A roof is better when it is vegetated

Aesthetic advantage, fashion effect, regulatory constraint or a new and really advantageous concept? Jeanne’s blog has decided: why you should seriously consider it!

The origin

In the 1980s, new environmental policies aimed at improving the quality of life in urban areas, as well as a growing concern for stormwater management, encouraged the development of green roofs in Europe. At the same time, the scarcity of green spaces caused by accelerated urbanization has also contributed to the development of green roofs. The design method comes from Germany. Extensive, intensive or semi-intensive, each version has many environmental, economic and social benefits. In addition to the proven positive impact of a green living environment on our health, a living roof has many benefits.

The benefits for you and others (living beings).

There are a multitude of short and long term benefits. The green roof contributes to the management of rainwater by reducing the risk of flooding: water is absorbed by the substrate, which limits the overflow of drainage systems. Then, thanks to photosynthesis, which leads to the absorption of carbon dioxide and the production of oxygen, the green roof improves the quality of the air. Of course, one suspects that a green roof also supports biodiversity: plants feed insects and diversify the food supply for pollinators, for example.

There are also advantages for the building in question. The thermal insulation is improved, the building stays cool in summer and retains heat in winter. The substrate and the plants act as a buffer between the UV rays of the sun and the building. Sound insulation is also improved. Depending on the thickness of the green roof, one can expect a soundproofing up to 8 dB (knowing that a soundproofing of 10 dB corresponds to a reduction of 50%). Two main disadvantages can be noted: the difficulty of locating leakage zones and the heaviness of the infrastructure.

To each his own green roof

There are different types of green roofs, they can be intensive: there is no constraint on the cultivated plants (trees, ornamental vegetables). They can be extensive: low vegetation is planted that requires very little maintenance. Finally, the vegetation cover can be semi-intensive: the thickness of the substrate is between the two.

At Pocheco

At Pocheco, we chose an extensive roof, made up of different varieties of sedum that require no special care, neither watering nor fertilizer. In summer, 70% of the water that falls on these roofs is absorbed by the plants and the substrate, then evaporated. The remaining 30% of water is stored in our rainwater harvesting tank. In winter, the ratio is reversed: we recover 70% of the rainwater that falls on these roofs, and 30% is evapotranspired. The advantages mentioned above can be observed at Pocheco. The roof effectively insulates the outside environment from noise in the workshop and thermally insulates the buildings, so we save energy. A roof, like the one we have, has a lifespan of 100 years, twice that of a conventional roof. The substrate is made up in part of tiles from the old factory roofs. We simply crushed them. This allowed us to transform a waste product into a resource.

We can then say that a green roof is eco-economic: it is an ecological solution that introduces life into the act of undertaking and at the same time makes us save money on the long term.

Our green wall

We also decided to plant our rainwater collection tank to encourage biodiversity around the site and to make it more aesthetic. We put in foxgloves, ferns, sedges, creeping bugles, meadow salsify and wild strawberry plants, among others. Of course, care must be taken to select appropriate plants, those that are native (from a similar range) to respect their naturalness.

A small step for the planet, a big step for your commitment

So yes, green roofs are blooming in our cities and countryside because it’s prettier, but it’s not all pretty. These living roofs allow us to take one more (rather pleasant) step towards a greener and more environmentally friendly world. 

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