Making green roofs even greener

Researchers at the University of B.C.'s Okanagan campus are trying to green up an already green idea.

Professor Kasun Hewage and master's student Fabricio Bianchini, both engineers, are investigating whether they can improve the environmental footprint of green roofs.

Because they are testing the roofs in a drier climate in the Okanagan than where the roofs are normally used, their research could also help prove the roofs' usefulness in arid regions throughout the world.

Green roofs have been used for decades in Europe, and have more recently caught on in North America.

There are examples of green roofs in downtown Vancouver, including at the Vancouver Public Library and the Vancouver Convention Centre.

The green roofs have a range of benefits which include absorbing green-house gases, lowering temperatures directly above the gardens and reducing run-off.

The green roofs also help filter dust and potentially harmful chemicals, and reduce the heating and cooling loads on buildings.

However, Hewage and Bianchini found the benefits of green roofs are diminished by the pollution created during the manufacture of the plastics and rubber mats that provide drain-age for the plants.

The researchers' life-cycle analysis showed it would take as much as 25 years to compensate for the environ-mental damage caused from making the plastic in the matting.

Life-cycle analysis is an examination of the environmental effects of a product from cradle-to-grave. The analysis includes the extraction of raw materials, manufacturing and disposal or recycling of materials at the end of the product's life.

The researchers' assessment also compared the toxic emissions from the industrial production of the plastic to the air pollution removed by the plants during the lifespan of a green roof.

"The current green roof is not sustainable enough because some of the manufacturing materials themselves emit gases, some toxic materials," says Hewage.

Once it was known that the mats diminished the benefits of the green roofs, Hewage and Bianchini decided to test the use of construction material waste as a drainage base to replace the plastic mats.

The construction waste is abundant by the time a green roof would be constructed, would produce no additional manufacturing pollution and would also be a unique way to reduce the amount of waste going into landfills.
Source:Yahoo