As organisations look to minimise the environmental impact of their buildings, air source heat pump retrofit is increasingly seen as a priority. But from system compatibility to optimal sizing and design services, early dialogue with heat pump manufacturers is advisable to achieve optimal outcomes says Neville Radford, Specification and Sector Manager at Baxi.
The UK’s legally binding 2050 net zero target will require virtually all heat in UK buildings, including the public sector estate, to be decarbonised. One of the favoured decarbonisation strategies is to replace fossil fuel heating with effective heat pump systems. While this is absolutely achievable in existing non-domestic buildings, it would be naïve to ignore the common issues. Available budget, time, space and electrical capacity, as well as running costs, are just some of the complex variables that may need to be balanced.
Furthermore, each building will likely have its own unique requirements, making it important that energy and estates managers understand at the outset the actionable options across their estate to achieve maximum heat pump performance.
This is where early engagement with manufacturers can help. Gone are the days when manufacturers were just box shippers. Today, solutions providers and manufacturers like Baxi provide expert support throughout the lifetime of the heat pump. From initial feasibility surveys, product selection, system design and technical support to specialist commissioning and tailored maintenance programmes, they help ensure optimal performance at every step. Let’s consider the many benefits this delivers for energy managers.
Feasibility survey
When planning a heat pump retrofit, the first step should be for your chosen manufacturer to carry out a feasibility survey. This will identify any potential challenges and help confirm from the start if a heat pump is considered viable for the building.
One of the key considerations when retrofitting heat pumps into existing non-domestic buildings is that heat pumps operate most efficiently at lower temperatures from 35 to 55°C. Older systems, however, typically operate at flow and return temperatures of 82/71°C, or potentially 80/60°C, with the emitters sized accordingly.
As part of the survey, manufacturers will assess the size of the existing emitters (radiators) and advise on whether an upgrade is necessary to enable the heat pump to operate at lower flow temperatures.
Accurate heat loss calculations are a key element of the survey to ensure that the heat pump is sized accurately. The building should also be optimised for energy efficiency where possible as draughty buildings make achieving and maintaining optimal temperatures challenging. Implementing fabric upgrades – such as adding or upgrading insulation and/or draught proofing – can help address this. Limiting the amount of heat lost to the environment can dramatically reduce the size or capacity of the solution needed, and in turn lower capital expenditure when refurbishing the system, while improving running costs.
The survey will also determine the available external space to site the heat pumps, the project timeline, budget and the operating costs, all of which will be critical to ensure the project is viable.
Electrical supply and design considerations
Commercial heat pump installations can require significant electrical capacity, but early dialogue with heat pump manufacturers can help you navigate the essential electrical design considerations. This includes determining the electrical infrastructure required to support the new ASHPs, identifying if a new supply is necessary, which can impact project timelines and costs, the power supply type, overcurrent and fault protection requirements, and smart grid/tariff integration to take advantage of cheaper energy tariffs.
Technical design
The next area where manufacturers can provide value-added support is the system design. Experienced manufacturers will be able to support consultants with pre-sales technical design services, engineering a series of tailored design options.
By simulating the energy, carbon and capital expenditure of each option, energy managers will have a clear understanding of the impact of each. This will allow them to ensure that the best choices can be made within the project requirements. This might include a hybrid heat pump configuration combining heat pumps with existing boilers as an early stage of decarbonisation to manage operating costs and maximise energy efficiency.
Early collaboration for whole life support
The ultimate aim is to achieve a high-performing, efficient system that meets all project and regulatory requirements throughout its lifetime. Early discussions with heat pump manufacturers will help deliver this at every step from early feasibility and technical design support to specialist commissioning for optimal performance, aftersales service and ongoing maintenance programmes.
Experienced manufacturers like Baxi can break down the complexities of the project to help energy managers make the right decision to meet the specific needs of their building. Working together, we can set the public sector estate on the right path towards decarbonisation and improved efficiency.
For more information on Baxi’s heat pump solutions, visit baxi.co.uk/commercial
This article appeared in the June 2026 issue of Energy Manager magazine. Subscribe here.
