Earthly matters

Stone Age people built circular dwellings cut into the ground and topped with poles covered with reed mats and sod. Archaeologists surmise that they were built that way to take advantage of the more constant temperatures afforded by the subsoil and putting sod on the roof provided water proofing and insulation.

Flash forward 10,000 years and modern architects are using some of the same thinking by creating green roofs. Flat commercial roofs are usually covered with tar and gravel. In low slope situations a roofing system called torch-on is used. Both systems have the disadvantage of being negatively affected by UV light, and they continuously emit volatile organic chemicals, leach heavy metals into the storm water system and contribute to flooding.

Green roof technology takes many forms and utilizes many types of plants determined by the site requirements, including drought and cold conditions. In all cases they provide several advantages over standard commercial roofs. From an environment point of view, green roofs promote biodiversity by creating valuable inner city habitat and feeding stations for insects and birds. They generate oxygen and help clean city air by absorbing airborne pollutants. Interestingly, they store tonnes of water which reduces flooding.

Best of all, green roofs have financial advantages. By adding a layer of growing matter to a roof system, the heating and cooling requirements of a building can drop by as much 50 per cent. This money saving feature is driving industry to adopt green roofs in North America.

For more information on green roof technology, start with these resources.

www.xeroflor.ca