Exploring the role of alternative clean heating solutions: our response

We believe that electric boilers without energy storage are very unlikely to play a significant role in decarbonisation due to their high running costs, lack of flexibility and demand on both the local network and total grid generation, particularly at peak times. 

Yes, electric boilers with either hot water storage or other thermal energy storage technologies could play a minor role in decarbonisation of heat in homes. Specifically, these technologies could play a role in homes with existing wet heating systems, no space for an external heat pump unit and too high a heat loss for a fully indoor heat pump that connects to outside air through short wall ducts to provide a significant proportion. Flexibility of charging could work well with time-of-use tariffs to keep running costs down, while also managing peak impacts on the electricity network and grid. 

Electric boilers with electrical battery storage could operate in a similar way (ie with time-of-use tariffs and flexibility), but capital costs and product lifetimes make this currently unattractive for consumers. In homes with solar panels, electric boilers along with electric batteries are more likely to be a preferred approach due to the combined benefit from managing both excess generation and heating electrical demand. There will also be some benefit from diverting solar generation to any electric heating system, both directly when possible and via the battery at other times. 

We should stress that much of this benefit is also possible with a heat pump in combination with storage and generation. As such, electric boilers should still be viewed as a secondary option where heat pumps are not possible, as with any form of direct electric heating. 

It is our view that infrared heaters could play a minor role in decarbonising heating in a similar way to panel heaters or electric radiators which are typically used as supplementary heating and so provide the sole heating system for a particular room or top up secondary heating to a room.  

While we’ve has heard positive experiences from individuals with infrared in their homes, this is limited and the report by Leeds Sustainability Institute for DESNZ ‘Infrared heating: investigations from literature and user experience tests’ states that there’s insufficient reliable published data on the use of infrared heating systems in real-world contexts to effectively evaluate their potential as a low carbon technology in the UK. 

Infrared panels may not produce a homogenous heat in a room, due to a warmer area within the range of a panel. This might suit some occupants but may not suit others. There can also be line of sight issues – i.e. between a person and the panels and this can be especially so in cluttered homes, where panels may be out of sight, or become covered in some way – which could impact thermal comfort. There are also sometimes situations where there is no suitable location for panels that is acceptable to the householder. 

As infrared depends on suitable temperature control by the user, there may be situations where this does not happen. For example, in cases where the user does not understand how they should control the panels or expects more automation with controls, there is a risk that this may not result in bill or carbon savings. 

There could also be issues for some properties where infrared heating provides thermal comfort for occupants at temperatures below 18C, but where the property requires sufficient warmth throughout (eg minimum of 18C) to avoid damp issues.  

Overall, the thermal comfort of householder to any heating type is difficult to measure. As such, we believe future trials on the effectiveness and user experiences of infrared heating should be conducted.  

We agree that panel heaters and electric radiators should play a smaller role in decarbonising heat, primarily because of their much lower efficiency compared with heat pumps.  

Direct electric heating converts electricity into heat on a one‑to‑one basis (COP = 1), whereas heat pumps typically achieve a COP of 2.5 to 4 and thereby substantially reduce running costs for households and improve overall system efficiency. This efficiency gap is the key reason these technologies should not be deployed widely as part of a decarbonised heating strategy. 

We do not consider their “limited ability to load shift” to be the decisive factor. Load‑shifting limitations can be mitigated through storage technologies, like electric batteries, but the primary issue is that their intrinsic efficiency is lower than that of a heat pump, which can result in higher energy bills for consumers. 

While we expect heat pumps to play the leading role in heat decarbonisation,  there are specific circumstances in which panel heaters and electric radiators are appropriate and sometimes preferable to other heating technologies. This includes: 

• As secondary heating, where a primary technology heats the main living space (for example, an air‑to‑air heat pump), and electric panel heaters are used to provide top‑up or room‑specific heating in spaces such as bedrooms, kitchens, bathrooms or hallways. 

• Homes where heat pumps are not feasible due to space constraints, for example, properties without external space for an outdoor unit or where internal storage capacity is inadequate. 

• Small or highly efficient homes with very low heat demand. In such cases, the capital cost and system complexity of a heat pump may not offer proportional benefit. 

