The answer to the most obvious way to use rooftops in terms of sustainability is by installing solar panels. It seems very straightforward and the go-to solution when we want to make our existing homes eco-friendly. However, there has been a rapid increase in having green roofs as an alternate solution. One of the common misconceptions is that green roofs (also called eco-roofs, living roofs, vegetative roofs, etc) are a new experiment. They have existed in Europe, especially in Germany, since the 1970s. Today we have modern adaptations of this concept.
What are green roofs?
A green roof is a layer of vegetation or plants grown on top of existing homes. Various types of green roofs can be installed depending upon the location and slant of the roof. Green roofs are becoming a key factor in increasing sustainability efforts in urban areas. Although most efforts are made to make rooftops visually appealing, the intentional use of using plants on roofs can help with temperature regulation, water drainage, cleaning the air, and much more. Let’s understand why green roofs can be a viable solution towards a sustainable future.
Improving water drainage
Any house or building needs a proper draining system on the roof as a way to counter flooding. Usually, a network of pipes is fixed together to direct the water into the sewage system. With the climate crisis at its peak and impending natural disasters, a green roof is a terrific way to naturally store water in plants and the substrate before releasing it back into the environment.
Increase in the life-span of the roof
Contrary to the popular myth that green roofs reduce roofs’ lifespan, it protects them from elements that cause decay. Every roof needs to deal with heavy rain, wind, ultraviolet rays of the sun, and extreme temperatures. The barrier of greenery helps protect the waterproof membrane underneath and ensures your rooftop’s life expectancy lasts well for decades. Green roofs have been known to improve a roof’s life span by double, if not triple the expected timeline.
This is the biggest advantage of green roofs over traditional ones. A typical roof can have poor insulation which results in heat loss in winter and trapped heat during the summers. A green roof can make a massive difference by improving energy efficiency. Plants absorb the sun’s energy and therefore reduce the temperature of the roof in summer, whilst aiding thermal efficiency in the colder winter by locking heat inside.
Improve air quality
Urban or residential areas lack clean air is common knowledge. The Environmental Protection Agency reported that there was a 15% increase in days with unhealthy air in 2017-2018. Green roofs can help in improving it. According to a study, green roofs can help reduce 37% sulfur dioxide, 21% nitrous acid, and 0.2kg of dust particles / per square meter each year. In addition, it traps carbon dioxide as well.
Support wildlife habitats
Green roofs also help support wildlife and in turn, can create a healthy habitat. Green roofs are perfect for attracting birds and other wildlife to create a thriving eco-friendly habitat. It definitely doesn’t replace ground environments, yet a viable improvement in the long run. Each green roof will support varying habitats, dependent largely on the type of vegetation included. According to a survey in Switzerland, the study of 11 green rooftops found there to be an incredible 172 separate species.
A sustainably built green roof is made up of layers.
Key among these is a waterproofing membrane and root barrier to ensure there is no leakage.
The irrigation and drainage layer take care of distributing, storing and draining excess water.
The growing medium and vegetation is the top layer.
This is not to say that having green roofs don’t come with challenges. They do tend to be slightly more expensive than the traditional option. One of the significant reasons for this is the extra support required to handle the increased load. Green roofs are heavier and as such, require more structural support to be implemented. Typically, the addition of a green roof will add between 50 and 200kg/meter squared to an existing rooftop. Although some rooftops will need to be retrofitted to cope with the increase in load, fortunately, flat roofs are often able to handle this capacity. Green roofs require maintenance, like any other garden. The purpose of having green roofs is to enjoy the benefits while giving back to nature. This requires regular tending.
As you can see there are more benefits to having a green roof and the drawbacks are nothing that cannot be handled. In the long run, green roof technologies not only provide the owners of buildings with a proven return on investment, but also represent opportunities for significant social, economic, and environmental benefits, particularly in cities.
Written by Kritika Rao