Heating Retrofit Has No Single Answer

The decarbonisation of social housing heating is moving beyond pilot projects and into programme delivery. Yet the diversity of social housing stock, and the absence of a single technology capable of meeting that diversity, remains an underacknowledged constraint on achieving both pace and scale. 

With 85 per cent of UK homes still connected to the gas network and the transition to electrified heating accelerating, the sector faces a fundamental shift in how energy is managed. The gas model matched supply to demand. The electrified model must do the reverse, matching demand to available supply, particularly as the contribution of variable renewable sources grows. 

The case for flexibility 

Flexibility in heating systems means more than product choice. It refers to the capacity of a system to vary when and how it consumes energy, in response to external signals including time-of-use tariffs and demand-side response mechanisms. This requires technologies that can store energy intelligently, pre-heat homes ahead of peak periods and reduce consumption when grid stress is highest, without compromising resident comfort. 

Thermal storage sits at the centre of this. Smart water cylinders can store energy when it is cheapest and greenest, reduce wasted heating by learning household usage patterns, and participate in demand-side response schemes that generate a return for both landlords and investors. Infrared heating systems can use the thermal inertia of the building fabric itself as a heat store, pre-heating ahead of peak periods and switching off briefly when required. 

These are not experimental propositions. Revised Energy Performance Certificate methodology, now expected in the second half of 2027, introduces a Smart Readiness metric alongside Heating System and Fabric Performance metrics. Properties with smart controls and thermal storage will have a direct compliance route to EPC C through Smart Readiness, a recognition that the sector’s policy framework is beginning to reflect the technical reality of flexible, low-carbon systems. 

Flats demand different solutions 

The current emphasis on heat pumps as the primary low carbon heating solution creates a particular gap for flats and small terraced properties. Flats account for roughly 30 per cent of the total UK housing stock and close to half of social housing. Communal heat networks have been one response, but new regulation introduced in January 2025 now requires social landlords operating such systems to register as regulated energy suppliers, a compliance burden that has led a number of providers to withdraw planned schemes. 

The result is a property type that lacks a settled solution. Direct electric heating, including infrared, and compact smart water cylinders designed specifically for smaller homes with limited cupboard space, are among the alternatives being deployed. Solar sharing technologies that distribute rooftop generation across blocks of flats are also available. The lesson from this phase of decarbonisation is that no single technology can serve the whole market, and prescribing one creates risk. 

Affordability and resident experience 

Fabric improvements across the housing stock have reduced space heating demand significantly. The consequence is that hot water now represents a proportionally larger share of a home’s energy use than it did previously. In some monitored properties, hot water energy consumption has exceeded combined space heating and background usage. This shift places smart hot water management at the centre of any serious approach to resident affordability. 

A smart cylinder can heat only what a household will actually use, store energy in cheapest and lowest-carbon periods, and integrate with solar PV, heat pumps and smart tariffs. Evidence from monitored deployments suggests that oversizing of hot water systems is common, with average tank heating volumes running approximately 50 per cent above actual demand, adding avoidable cost and carbon. 

For the Healthy Homes Hub, reducing unnecessary energy consumption in hot water is directly connected to thermal comfort outcomes. A home that wastes energy heating unused water in peak periods is paying more than it needs to while offering no additional comfort. 

Funding, data and the emerging model 

Financing retrofit at scale will require capital beyond what housing associations can raise alone and beyond what government subsidy can deliver. Private capital is entering the sector, initially through new build and increasingly into retrofit, attracted partly by the value streams that flexibility creates. Demand-side response income, solar optimisation and grid balancing services are becoming viable revenue sources that can contribute to the business case for investment. 

Alongside funding, data management is an emerging operational challenge. Smart heating systems generate half-hourly readings across multiple components in each property. At estate scale, this produces a volume of data that most landlord organisations do not currently have the staffing or analytical capacity to interpret. What providers need is a consolidated view that surfaces the actions required, whether that is a maintenance flag, a fuel poverty concern or evidence of resident disengagement with the system. 

One model attracting interest combines low carbon technologies, private finance, energy market income and home energy management within an inclusive rent structure, where the landlord accepts responsibility for delivering a guaranteed minimum temperature. This approach addresses fuel poverty directly, reduces damp and mould risk, lowers maintenance and compliance costs, and reduces the carbon footprint of the estate simultaneously. 

Practical steps for housing providers 

• Review your housing stock by property archetype to identify where heat pumps are appropriate and where alternative direct electric or hybrid solutions may be better suited, particularly for flats and small terraced homes. 

• Consider the role of smart hot water storage in any retrofit specification. As space heating demand falls, hot water efficiency becomes proportionally more significant to resident energy costs. 

• Assess the compliance implications of communal heat networks under the heat network regulation regime that came into force in January 2025 before committing to communal solutions for flatted stock. 

• When evaluating supply chain partners, ask for real-world performance data from occupied homes, not laboratory or modelled estimates. Request evidence of commissioning quality, resident engagement processes and ongoing remote technical support capability. 

• Explore whether demand-side response or time-of-use tariff income could contribute to the business case for heating investment, and what data infrastructure would be needed to capture that value at scale. 

• Consider how estate-level heating data will be managed and acted on before specifying systems, to avoid accumulating monitoring data that cannot be used operationally. 

• Track developments in minimum thermal comfort guarantee models, where landlords take on responsibility for heating outcomes rather than equipment alone, as an approach that may address fuel poverty, damp and mould, and compliance obligations within a single financing structure.