• Properties, or parts of properties, that are intermittently occupied. For example, holiday lets or second homes that may be unoccupied for long periods. This is because heat pumps are most efficient when maintaining heat, whereas direct electric systems can better suit irregular heating patterns. 

• Situations requiring low‑cost, low‑disruption installation. This is particularly the case where upgrades are needed quickly or where a building is awaiting deeper retrofit in the future. 

From a decarbonisation perspective, where a full heat pump or thermal storage system is not viable, direct electric heating remains preferable to hybrid heat pumps. This is because hybrid heat pumps retain a reliance on fossil fuels and therefore remain a direct‑emissions heating system, locking households into carbon emissions for the lifetime of the appliance (potentially 15 years or more). As Great Britain’s electricity system continues to decarbonise, direct electric heating will deliver progressively lower emissions.  

We agree that high‑temperature heat pumps could play an important role in decarbonising heating of buildings, particularly for a subset of UK homes where achieving acceptable performance with standard low temperature systems is not viable. Their potential role is being examined through ongoing UK Government analysis into the costs of decarbonising complex‑to‑decarbonise homes, which we are supporting the Department with.  

For domestic properties, the key barriers to the installation of high temperature heat pumps are:  

• Upfront unit costs, which are typically higher than standard systems (although some evidence suggests this is more than offset by reductions in ancillary costs such as radiator replacements).
• Running costs: Operation at higher flow temperatures can reduce efficiency, increasing running costs.  
• Installer familiarity and confidence, which remains limited. 
• Low product availability in the domestic market. 
• Low consumer awareness. 

These barriers could be overcome by providing targeted capital support to homes where high‑temperature systems are the most appropriate solution. Performance‑based incentives that reward whole‑system and lifetime outcomes rather than headline COP could also be explored. Clearer guidance within government-backed schemes on when high‑temperature solutions are appropriate could help prevent inappropriate installations, as well as expanded accredited training to build installer competence. Market confidence may improve with clearer policy signalling of a defined, limited role for high‑temperature systems and better consumer information and tailored advice for complex properties.  

A key risk of using high-temperature heat pumps is “performance lock‑in”, where they are installed to avoid necessary internal upgrades (e.g. radiator optimisation), which may boost short‑term uptake but embed higher flow temperatures, resulting in lower efficiency and higher energy consumption (and bills) over the system’s lifetime. This risk could be mitigated by scheme rules and advice that prioritise future‑proofed designs and make the long‑term performance implications of different design choices explicit. 

We believe that air-to-air heat pumps could have a significant role to play in decarbonising home heating, but the scale of that role is unclear. 

There are several barriers that prevent the installation of air-to-air heat pumps in domestic properties, as well as several factors that could improve uptake.  

Key barriers 

Air-to-air heat pumps have a smaller external unit than an equivalent air-to-water system, which could make them an option for some flats and homes with limited external space. There is uncertainty about where these smaller units can be sited, including whether it is acceptable to fit them on balconies and suspended from external walls. 

Internal air-to-air monoblocs can potentially heat properties with no external space even for a small external unit. These require two holes to be drilled in the external wall of the property and can provide heating (and cooling) for a large room or open plan space. This technology is not established in the UK and there is little understanding of how much heating a single unit would provide in a multi-room home. 

Installation of air-to-air systems is likely to make more sense in homes without an existing wet heating system as this would have to be removed prior to installation of an air-to-air system. Whilse air-to-air systems are typically cheaper and less disruptive to install than air-to-water systems, the current installer base does not see air-to-air heat pumps aligning with the skills of air conditioning or ventilation engineers.  

Air-to-air systems also typically do not provide domestic hot water (although some models do), so households require an additional solution, such as an electric cylinder or point‑of‑use water heating. This is a manageable design consideration, but it can affect whole‑system costs and needs to be factored into policy and consumer guidance. 

There’s also confusion among households around an air-to-air heat pump’s internal monoblocs as well as split units, with some believing they are a ventilation system too, as they seem to blow air into the room, whereas most units on the market do not provide any ventilation. 

Potential factors to improve uptake 

Active cooling is a key driver in the sale of air-to-air systems for the UK domestic market, with systems typically marketed as air conditioning rather than as heating systems. If the two functions were marketed equally, then the desire for active cooling could prove an effective driver for the decarbonisation of heating. 

