noticeable as you drive past.
The financial benefit of green roofs is apparent wherever the system is located. Installing a green roof protects the waterproofing from UV damage; prolonging the waterproofing life-cycle and providing water and economic benefits.
The green roof market has boomed and evolved over the past decade and does not show any signs of slowing down.
They are seen as a vital part of the solution to the problems created by the rapid rate of urban development by replacing the natural vegetation that would otherwise be lost. The benefits that come with a green roof are vast and easily tailored to enhance certain benefits if needed.
Great opportunities are out there for roofing contractors to take advantage of and establish themselves in the market where the sky is quite literally the limit.