By Niall Parkin, Sustainable Fuels Product Manager at Calor
Over the past two years, the UK’s transition to low-carbon heat has moved decisively from strategy to implementation. Electrification now sits at the centre of national policy, supported by the £7,500 Boiler Upgrade Scheme (BUS) and the government’s Warm Homes Plan, which sets out ambitions to upgrade millions of homes. Heat pumps are rightly seen as a cornerstone of that journey, and their role will only expand in the years ahead.
To deliver that transition at scale, however, we need to be cognisant of the realities of Britain’s diverse housing stock, and of the installers responsible for the change on the ground. While policy is necessarily national in scope, housing is shaped by local variations and intricacies, from differences in property age and construction, to density and existing energy infrastructure, that influence how the transition can be delivered in practice. For installers delivering low-carbon heating, these are not theoretical considerations, but practical constraints that shape every project detail, cost discussion and timeline.
Across the UK, around 4.4 million homes, approximately 15.1% of households, are not connected to the gas grid. Many rely on established wet central heating systems that continue to provide consistent, high-temperature heat in colder, more exposed and often damp rural climates. For installers working in these areas, decarbonisation is rarely a straightforward technology replacement exercise. It is shaped by the condition of the building, the capacity of the local electricity network and the financial reality facing households.
The debate, therefore, should not centre on whether electrification is essential, but on how to deliver carbon reduction at pace in homes that are not yet fully prepared for it, while supporting installers to manage the transition pragmatically. This includes considering the role that lower-carbon alternatives, such as renewable liquid fuels including BioLPG, can play in reducing emissions in the interim.
Understanding the UK’s housing stock
Heat pumps deliver their best performance in buildings with strong thermal envelopes and reduced heat loss. This is why the Warm Homes Plan places insulation and efficiency upgrades at the heart of its approach – improving fabric is not only compatible with electrification; it is foundational to it.
However, many off-grid homes were built long before modern energy efficiency standards were introduced and often require significant fabric upgrades before low-carbon heating systems can operate at their most effective. According to the English Housing Survey 2022–23 energy report, the average cost of improving a pre-1919 property to EPC C stands at £10,664. Detached homes average £8,284, while properties rated the least energy-efficient in Band E-G require on average £13,509 to reach that benchmark. Rural off-grid homes frequently fall into more than one of these categories, meaning they often face multiple pressures at once.
This does not mean that electrification is impossible, but it does make implementation more complex for off-grid households. In many cases, insulation, glazing improvements or emitter upgrades must precede the installation of a heat pump to ensure optimal performance. For households, this introduces additional capital requirements beyond the upfront cost of the heating appliance itself. For installers, this often means managing phased projects, navigating funding constraints and advising customers on sequencing rather than delivering a single appliance swap.
Alongside this, infrastructure readiness adds a further layer of complexity to how the housing stock can transition. The 2024 Regen report for the MCS Foundation highlights mounting pressure at distribution network level, particularly in relation to low-voltage grid capacity and local planning. In rural areas, this can mean connection constraints, approval delays and reinforcement timelines that sit outside the scope of a single installation project.
The strategic role of sustainable fuels
Taken together, these constraints shape the pace and sequencing of the transition, making it important to maintain steady progress in carbon reduction as homes and networks are prepared for greater electrification. Bringing these properties on the sustainability journey therefore requires pathways that can be implemented quickly and with lower levels of disruption, and that can be delivered using the existing installer network, skills and supply chains already operating in off-grid areas.
LPG has long provided reliable heating in rural Britain, supported by well-established infrastructure. Its renewable counterpart, BioLPG, offers equivalent operational performance to LPG with substantially lower lifecycle emissions. Parliamentary written evidence submitted in 2024 cites lifecycle carbon reductions of between 40% and 80%, depending on feedstock, with some submissions indicating savings of up to 90% compared with conventional LPG. For households already using LPG, switching to BioLPG can be achieved without changes to boilers or heating systems, enabling immediate emissions reductions and allowing installers to deliver carbon savings without additional system redesign, retraining or extended installation times. For those currently reliant on heating oil, conversion to LPG, and subsequently BioLPG, can also represent a more straightforward step to decarbonisation than electrification, typically requiring fewer property alterations and reducing the risk of unforeseen retrofit complications.
The importance of compatibility should not be underestimated. Many off-grid properties already rely on LPG or heating oil, often delivered through wet central heating systems. For properties awaiting insulation upgrades or operating within constrained electricity networks, this can provide a practical interim pathway where full electrification is not yet feasible. Carbon savings can therefore be realised using existing systems, allowing emissions reductions to begin while building and network upgrades are sequenced.
Hybrid heating systems can then support further progress. By combining an air-source heat pump with an LPG or BioLPG boiler, hybrid configurations allow a significant proportion of heat demand to be met electrically, while retaining high-temperature support during peak conditions. This reduces strain on local electricity networks and provides resilience in properties with higher heat loss. For installers, hybrid systems can also offer a more manageable transition pathway, combining established expertise with heat pump installation skills and spreading project complexity over time.
Although the Boiler Upgrade Scheme currently supports standalone heat pumps, hybrid systems are not fully recognised within it. In contrast, the Netherlands is targeting one million hybrid heat pumps by 2030, reflecting a view that managed electrification can bridge infrastructure and housing constraints effectively.
Taken together, renewable liquid fuels and hybrid systems offer a structured route forward. They enable rural households to reduce emissions immediately, before progressing towards greater electrification as homes and networks become ready, while supporting a stable and scalable delivery model for installers operating in dispersed rural markets.
Delivering a transition that includes every home
The Warm Homes Plan seeks to cut emissions while also reducing fuel poverty and improving housing quality. Delivering against those goals will depend not just on ambition, but on how effectively solutions can be deployed across the full diversity of the housing stock and on whether installers have practical, fundable pathways they can confidently recommend to households.
Renewable liquid fuels provide measurable lifecycle carbon savings in the near term, while hybrid systems can help manage peak electricity demand and protect local grid stability. Retaining and progressively decarbonising existing wet heating infrastructure allows investment to be phased rather than concentrated, reducing disruption and financial strain for households.
The heat pump roll out will continue as insulation standards improve and network capacity strengthens. Over time, more homes will be fully electrified. However, the pace of change will not be uniform and a strategy that recognises housing diversity is more likely to maintain momentum, particularly where installers are sequencing upgrades property by property in response to local constraints.
The 4.4 million homes that are not connected to the gas grid represent a substantial proportion of the housing stock. Ensuring that these properties are not left waiting for ideal conditions to align is critical to achieving national carbon targets. Integrating sustainable fuels alongside electrification does not dilute ambition; it strengthens delivery by acknowledging that decarbonisation is a systems challenge shaped by buildings, infrastructure and household economics.
A sustainable heat transition will depend not only on the technologies promoted, but on the flexibility with which they are deployed. By combining electrification with renewable liquid fuels where appropriate, the UK can deliver carbon reduction that is steady, inclusive and grounded in the practical realities of rural Britain and capable of being delivered at scale by the installer workforce that underpins the transition.
www.calor.co.uk.