Air-to-air systems can also offer more flexible zoning and quicker heat delivery. Individual indoor units can serve different rooms or spaces, allowing households to heat only the areas they are using. Warm air delivery also provides faster temperature changes than low‑temperature hydronic systems, which may appeal to households with intermittent occupancy patterns. 

Given their simpler installation requirements and the existing skills within adjacent trades, air-to-air heat pumps could scale more quickly in certain segments of the market. This could help deliver early carbon savings, especially in the significant share of the housing stock currently heated with direct acting electric heating, as well as storage heaters. 

European evidence  

We’re taking over presidency of EnR, a network of 27 European Energy Agencies in 2026. This network provides the ability to draw in best practice from around Europe where there is a growing evidence base around passive and active measures. We would welcome a conversation with DESNZ about how we can use our membership of the network to inform the UK’s policy development in this area.  

Cooling Challenge  

Under the Low Energy Inclusive Appliances (LEIA) programme, we lead the Ayrton Sustainable Cooling Challenge, on behalf of DESNZ, DSIT and FCDO who provide strategic direction. The Challenge aims to ensure that, in a warming world, the growing need and demand for cooling in developing countries is met by supporting the development of sustainable and affordable technologies, business models and financing mechanisms. The challenge is aimed at developing countries but there are developments and best practice which are likely to be of interest to the UK as well.  

In this role, we convene the Ayrton Sustainable Cooling Challenge Steering Group. This is the advisory and coordination body which brings together representatives from each of the contributing UK Government departments, programme implementers within the Challenge portfolio and key external stakeholders, such as Sustainable Energy for All (SEforAll) and the United Nations Environment Programme’s Cool Coalition. The purpose of the Steering Group is to oversee and review the delivery of the challenge plan, identify opportunities for cross-programme collaboration and track activity for monitoring, reporting and learning purposes. 

The Ayrton Fund has provided a helpful framework for increasing the visibility and coordination of ICF programmes across UK Government departments. We see potential to build on this progress to further enhance coordination and better integrate efforts across UK Government departments with a view to maximising the overall effectiveness and value for money of ICF funded interventions.  

The challenge has made positive progress, bringing UK Government funded cooling-related work together, leading to an enhanced ecosystem understanding, sharing of lessons learnt and collaborative activities. An example of a collaborative activity facilitated by the challenge is that of LEIA/Energy Saving Trust and SEforAll working together with the UNEP Cool Coalition to, for the first time, fully integrate access to cooling in the 2025 Global Cooling Watch Report (GWC).  The GWC is a high-profile and influential publication that informs the commitments of the 72 signatory countries of the Global Cooling Pledge.

Yes, we agree that networked heat pumps can play a key role for buildings with limited outdoor space. This is demonstrated by Kensa Utilities’ “Heat the Streets” project, which demonstrated that shared ground‑loop (networked) heat pump systems can enable low‑carbon heating for terraces, tenements and flats where individual air‑source heat pumps are impractical. Nesta has received this approach as a scalable option for space‑constrained, medium‑density housing. 

We would point to Nesta’s “A networked approach to low- carbon heat”  for evidence or views on appropriate business models and steps required to support them. 

We would point to Nesta’s “A networked approach to low-carbon heat” for evidence or views around the public appetite.  

Heat recovery ventilation is important for providing sufficient ventilation that is low carbon and fuel saving for both new and existing homes (primarily for high airtight homes). Ventilation measures are important for providing safe and healthy homes, particularly alongside low carbon retrofit measures. This is reiterated by a new study showing that dwellings in Great Britain are more airtight than previously thought.

While heat can be recovered from expelled air via conventional Mechanical Ventilation with Heat Recovery (MVHR) systems to warm the incoming air, we believe exhaust air heat pumps could have a role. Exhaust air can be used as the heat source for both an air to water heat pump for heating hot water and potentially for space heating too via hydronic emitters. 

There could be potential for future developments of systems, such as to incorporate exhaust air heat pump technology to further improve MVHR efficiency or for ventilated exhaust air as a heat source for an air to air heat pump. 

