Saturday, July 20, 2024

The better the data, the better the heat pump performance

Real measured data of a building, including its thermal profile and energy usage, is critical to designing successful heat pump solutions, says Andy Green, Baxi’s Head of Technical Solutions

As energy managers start to consider the options for decarbonising heat in their buildings, heat pumps will frequently be the favoured solution. Certainly, high temperature air source heat pumps (HT ASHPs) like our Auriga+ R290 (propane) series bring greater design options in existing buildings. But swapping out boilers for heat pumps is not always as simple as it is made out to be. And this is where taking time to gather real, measured data on the existing building and heating system can be beneficial.

Understanding the building’s thermal profile

The merits of ASHPs are well established and introducing them into older buildings is certainly possible. However, there is no escaping the fact that it is frequently more complicated than in new buildings which are designed to be net zero.

One of the problems with existing buildings is the lack of thermal modelling and legacy issues. In dated buildings, any design information is limited at best. However, a full understanding of the thermal performance of a building is absolutely essential in order to develop solutions that will improve its operational efficiency.

So what data do we need to truly understand the building? Information relating to comfort levels in the building, the original design temperature and loads, any hydronic inefficiencies, as well as changes to the building and/or heating system, is key. Are there any bounding constraints? Are electrical capacities sufficient? Does budget allow for 100% of the required heating power to be via ASHP? Is there adequate space? And are there any complementary technologies that could support the operation of an ASHP, such as solar PV? The aim is to understand what may be able to change and what cannot, as well as any risks.

Installing ultrasonic heat meters, carrying out a detailed heat loss calculation, and analysing gas meter readings will then provide deeper insight. An optimal scenario would involve a year’s worth of data with installation planned for warmer months.  

Fabric first

As part of this investigative pre-design process, it’s advisable to identify any feasible opportunities for fabric upgrades. A fabric first approach should always be the initial consideration when considering a switch to heat pumps to reduce heat loss from a building. The benefit of reducing heat loss is that it can significantly reduce the size or capacity of plant required – thereby reducing capital expenditure – while improving running costs by limiting heat loss to the environment. One example might be to improve insulation.


With fabric upgrades addressed, heat experts like Baxi can then use this real measured data to engineer different solution scenarios. Optioneering is a valuable design support process that enables energy managers and designers to make the best choice for a specific building within the project requirements and constraints. The digitally produced solutions, backed with predicted energy and carbon savings and capital expenditure modelling, provide precise, validated advice to help make the move to low carbon heat more seamless.

Hybrid solutions

While the initial intent and brief may be to move directly from gas boilers to full electrification of heat, depending on the building and the retrofit challenges, a compromise may be required. A hybrid solution is nearly always a fast, efficient and affordable answer so should not be overlooked as an achievable option on the road to net zero. After all, even a modestly sized heat pump will enable a large portion of the heat in the building to be decarbonised. As such, a hybrid system can be a quick win solution for energy managers, delivering immediate sustainability improvements while overcoming major challenges including budget and risk.


Once the design is locked in, it’s advisable to set performance targets that should be reviewed on a regular basis to ensure that the building is performing as designed.

When the targets have been hit, close monitoring will then open up the opportunity to identify and implement additional improvements to optimise the solution and deliver still greater savings.

In conclusion, the more accurate the data, the better the heat pump performance and value – and the more truly sustainable the solution. Having real, measured data allows for the possibility to design and evaluate multiple validated solution scenarios and, in so doing, arrive at the best solution in every case.

For more information on Baxi’s commercial heat pumps, visit:

This article appeared in the June 2024 issue of Energy Manager magazine. Subscribe here.

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