How to cope with increasingly polluted and hot cities due to intensive overbuilding? Is there a way to limit the environmental impact of buildings and reduce heat islands?
Observing the principles dictated by bio-architecture, we will find a method that is not only simple and effective, but also has a great aesthetic potential: the roof garden.
Example of a green roof
What is that?
The roof garden, or green roof, is a covering system that provides a vegetable surface arranged along the upper horizontal roof of buildings. It is useful for the recovery of these spaces, often not used, but also to the improvement of new buildings.
With the green roof you rediscover an ancient tradition, just think about the fascinating hanging gardens of Babylon or the roofs covered with plates in Scandinavia. This technology was only recovered by the designers in the nineteenth century and today has become an instrument to cope with the uncontrolled urbanization. This in fact increasingly reduces the green spaces available to the population.
Representation of the Hanging Gardens of Babylon
On which covers can they be made?
The green roof can now be realized on almost all types of roofing thanks to modern and simple technologies and materials that allow light green structures in terms of burdening loads.
Technically it is possible to realize greening up to 45 ° inclination, however, in this case, the costs tend to increase significantly. For the greening of completely flat roofs a particularly efficient drainage layer is necessary. while slightly inclined roofs (1 ° -2 °) are the simplest to be greened.
Faculty of Arts, Media and Design of the Nanyang Technical University of Singapore
What are its advantages? Let’s find out
- They can accumulate from 50% to 90% of rainwater and return part of it to the atmosphere, thus regulating the outflow, which the progressive cementification of the land has reduced. Reducing overall water loss by 50% -90%,with a decongestant action against the disposal systems.
- Performing a regulating function of the humidity of the air, they make in effect air more humid thanks to the evapotranspiration of the water vapor, they can cool in the summer: it is estimated that on a green cover the maximum summer temperatures are around 25 °. They also improve the thermal insulation of the roof in winter, thus contributing to the overall energy saving of the home.
- Thanks to what has been said, they are able to counteract the phenomenon of the “heat islands” of the cities, mitigating the city’s microclimate and bringing an advantage to the global management of urban areas.
- They contribute to the acoustic insulation: reducing the transmission of noise inside the building thanks to the vibration dampening and the sound absorption by the vegetation.
- They filter the powders, capturing up to 20% the fine particles present in the atmosphere, and reduce carbon dioxide by limiting the urban pollution and making the air cleaner.
- They protect the waterproof covering from atmospheric agents such as UV rays, from temperature changes of freeze-thaw and from bad weather such as hail, increasing its durability.
- They absorb the electrosmog, that is the electromagnetic waves emitted by cellular networks and by transceivers.
- They create new habitats for plants and animals by increasing biodiversity in urban areas.
All this without considering that the perception of a more pleasant and closely connected space with the landscape, as well as the quality of the air, greatly influence our psycho-physical wellbeing.
Parkroyal Hotel in Singapore
Their success is undoubtedly linked to a responsible choice of materials, to a careful use of laying techniques, and, ultimately, but not less important, to a careful selection of the plant species which, also encouraging the settlement of animal ecosystems, must be chosen on the basis of climatic and environmental data of the area.