A green roof is a living installation, partially or totally covered with plants and growing entities over a waterproof membrane. A green roof may also contain drainage and irrigation systems. The installation of such rooftops is rising in popularity in the UK, especially in London City Centre, where more and more residents are choosing this innovative method of introducing nature to their urban environment.
The components used in the installation of a green roof provide a wealth of benefits to both your immediate surroundings and the wider environment. However, the installation process also has an effect on the components used in the structure of your building. How much effect it has will largely depend on the function of your green roof and whether it is defined as being ‘extensive’, ‘intensive’ or ‘biodiverse’.
Extensive Green Roofs
This type of roof is designed to reap all the benefits that green roofs have to offer, but at minimal cost and with very little required maintenance.
Intensive Green Roofs
Intensive green roofs are often referred to as ‘roof gardens’ and are more costly than the previous option. These roofs are often employed as recreational space for the building’s occupants, making it the ideal tranquil relaxation spot for many inner-city businesses.
A biodiverse roof is similar to an extensive roof in that it is very low maintenance, due to the employment of recycled materials.
The Benefits of a Installing a Green Roof
There are a number of benefits to installing a green roof, perhaps the most prominent of which is the associated BREEAM ratings. The Building Research Establishment’s Environmental Assessment Method is a common system used to establish a building’s environmental performance. Widely accepted as the standard for best practice in sustainable building design, these measures can be carried out on new constructions and/or major refurbishments on existing buildings.
In addition to this, there are also a number of different BREEAM Schemes open to different types of building usage; from educational establishments to retail, healthcare and small offices. There are also many more benefits to installing a green roof, some of which are as follows:
A green roof can act as an additional protective covering for your roof’s waterproof system. It will protect your waterproofing from the sun’s UV radiation, from atmospheric pollutants and weather conditions. This added protection can seriously extend the lifetime of your waterproof layer.
Limiting Flood Risk
Our country’s urban cities are covered in permeable ground and artificial ‘hard’ surfaces, through which rainwater cannot drain through. It is mainly for this reason that many of our most densely populated, low-level areas experience flooding from time to time. The majority of our rooftops shed water almost immediately, contributing further to this drainage problem.
Installing a green roof will reduce the volume of run-off rainwater as the plantlife will help absorb the moisture much more effectively than exposed, stone surfaces. It is believed that on average, a green roof will retain around 35% of yearly rainfall and release it back into the atmosphere via evaporation and transpiration.
Solar Panel Integration
If you are thinking of installing solar panels, or already have solar panels fitted to your roof, then building a green roof around them can have a positive influence on their performance. Planting flora on your roof will ensure your solar panels do not overheat, which has been proven to reduce their energy production. An increase in temperature of just +30°C can reduce your solar panel’s performance by as much as 2.5%.
Carbon Dioxide Capture
Green roofs are also believed to help towards the capture of carbon dioxide – a massive benefit in smoggy urban city centres! Around 375 grams of carbon dioxide can be absorbed per square, according to research made by the Michigan State University (US). This sounds insignificant, but if all of our capital city’s residents were to install a green roof this would remove an amount of carbon from the air equivalent to over 10,000 heavy duty vehicles per year.
London to Build More Green Roofs
London is already set to build more green roofs following an update to the ‘Green Roof Organisation’ (GRO) code. This update coincides with the Mayor’s ‘London Plan’ for a greener city and reflects a wider, growing movement amongst local councils and authorities across the UK. This update particularly focuses on waterproofing and the installation of materials in which plants will grow.
The Mayor of London’s plan calls for more green roofs to be designed wherever possible. This campaign has the potential to improve London’s drainage capabilities and the city’s cooling effect during the summer months. Green roofs also provide cleaner air and a more pleasant living/working environment. The number of green roofs in the capital is already soaring, although there are still less than a thousand in the city centre. As environmental concerns grow over time, we should expect this figure to grow rapidly.