The Rise of Green Roofs

While some still may label green roofs as a novel concept, they are springing up across the country on some of our most iconic buildings, including the Fairmont Hotel in Vancouver and its sister Royal York location in Toronto. Moving green roofs out of the domain of the extraordinary to the ordinary, with the City of Toronto leading the way, is becoming a priority for both Canadian cities and those across North America.

In May 2009, Toronto passed a bylaw requiring all new buildings—including residential buildings over six stories high, schools, and commercial buildings—to have green roofs. It was the first city in North America to pass such a bylaw, but provinces and municipalities across the country have recently undertaken extensive initiatives to green-up their rooftops, too. Many independent organizations, such as Alberta Ecoroof Initiative, are also partnering with private businesses to green the black tops.  

So why are cities so eager to overhaul their rooftops—and do the benefits extend beyond the environmental? Green Living takes a look at what green roofs are, and why businesses and communities are increasingly opting for them.

What is a green roof?

A green roof is a vegetated or "green" area that becomes a part of a building's roof. It generally includes six components: vegetation, a growing medium, a filter layer, drainage layer, root resistance layer and a waterproof membrane between the greenery and the physical roof of the building.

Why build a green roof?

They make environmental sense. The most obvious benefit of building green roofs in urban areas is the contribution they make to improve our environment. Green Roofs for Healthy Cities, a Canadian non-profit organization dedicated to promoting the installation of green roofs throughout North America, outlines dozens of their environmental benefits on its website. These include: serving as a natural filter for rainwater and run-off water, filtering the air, and increasing the exchange of carbon dioxide and oxygen in urban centres (meaning that we get to breathe in more fresh air!).

The numbers attached to these benefits reveal just how important green roofs are. According to Green Roofs for Healthy Cities, just 1.5 square metres of uncut grass on a green roof produces enough oxygen to supply one human with a year’s supply of oxygen, and 1 square metre of grass can remove 2 kg of harmful particles from the air annually. In addition, according to the Alberta Ecoroof Initiative, green roofs can also help mitigate the "urban heat-island effect," which refers the tendency for urban centres to be warmer than the area around it.

While the raw environmental benefits are reason enough to build green, companies can also use them to help meet their sustainability goals.

"As an association, we are trying to reduce our carbon footprint," said Alex Versluis, the YMCA's vice-president of property management. The YMCA recently started construction on a green roof project at its Metro Central location in downtown Toronto. Plans for the roof were in motion long before the City of Toronto passed its bylaw. In addition to needing to repair the existing roof, the organization recognized all the benefits—environmental, social and educational—one had to offer, he said.  

Big savings. The roof refurbishment project the YMCA Metro is undertaking has a budget of $500,000, with $250,000 of that going directly into building a green roof, said Versluis. Despite the hefty price tag, he is confident that ends will justify the means. According to a 2006 study published in the Journal of Environmental Management last year, green roofs are generally 10 to 14 percent more expensive than conventional roofs.

"It pays back in a lot of different ways," said Versluis, citing goodwill from the community, less run-off water and extending the life of the roof as a few of the cost-mitigating benefits. Also, according to a 2004 study conducted by the City of Toronto, green roofs lasted twice as long as conventional roofs.

Green roofs can also help businesses cut their heating and cooling costs—another study, this time conducted by Environment Canada, found that basic green roofs can reduce summer cooling costs for a one-story building by up to 25 percent. The energy cost savings are even more impressive when looked at from a city-wide scale. The aforementioned City of Toronto research also examined how much cash the city would save as a whole through the widespread implementation of green roofs. Citywide savings from reduced energy for cooling would be $21 million, and savings for reduced demand during peak times would top off at $68 million.  

Some business, however, are getting creative with how their leafy roofs can save them some green. The Fairmount Waterfront Hotel in Vancouver uses its green roof to grow herbs, flowers and vegetables and saving the kitchen food costs—up to an estimated $30,000 a year.

Community building and education. The YMCA recognized that a green-roof project could be a tool for community building, an idea that’s gaining traction in other projects.

"We started it so we could have volunteers involved in the discussion," said Versluis. For example, YMCA members were able to participate in various stages of the design process through town hall meetings, emails and blogs—all of which aimed to engage the membership and foster a sense of community around the construction.

Marlene Etherington, volunteer chair of the steering committee for the YMCA’s green roof project, said she has already received more than 100 inquires from people interested in assisting with the actual construction of the roof. She was first drawn to the project by its novelty and the chance to learn. "I didn't know anything about green roofs and wanted to be learning about it," she said.

Through the construction of the green roof at the YMCA and other projects throughout Canada, businesses are showing increasing commitments to sustainability and demonstrating that, in many cases, green roofs are a viable option. Canadian cities have started to build differently and better for the environment, and with the growing momentum of this movement, we can look forward to further environmental innovation from our communities and businesses.