In recent years we’ve grasped onto concepts like rooftop farming and green roofs, not just in the temperate climate of the west coast, but also in cities with less moderate climates across the country. Prompted by environmental and social pressures, it’s a movement encouraged by many cities and the people who live in them.
When Lufa was ready to launch, it found Montreal hadn’t yet developed zoning guidelines for urban agriculture on commercial/industrial sites. That meant the company had to navigate the zoning and building codes and make requests for variances, followed by public consultations. “Fortunately, our experience has been mostly positive to date and we haven’t encountered significant obstacles to rooftop agriculture uses. Tax classification has probably been our most significant challenge to date — we’re still a farm, though in some cases we’re assessed as if our greenhouse was office or commercial space — though city officials have been very proactive about working with us to resolve these issues,” says James Rathmell, Lufa’s chief of staff and corporate development manager.
Rathmell points to Boston’s year-old art. 89 as a stellar example of how cities can provide blanket zoning rules to facilitate urban agriculture, both on personal and commercial scales. The city-wide zoning bylaw allows for commercial urban agriculture on a wide scale to boost food access to underserved communities, provide new opportunities for local business growth, and develop knowledge and education about healthy eating. It includes an allowance in all zoning districts for both open-air farms and greenhouses on the roof level, and includes conditional use for larger buildings.
Although more involved and susceptible to public concern, rooftop farming is an extension of the green roof approach, which is seen as a natural progression of green buildings and is being encouraged, even mandated in some cities for any new building of a certain size as communities explore more ways to reduce their environmental footprint.
There are a variety of approaches to green roofs, the planting material used and the depth of soil that sits at its base, the amount of maintenance required, and the degree of the environmental benefits, but essentially they are likened to a garden on top of a flat-roof building. At its base, a waterproof membrane lies over the roof structure, followed by a drainage layer and landscape cloth which is covered by a growing medium in which the plants, which can include trees, are grown.
Both rooftop farming and the more passive green roofs will likely result in more comprehensive regulations, which may be influenced by frameworks in other urban centres, observes Laura Kumpf, an associate with Miller Thomson LLP in Edmonton. She points to Edmonton’s food and agriculture strategy, fresh, which recommended pursuing opportunities in existing neighbourhoods for urban agriculture, which involved “assessing the regulatory barriers for green roofs in order to encourage food production on rooftops.” Although the Alberta city hasn’t yet entertained a green roof proposal, the community recognized it is an approach being developed in other Canadian cities. “The benefits of rooftop farming are multifaceted by improving air quality, reducing urban temperatures and impact on drainage systems, supporting local businesses, and creating sustainable and economic opportunities for repurposing unused spaces. Further, rooftop farming is a natural progression for the design and construction of green buildings, improves access to healthier food, and reduces a municipality’s environmental footprint.
“A municipality may have regulatory barriers unintentionally limiting rooftop farming,” says Kumpf. “I would say legal frameworks for rooftop farming is still quite novel and the United States has probably made more progress in this respect.” Germany, too, is considered a leader in this area with green roof policies dating back to the 1980s. Now, 15 per cent of the flat roofs in that country are covered in vegetation. In Stuttgart, green roofs are required on all new flat-roofed industrial buildings. Across Europe, more than 75 municipalities provide incentives or requirements for green roof installations.
In North America, communities have been slower to the concept, but there are many proponents and incentives. In 2010, Toronto became the first city in North America to have a bylaw requiring the construction of green roofs on new development. Anyone applying for a building permit for a development of more than 2,000 square metres is required to install a green roof. The mandatory coverage of available roof space varies from 20 to 60 per cent, depending upon the development’s gross floor area.
The city recognized the same standards shouldn’t be applied to industrial/commercial buildings, which are often a single storey and the bylaw was tweaked to allow an alternative for industrial/commercial buildings, using the cool roof approach using solar reflectivity and thermal emissivity. Those unable to meet the green roof requirement can apply for an exemption, paying cash in lieu, which is funnelled into the city’s eco-roof incentive program. The application for exemption is reviewed by the chief planner. The bylaw is expected to be further tweaked in the next year or so to reflect updated construction standards.
Toronto has issued 123 building permits under the green roof bylaw and another 46 are currently under review. “So you’re going to have a visible change in Toronto from the green roof component,” says Jane Welsh, the city’s planning project manager. “So far it’s been working well and we’ve had very few requests for a variance or exception [less than five per cent].”
On the west coast, Port Coquitlam, B.C., is another community that has instituted a green roof program. Its zoning bylaw amendment requires commercial or industrial buildings that are more than 5,000 square metres to have a green roof on at least 75 per cent of the roof area, not including space occupied by mechanical equipment.
Toronto environmental lawyer Dianne Saxe is encouraged by the increased use of green roofs. “There are many potential advantages to using the roofs of buildings . . . for growing things instead of [a surface] of cement and gravel,” she says, citing the overall positive impact on the environment, reduction in the urban heat island effect, as well as the assistance they provide in the management of storm water runoff, which in itself is becoming a major environmental concern. “As climate change increases the intensity of storms, that will be an incentive.”
While some bylaws address the issue head-on by requiring green roofs on buildings, Saxe says their development can be encouraged through other means as well. She points to municipal storm water charges, implemented by some cities and being considered by many more, as another reason for building owners to create a green roof. A green roof acts like a sponge, absorbing the runoff, which later evaporates, helping in the overall management of the community’s storm water. In communities that impose storm water charges, a green roof can be an effective way to offset those costs.
The concept of developers using green roofs to meet city-wide storm water standards was an option suggested in a 2006 report, “Regulatory Options for Promoting Green Roofs in British Columbia.” Bill Buholzer, a partner with Young Anderson Barristers, co-wrote the report as a way to examine how communities could encourage the process. Now, he’s noticed the Vancouver market has readily adopted the idea.
The overall concept of the green roof has since become something of a trend and builders are now keen to feed the demand for those wanting to be seen to live green, says Buholzer. He now watches out the window in his downtown Vancouver office as yet another building designed to be topped with a layer of vegetation is developed in what is becoming something of a standard architectural practice in that city. “Developers recognize the marketability of a green roof feature in their buildings,” he observes. “It’s something the market has responded to in an interesting way.”