24 September 2025
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By Paul Smith, Managing Director, NIBE Energy Systems Limited
The UK’s journey to decarbonise home heating is gathering pace, with heat pumps now widely recognised as a key technology in delivering net zero. There are however, three homeowner concerns that continue to influence choice:
1. Noise
2. Efficiency
3. Compliance with evolving regulations
Government policy, from the Future Homes Standard to the tightening F-Gas rules, is driving the industry toward low-GWP refrigerants and higher efficiency standards. Exhaust Air Heat Pumps (EAHPs), using R290 refrigerant, deliver a compelling answer. They combine quiet operation, strong thermal performance and future-proof refrigerant choice, making them a smart fit for new builds and suitable retrofits alike.
Many homeowners are surprised to learn that EAHPs can operate at sound levels quieter than a typical household refrigerator. Because they recover heat from the building’s extracted indoor air, rather than using large outdoor fans, they generate very little external noise. This makes them particularly wellsuited to urban areas, apartments and noise-sensitive developments, where maintaining a peaceful living environment is just as important as achieving energy efficiency.
Quiet Mark
As an example; NIBE is one of the few heat pump brands to have multiple models accredited by Quiet Mark, the independent international certification for low-noise products. This recognition covers a range of our products, including the NIBE S735 exhaust air heat pump. Quiet Mark certification provides both homeowners and specifiers with a clear, trusted benchmark, giving confidence that low-noise performance has been independently verified. Efficiency isn’t simply about the seasonal performance figure though, it’s about delivering consistent comfort at the lowest possible running cost, across a range of real-world conditions.
Higher flow temperatures
R290 refrigerant (propane) has thermodynamic properties that allow higher flow temperatures without significant efficiency loss. In practice, that means exhaust air systems can produce comfortable heating and hot water, even in colder conditions, without relying excessively on electrical back-up.
Because EAHPs harvest heat from ventilated indoor air (which is already warmer than the outside environment), they can achieve higher coefficients of performance (COP) more consistently. This makes them particularly attractive in well-insulated new builds with mechanical ventilation, where waste heat recovery is optimised.
As energy prices remain volatile, and as the Future Homes Standard pushes for tighter building envelopes, this type of integrated heating and ventilation approach could prove a strong route to meeting both environmental and cost saving goals.
F-Gas phase-down
Regulatory change is perhaps the strongest driver for refrigerant innovation in the UK and Europe. The ongoing F-Gas phasedown is rapidly reducing the availability of high-GWP refrigerants: under recent international and regional agreements, developed countries are committed to reducing HFC production and consumption by around 85% by 2036 (effectively to roughly 15% of earlier baseline levels), a timetable that is pushing manufacturers towards low-GWP alternatives such as R290.
R290, with a GWP of just 3, comfortably meets this requirement. By adopting it now, manufacturers and installers are effectively future-proofing systems against further regulatory tightening.
Outdoor noise sources
Noise regulation is another consideration, particularly in urban areas, and here exhaust air units again score highly. By minimising or eliminating outdoor noise sources, they can help projects comply with planning requirements without the need for complex acoustic mitigation. The combination of low-GWP refrigerant and quiet, compact operation puts R290 EAHPs in a strong position to thrive in the next wave of UK building regulations.
The UK housing stock presents a mix of opportunities and challenges for heat pump adoption. Exhaust air units are best suited to properties with good insulation and mechanical ventilation, common in new builds, but increasingly achievable in deep retrofits.
They require no outdoor space, making them ideal for apartments or terraced homes where garden space is limited. Their ability to integrate heating, hot water and ventilation into a single appliance also reduces installation complexity and footprint.
R290 exhaust air systems offer a rare combination of solutions: They are quiet enough for even the most acoustically sensitive sites, efficient enough to keep running costs competitive, and compliant enough to sail through the most stringent future regulations. For installers and specifiers, they represent a product choice and a strategic alignment with
where UK home heating is headed. As regulations tighten and customer expectations rise, the quiet revolution of R290 EAHPs is one the industry can’t afford to ignore.