As exhaust air heat pumps are often smaller powered units, we believe they could have a role in properties with low heat demand and properties where there is insufficient outside space for an AWHP. Introducing any type of ventilation that can extract heat from the exhaust air can have benefits in decarbonisation and building/occupant health, particularly for buildings with higher air tightness. 

Heat batteries can play a role through working with direct electric resistive heating to store heat for later use by the heating system. This would enable the use of time of use tariffs to lower running costs and encourages shifting of electricity usage to times of lower demand. The effect is very similar to the use of an electric boiler with hot water accumulator, but the space requirement is less. Systems are also available with smart controls that could help minimise running costs and/or improve network capacity management. 

In principle, heat batteries could also be used to store the output of a heat pump to combine the high efficiency of the heat pump with the load shifting potential of the heat storage. However, this might encourage more frequent fluctuation in heat pump output which could significantly reduce the Seasonal Performance Factor (SPF). Also, any thermal storage system would require a heat pump flow temperature that is higher than the design flow temperature for the heat distribution system, which would further reduce the SPF. This would be particularly significant for phase change heat batteries which (currently, at least) require input temperatures above 60°C. 

It seems likely that flexible operation with a heat pump would be more effective if achieved through an electric battery rather than a heat battery. This would allow load shifting while allowing the heat pump to run steadily and at a lower flow temperature. We are currently modelling running costs and potential savings for this scenario and hope to publish results in spring 2026 which we would be happy to share with the Department.  

Heat batteries can also be used in place of a conventional hot water cylinder to provide domestic hot water, together with a heat pump or with direct electric heating. This can be a helpful option where there is limited space for a hot water cylinder and the system being replaced uses a combi boiler. 

As stated earlier, any thermal storage technology used in combination with resistive electric heating, whether from the grid via a time of use tariff or from surplus onsite generation, could be managed to help limit strain on both the local network and the wider grid.  

For this to be effective, there would need to be both significant roll out of the technology and strong correlation between the economic drivers (such as tariff structures) influencing householder control choices and the needs of the network and grid. This might be achieved through offerings where householders give over some of the control of their heat storage to a third party, or simply through better coordination, and presumably commercial arrangements, between DSOs and energy suppliers to ensure tariffs support beneficial behaviours. 

As mentioned above, we believe energy storage with heat pumps is more likely to take the form of electric batteries, but both are potentially feasible and would benefit from the same increased integration between householder drivers and needs of the network and grid. 

Modern high heat retention storage heaters (HHRSHs) can play a modest but useful role in heat decarbonisation in homes without a wet central heating system, alongside air-to-air heat pumps. 

Specifically, HHRSHs can play a role in homes where heat pumps are not feasible where heating patterns are relatively consistent and predictable. Their main contribution is their ability to reliably shift demand to off-peak, lower carbon electricity periods.  

Our modelling indicates that HHRSHs can be significantly cheaper to run than older storage heaters and cheaper than direct electric heating. This is primarily due to improved heat retention and better alignment with low-cost tariff periods, respectively. However, in comparable dwellings they remain more expensive to run than heat pumps, reflecting the latter’s considerably higher efficiency. 

HHRSHs therefore offer a practical alternative in homes where a heat pump is unsuitable. The Scottish Government’s Heat in Buildings Strategy treats modern storage heaters as an accepted clean heating option within this hierarchy. 

Despite their benefits, HHRSHs also have limitations. Their flexibility is reduced once charged because stored heat can be depleted if weather or occupancy patterns change unexpectedly, which may result in households needing to draw additional electricity to heat their home during peak‑time (through controls like ‘boost’). In addition, HHRSHs are local space heaters rather than whole‑home systems: they heat individual rooms and do not provide domestic hot water. As a result, households often install multiple units and rely on secondary heating and separate hot water systems. These features do not affect their decarbonisation potential but do introduce uncertainty when quantifying savings, as room level heating patterns and systems vary.

Being listed within the SAP Product Characteristics Database (PCDB) confirms a technology’s tested product performance but does not reflect real‑world operating behaviours such as charge timing or peak avoidance. Therefore, if government grant schemes wish to ensure storage heating performs as intended under a decarbonised, flexible system, criteria beyond SAP eligibility may be appropriate. These could include: 

• proven capability to charge during off‑peak or smart‑tariff periods; 
• advanced smart controls (e.g. adaptive start, weather responsiveness); 
• minimum heat‑retention performance. 

