Roofs: The last urban frontier

Green Real Estate April 8, 2011

shoppingcartBy Elden Freeman
As spring approaches, the milder temperatures offer a good opportunity to take stock of outdoor inventories and property maintenance needs.

If a visual inspection doesn’t do the job, April showers will certainly indicate whether your roof needs repairs or replacement. When assisting clients this spring, consider recommending a completely new take on the traditional tar-and-shingle roof – I’m referring to cool and green roofs.

These surfaces are what some city planners consider the last urban frontier of unused space.

Anyone who’s been on a rooftop in summer knows there’s a mass of heat emanating from its surface, especially in urban areas where other materials such as concrete assist in heat retention. On a hot summer’s day, the rooftop temperature of a black surface could climb to nearly 90 C, compared to 50 C on a white roof.

Warmer temperatures shorten your roof’s lifespan and hike temperatures inside the building or house. These warm surfaces contribute to the build up of heat in dense urban areas and that leads to a surplus of problems, including increasing summertime peak energy demand, air conditioning costs, air pollution, greenhouse gas emissions, heat-related illness and mortality. Cool roofs go a long way toward reducing these issues.

Cool roofs use materials that reflect solar energy and reduce the transfer of heat to interior spaces. As a result, the roof stays cooler and so does the house. Cooler homes mean fewer burdens on air conditioning systems. Using less energy to cool your house is a win-win for your clients’ pocketbook and the environment.

Two characteristics determine the coolness of a roof. The first is called solar reflectance (also known as albedo) and it is the percentage of solar energy reflected by a surface. The other is called thermal emittance and it is the percentage of energy a material can radiate.

For residential buildings, cool roof materials include clay tiles, metal coatings and composite shingles. There’s no need to worry any more about cool roofs standing out like a sore thumb because of their white colour. They come in a whole range of colours and can’t be visually distinguished from standard roofs. They cost about 20 cents more per square foot than traditional roof shingles. You could also choose to install white or lighter-coloured shingles and the cost of the roof will be the same as conventional asphalt shingles. For flat or low-grade roofs, membranes are typically used and they cost about the same as a conventional roof.

Green roofs are a little different but carry similar benefits. They use rooftop vegetation to lower temperatures. The environmental benefits of eco-roofs are numerous. Green roofs help reduce urban heat and associated energy use, which is a particular concern as global temperatures rise. Green roofs also help manage storm water runoff, enhance biodiversity, improve air quality, and beautify our cities.

In January 2010, Toronto became the first North American city to require green roofs on new residential, commercial and institutional developments over a certain size. The city is offering grants to help owners retrofit existing buildings with cool or green roofs. Other communities are likely taking note.

As real estate professionals, boning up on information that will help your clients save energy costs and the planet makes good business sense. Cool roofs are cool in more ways than one.

Elden Freeman B.A., M.E.S, broker is the founder and executive director of the non-profit National Association of Green Agents and Brokers (NAGAB). Freeman says he believes that Realtors across Canada can play an important role in educating their clients on increasing energy efficiency and reducing greenhouse gas emissions. (877) 524-9494;;