More than half of the world's burgeoning population currently lives in cities. With projections showing that urbanization combined with overall population growth could add another 2.5 billion people to urban areas by 2050, measures for better environmental performance of cities gain critical importance.
Sustainable buildings are an important part of the solution and bring a range of benefits, says Mark Hutchinson, vice-president of green building programs at the Canada Green Building Council.
The impact of Canada's LEED green buildings from 2005 to 2015, for example, translates into a reduction of 1,261,016 tonnes of carbon dioxide equivalent of green-house gas emissions, which is the equivalent of taking 238,377 cars off the road for one year. In addition, 231,608 square metres of green roofs, an area the size of 153 NHL hockey rinks, were installed, which contribute to reducing urban heat.
"Urban heat island effect is an important consideration," explains Mr. Hutchinson. "All built surfaces collect solar energy during the day, which is either transmitted into the buildings, where it creates demand for cooling, or radiated back into the atmosphere, where it increases overall temperatures."
As relatively easy steps for addressing urban heat generation on rooftops, Mr. Hutchinson suggests green roofs, solar panels or membranes that reflect a greater percentage of solar radiation. "At ground level, planting more vegetation and minimizing parking by moving it underground can have a big impact," he adds.
When people think of green buildings, energy efficiency often comes to mind first, but Mr. Hutchinson says other aspects, such as water, are equally important. "Water use puts a lot of stress on our water and sewer systems, which is an issue in many municipalities," he says. "It makes sense to use this resource as efficiently as possible."
A green building achieves, on average, a 40 per cent reduction compared to a conventional building's water consumption, says Mr. Hutchinson. Strategies can include low-flow fixtures, rain-water harvesting and re-using gray water.
Since rates for water use are comparatively low in Canada, savings don't usually have a big impact on a resident's bottom line, but cities are starting to recalculate their costs, he adds. "Municipalities are trying to recover more of their costs, including capital costs necessary for upgrading water systems and treatment plants, which can be substantial for larger cities with older systems."
Improved sustainability can also be achieved by recycling construction and demolition waste, says Mr. Hutchinson, who adds that from 2005 to 2015, LEED buildings recycled over 1.6 million tonnes of materials equalling 491,174 garbage truck loads.
"Historically, construction materials have made up a significant proportion of the waste received at landfill, but that doesn't have to be the case. LEED projects divert on average 85 per cent of the material generated during construction," he says, adding that a growing industry around accepting, sorting and recycling material is supporting this practice.
Reducing landfill can have a big impact on municipalities, says Mr. Hutchinson, who believes this aspect of green building can easily be replicated across all construction projects.
| By the numbers |
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| The green building industry generated $23.45- billion in GDP, which represents 297,890 full-time jobs in 2014. This is more jobs than Canada’s oil and gas extraction, mining and forestry industries combined, which collectively employed approximately 270,450 workers in 2014. Source CaGBC |
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