by Ashleigh-Ellan Kavanagh

Created on: April 20, 2010

Green roofing is a very very new construction technique.

Green roofing has a greater initial outlay than conventional roofing techniques. However, compared to regular roofing, they reduce costs in the long term. They also require less maintenance than conventional roofs which also reduces costs. It would work out cheaper than using reclaimed roofing materials. Reclaimed items are also quite often greater in price than brand new manufactured items due to the extraction and extra processes involved. They also last just as long as new manufactured items so overall, it may be better with cost in mind to buy new items, where-as environmentally speaking, it is better to use reclaimed materials. Waste disposal costs roughly about £38/tonne which is reasonably cheap when you consider that it has a tiny environmental impact. It can also be done for free via composting heaps, so could be used to recycle any spare green roofing products. Creating a personal compost heap for your site has a fairly low initial outlay when you consider the cost of either disposing the waste in a conventional landfill or paying for professional disposal via an anaerobic respiration plant.

The energy that can be saved by using these techniques can be huge. If 50% of the houses in New York had a green roof of either kind it would lead to almost 1 degree drop in surface temperature. Every degree we take off the surface temperature roughly 495million KWh of energy could be saved. Roughly, if construction projects used just reclaimed materials they would save an estimated 6 tonnes of materials, 122 million tonnes of waste product and about 18% of carbon dioxide emissions. This is a huge chunk of overall global pollution. Green roofing is effective for keeping in heat, and retaining storm water which provides extra qualities to the roofing. It is expensive initially but when compared to the costs of maintaining the conventional roof, it works out cheaper in the long term. Using reclaimed materials makes a large positive effect on the embedded energy of the whole project. The embedded energy includes processing and transport. As there is no production energy needed and only a small amount of other energies needed means its embedded energy is lower. There is almost no energy needed to compost waste, except from that needed by the bacteria to complete the process. This also saves a lot of energy compared to incineration or using landfill sites.

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