Living roof: The days of boring and bird-poo-covered roof tiles are over! Now, a roof can be anything you can imagine. Across the world, there is a movement to make roofs a slice of green heaven. This is especially nice if you live in an urban environment. So let’s green our skies!
Humans have put plants on top of structures since antiquity. The ziggurats of Mesopotamia had trees growing from the terraces. And the medieval Egyptian city of Fustat had high-rise buildings with roof gardens on the top that were so complex they used ox-drawn waterwheels to irrigate them. Back then, roof gardens were all about showing off. Nowadays, with most of us living in an urban environment, a living roof is all about still feeling we are somewhere near to the ground. Or at least we have some access to an imaginary jungle nearby!
Living roof functionality
Here’s the good news about living roofs, they are not just a pretty home improvement accessory for discussing around a barbeque. They actually have an impact on your heating bills. Plants launched up onto a roof have the ability to reduce the overall heat absorption of the building. This then reduces energy consumption. In a normal city, heat from the sun is absorbed by buildings and roads, which then is re-radiated back into the air, making the city even hotter.
However, if plant surfaces are introduced, this changes the temperature. Plants absorb the heat and as a result of transpiration, the atmosphere around them does not rise more than 4–5 °C. And due to extra insulation, they keep your gaff nice and toasty in winter. They look pretty too, so it’s win-win everywhere.
As an example of what a difference the greening of our roofs could make, take Tokyo as an example. The temperature of the entire city could be lowered by about a degree if just half of all rooftops had green roofs. This would make a savings in the daily electricity bill of about 100 million yen, which is not a small amount of money in anyone’s language.
Living roof types
As far as green roofs go, there are two types. One is an intensive roof. These are the ones where you can grow crops and have lush vegetation and really show yourself off to the neighbours. These are heavier and require more maintenance, so you might want to be rich and have a fleet of gardeners when considering this option. But if you want to just plant your roof and be done with it, then you can get an extensive roof, which is made up of a lighter layer of vegetation and they generally look after themselves. Also the plants are important. Usually they are breeds that only need a shallow root system, and will be hardy enough for the dry, hot, windy conditions of a rooftop. So get your eco-freak on, and green up your roof, your neighbours will think your house lid is deadly!
GALLIE CRAIG
The Gallie Craig coffee shop at Drummore in Stranraer, Scotland has the most spectacular position, perched above cliffs overlooking the Mull of Galloway. In light of the outstanding natural beauty of its location, the project underwent rigorous planning authorisation before construction could begin; with a green roof system being the obvious choice to crown the building.
MENDIP GREEN PRIMARY
Green roof technology has been used at Mendip Green School in Weston-Super-Mare, UK. The main sloping roofs, built at a 15o pitch, provide a significant visual amenity, being highly visible from neighbouring houses and gardens, as well as a busy road alongside the school boundary. The green roof system consists of a series of carefully designed layers to provide a stable long-term base for the planting and complete waterproofing to the building.
RIVER QUARTER
This is a roof-top retreat for residents of a stunning new development of flats and leisure facilities in Sunderland. The River Quarter, a £10 million mixed-use development comprising a mix of commercial and residential accommodation in Sunderland city centre. The green roof was installed over the car park structural concrete roof deck.
CO-OP, OAKHAM:
A green roof has helped the new Oakham Co-Op become one of the most energy efficient retail stores in the country. The new building incorporates a range of energy saving features including the ZinCo green roof which is planted with local species to create a wildlife habitat. It is anticipated that the building will achieve a reduction in CO2 emissions from 103kg/m2/year to just 40kg/m2/year. The roof features sedum-based plants that will require minimal irrigation and maintenance. The roof offers notable ecological benefits, providing a natural habitat for plants and wildlife, while helping to reduce air and noise pollution, cutting carbon emissions and assisting with rainwater retention and attenuation.
BENEFITS OF A GREEN ROOF
Water Retention
Depending on their design, green roofs retain between 50 and 90% of rainwater. A large proportion of this water evaporates, whilst the rest gradually drains away. Pipes, drains, water butts etc. can all be incorporated into the green roof and can help to reduce drainage costs. The risks of flooding are reduced and some of the burden is taken from the sewerage system.
Improving the Microclimate
Green roofs humidify the air and provide some cool air. This is particularly effective on rooftops that lie adjacent to residential or office spaces, but also makes a valuable contribution to improving the microclimate in our urban centres. Furthermore, air conditioning systems have a much greater affect due to the reduced heating.
Improved Noise Protection
Green roofs reduce sound reflexion by up to 3 dB and improve the sound proofing of a roof by up to 8 dB. These benefits are particularly useful for buildings which lie under flight paths or which contain very strong sources of noise (e.g. nightclubs, etc.).
A Larger Living Space
Landscaped roofs can go a considerable way to help compensate for green spaces, which are lost during building works. In particular, extensive species-rich landscaping can provide diverse opportunities for offering a balance.
Living Roof: Reduced Renovation Costs
When placed under a green roof, waterproofing is better protected from UV rays, hail and the hot and cold. Oscillations in temperature are reduced and the life expectancy of the roof waterproofing is vastly increased.
Living Roof: Landscape
Having a green roof means that the piece of land in question can be better utilised: the green roof can be taken into account as a substitute for sacrificed landscaped areas.
Living Roof: Additional Space
Rooftops can be put to a number of different uses – from a pure nature reserve to a relaxing garden to a rooftop cafe or playground/sports pitch. And all this can be achieved without having to purchase new and expensive land.
Check out this website for some more fascinating ideas about green roofing. You are already thinking about what you can do to your own roof now, aren’t you….
