Living Roofs In The Concrete Jungle

City planners have finally come upon an idea that is both smart and pretty the ‘Living Roof’. Living roofs are simply a roof that’s made of grass or some other type of growing medium. You can actually go back to early Viking homes and see that they had roofs made of grass. Today, you can find their ancestors in the Faroe Islands building essentially the same kind of roofs.

But it doesn’t stop there. You might be surprised to see the top of City Hall in Chicago. it’s actually a ‘living roof’ too beautifully landscaped with grass, flowers and small trees. The California Academy of Sciences also has a completely natural ‘living roof’ that quiet beautiful too.

So, living roofs aren’t anything new. What’s new is that city planners now understand more about their benefits. These benefits can be divided into environmental benefits and outright financial benefits.

Here are some of the environmental benefits use Living Roofs  Concrete Jungle :

  • They moderate the temperature of rainwater runoff.
  • The plants on the roof release water back into the atmosphere.
  • They insulate the building for sound, i.e. the soil blocks low frequency sounds and the plants themselves block high frequency sounds.
  • They filter pollutants out of rainwater that passes through them.
  • They filter pollutants out of the are they breathe. just like a forest does.
  • They help mitigate potential problems with storm water runoff.
  • They can actually act as flora and fauna sanctuaries or even become breeding grounds for species which have disappeared from the area.

Those are some of the environmental benefits of living roofs, but what about the outright money-saving benefits? Here’s a few of those:

    • They reduce cooling costs of a building between 50% to 90% via evaporative cooling depending on whether the living roof is enclosed as a terrarium and is designed to act as a passive solar heat reservoir or not.
    • They reduce heating costs by adding mass and thermal resistance.
    • They can be designed to extend the life of the roof itself, e.g. increased protection from UV damage.
    • They increase the value of the real estate itself.
    • Various types of tax incentives.
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Really the only serious disadvantage of living roofs is that they need to be a bit stronger than traditional roofs. But that’s about it and it’s really a small price to pay for the much greater advantages.

Another set of terms which applies here pertains to the density of plants on the roof and the amount of work required to maintain them. Three different terms are used:

  • Intensive
  • Semi-intensive
  • Extensive

On an ‘intensive’ roof you’ll find 80-150 lbs. of vegetation per square foot. On and ‘extensive’ living roof you’ll find less only about 10-25 lbs. per square foot. Semi-intensive would be somewhere in between.

Today’s trend toward living roofs started in Germany in the 1960’s and today in Germany you’ll find about 10% of all roofs classed as ‘green’ or ‘living’ (the terms are used interchangeably). In general, European governments are ahead of the US government supporting the use of ‘living roof’ technology but the US is catching up.

No doubt about it, living roofs make sense and as people began to understand how much that add to an enjoyable life, you’ll be seeing more of them.

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