These features are widely available in modern units and already form part of typical SAP Appendix Q recognition and Lot 20‑compliant products.

A “heat pump first” hierarchy remains appropriate, but any requirement to demonstrate heat pump unsuitability should be proportionate and administratively light‑touch, such as a short, standardised advisory‑level screening based on known property characteristics (e.g. space constraints, existing system, fabric limitations). 

Electric underfloor heating is not specifically mentioned in the consultation document. This could have a role, in the same way as panel heaters and infrared panels as secondary or top-up heating. We refer to our response to Question 5. 

We believe solid biomass could have a minor role to play in decarbonising heat. However, its role will be limited by constraints regarding internal and external air quality as well as space, availability of sustainable and affordable fuel and user acceptance. 

While there is mixed evidence about the level of PM 2.5 and other pollutants from different types and sizes from biomass burners, it is clear that emissions can be managed more successfully in larger and more automated systems. Domestic open fires and log stoves are causing increasing concern over internal and external air quality, while pellet and chip boilers still emit sufficient pollutants to raise concerns over their use in any area with a risk of local air quality issues. 

We would argue that most built up areas are better suited to either heat networks or individual heat pumps. There is no need to support any form of biomass burning in these areas unless it is to provide heat through a network and/or to a large non-domestic user, and there is a suitable location for the plant with adequate emission controls and air quality monitoring. 

Some homes and businesses in rural areas, particularly isolated buildings, may be able to burn wood without risking negative impacts on air quality, provided the combustion system, fuel quality and operation are all appropriate. Some of these homes would have access to cheap or free wood fuel through their role in, or association with, farming, forestry, woodwork, arboriculture, landscape gardening etc. It therefore makes sense to enable these households to decarbonise quickly and cheaply by installing appropriate wood boilers, if they prefer, even in homes where a heat pump would be technically feasible. This is very much a niche market, but it is still important to allow building owners to adopt their preferred low carbon heating system within an appropriate set of constraints. 

Given the multiple factors influencing the suitability of solid biomass burning, we think it would be useful for the UK Government to produce a more definite set of requirements to guide homeowners and businesses in making decisions. As air quality is the primary concern, explicit and evidence-based regulation is needed on what technologies and what fuels were allowed where. This might prohibit all wood burning in some areas, while in others limit it to certain technologies, standards and fuel types. This approach would provide an appropriate framework for customers and suppliers to make choices about heating systems. 

It is our view that if there were clear and comprehensive regulations on where different solid biomass options were permitted, then any building in a permitted area could install a permitted system subject to space, fuel availability and owner or occupier preference. Some of those buildings would be suitable for heat pumps and some would not, but if a building were suitable for both then there is no value in mandating one solution over another.   

Alternative electric heating systems present some challenges for some people with protected characteristics, but for others there may also be benefits compared to heat pumps or other heating systems. 

The following issues may have differential impacts on people with protected characteristics, depending on the heating technology used, how it is specified and installed, and controlled.  

Surface temperatures and physical safety 

Some forms of alternative electric heating, such as panel heaters and infrared panels, may have emitter surface temperatures higher than traditional wet radiators. 

This potentially affects the following protected characteristics: 

• Disability 
• Age (children and older people) 
• Pregnancy and maternity 

This can present a burn or contact risk for: 

• children 
• people with sensory impairments 
• people with reduced mobility or balance 
• people with cognitive impairments or dementia 

Unless units are installed out of reach, protected with guards or otherwise mitigated through specification and layout, this may pose a higher safety risk than lower‑temperature emitters typically used with heat pumps. 

In some settings, electric underfloor heating may be a more suitable electric alternative, particularly in small rooms where higher‑temperature emitters are not appropriate. However, this also requires careful consideration of installation constraints, control usability and running costs. Installer guidance and system design must explicitly consider surface temperature risks and household composition where protected characteristics are present. 

