If humanity wants to keep average global warming within 2.0ºC of pre-industrial times—the stated goal of the Paris Climate Accord—every building on the planet will need to be “net-zero carbon” by 2050, the World Green Building Council concludes in a report released this week.
And that finding poses huge challenges for urban Canadians increasingly housed in glass towers described in another report as giant “greenhouse gas-emitting thermal holes.”
“We need nothing short of a dramatic and ambitious transformation from a world of thousands of net-zero buildings to one of billions, if we are to avoid the worst impacts of climate change,” said CEO Terri Wills. “Businesses, governments, and NGOs hold the key to this transformation, but they must commit to aggressive action. It is possible to create a world in which every single building produces zero carbon emissions, but we must start today.”
Buildings emit about the same annual volume of GHGs as China, WorldGBC observes. To meet the global climate challenge, that leakage must be staunched by a new generation of “highly energy-efficient buildings which generate or supply the energy they need to operate from renewable sources to achieve net-zero carbon emissions.”
Last year, the Council hosted a gathering of green builders from 10 countries that all promised to deliver zero net carbon certification programs by the end of 2017. Its latest report, however, addresses only emissions during a building’s operation; it does not deal with the carbon embedded in building materials (such as cement, one of the world’s largest emission sources during production), or used during construction.
Even so, reducing buildings’ operational emissions to zero by mid-century would require “a monumental and coordinated effort by businesses, governments, and non-governmental organizations,” the Council concedes, noting that only 500 commercial buildings and a couple of thousand homes around the globe meet that standard to date.
The target is supremely challenging. According to the International Energy Agency, the world currently holds 223 billion square metres of built urban space, with nearly 200 billion more expected to be added by 2050. Less than 1% of that is renovated each year—too slow a pace to address even half of it by mid-century. “To achieve universal net-zero carbon in the building sector by 2050,” WorldGBC advises, that rate needs to triple, starting immediately, a step up that “must accelerate for every year of delay.”
Meanwhile the urgency and challenge of retrofitting buildings already standing in Canada—or still being built—came under scrutiny in Toronto’s NOW weekly, which notes that “in a city where half our greenhouse gas emissions now come from leaky buildings, the glass condo boom may be setting us up for failure.”
Many of the glass-walled condominium towers that are a ubiquitous presence on the skyline of Canada’s largest city, and dominate others’, are “greenhouse-gas-emitting giant thermal holes,” NOW declares. “Anyone living in a glass box knows that all those windows have them cranking the thermostat in the winter to keep warm, and blasting the AC in summer to keep from getting heat stroke.”
A third of Toronto’s households occupy high-rise condos, the paper writes, citing Statistics Canada. And “since most of the floor space that will exist in 2030 has already been built, retrofitting our existing building stock is critical to meeting our climate change goals.”
“But how the hell do we deal with all the floor-to-ceiling-glass condo towers already crowding the skyline?” NOW asked Jim Baxter, director of the city’s environment and energy division.
“I don’t really have a solid answer for that,” Baxter replied. “The new condos are basically floor-to-ceiling windows, and windows are large thermal holes. So you have entire sides of buildings that are open to the outside.”