Toronto Trying to Force Green Roofs – Could Your City be Next?

  • Published on April 21st, 2009

Green roof on top of Chicago City Hall

North of the border a controversy is starting to gain steam in the nation’s largest city, Toronto. The city has proposed a by-law that would make ‘green roofs’ mandatory in new construction of condos higher than 7 storeys and office or retail complexes greater than 54,000 square feet (about 1/4 of a Wal-Mart Supercenter). The proposed law would require 30-60% of the surface area of buildings’ roofs to be green (depending on the size of the building) and violators would be subject to fines up to $100,000.

A green roof is partially or completely covered with vegetation and soil that has been planted over a waterproof layer on top of the standard roof of a building. The benefits of these roofs are many, including reduced storm water runoff, reduced noise pollution, and increased longevity of the roof by protecting it from natural elements.

Green roofs are also getting attention in this era of greenhouse gas mitigation because of their potential to reduce energy use. The layer of soil and vegetation above the traditional roof provides an additional layer of insulation that reduces cooling in the summer and heating in the winter. Green roofs also reduce the severity of the urban heat island, which is the increase of city temperatures by several degrees over surrounding rural areas. A reduction of the heat island effect means a cooler city and less energy used for air conditioning.

So why all the fuss in Toronto? A battle is evolving between the City of Toronto and the powerful land development industry. For several years the city has been led by a pro-environment mayor who is determined to make Toronto a global centerpiece of environmental responsibility. Some representatives of the city council are so dedicated to the green roof plan that they want it broadened in scope. Deputy Mayor Joe Pantalone has asked city staff to deliver an expanded green roof by-law that would include schools, low-rise commercial buildings, and even private residences.

The developers are publicizing the additional costs involved with building a green roof, which they claim is $18-$28 per square foot over traditional roofs. They argue that this will result in more expensive housing, office space, and retail goods, costs that will be passed on to the tax-paying consumers of these products.

The city has decided to postpone a scheduled April council vote so that the issue can be discussed by the Toronto Planning and Growth Committee again on May 6.

A number of questions came to mind as I reviewed this intriguing story:

  • Instead of strong-arm regulatory tactics, wouldn’t incentives or tax breaks be a much more appealing way to encourage green roof construction? This voluntary approach has been promoted by the developers as a reasonable alternative to the proposed by-law
  • Has the City of Toronto researched the realities and benefits of implementing and maintaining these roofs on such a large scale? Lawrence Solomon of the Financial Post raises some excellent points and encourages the city to be deliberate and proceed with caution. A pilot project and comprehensive life cycle assessment of green roofs would be logical approaches before approving a city-wide by-law
  • Most importantly, is the city overstepping its bounds by trying to force this kind of expensive building construction? There are a myriad number of ways that the government influences the construction of buildings. Often this is in the name of public safety, such as sprinkler regulations and electrical codes. Can a by-law that has been proposed to combat climate change be considered a public safety law? Or is this an example of a city going too far by trying to regulate a component of construction that is best left to market-based approaches?

If this by-law does pass, it will be interesting to see if this kind of regulated green development policy will spread to other cities in North America.

Image: The Udall Legacy Bus Tour Views From the Road at flickr under a CC License

Stephen Boles is co-founder of Kuzuka, a marketplace website that will bring a new level of convenience and confidence to carbon offset customers and provide consulting services to organizations that want to assess and reduce their carbon footprint.

About the Author

Steve Boles doles out thoughtful commentary about all the latest issues, news blips and misconceptions surrounding the growing green movement as a contributor to Red, White, and Blue and his personal blog The Buzz ( Steve spent seven years working as a scientist at one of the world’s leading climate change research centers, the Institute for Earth Oceans and Space (EOS) at the University of New Hampshire. Steve recently moved his family to small-town Ontario, Canada. Steve and his wife, Jenni, recently co-founded a company called Kuzuka. Kuzuka is a marketplace for carbon offsets that will bring a whole new level of convenience and confidence to individuals and businesses choosing to offset their tread on this planet. Kuzuka also provides carbon management services to businesses that are interested in measuring and reducing their corporate carbon footprint.


  • Is there a real benefit to green roofs when compared to solar panels? I'm not convinced. Solar panels provide energy that the building below it is using. Reducing the load on the electrical grid will reduce emissions from power generation facilities…this will also reduce the heat island effect of cities as the solar panels will absorb some of the solar radiation that'd otherwise become heat.

    Now, if you put up a green roof instead you gain insulation bonuses. You also now require fertilizer, landscaping, water, etc. And all this must be brought to the roof. Also, does having an un-mowed roof subject you to nuisance laws? I'd take a look at the google campus if you want to see how a roof done right works.