Heating responsiveness and medical or care‑related needs 

Heat pumps typically operate using a steady, low‑temperature heating pattern, designed to maintain a stable background temperature rather than deliver rapid heat boosts. While this approach can be beneficial for many people, particularly those who require consistent warmth, it may not suit everyone. 

This potentially affects the following protected characteristics: 

• Disability 
• Age 
• Pregnancy and maternity 

Some individuals may have: 

• medical conditions requiring rapid temperature increases.
• pain or circulation issues triggered by feeling cold. 
• care routines requiring different heating patterns in specific rooms. 
• visiting carers with short time windows and immediate comfort needs. 

The limited ability of many heat pump systems to provide fast, high‑temperature boosts may therefore pose challenges for some households with protected characteristics, particularly where individual room control or supplementary heating is not available. 

System design should allow for flexibility, which may include supplementary heating where appropriate and clear discussion with occupants about whether steady‑state heating is suitable for their needs. 

Heating “on demand” and habitual control behaviours 

Some households currently manage their heating using very simple behaviours: 

• switching heating on when cold 
• switching off when warm, going out, or going to bed. 

This binary “on/off” approach may suit certain forms of direct electric heating better than heat pumps, which rely on anticipatory control and continuous operation. 

This potentially affects the following protected characteristics: 

• Disability 
• Age 

For people with: 

• cognitive impairments 
• learning disabilities 
• limited digital confidence 
• long‑established habits 

For this group, the shift to a system where heating must be planned in advance, rather than reacted to, may be difficult or distressing. 

Support must recognise that behavioural change is not equally achievable for all households, and that some users may struggle to adapt to control strategies required for optimal heat pump performance. 

Understanding heating controls and system complexity 

New heating technologies introduce new control interfaces and potentially new heating patterns. These can be difficult for some people to understand or use effectively. 

This potentially affects the following protected characteristics: 

• Disability 
• Age 

This issue is compounded where: 

• carers also need to understand the system 
• carers are visiting rather than resident 
• carers have limited time to learn unfamiliar controls 
• multiple heating technologies are present in one home 

In some systems, effective use of controls is critical to achieving efficiency. For example, some infrared heating approaches rely on occupants accepting lower air temperatures due to radiant comfort. This requires behavioural and perceptual adjustment that may not be realistic in all households. 

Poor control usability risks excluding some people from achieving comfort or affordability benefits and may increase reliance on carers or other support networks. 

Electricity tariffs and financial accessibility 

Some heating systems, including heat pumps, can deliver better value and lower carbon impact when paired with variable or time‑of‑use electricity tariffs. 

However: 

• not all households can understand or manage tariff complexity 
• not all households can shift heating patterns to suit tariff structures 
• some households require heat at specific times regardless of price signals 

This potentially affects the following protected characteristics: 

• Disability 
• Age 
• Socio‑economic disadvantage (intersectional impact) 

While some alternative electric heating systems may be less dependent on tariff optimisation, the broader trend towards tariff complexity risks disadvantaging people who are unable to engage with these systems. 

Assumptions about tariff optimisation should not be embedded into programme design without considering accessibility and fairness. 

Evidence gaps and need for further work 

Available research suggests that disabled people and households with protected characteristics can face additional barriers in retrofit and heating system transitions, including with heat pumps. However, evidence specific to alternative electric heating technologies remains limited. 

We therefore consider that: 

• Further trials of alternative electric heating systems are needed, explicitly including households with protected characteristics. 
• Trials should assess comfort, safety, usability and ease of control, not just technical performance. 

• Outcomes should inform guidance on where and for whom different technologies are suitable. 

To address these issues, we recommend that: 

• Manufacturers be required to provide clear, accessible guidance on: 
  • suitability of their products for households with protected characteristics. 
  • surface temperature risks. 
  • control complexity and user requirements. 
• Installers be required to: 
  • assess household needs beyond fabric and heat loss. 
  • consider protected characteristics as part of system specification. 
  • provide tailored handover and support. 
• Programmes and policy frameworks explicitly recognise that: 
  • no single heating technology or control strategy will suit all households. 
  • flexibility, choice, and support are essential to avoid exclusion. 
  • the availability of impartial, tailored advice will be crucial to ensure all households properly understand what will work for them.