Davide Natuzzi, Salix
The UK’s new Warm Homes Plan (WHP) marks the largest public investment in domestic energy upgrading in the country’s history. Published on 21 January 2026, the plan sets out how £15 billion will be deployed to retrofit five million homes by 2030, focusing on electric heat pumps, rooftop solar, insulation, smart controls and improved housing standards. With residential buildings accounting for around one‑fifth of national emissions and more than 24 million fossil‑fuel boilers still in operation, the challenge is vast and technically complex.
What is often overlooked in commentary around the Warm Homes Plan is the deep pool of technical learning already generated by the Public Sector Decarbonisation Scheme. Our teams at Salix have delivered the scheme since its launch in 2020 on behalf of the government.
Since then, we have supported more than 1,400 public‑sector decarbonisation projects, from hospitals and schools to museums and council campuses, with more £3.5 billion of investment delivered or committed up to 2028.
As the Public Sector Decarbonisation Scheme completes its existing Phase 3c and Phase 4 commitments, the question is how do we transfer the knowledge and skills of the scheme, into the delivery of home retrofits under the Warm Homes Plan?
Our work delivering the Public Sector Decarbonisation Scheme can directly improve the performance, cost‑effectiveness and credibility of the Warm Homes Plan.
1. Accurate heat‑loss calculations: the first critical lesson
A first insight from Public Sector Decarbonisation Scheme is that heat‑loss modelling determines everything: system sizing, running temperatures, controls logic, and ultimately, heat pump performance.
Across public buildings funded through Public Sector Decarbonisation Scheme, technical assessments consistently revealed poorly understood thermal characteristics. Many sites had oversized boilers, undersized emitters, or inconsistent insulation conditions mirrored in UK housing, which is often described as among the least energy‑efficient in Europe.
The Warm Homes Plan shifts emphasis from a traditional fabric‑first approach toward electric heat pumps and solar, while still retaining fabric measures where cost‑effective. This shift increases the importance of accurate heat‑loss calculations because:
- Heat pumps must be sized to low temperature heating, not boiler‑replacement approach
- Radiators and pipework often require upgrading
- Comfort levels depend on real, not assumed, thermal behaviour
If heat pumps underperform in the Warm Homes Plan, it will rarely be the technology that fails, it will be the calculations.
2. System temperatures, emitters, and controls: lessons on low‑temperature heating
The Public Sector Decarbonisation Scheme has demonstrated repeatedly that converting large buildings from fossil‑fuel heating to low‑temperature systems requires, full emitter audits, hydraulic modelling, upgraded pipework and pumps and critical recalibration of controls.
These are the same technical pitfalls facing the Warm Homes Plan, but on a vastly larger and more fragmented scale across millions of homes.
The Warm Homes Plan significantly expands the Boiler Upgrade Scheme with grants up to £7,500 for heat pumps and additional support for air‑to‑air systems. However, subsidy alone does not guarantee performance.
Our Public Sector Decarbonisation Scheme experience shows that heat pumps consistently underperform when controls are not reconfigured to weather‑compensation strategies, radiator circuits designed for 70°C cannot achieve comfort at 45°C without emitter upgrades, commissioning quality is the decisive factor in operational success.
3. Grid capacity and demand modelling: public‑sector rigor applied to homes
I believe, one of the least discussed but most influential insights from the Public Sector Decarbonisation Scheme is the need to model local electrical capacity and peak demand when electrifying heat across multiple buildings. Homes present similar challenges. The Warm Homes Plan includes significant scale‑up of heat pumps, solar PV, battery storage and heat networks.
Public Sector Decarbonisation Scheme projects, especially those on campuses and hospital estates, have shown that local substations can become limited very quickly when multiple heat pumps are installed and smart controls and load shifting significantly alleviate peak demand but must be designed from the outset.
As millions of homes electrify simultaneously, the Warm Homes Plan must embed grid‑aware retrofit practices, exactly the type pioneered in public sector decarbonisation projects.
4. Delivery, commissioning and quality assurance: where outcomes are won or lost
Another powerful lesson from our work delivering the Public Sector Decarbonisation Scheme is that technical quality determines energy and carbon savings. The Warm Homes Plan risks encountering the same pitfalls unless commissioning and quality assurance are prioritised.
Public Sector Decarbonisation Scheme projects have shown that monitoring & verification (M&V) frameworks are essential for validating carbon savings. Installers need training in low‑temperature hydronics, not just heat‑pump installation.
This aligns with Warm Home Plan’s ambition to create 180,000 new jobs across retrofit and clean heating by 2030 – but only if technical standards match the scale of investment.
4. Data: the quiet foundation of every successful retrofit
Through our Public Sector Decarbonisation Scheme assessments we see that data quality is the single biggest predictor of project success. The Warm Homes Plan includes new regulatory standards for the private rented sector, potentially upgrading nearly three million rental properties in four years. I believe, success will depend heavily on accurate EPC revisions, heat‑loss models, smart meter data integration and robust retrofit assessment frameworks.
The Warm Homes Plan is a once‑in‑a‑generation opportunity to transform the UK’s housing stock. To succeed, it must integrate the technical verification, the delivery governance and the commissioning and M&V standards that have defined the Public Sector Decarbonisation Scheme.
As Public Sector Decarbonisation Scheme funding ends and the focus shifts to homes, the UK must carry forward these engineering lessons. The Warm Homes Plan can succeed, but only if it considers technical quality as the foundation of its strategy. If it does, the UK will not only decarbonise its homes but build a retrofit market capable of sustaining net‑zero ambitions for decades to come.
Visit our website to find out more about our work.
This article appeared in the April 2026 issue of Energy Manager magazine. Subscribe here.
