Benefits of Green Roofs
Monday, July 20th, 2009Green roofs are vegetated roof systems that passively perform no less than 8 highly beneficial and cost-saving functions, including stormwater runoff reduction, heating and cooling load reduction, and extending the service life of the roof by 40 -60 years. They also mitigate urban heat island effect, absorb carbon dioxide, sequester air-borne particulates, provide urban wildlife habitat, reduce noise pollution, and other services that not long benefit the building but also the surrounding community.
Due to the many benefits of green roofs, many municipalities offer incentives to make the initial cost of a roof compatible to a conventional roof. Some examples are:
- Faster approval/construction permitting process
- Reduced stormwater/wastewater system development charges
- Reduced stormwater/wastewater usage fees
- Reduced size of stormwater management ponds or cisterns
- Grants rewarding energy efficiency or economic and environmental objectives
- Density bonus / larger floor area ratio
- Satisfy minimum parkland / green space requirements
- Greenhouse gas emissions trading credits, stemming from energy savings
The installation cost can range from $10/sq ft to $50/sq ft or more depending on the type of roof you want, plant selection & availability. Although installation of new green roofs cost more than conventional roofs, they are competitive on a life-cycle basis due to reduced maintenance & replacement costs.
An example of an existing green roof is in the Fairmont Waterfront Hotel in Vancouver. They spent $25,000 CAD to install a 2,100 sq ft green roof with a soil depth of 18″. They currently use it to grow herbs vegetables for the hotel’s restaurant. Annual food production saves the hotel an estimated $25,000 to $30,000 in herb costs alone.
For more information on green building practices please visit Cascadia’s Green Facts Sheet.
