John Mava was looking for work when a construction project started behind his house. When he visited the site and saw how different construction was in Canada compared with his native Nigeria, his interest was piqued.

“I said it would be great for me to have knowledge about this,” said Mava, who learned that in Canada, construction uses timber rather than bricks and has a focus on the environment.

The experience led him to apply to the YMCA’s Power of Trades programme and through that he became one of the first hires at Build, a new social enterprise by the Ottawa non-profit EnviroCentre.

Launching in September, Build aims to tackle what environmental advocates and some political leaders describe as two intersecting issues: the urgent need for retrofits in Canadian homes to combat the climate crisis and the shortage of skilled workers to do the job.

Buildings are one of the top-five greenhouse gas emitters, according to the federal government’s most recent overview of Canada’s GHG emissions. This prompted the Canadian Climate Institute to conclude that “Canada’s climate progress has been modest and is at risk of going in the wrong direction”.

Melanie Johnston, a director at EnviroCentre who is responsible for the launch of Build, said: “We are seeing drastic reductions in GHG emissions by providing building envelope upgrades.”

Build’s goal is to provide training in insulation installation, air sealing and other retrofitting skills for people who normally face barriers entering the industry, including women, Indigenous people and newcomers to Canada, such as Mava.

Retrofitting means upgrading a building to improve its energy performance. This can range from minor modifications, such as caulking, to major ones, including overhauling heating and cooling systems.

Retrofits can also provide non-environmental benefits, such as household cost savings or improved indoor air quality. Johnston says they can also lead to “less visits to emergency rooms for asthma attacks or lost days at school or work”.

The Pembina Institute has found that for Canada to achieve its goal of net zero emissions by 2050, about 600,000 homes will need to be retrofitted each year. Updated building codes mean new buildings produce lower emissions, but older ones require retrofitting, especially since 80% of the buildings that will exist in 2050 have already been constructed.

For the past few weeks, Build has been preparing for its September launch by training its first two mentees, Mava and Allan Kanobana. They have been learning the fundamentals of health and safety, PPE use and other theories, while also getting their warehouse ready for opening.

The warehouse is where mentees will learn practical skills, such as insulation and drywall installation and conducting pre- and post-retrofit home assessments.

Most of their training will be in-house, but they also work with groups such as Toronto’s Building Up to share resources.

“It’s very, very interesting,” said Kanobana, “When you look at the building science and the building codes and how building is practised here, it’s very different from where I come from.”

Kanobana moved to Canada from Rwanda in 2024, hoping to give his children a better education. He has a background in occupational health and safety and, like Fava, came to Build through the YMCA.

Johnston said Build has been recruiting newcomers through programmes from the YMCA and the Ottawa Community Immigrant Services Organization. A common employment barrier faced by newcomers is a lack of Canadian work experience, and projects such as the YMCA’s Power of Trades help to bridge that gap.

“We’re really about educating and making sure that the space is inclusive and ready as we’re bridging individuals into it,” said Katie Sexton, a vice-president with the YMCA who oversees the Power of Trades programme, which has an 84% employment rate after completion.

Since 2017, vacancies in skilled trades in the residential construction sector have increased by an average of 11% annually. The impact of Covid-19, bias against blue-collar work, and Canada’s ageing population have aggravated the issue. According to Statistics Canada, more than 245,100 construction workers are projected to retire by 2032, leading to a shortage of more than 61,400 workers.

The federal government says immigration is one solution to this problem, but immigrants face barriers beyond a lack of training.

“The construction industry is historically mostly male, white people,” said Johnston. “We have heard anecdotally through some of the trainees that the environment is not always welcoming.”

That is why another goal for Build is to create a positive and welcoming space for mentees. “We’d like to be able to roll out a tool kit for employers to help them remove some of the older toxic behaviours that you might see in the construction environment,” said Johnston.

Build aims to take on two more mentees by the end of the year and to retrofit the homes of hundreds of clients in the Ottawa area, most of them people who are already familiar with EnviroCentre through their work in the affordable housing sector.

Mava said the environmental impact of the work was central, citing a trip to Huntsville, Ontario, to see the retrofitting of a house where the owner told him he was doing it for his grandchildren.

“He doesn’t want a situation where his kids will ask him: ‘What did you do about it?’” said Mava, referring to the climate crisis. “I don’t want my kids to ask me: ‘John, what did you do about this?’ With this, we’ll be able to reduce the emissions and then the kids will be happy in the future. I’ll be able to say: ‘Yes, this is my own contribution to it.’”

• A version of this article was originally published in Canada’s National Observer and has been republished in the Guardian as part of our ClimateDesk partnership.