Like many others, Orianne Landers left school feeling it had failed to prepare her for the challenges of life. “I did OK at GCSE and A-level. But the subjects I took aren’t much help to me now. I took English and drama, which helped with confidence,” she says. “But they’re not as useful as you think they’re going to be.” Landers, 25, soon found her calling in construction. “I did a painting and decorating qualification. That got me thinking about getting a house one day. I thought it would be easier if I could do all the maintenance work myself.” Then her training provider, B4Box, offered her the opportunity to take a course in retrofit. “I’m obsessed with recycling and biodiversity and stuff like that,” she says. “I’m always bringing in my WWF Living Planet reports to the workplace. It’s just the way I was brought up. It was drilled into us as kids.” Landers is retrofitting a redbrick, semi-detached house in suburban Stockport, Greater Manchester, with a team of builders from B4Box. From the outside the house is unassuming, on an ordinary council estate. Step inside, however, and the building has been gutted. The plaster is gone, with brickwork and wiring exposed. The sounds of hammering and drilling echo around, as builders in hi-vis workwear install insulation and block up the chimney. Measures such as loft and external wall insulation, draught-proofing doors, and swapping double-glazed windows for triple-glazed will all help prevent the property leaking heat. “Every conceivable crevice is completely sealed,” Landers says. B4Box has even installed a switching monitoring system that reads humidity levels and feeds them back to the tenant to prevent damp. Buildings are among the biggest contributors to greenhouse gases. Figures released by the Climate Change Committee (CCC), which advises the government on climate policies, show they contributed 17% of UK emissions in 2019, third only to energy generation and transport. Retrofit could also be a vital tool in alleviating the cost of living crisis. Household energy bills are expected to reach more than £3,300 a year this winter and more than 8m UK households face fuel poverty, so cutting energy demand could be crucial. “The cheapest energy is the energy we don’t consume,” says Chaitanya Kumar, the head of environment and green transitions at the New Economics Foundation thinktank. “We know that on average retrofit could cut household energy demand by about a quarter. A 25% reduction on a £3,000 bill is a chunky saving.” However, rather than ramping up retrofit to address the climate and energy crises, successive Tory governments have slashed support for it, reducing uptake from 2.3m insulation installations in 2012 to 72,000 in 2021. The retrofit schemes the government has launched have been deemed inadequate, with a parliamentary public accounts committee last year condemning its flagship green homes grant scheme a “slam dunk fail”. The CCC, in its progress report this year, also criticised the government for a policy gap on domestic retrofit. Decarbonising housing stock is a huge logistical challenge. The UK Green Building Council estimates that to achieve net zero carbon by 2050 Britain will need to retrofit almost all of its 29m homes, working out as more than 1.8 homes every minute. Another significant barrier is that retrofit is perceived as being disruptive for householders due to the building work involved. But B4Box may have found a solution. Its trainees study multiple trades (as “multis”) rather than specialising in one, meaning they can carry out general repairs and maintenance to brickwork, paint, plaster, woodwork and other elements of existing buildings. B4Box, which was recently nominated for a low carbon skills award, could offer a model for scaling up retrofit, says Mark Cox, a B4Box site manager. “When you take a property apart, like you’re doing a deep retrofit, you’ll be doing a lot of the intrusive work like insulating the walls, which multis can do. And when you’ve completed the retrofit, the way the property comes back together – the plastering, joinery, painting and decorating – a multi can do that.” Jamie Hough, 38, had been unemployed for 18 months before joining B4Box in 2010. He now trains the multis and thinks multi-skill construction makes building more cost-effective and time efficient. “Other companies will send five different tradesmen in five different vans to the same job. We’ll send one van with three people in it who will do the same work that those five people will do.” Rather than performing one task on a project, trainees will also see it through from start to finish, which Hough believes improves the quality of the building work. “Plasterers can be messy. They can make hard work for you sometimes. But if you’re doing the plastering and the next step you want to be as neat as you can. The same with the joinery. You want to get it as neat as you can because you’re going to be painting it afterwards.” Training multis could also address the lack of skilled workers. UK100, a cross-party network for locally elected leaders in the UK who have pledged to switch to 100% clean energy by 2050, estimates the country needs 455,076 full-time construction jobs. “Even if you pumped hundreds of billions of pounds right now, there isn’t enough capacity in the system to soak it up,” Kumar says. “You still have a lag between investing £1m today and seeing the result of it because the skill supply is so short at the moment.” For Aileen McDonnell, who set up B4Box in 2008 and sits on the Greater Manchester mayor Andy Burnham’s retrofit taskforce, this labour shortage is an opportunity to give local people meaningful employment. “I grew up in Wythenshawe [a working-class area of Manchester]. I had a university grant, the state paid for me to study. That was a good investment in me that doesn’t happen any more. It’s about finding people like Jamie – and there are thousands of them.” B4Box trainees include people disadvantaged in the labour market such as women, older workers, people with disabilities, the long-term unemployed and ex-offenders. It has trained 1,400 people in Greater Manchester since 2008 and 80% of its current operatives live in Stockport. Unlike many construction colleges, B4Box also guarantees trainees the on-site experience they need to pass their apprenticeships. “Every year there are thousands of people going to construction colleges but they can’t actually complete that qualification unless they’re employed for the next bit of evidence in their portfolio,” says McDonnell. “It would be like medical students suddenly finding out there’s no such thing as junior doctor placements any more, or they’re in such short supply that they’re all chasing them.” A freedom of information request submitted by the trade union Unite in 2018 found that, of the 203,400 people who undertook a construction course in 2016-17 just 21,010 – 10% – were linked to an apprenticeship. The lack of on-site experience means many fail to qualify, causing a skills supply shortage compounded by the exodus of eastern European construction workers since Brexit. For Roy Cavanagh, a former training and apprenticeships executive at Seddon Construction and former chair of the Construction Industry Training Board’s Construction Skills Network for the north of England, the B4Box model shows the possibility of tackling the climate crisis while at the same time investing in workers. “B4Box doesn’t treat people like commodities,” he says. “They treat them like people.” Tell us what you think about the Guardian’s climate reporting – it takes just 2 minutes