Richard Brown at Ideal Commercial Heating explores key pointers for specifiers looking to transition projects from gas boilers to heat pumps.

The electrification of heat is now firmly embedded in the future of the UK’s built environment. Yet successful deployment relies on far more than replacing one appliance (a boiler) with another (a heat pump). It demands careful design, an understanding of buildings in their entirety, and a rigorous approach to specification. The most successful projects are those where heat pumps are treated as part of a whole-building strategy rather than as a single equipment substitution.

Start with the building

Before plant selection is even considered, attention should be given to how heat demand can be reduced at source. Improvements to fabric, insulation levels and air tightness can reduce peak heating loads by as much as 60 to 70%. This has a direct impact on the size of heat pump plant required, the capital cost of the system, and the achievable seasonal efficiency. This fabric-first mindset is reflected in industry guidance such as CIBSE AM17.

Understanding the client brief & project objectives

Commercial heat pump projects succeed when technical solutions are aligned with the client’s objectives, whether the primary driver is carbon reduction, regulatory compliance, operating cost control, resilience, reputational performance or a combination of these.

Budget constraints, expectations around comfort, requirements for redundancy and resilience, and plans for future building use all influence the most appropriate system approach. The way in which the system will be operated and maintained, and how it will be handed over to facilities teams, is equally important.

These considerations often lead to more nuanced solutions than a straightforward move to fully electric heating. In many cases, hybrid systems that combine heat pumps with boilers provide a pragmatic balance between decarbonisation, cost control and operational confidence. Hybrid systems can reduce upfront capital investment, maintain resilience during peak demand, allow gradual upgrades to distribution systems, and provide reassurance to facilities teams adapting to unfamiliar technologies.

Working within regulatory & best practice frameworks

Designers and specifiers are supported by a wide range of established guidance that helps shape better outcomes, such as CIBSE AM17 for large non-domestic heat pump installations, as well as CIBSE CP1 guidance for heat networks, Building Regulations Part L, and frameworks including EPCs, SAP, and MEES. 

Core system design considerations

Once objectives are established and building performance is understood, attention turns to detailed system design. Accurate load calculations and a clear understanding of the building’s heat profile across the year are fundamental. Designing solely for peak conditions often leads to oversizing, which in turn reduces efficiency, increases cycling and undermines long-term performance.

Operating temperatures are another critical factor for system specification. Heat pumps deliver their best efficiencies at lower flow temperatures, which may require changes to emitters, distribution systems or control strategies, particularly in retrofit scenarios. Domestic hot water demand introduces further complexity, as it often requires higher temperatures and may influence whether additional technologies such as immersion heaters or supplementary heat sources are required.

Existing building services infrastructure cannot be ignored. Legacy pipework, radiators, controls and hydraulic arrangements impose real constraints, and assumptions that everything can remain unchanged frequently lead to compromised performance.

Refrigerant selection is becoming an increasingly important part of specification. With tightening F-Gas regulations and proposed future restrictions on higher global warming potential refrigerants, designers are under growing pressure to consider not only current compliance but also long-term regulatory risk and environmental impact.

The often-overlooked role of thermal storage

Well designed buffer vessels and thermal stores remain one of the most effective tools for improving commercial heat pump system performance as they help to reduce peak loads on heat sources, smooth daily demand fluctuations and allow heat pumps to operate more consistently.

Practical realities: acoustics, space & planning

Beyond calculations and schematics, successful projects must address the practical constraints of real sites. Acoustic performance is frequently one of the most sensitive issues, particularly in urban, residential-adjacent and mixed-use environments. Noise impact on occupants and neighbours must be considered from the outset, with mitigation measures such as acoustic enclosures, anti-vibration solutions and intelligent control strategies designed in rather than added retrospectively.

Space planning is an equally critical consideration. External units require adequate clearances for airflow, maintenance access and safety. Roof-mounted installations introduce structural loading considerations, while ground-level plant may need to accommodate access, security and visual impact. Certain refrigerants bring additional requirements around positioning and exclusion zones, which must be factored into layout decisions at an early stage.

Towards better outcomes

Commercial heat pumps are becoming a core component of the UK’s low-carbon building services landscape. However, their success depends on both the equipment and the quality of design, specification, collaboration and long-term thinking that underpins each project.

By prioritising building performance, aligning technical solutions with client objectives, applying established guidance and giving proper attention to practical installation realities, heating systems can be delivered that not only reduce carbon but also perform reliably, efficiently and economically throughout their lifecycle.

Richard Brown is head of specification at Ideal Commercial Heating