Green roofs are a trend that is spreading all over the world. The UN points to urban gardens on the roofs of buildings as a concrete anti-crisis measure to help the population’s livelihood in certain countries, but it is also true that they are a nice eye-catcher and provide several other concrete benefits.
Integrating urban buildings with green roofs, in fact, is not only an operation that affects air quality and the landscape. But also a way to transform buildings by making them more energy efficient.
Green roofs: the main advantages
But let’s take a closer look at what the advantages of green roofs are:
1. Reduce water infiltration
Firstly, green roofs help to reduce water infiltration. In some cases, especially in summer, water infiltration is almost completely eliminated. A well-designed green roof absorbs up to 90 per cent of the amount of rainwater that usually runs off into the outdoor gutters, thus reducing the water load of the sewer system, among other things.
2. Energy saving
A green roof serves to better insulate the building and protect it from the sun in summer. In a building with a large roof, this saving can amount to several hundred euros. This function as a heat insulator and thermoregulator has been known since antiquity. It is therefore true that a green roof involves initial costs, but these are amortised very quickly.
3. The contribution to air quality
A third major benefit associated with green roofs is that they contribute to the absorption of CO2 in the atmosphere. If present in large quantities, they could contribute significantly to improving urban air quality.
4. A barrier against noise pollution
Green roofs provide a natural barrier against noise pollution. Green roofs can absorb external noise by reducing sound reflection by 3 to 8 decibels, depending on the components used.
5. Protection from temperature fluctuations
A green roof can protect roof construction materials from temperature fluctuations, ensuring that the layers can breathe perfectly.
6. Green roofs support photovoltaics
A green roof supports photovoltaics, doubling the energy benefits and synergistically combining the electricity produced to power the irrigation system as well.
7. An aid to biodiversity
An aid to biodiversity: green roofs increase urban green spaces and above all provide a hospitable habitat for birds and various animal species.
8. Combat the heat island effect
Green roofs help combat the heat island effect: temperatures in the city are always higher than in the countryside. Well, here is a help to limit this phenomenon.
9. Urban agriculture
Green roofs also offer a further advantage to be taken into account: the possibility of additional cultivation areas for urban agriculture, for the creation of hanging gardens or simply to enjoy raised gardens in which to find a pinch of nature even in the city centre.
What about the costs of a green roof?
As far as the costs of a green roof are concerned, we must distinguish between the costs of construction and those of maintenance.
Those associated with construction can vary significantly, depending on the difficulty of the work and the materials used, but we can assume a range of 30 to 40 euros per square metre.
As far as maintenance is concerned, there are no higher costs than for the care of an ordinary garden.
Of course, before embarking on this project without incurring subsequent costs and inconveniences, all authorisation aspects (local regulations, especially in areas where there are strong landscape restrictions and condominium regulations) and technical aspects must be verified.