Every credible route to net zero in the UK runs through the buildings that are already standing. Around 80% of the homes that will be in place in 2050 are already built, and most leak heat. Fixing them is the largest practical climate task the country faces. It is also the one where ambition and delivery have drifted furthest apart.
The numbers set the scene. The Climate Change Committee says retrofit must ramp up to roughly one million homes a year by 2030 to keep the UK on track. The Government’s flagship Warm Homes Plan, launched in January 2026 with £13.2 billion, aims to upgrade five million homes by 2030. That sounds substantial. Measured against the scale required, it covers only a fraction of the stock.
Andrew Spencer has spent five years inside that gap. He is Energy and Carbon Services Director at Equans UK and Ireland, where he has delivered more than £135 million of low carbon retrofit through the Public Sector Decarbonisation Scheme, supporting over 30 public sector partners. His diagnosis is that the problem is not technical, and it is not really about money alone. It is about treating a national infrastructure challenge as something smaller.
The scale of the shortfall
Spencer’s framing of the gap is matter of fact. “To meet our current 2050 targets within the UK, we need to retrofit between 1 and 1.5 million buildings per year,” he says. “Our current targets that we’re meeting are under 100,000 per annum.”
That is a tenfold to fifteenfold shortfall. The official advice agrees on the direction. The CCC has repeatedly warned that the UK is off track on existing homes, and earlier called the absence of a clear insulation strategy a “shocking gap in policy”.
Spencer does not soften it. “We’re just not, we’re not meeting our targets,” he says. “It’s quite simply we’re not going at the pace and scale required.” Asked why the gap persists when everyone can see it, he points to three things that have to move together. “Workforce, funding and policy, and the alignment of all three really.”
A workforce that does not yet exist
Start with people. The skills shortage is the constraint most often cited, and the estimates are wide. “The estimates vary, they really do,” Spencer says. “Between 200,000 to 500,000 within the industry.” He lists the roles. “That’s installers of insulation, heat pumps and ventilation, electricians are required into the system.” Then come the professional roles under the PAS 2035 retrofit standard. “Retrofit coordinators, designers. We need surveyors, assessors.”
Independent estimates sit inside that same range. The Construction Industry Training Board has put the figure at an additional 230,000 trained workers by the end of the decade. The Warm Homes Plan itself promises to create more than 180,000 green jobs by 2030.
For Spencer the headline number misses the real issue. The bottleneck is competency, he argues, rather than raw head count. The market is too fragmented to scale. “We’re highly SME based within the UK, regionally fragmented, and we’re just not scaled for programme delivery.” Training does not move fast enough to close the gap either. He describes a pipeline that takes “12 to 24 months for competency,” is “poorly funded,” and “lacks a clear career pathway.”
Funding that will not stretch
Money is the second leg, and Spencer is clear that the state cannot carry it alone. “We’re looking [at] about a 10 to 20 billion annual requirement,” he says. “The public purse can’t take that. So private funding is required in that space.”
Set the Warm Homes Plan against that annual figure and the limits show. Its £13.2 billion runs across five years, to 2029/30. The public schemes that came before it have a thin record on reach. The Great British Insulation Scheme was forecast to help 300,000 households by 2026, yet had reached fewer than 45,000 at the point Parliament’s Energy Security and Net Zero Committee reviewed it.
The policy backdrop has also shifted under delivery. In June 2025 the Government confirmed it would commit no further investment to the Public Sector Decarbonisation Scheme beyond already awarded projects, ending new funding for the very programme through which Equans delivered its public sector work. That scheme had issued more than £3.5 billion across nearly 1,400 grants over its lifetime. Its closure to new bids underlines Spencer’s central worry about stability.
Without a steady pipeline, he argues, the supply chain has no reason to invest. “Our workforce is quite largely SME in the UK, and they’re not investing into the workforce because there is no stability around funding over the long term.”
An infrastructure problem in disguise
Spencer’s sharpest point is about how government classifies the task. “At the moment what is happening is we’re looking at this as a construction problem in the UK,” he says. “It is not a construction problem, it is an infrastructure problem within the UK that needs to be aligned, and I believe government need to take that stance and move forward.”
The distinction matters because infrastructure attracts patient capital and long horizons, where project-by-project construction does not. He sees the same flaw in policy that sets targets without enforcing standards. Headline ambitions exist, “but then when you dive down into the standards and the policies that back that up, they’re not being policed correctly.” The result, in his words, is that “we’re falling short at the bottom.”
Where Spencer still finds optimism
For all that, Spencer does not present the position as hopeless. He points abroad for proof the task is doable. “Where I think the built environment is done better is in the likes of Germany, where they’ve had strong policy over this over quite some time with funding,” he says. “The German market is one that I look to and go, yes, it can be done.”
He also points to a place-based model Equans is piloting in the West Midlands. The firm is delivering what it and its partners describe as the UK’s first net zero neighbourhood in Brockmoor, Dudley, backed by £1.65 million from the West Midlands Combined Authority and covering up to 300 homes. Homes there are getting deep retrofit, with solar, batteries and low carbon heating, alongside transport and green space improvements.
The case for working at neighbourhood scale, in his telling, is that it creates the one thing the market lacks. “When you use systems thinking, actually you can drive the demand, the pipeline and a solid stable pipeline over the long term to create the environment to make it a success.” Devolution, he believes, is a mechanism that unlocks it, with combined authorities in Greater Manchester and the West Midlands already pulling those levers.
The gap, then, is real and wide, and the data offers no comfort. Yet Spencer’s argument is that the shortfall reflects a category error as much as a shortage of cash or hands. Reclassify retrofit as national infrastructure, give the supply chain a stable pipeline, and the workforce and funding follow. “Far too long have we been talking about this,” he says. “A bit of change and a bit of action is where I’m at.”
Andrew Spencer is Energy and Carbon Services Director at Equans UK and Ireland. He spoke to the Climate Solutions News podcast ahead of Reset Connect London on 23 and 24 June.
