Choosing the right heat pump – why specification matters by John Felgate
The Future Homes Standard, set to come into force in 2027, will require new-build homes to produce 75 – 80 percent less carbon than those built under previous regulations in the UK.
For housebuilders, that is not a distant deadline, it is fast approaching. And decisions made on site now, from system specification through to fabric design, will determine whether completed homes meet that bar.
Heat pumps will sit at the centre of the drive towards net-zero homes, empowering developers to deliver renewable heating solutions in their new builds. But matching the right type to the right property is essential if they are to perform to their potential.
There is no single ‘correct’ heat pump, and the right choice depends on land, layout, and how the building will be used.
A standard suburban retrofit for example is usually best served by an air-to-water monobloc unit to offer the lowest complexity option as it works with existing wet heating systems and typically only requires an outdoor unit and hot water cylinder.
Meanwhile, in new-build housing, where the measures outlined in the future homes standard will play its largest part, ground source, air-to-water or a shared ground loop heat pump system will all deliver efficiency gains.
Where land allows it, ground source heat pumps come into their own. On large rural sites, horizontal collectors buried at around 1.2 metres make trenching economical and deliver excellent efficiency from a heat source that holds a stable, above-zero temperature year-round.
Additionally, where garden space is limited, vertical boreholes drilled 50 to 200-plus metres down achieve the same ground-source performance from a minimal surface footprint, which makes them well suited to high-value properties or listed buildings where an external unit would be visually intrusive.
Where a property sits near a lake, river or suitable watercourse, water source heat pumps deserve consideration too. Closed-loop systems submerged in an existing water body often beat boreholes on cost while delivering some of the highest seasonal efficiencies available. Open-loop systems, drawing from rivers, aquifers or mine water, can go further still, extracting heat directly from flowing water rather than through a buried collector.
Air-to-air heat pumps certainly have a role in flats and apartments, but their application is broader than that. While heating output and efficiency reduce as outdoor temperatures fall, modern systems continue to operate effectively in typical UK winter conditions. They offer the additional benefit of providing both heating and cooling from a single system.
As with any heat pump technology, performance is enhanced in well-insulated, airtight buildings, making them particularly attractive for new-build homes. However, they can also be suitable for existing properties where heat losses are appropriately managed and the system is correctly designed. Capacity and distribution options vary by system, with both multi-split and ducted solutions available depending on the building layout.
They also often do not heat hot water and so are "heating only" solutions, meaning that you will need another source for hot water. Additionally, converting to air to air in a retrofit or refurbishment project means not only installing new units, but also leaves developers with a redundant system to remove.
For housebuilders working at scale, adhering to the Future Homes Standard will represent a challenge. At STIEBEL ELTRON UK we are here to support them to rise to this, providing specification from the earliest design stages, covering heat loss modelling, system sizing and installer training through our contractor programme. Our range spans air, ground and shared-loop systems, with a technical team working directly with developers across the UK.
The Future Homes Standard has set the destination. Matching the technology to the property is how the sector gets there without having to go back and do it again.