Green Roofs Are Blooming!

Green roofs on a building in Manhattan

Green roofs are also called vegetated roofs or living roofs.

Of course it is not a green-painted roof but a living roof that is intentionally planted with vegetation. Homes as well as commercial buildings can carry these living roofs.

Really? Why would you do this?

A living roof can save energy, greenhouse gas emissions and replaces some of the original vegetation displaced by the building under the roof.

These are some of the benefits:

  • They reduce buildings heating up in summer and cooling in winter, maintaining a pleasant even temperature. A study by Environment Canada showed 26% reduction in summer cooling needs and identical reduction in winter heat losses;
  • Therefore conventional heating and cooling costs, and their greenhouse gas emissions are reduced;
  • Living roofs reduce the urban heat island effect, where many buildings with heat-radiating roofs create a warm mini-climate;
  • The life-span of the roof is actually increased two or three times according to Penn State University’s Green Roof Research Center;
  • Stormwater run-off is reduced. Eco-roofs can retain up to 75% of rainwater, and gradually release it back into the atmosphere through condensation and transpiration;
  • Any pollutants in the rainwater may be trapped in the vegetated roof's soil;
  • Vegetated roofs also filter CO2 out of the air through photosynthesis;
  • They provide habitat for insects and birds and generally bring city-dwellers face-to-face with Mother Nature once again. You can even grow flowers, fruit, vegetables, even woodlands on a flat roof! Or just have your lunch break in your rooftop garden...

So you see, in many ways the living roof has re-appeared at the right time, a time of global warming, energy shortages, pollution and distance from natural processes.

The Hanging Gardens of Babylon are often cited as the earliest green roof, about 500BC. But this history may go much further back than that.

It is hard to believe that our early ancestors, who first lived in caves, did not know of the use of living grass sods and other plants on their roofs.

Indeed the medieval Scandinavians used sod roofs to improve insulation and the Vikings in Newfoundland used them. And here, in the Faroer Islands you can still see the continued expression of that influence.

They knew that green roofs meant energy efficient homes to them, though these terms only became familiar to us in the 20th century. Green roofs have a long history and re-appear in our future In the 1960's Germany experienced a great interest in green roofs and today about 10% of German roofs are "green."

There is a growing Europe-wide application of vegetated roofs and Americans have also seen the light. In fact a number of American cities have regulations promoting living roofs.

Are they here to stay?

Well, an eco-roof was put Rockefeller Center in New York City in the 1930's. Still flourishing today after nearly seventy years of service. They are appearing everywhere.

Green roof research is conducted in universities and research centers in Germany, USA, UK, and Canada.

The pressures of effects of global warming, energy shortages and climate change mean that vegetated roofs will bloom.

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