Victoria may be seeing a lot more green in its future. But not where you’d expect it. Picture a variety of plants or grasses growing on a rooftop near you. Councilors Matt Dell and Jeremy Caradonna tabled a motion on Jan. 11 to remove barriers to adding green roofs, rooftop solar, and rooftop patios to Victoria’s built environment. 

Current municipal barriers to building green roofs include zoning and FSR (Floor Space Ratio) bylaws. Adding green and solar to rooftops, said Caradonna, “aligns with our climate and sustainability goals.” “We are hoping to bake these options into the city’s OCP (Official Community Plan),” he said. 

Green roof technology in Canada has gained popularity recently because of its many environmental benefits. In 2006, the federal government published a Green Roofs Resource Manual for municipal governments in which climatological big sister, Vancouver was featured. In it, motivators for incorporating green roofs in cityscapes include stormwater run-off and reducing greenhouse gas emissions.

By improving the insulation of buildings, green rooftops also can lower energy consumption on hot days, contributing to more sustainable and eco-friendly urban environments. Additionally, green roofs help mitigate the urban heat island effect by absorbing and deflecting sunlight, ultimately lowering temperatures in more densely populated areas.

On the downside, the cost of installing green roofs can pose a financial barrier for some property owners. The construction and maintenance of these systems also involve specialized materials and expertise, making them more expensive than traditional roofing methods.

Furthermore, the weight of the green roof and the need for additional structural support can add to the overall expenses, especially in a city like Victoria, where rainfall can be significant over many days. Insurance also poses a challenge for property owners who may incur the risk of leaking.

These were some of the same considerations and concerns city councilors raised at their meeting.  

City staff member Karen Hoese reminded councilors that the city is already incentivizing the installation of green roofs and systems through its Rainwater Rewards program. “We already have 24 properties receiving credits for green roofs under the program and 38 projects with green roofs proposed under construction and new development,” she said.

Toronto was the Canadian vanguard

In 2009, the city of Toronto became the first in Canada to pass a bylaw requiring all new construction with a footprint exceeding 2Ksq metres to incorporate a green roof. The green roof that covers the Convention Centre in Vancouver is the largest in the country and features 400K native plants and grasses.

The Convention Centre roof has had its problems with leaks in the past. Moist climates, like Victoria’s, are also conducive to the growth of fungi, mold, and other plant diseases. Climate change and heavy rains may exacerbate these problems. Excessive moisture on the green roof substrate can create an environment that promotes the development of these pathogens, posing a threat to the vegetation and the structural integrity of the roof. 

Managing and preventing these issues may require additional maintenance efforts and expenses, reducing the overall feasibility of green roofs in such climates. Furthermore, the constant moisture can attract pests, such as insects or rodents, which may negatively impact the green roof ecosystem and potentially lead to broader pest control challenges.

There are some challenges because water weighs a lot

One significant concern is the potential for increased weight due to water retention. In consistently moist conditions, green roofs can become saturated, leading to excess water weight. This additional load may strain the building structure and require more robust support, contributing to higher construction costs. Moreover, the added weight can lead to issues such as soil erosion and compaction, affecting the overall health and longevity of the green roof system.

The University of Victoria’s David Turpin building is one positive example of getting the challenge right.

Any initiatives would be voluntary

Challenges that arose from some councilors addressed similar construction issues and insurance liability concerns. Coun. Marg Gardiner’s request was that the motion not include “any blanket regulations or aspirations. I wouldn’t like to see it be mandatory,” she said, “because if something is mandated, they have to accept the liability. Once they have a leak, the insurance won’t cover them. And then you’re into a nightmare, be it a rental or condominium buildings.”

Gardiner raised the distinction between green roofs and “green on the roof” and spoke to the practicalities and flexibility the second option allows. In response,  Caradonna was quick to point out that, because of existing bylaws and insurance models in Victoria, the motion to reduce barriers was simply that and did not imply “any move to compel action.”

These are all things to consider, said Dell, “as we try to build a more livable climate-friendly green city in the future.”