  • As an environmentalist and roofing contractor I have been involved in environmentally conscious roofing since 1980. The main function of a roof is to make a building watertight. Just a small amount of water allows mold and mildew to grow causing a myriad of medical problems. Medical attention equals energy use. Improper materials, added weight, non sustainable materials, expense and materials that do now work are major issues in the roofing industry. Every building, residential, commercial and industrial have a roof and the consequences of there failure impact all of us.

    The white roof option saves significant cooling cost and energy use. White acrylic roofs are water based and have low Volatile Organix Compounds (VOC's). This means very little Greenhouse Gases as in asphalt roofs made from petroleum. Less power is being generated so less coal or oil being burned. According to the US EPA a black tar roof reaches 166 degrees F on an 85 degree day. High performance white coatings never exceed 92 degrees F. And they cost less than tar roofs.

    There are many solutions available now for many of the environmental problems that Humans are facing. Because this is an emergency situation it would be wise to embrace them to get the ball rolling and the benefits accruing. Debate and delay are not the friends of our planet.

  • It's about time that the larege cities of todays world are mandating green roofs. It erks me that the biggest concern is the expenses, because it's either spend a lot now, and save the earth and human life, or don't and regret it later.

    more designs should be encouraged, supported and proposed for large cities and even smaller cities who are continually building out, verses up!

    lets work together and change the world!

  • I dont see it as a negative decision to force developers to build green roofs on new projects. Such a law has been in place since 2002 in Tokyo, Japan. Developers are still doing business if only at a lower bottom line. Companies would not be affected by this since the cost savings of cooling and lower absenteeism would more than compensate for the initial purchase or rental cost. In Chicago's city hall for example their green roof has saved the city $3600/yr in cooling costs.

  • It is funny to see how things in North America are going from one extreme to another – always and no matter what it is.

    Not even 10 years ago roofs in North America had only the function to protect the inside of buildings against the elements and to generate a descend profit for roofers because there was a constant need for fixing and repair.

    Now with the green wave from Europe everybody’s attention is on the roof and has ideas how wonderful it would be if we created a paradise up there.

    Since we successfully destroyed the paradise on the ground dreamers believe roofs – especially green roof – can bring things back, right into the city and with a huge job and profit machine.

    I would like to suggest four things:

    1st: Stop dreaming, start thinking.

    2nd: Fix the problems on the ground. This is cheaper, more efficient and less risk for the investment of a building.

    3rd: Standardize green roof technology first as it is in other countries since decades.

    4th: The Cities should be a role model with countless green roof installations first, go from there and make a law based on this experience.

    As more “green” you request by law the more costs will be generated and environmental benefits will dramatically decrease at the same time. At the end a new industry will be dead before even started, no help for the environment and a bigger hole in the pocket of the people than before. This is a lesson learned from Europe where things are obviously even more ahead than I thought.

    FYI: In Europe are many laws to force "green" but based on what I said above plus they try to fix the environmental problems before they are a problem.

    Jorg Breuning

  • In my opinion the controversy is not about whether or not green roofs are beneficial. Green roofs provide a lot of benefits over traditional roofs – that much is clear. But they are considerably more expensive, and the controversy lies in the City's desire to make these expensive roofs mandatory. The developers claim the price increase is $18-$28 per square foot – I have not researched whether this is accurate or not. Giving them the benefit of the doubt and assuming a $25/square foot premium over traditional roof costs, this would add $2.5 million to the cost of a typical 100,000 square foot big box retail store. Would this make or break a company's decision to locate in Toronto as opposed to the suburbs? I can't answer that question. But I do think that it is an expensive requirement for the City to make mandatory, especially when the costs will no doubt be passed on to the individuals that live in those buildings or shop in those stores.

  • Spain already passed legislation making solar panel on roofs mandatory on new buildings that fit certain specifications. I don't understand why this is still treated as such a controversial issue.

  • The "increased costs" are only of a concern to the developers. The users of green roof complexes would see the increased rent and maintenance costs outweighed by reduced air conditioning costs. Developers don't care about ongoing cost savings they only care about building the cheapest building they can to make the most profit. The government is there to balance the rights of the developers to make money with what is best for the citizens of the city.

    The Developers still make money as they just increase prices but they have to compete with rent prices from existing non-greenroof buildings. This may slow the growth of new building projects for a couple of decades but then things would return to normal.

    One option would be to raise rates and give rebates to all those with green roofs. This would allow private residential owners to get in on the game as well even though it would never really be cost effective for them.

  • I think that's great. here in CA our mandate is white painted roofs now and solar (for new residential) by 2020. I think green roofs are far better than the white paint option.

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