More green roofs set to grow in North Vancouver?
Green roof on top of the City Market in Central Lonsdale
On March 4th, 2024, council in the City of North Vancouver voted unanimously to investigate how to incentivize green rooftops. City staff will explore ways to incentivize and permit innovative rooftops, including, but not limited to, green roofs, green solar roofs, blue-green roofs, rooftop food growth and rooftop patios.
What are green solar and blue-green roofs? Green solar roofs combine green roofs and solar panels in the same system, providing the benefits of renewable energy generation along with those of green roofs. Blue-green roofs increase the volume of water stored for irrigation purposes and control the water released for stormwater management.
Some buildings in Central Lonsdale already incorporate green roofs. The roof above the Loblaws City Market in the “Local” building is covered with plants. It’s an “extensive” green roof that covers most of the area and is not a place for humans—keeping it wild, so to speak, for the birds, insects and plants to prosper. It’s lovely to look at from the adjacent apartments, and it reduces the air temperature for these west-facing homes.
“Intensive” green roofs like the one pictured here at the corner of 15th and St. Georges allow for people to use the space as an extension of their suite or as an amenity that all residents can enjoy.
Green roof on a residential building at the corner of 15th and St. Georges
Green roofs are not limited to large strata buildings. Here’s an example of a green roof on top of a house in Central Lonsdale. It is a balcony and a delightful place to sit.
While green roofs typically cost more to install than a traditional roof, they extend the life of the roof membrane and reduce overall building heating and cooling costs. As the North Shore continues to densify, we will need more places for people to recharge, so rooftop parks are a pragmatic way to increase green space. But green roofs can do much more. Here are some of their other benefits:
Control stormwater runoff – Vegetation absorbs stormwater, reducing stormwater runoff intensity. Designers can achieve specific stormwater runoff levels through careful materials selection. According to the North Vancouver Streemkeepers, stormwater running off pavement and other hard surfaces is one of the biggest threats facing our creek ecosystems. The smaller creeks in the city are vulnerable to road contaminants, and their fragile habitat can also be easily overwhelmed and damaged by storm surges. So green roofs help reduce the burden on our municipal stormwater systems and help fish and other aquatic life survive our big rain “events”.
Mitigate fire threat - Retained water in rooftop plants (succulents like sedum) can decrease the chances that a fire will start on a green rooftop. Also, green roofs don’t burn as hot as conventional roofs, reducing the chances for a fire to spread to other buildings.
Regulate temperature extremes – green roofs absorb less heat from the sun than traditional roofs, so they lower the surrounding air temperature. This reduces the heat-island effect, which is especially pronounced in dense urban areas.
Improve air quality – green roofs help improve air quality because vegetation filters dust, absorbs carbon dioxide, and produces oxygen.
Extend roof life – green roofs protect underlying roofing materials in various ways. They protect from mechanical damage by shielding against ultraviolet radiation and moderating temperature extremes, which minimizes the expansion and contraction of roof materials.
Reduce building maintenance costs - Green roofs prolong the service life of heating, ventilation, and HVAC systems through decreased use.
Support natural systems - Flowers and trees give pollinators and other creatures a welcome escape from the concrete that often surrounds green roofs. Green roofs directly support a diversity of plants and insects, provide bird habitat, and nurture pollinators like bees, which are necessary for food growth.
Reduce noise – Green roofs provide increased sound insulation for the building. Green roofs can also absorb sounds that bounce off hard roofing surfaces.
Improve aesthetics – Green roofs can transform the urban landscape by improving views and allowing structures to merge with surrounding landscapes. Having a view of a green rooftop can also increase property values.
Kudos to the City of North Vancouver for considering green roofs an integral feature of a climate-resilient city. We will watch what staff comes back with regarding recommendations in the pertinent bylaws and guidelines.
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