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If this summer has felt different, you’re not imagining it. The UK has just come through one of its hottest summers on record, with three separate heatwaves pushing homes and workplaces across Sussex well past comfortable. The Guardian reported that extreme heat contributed to around 2,700 deaths this summer — a stark reminder that overheating indoors isn’t just uncomfortable, it can be genuinely dangerous, especially for older residents, young children, and anyone with a health condition.
For years, home energy conversations in the UK have focused almost entirely on winter: staying warm, cutting heating bills, insulating draughty rooms. But as summers get longer and hotter, Sussex property owners are increasingly asking a different question: how do I keep my home cool without sending my electricity bill through the roof?
The answer, for a growing number of homes, is an air-to-air heat pump – a single system that can both heat your home in winter and cool it in summer.
Why Sussex homes need a cooling solution, not just a heating one
Traditional UK homes were built for a climate that no longer quite exists. Thick curtains, small windows, and good loft insulation help retain winter heat, but they trap summer heat just as effectively. As heatwaves become more frequent and severe, many Sussex homeowners are finding that the same building fabric that once kept them warm is now working against them for several months of the year.
Retrofitting cooling into a UK home has historically been an afterthought; a portable air conditioning unit here, a standing fan there. These are inefficient, noisy, and only ever a short-term fix. What’s changed is that the same low-carbon technology now heating hundreds of thousands of UK homes can also cool them, properly and efficiently.
What is an air-to-air heat pump?
Most people picture a heat pump as a system that heats water for radiators, underfloor heating, or a hot water cylinder, technically known as an air-to-water heat pump. These extract energy from the outside air and use it to heat water that then circulates through your home’s existing pipework.
An air-to-air heat pump works differently. It still extracts energy from the outside air, but instead of heating water, it heats (or cools) the air directly. Indoor units (mounted on a wall or ceiling, similar in appearance to the air conditioning units you might recognise from hotel rooms) distribute warm or cool air straight into each room. Because the same system runs in reverse for summer cooling, one piece of equipment does the job that would otherwise need a boiler and a separate air conditioning unit.
Why air-to-air heat pumps solve two problems at once
For Sussex property owners, the appeal is straightforward: one system, one installation, one set of running costs, covering both ends of the British weather.
COLD WEATHER: Efficient, low-carbon heating that can cost less to run than electric heating and, depending on your current system, less than an ageing gas boiler.
HOT WEATHER: Genuine, whole-room cooling that goes far beyond what a portable AC unit or fan can achieve – increasingly important as heatwaves become a regular feature of the Sussex summer.
HOT WATER: Some systems now include an add-on module for hot water too, effectively combining air-to-air and air-to-water functionality so a single setup can handle heating, hot water, and cooling.
Is your property actually suitable? Here's what determines it
An air-to-air heat pump isn’t automatically the right fit for every home, and understanding your property’s readiness before you commit is essential to getting a good return on the investment. The main factors are:
1. Your existing heating system
This is the single biggest factor in how much you’ll save. Air-to-air heat pumps tend to deliver the strongest bill savings for properties without a “wet” central heating system — that is, no network of pipes and radiators or underfloor heating. Homes currently using storage heaters or electric radiators are prime candidates, since an air-to-air heat pump typically uses three to four times less electricity to deliver the same warmth. Homes with electric boilers can also expect significant savings, as can properties with inefficient or ageing gas or oil boilers, though the exact saving depends on your current fuel price, boiler efficiency, and the efficiency of the heat pump itself.
2. Available space, indoors and out
Each room you want heated or cooled needs an indoor wall- or ceiling-mounted unit, plus there’s an outdoor unit to site. For flats, this is where things get more specific: a smaller flat with fewer rooms may only need one or two indoor units, but finding a suitable spot for the outdoor unit — one with good airflow that won’t disturb neighbours with noise — is often the deciding factor. This unit is typically located on a flat roof, which means permission from whoever holds legal rights over that space.
3. Your budget, and what you want the system to do
Costs scale with the number of rooms covered. As a rough guide, a single-room system for both heating and cooling starts around £2,500, while a full system for a 3–4 bedroom home is closer to £8,000. Adding a hot water module typically adds a further £3,000 or so. Better-insulated homes generally need smaller, less expensive systems, since there’s less heat loss (or gain) to compensate for.
How BHESCo's Energy Saving Service can help
Working out whether your property is ready for an air-to-air heat pump — and how it fits alongside other options like solar PV and battery storage — isn’t always straightforward from a spec sheet alone. That’s exactly what BHESCo’s Energy Saving Service is designed for.
A BHESCo energy survey looks at your property as a whole: your current heating system, insulation levels, available space, and energy usage patterns, to give you a clear, independent picture of:
- Whether an air-to-air heat pump is likely to be cost-effective for your specific property
- How it could work alongside solar PV and battery storage for even greater bill savings
- What grants and financial support you may be eligible for
- A realistic, property-specific estimate of costs and savings
As a Sussex-based community energy co-operative, BHESCo isn’t selling you a single product — the survey gives you the independent, whole-property view you need before you invest.
Grants and funding available in 2026
Cost is often the biggest hesitation when it comes to heat pumps, but there’s meaningful support available. A BHESCo energy survey can help clarify which of these you’re eligible for, and how they apply to your specific property and circumstances.
Boiler Upgrade Scheme (BUS):
Government grant that reduces the upfront cost of replacing fossil fuel heating with a heat pump.
Warm Homes Loan Scheme
Launching Autumn 2026, this will offer low-interest loans to help households fund low-carbon heating upgrades.
Frequently Asked Questions (FAQs)
How is heating and cooling delivered to each room?
Air-to-air systems extract energy from the outside air and distribute it by directly heating or cooling the air itself, via wall- or ceiling-mounted indoor units similar to hotel air conditioning units.
Does an air-to-air heat pump only make sense for homes without gas central heating?
It tends to make the most financial sense for properties without a wet central heating system — for example, homes using storage heaters, electric radiators, or electric boilers, where savings can be substantial. Homes with inefficient boilers or high fuel costs can also benefit, though the exact saving depends on current fuel prices and system efficiency.
Can an air-to-air heat pump provide hot water?
Not directly, but some manufacturers now offer add-on modules that provide hot water alongside heating and cooling, combining the benefits of air-to-air and air-to-water systems in one setup.
Can air-to-air heat pumps work in flats?
Yes, particularly in flats with fewer rooms. The main challenge is finding a suitable, well-ventilated location for the outdoor unit — usually a flat roof — with the necessary consent from whoever holds rights to that space.
How much does an air-to-air heat pump cost?
Costs depend on how many rooms need coverage: roughly £2,500 for a single room, and around £8,000 for a typical 3–4 bedroom home. A hot water module adds approximately £3,000. Better-insulated homes can often use smaller, cheaper systems.
Ready to find out if your property is suitable?
Every Sussex home is different, and the right answer for your neighbour’s flat may not be the right answer for your semi-detached house. Book a BHESCo energy survey to get a clear, independent assessment of your property’s readiness for an air-to-air heat pump, solar PV, and battery storage — and find out which grants you could put towards it.
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