In January 2026, the full details of the Warm Homes Plan was released by the UK government.
1. What is the Warm Homes Plan?
The Warm Homes Plan is the latest UK government programme aimed at improving the energy performance of our housing stock and it marks a move away from the short-termism that defined earlier schemes. Those programmes were target-driven and measure-focused. Install the loft insulation. Fill the cavity. Hit the numbers. Move on.
That approach delivered activity, but it rarely delivered long-term system performance. Deadlines were tight, targets were ambitious, and sequencing was often secondary to volume. The result? Predictable: performance gaps, compliance issues and, in some cases, large-scale remediation programmes that have cost both the industry and the taxpayer dearly.
The Warm Homes Plan signals a more serious, longer-term view. Targets have been pushed back to more realistic timeframes. There is greater emphasis on electrification, health, damp and mould, and value for public money. In other words, it’s less about ticking measures off a list and more about whether homes actually perform.
2. What kinds of upgrades are covered and who benefits most?
The Warm Homes Plan focuses on fabric improvements and low-carbon heating, including:
- Loft, cavity wall, solid wall and floor insulation
- Air source and ground source heat pumps
- Solar PV and battery storage
A central theme of the Plan is electrification of heat.
Electrification simply means moving homes away from fossil fuels like gas and oil, and instead heating them using electricity typically through air source heat pumps. Rather than burning gas in a boiler, a heat pump uses electricity to extract heat from the outside air and transfer it into the home.
This shift matters because electricity can increasingly be generated from renewable sources. Gas cannot.
But electrification only works properly if the home itself is efficient.
The real winners under this programme are not already high-performing properties. They are the older, harder-to-treat homes, particularly the millions of pre-war houses with suspended timber floors and solid walls.
These homes typically:
- Sit at EPC D, E or below
- Have high uncontrolled ventilation rates
- Lose significant heat through floors
- Struggle to run efficiently with low-temperature heating
Electrifying a modern, airtight home is straightforward. Electrifying a cold, leaky Victorian terrace without addressing fabric first is expensive and inefficient.
That’s why sequencing matters.
3. What does fabric-first mean and why does it matter now?
Fabric-first means reducing heat demand before upgrading the heating system.
In simple terms: fix the leaks before you upgrade the boiler.
Under gas heating, inefficient fabric was expensive but manageable. Gas boilers run at high temperatures and can brute-force comfort into a leaky home.
Heat pumps don’t work like that.
They operate most efficiently at lower flow temperatures. The higher the heat loss, the harder they have to work which reduces efficiency (COP), increases electricity consumption, and pushes up running costs.
That’s why fabric-first matters more under electrification than it ever did under gas.
In suspended timber floor homes:
- Floors often account for 15–25% of total heat loss
- Sub-floor air infiltration can represent a significant portion of uncontrolled ventilation
- Cold perimeter zones create thermal bridging at wall/floor junctions
If you insulate lofts and walls but ignore the floor, you haven’t created a high-performance envelope. You’ve created a partially upgraded one.
And partially upgraded systems are where performance gaps appear.
The Warm Homes Plan also needs to be viewed through a cooling lens. As UK summers become hotter, more homes will rely on active cooling, whether through reversible heat pumps or standalone systems. Airtightness and envelope performance matter just as much for keeping heat out as they do for keeping heat in. A leaky suspended timber floor doesn’t just waste heating energy in winter; it allows warm external air to infiltrate in summer, increasing cooling demand and reducing system efficiency. Improving the building envelope, including the floor, reduces both heating and cooling loads, future-proofing homes for a more electrified and climate-stressed environment.
4. How does an uninsulated floor can make things worse?
In suspended timber floor homes:
- Floors often account for 15–25% of total heat loss
- Sub-floor air infiltration can represent a significant portion of uncontrolled ventilation
- Cold perimeter zones create thermal bridging at wall/floor junctions
If you insulate lofts and walls but ignore the floor, you haven’t created a high-performance envelope. You’ve created a partially upgraded one.
And partially upgraded systems are where performance gaps appear.
Across nearly 5,500 UK installations, the average suspended timber floor starts at a U-value of around 0.82 W/m²K. After high-performance underfloor insulation, that drops to approximately 0.19 W/m²K — a reduction of roughly 77% in floor heat loss.
That is not marginal, it shifts the entire demand profile of the home.
| Underfloor Approaches Compared | |||
| Factor | Uninsulated Floor | Mineral Wool / PIR (Internal Lift) | Q-Bot UFI |
| Typical U-value achieved | ~0.82 | ~0.25–0.35* | ~0.19 |
| Heat loss reduction | – | Variable | ~77% |
| Airtightness impact | Poor | Minimal | 18–25% typical |
| Floor lifting required | – | Yes in 90% of UK homes | No |
| Resident decant risk | – | Possible / Common | Rare |
| Install duration | – | 3–7+ days | 1–2 days |
| Repeatability at scale | – | Workmanship dependent | Mechanically consistent |
5. How do these factors matter?
Heat pumps don’t respond to theoretical U-values. They respond to total heat demand and peak load.
In a typical suspended timber floor home:
- Annual heating demand: ~12,000 kWh
- Floor share: ~20%
- Achieved floor heat loss reduction: ~77%
- Whole-house demand reduction: ~20%
That level of demand reduction materially alters how the heating system operates: Lower peak demand, lower flow temperatures, higher seasonal efficiency.
At this point, the impact is no longer theoretical. It is measurable in electricity use and cost.
| The System Impact | ||||
| Metric | Heat Pump Only (No floor upgrade) | Heat Pump + Solar (No floor upgrade) | Heat Pump Only (With Q-Bot UFI) | Heat Pump + Solar (With Q-Bot UFI) |
| Floor U-value | ~0.82 | ~0.82 | ~0.19 | ~0.19 |
| Whole-house heat demand (thermal) | ~12,000 kWh | ~12,000 kWh | ~9,550 kWh | ~9,550 kWh |
| Seasonal COP | ~2.8 | ~2.8 | ~3.4 | ~3.4 |
| Heating electricity use | ~4,286 kWh | ~4,286 kWh | ~2,800 kWh | ~2,800 kWh |
| Heating cost @30p/kWh | ~£1,286/yr | ~£1,286/yr | ~£840/yr | ~£840/yr |
| Solar self-consumed electricity (indicative)* | – | ~1,260 kWh | – | ~1,260 kWh |
| Solar bill reduction @30p/kWh (indicative)* | – | ~£378/yr | – | ~£378/yr |
| Stacked annual impact vs baseline (HP-only, no floor upgrade) | – | ~£378/yr | ~£446/yr | ~£824/yr |
*Assumptions for solar: 4 kWp PV, ~3,600 kWh/year generation, ~35% self-consumption (no battery / typical), import price 30p/kWh. PV savings shown are whole-home electricity bill reduction from self-consumed solar (not “heating-only”, because solar and heating seasonality varies).
Solar reduces the cost of imported electricity. Over a 15-year heat pump lifecycle, that difference equates to roughly £6,000–£12,000 in avoided electricity exposure (tariff dependent).
Combined, the savings stack.
The Warm Homes Plan is built around electrification, health and long-term value for public money.
In suspended timber homes, electrification without addressing the floor leaves performance on the table.
The difference is not just comfort, it is:
- Lower system sizing
- Lower electricity exposure
- Reduced damp risk
- Improved durability
- Greater capital efficiency
Heat pumps are not failing homes. Homes are failing heat pumps.
Fabric-first, in suspended timber properties, must include the floor.