The ice storm drove thousands of Quebecers from their homes for a few days this spring. This new episode of severe weather should encourage us to build houses with a “resilient shell”, say experts.
By her own admission, Stéphanie Robillard-Sarganis went through “hell” when the ice storm caused a two-and-a-half-day power outage in her neighborhood of Saint-Eustache in early April. In just a few hours, the temperature in his house built in 1975 plunged below 10°C.
“We had to sleep under a pile of blankets, with our toque on our heads,” recalls this special educator, mother of two elementary-aged children. “We would have liked to have taken refuge elsewhere, but we had contracted gastro in family. We had no hot water and the food in the fridge was in the snow. »
This case is not unique. On the morning of April 6, nearly 1.1 million Quebecers were without electricity, which prompted the City of Montreal to open eight emergency shelters. This scenario is likely to occur more often in the coming years due to climate change.
Indeed, according to Hydro-Québec, these upheavals will put its network to the test with growing vegetation, forest fires, invasive species and extreme precipitation. These disturbances will also cause increasingly intense heat waves, according to Ouranos.
Indeed, Lady Weather does not only strike in winter. Almost every summer, mercury breaks records and claims lives. “In Montreal, the 2018 heat wave caused the death of 65 people,” recalls Dominique Thomas, civil engineering researcher at the University of Sherbrooke (UdeS).
This is why, argue the specialists, it becomes imperative to build “resilient” houses and buildings, able to remain habitable during heat waves or winter cold, without heating or air conditioning.
The key lies in the quality of the insulation and the impeccable sealing of the house, explains Emmanuel Cosgrove, of Écohabitation, an organization dedicated to promoting sustainable construction.
“The temperature in a house with no air leaks, triple glazing and thick walls with an insulation rating of R49 will change only 2°C in three days during a heating or air conditioning failure , he says, supporting studies. The sunshine and the heat released by the occupants will recover the degrees lost during a winter night. »
To illustrate his point, Mr. Cosgrove makes the analogy between a thermos bottle and a filter coffee maker. “The thermos will keep the coffee hot for a long time. The drip coffee maker has to stay on all the time because the heat is escaping through the glass of the carafe,” he explains.
This increased efficiency increases construction costs, acknowledges Emmanuel Cosgrove. “But that money will quickly be recouped in operating costs,” he adds. Ecohabitation also has a catalog of so-called “passive” kit houses, whose heating costs are reduced to around $1,000 per year.
However, consumers are not ready to pay for this quality, laments Montreal entrepreneur Simon Gareau, of the firm Devauban, which specializes in the construction of low-energy plexes. “When I talk about a LEED-certified project, everyone runs. People need to see. They’d rather put their money on nicer counters than in what’s in the walls,” he points out.
Mortgage financing rules work against high quality construction, noted for his part Patrick Ranger, general manager of the firm Belvedair.
To make the bill more digestible, the architects of Belvedair looked at where to put the money “where it counts”, says Patrick Ranger. Their solution: triple thermos windows and reduced wall insulation to R33 — still 35% higher than the Novoclimat standard.
“60% of the heat loss in a typical home comes from the windows and 12% from the walls. Triple thermos glazing alone reduces this loss to 40%. So dollar for dollar, it’s more cost-effective to put the money on quality windows,” says Ranger.
Stéphanie Robillard-Sarganis would like to own such a house, she says, “but it will not be possible with [her] salary as an educator”.
So how can you improve the resiliency of a 1970s bungalow, for example, whose exterior walls were then constructed of simple 2 x 4 studs? Several experts advocate an operation called “Deep Energy Retrofit” which basically consists of adding a second insulating envelope to the exterior or interior of the house. According to the organization Retrofit Canada, located in Edmonton, such an operation can increase the energy efficiency of a house by 70% and reduce its CO2 emissions by up to 400 tonnes per year.
“In an ideal world, this is the best solution, says Dominique Derome, from UdeS. But, realistically, few homeowners can invest that much money to re-vene their exterior or downsize their interior rooms. »
According to this engineer, an initial gain in efficiency can be quickly obtained by better insulation of the roof, by quality windows, but above all by hunting for leaks. “Buildings from before 1990 are not very airtight. Faults can easily be found by performing a leak test. By sealing the holes around windows and walls, you get better comfort immediately. »
Isabelle Thomas, director of the AriAction research group, suggests that Quebec establish a program for owners wishing to improve the resilience of their homes, in particular to avoid “eco-gentrification”. “It is obvious that we must support them, with technical and financial assistance, in this process,” says the professor from the University of Montreal.
Several social housing projects incorporate the notions of a resilient envelope, says Emmanuel Cosgrove, of the organization Écohabitation. “It’s a good thing since the state pays for the heating,” he said.
The resilient envelope in social housing also allows the most vulnerable people to avoid overcrowded shelters in the event of a power outage, winter and summer, underlines Daniel Pearl, Montreal architect behind the Place Griffintown project.
This building, whose construction is planned within two years, will integrate the most innovative notions of the resilient envelope: superior insulation, natural ventilation, exterior vegetation, absence of thermal bridges, etc. “My goal is for the temperature to stay between 15 and 30°C in the accommodations for 72 hours, without electricity,” summarizes Mr. Pearl.