Pragmatic pathway to decarbonisation
17 April 2026
The decarbonisation of existing commercial buildings presents a number of challenges, but hybrid solutions – combining a heat pump with boilers – could provide a practical and flexible way to deliver on carbon reduction commitments, says Steve McConnell, director of ICOM.
The recently announced Future Homes and Buildings Standard (FHBS) signals a decisive shift toward low-carbon heat, electrification and higher energy performance expectations. For heating engineers, consultants and energy managers, the question is no longer whether systems in new-build properties must decarbonise, but how to do so in a way that is technically viable, economically deliverable and aligned with operational realities.
Hybrid heating systems, which combine heat pumps with gas-fired boilers, offer a compelling and pragmatic solution. While this approach has historically been viewed cautiously by policymakers, real-world design experience increasingly demonstrates that hybrid strategies can bridge the gap between ambition and practicality, particularly in existing buildings where constraints are most acute.
Retrofit constraints
Heat pumps are widely recognised as a cornerstone of low-carbon heating strategies. However, their application in non-domestic retrofit scenarios is often constrained by the characteristics of existing buildings and systems.
Many commercial buildings were designed around high-temperature heat distribution, typically operating at flow temperatures of 70-80°C. These systems are frequently paired with emitters, such as radiators or air handling units, sized accordingly. Retrofitting such systems to operate efficiently with low-temperature heat pumps (typically 35-55°C) can require extensive and disruptive modifications, including emitter replacement, pipework upgrades and, in some cases, improvements to the building fabric.
Peak heat loads present an additional barrier. In sectors such as healthcare, hospitality and manufacturing, demand profiles can be both high and variable. Designing a heat pump system to meet these peaks often leads to significant capital expenditure, plant space constraints and, critically, limitations in available electrical infrastructure.
For many organisations, particularly those in general industry where energy costs directly affect competitiveness, these factors can make full electrification difficult to justify in the short term.
Best of both
Hybrid heating systems address these challenges by combining the strengths of both technologies. In a typical configuration, a heat pump is sized to meet the building’s base heating load, operating for extended periods at high efficiency. A gas-fired boiler supplements this by meeting peak demand or delivering higher flow temperatures when required.
This approach offers several key advantages:
Optimised efficiency: By focusing on base load provision, the heat pump can operate at lower temperatures and higher coefficients of performance, maximising both energy efficiency and carbon savings.
Reduced capital costs: Smaller heat pump installations require less upfront investment and are easier to accommodate within existing plant space constraints.
Minimal disruption: Retention of existing distribution systems and emitters avoids costly and disruptive internal modifications, which is an important consideration for occupied buildings.
Operational resilience: Dual heat sources provide redundancy and flexibility, improving system reliability and business continuity.
For energy managers, the real value lies in control. Modern hybrid systems can respond dynamically to external temperatures, energy tariffs and grid carbon intensity. Advanced control strategies enable prioritisation of heat pump operation when electricity is both low-carbon and cost-effective, while seamlessly switching to boilers during peak tariff periods or when higher temperatures are necessary.
Regulation compliance
The FHBS introduces a more stringent compliance framework, particularly for new buildings, while retaining familiar performance metrics such as the Target Emissions Rate (TER) and Target Primary Energy Rate (TPER). Although the policy direction clearly favours electrification and on-site renewables, it also allows for flexibility in how compliance is achieved.
This is where hybrid systems can play a strategic role. By balancing electrical and gas inputs, hybrid configurations can be modelled to deliver favourable outcomes across emissions, primary energy and delivered energy metrics. The growing emphasis on actual energy performance, rather than purely notional design targets, further strengthens the case for systems capable of optimising energy use in real time.
Importantly, hybrid systems integrate effectively with complementary measures such as solar PV, improved fabric performance and, where applicable, connection to low-carbon heat networks. For designers and specifiers, this creates opportunities to develop holistic solutions that meet both regulatory requirements and operational needs.
Carbon reduction
By enabling faster deployment of heat pumps across the existing building stock, hybrids can accelerate emissions reductions. As the UK electricity grid continues to decarbonise, the carbon intensity of heat pump operation will fall further, enhancing the environmental performance of hybrid systems over time.
At the same time, the continued use of gas infrastructure within hybrid systems provides a pathway to incorporate emerging low- and zero-carbon gases, including hydrogen and biomethane. This future-proofs installations and aligns with broader strategies for decarbonising the gas network.
From a grid perspective, hybrid systems offer flexibility. By shifting demand between electricity and gas, they can help manage peak loads and reduce strain on electrical infrastructure, which is an increasingly important consideration as electrification accelerates.
The transition to net zero in non-domestic buildings will not be delivered through a single technology pathway. While electrification is central to long-term strategy, the realities of the UK’s existing building stock demand flexible, scalable and pragmatic approaches.
Hybrid heating systems provide exactly that. They enable immediate carbon reductions, align with emerging regulatory expectations and offer a practical route for organisations seeking to balance sustainability goals with cost and operational constraints. In a sector where decisions have direct implications for both environmental impact and business performance, hybrid systems represent a highly effective step forward.
