Octopus Energy has unveiled a new cooling system designed to turn its existing Cosy heat pumps into air-conditioning units, potentially giving British homeowners a relatively inexpensive way to keep their properties comfortable during increasingly hot summers.
Announced on 14 October, the Cosy Cooler is expected to cost between £500 and £600 when it becomes available in 2027. Rather than requiring a separate outdoor air-conditioning unit, the system uses the existing heat pump and central heating pipework to remove heat from individual rooms. Octopus claims installation should take approximately three hours, with no major building work required.
It is an interesting development in a market where heat pumps have overwhelmingly been sold to British households as heating appliances, despite the underlying technology being capable of providing both heating and cooling. As summer temperatures rise and overheating becomes a more pressing concern, the ability to use equipment already installed in the home for a second purpose could strengthen the argument for switching away from conventional boilers.
The Cosy Cooler is a freestanding indoor unit, approximately 72cm tall and weighing around 28kg, that connects directly to existing radiator pipework. During cooling operation, the outdoor Cosy heat pump removes heat from the circulating water while the indoor unit draws warm air from the room, passes it across a heat exchanger and returns cooler air to the living space. The heat collected indoors is ultimately discharged outside through the heat pump.
The important distinction is that the system does not simply turn conventional radiators into air-conditioning units. Radiators are relatively ineffective at cooling rooms, particularly when compared with purpose-designed fan-assisted equipment. Circulating sufficiently cold water through ordinary radiators can also introduce condensation problems, potentially affecting pipework, floors and surrounding surfaces.
Octopus says its approach avoids this by maintaining water temperatures that prevent condensation on the existing heating circuit, while the dedicated indoor unit provides active cooling. It also eliminates the need for the large exhaust hose associated with conventional portable air conditioners, which typically require a window or external opening to discharge unwanted heat.
For homeowners, that could be a meaningful advantage. Retrofitting conventional air conditioning into an existing property can be expensive and disruptive, particularly where refrigerant pipework, electrical connections and external equipment need to be accommodated. Octopus estimates that conventional installations typically cost between £2,000 and £6,000, although actual prices depend heavily on the number of rooms being cooled and the installation requirements.
The proposed £500-£600 price point is therefore attractive, but the comparison requires some qualification. The Cosy Cooler is an accessory for households that already have a compatible Octopus heat pump. It is not a standalone cooling solution, and the cost of the original heating installation is not included in that figure. Octopus has also not made clear whether its indicative price includes fitting.
There is another distinction that homeowners should understand. Each Cosy Cooler is intended to cool an individual room, with some Cosy heat pump models capable of operating two or three units simultaneously. That is quite different from suggesting that a single £500 device will provide effective cooling throughout an entire house.
Nevertheless, room-by-room cooling could suit many British homes. Bedrooms that become uncomfortably warm during summer nights, south-facing living rooms with substantial glazing and upstairs rooms that retain heat long after sunset are obvious candidates. Many households do not necessarily need whole-house air conditioning — they need a practical way to make one or two rooms comfortable during the hottest periods.
What remains unclear is how much cooling the system can actually deliver.
Octopus has not yet published detailed cooling-capacity figures, independently verified efficiency data or expected electricity consumption. Those omissions are understandable for a product still undergoing trials, but they will become important when homeowners begin comparing it with established air-to-air heat pumps and conventional split air-conditioning systems.
A unit costing £500 to purchase is not necessarily inexpensive to operate. Cooling performance depends on the amount of heat being removed, the temperature difference between the indoor and outdoor environments and the electricity required to operate the equipment. In this case, homeowners will also want to understand the energy consumed by the outdoor heat pump and the indoor cooling unit working together.
Noise will be another consideration. Octopus describes the device as quiet, but has not yet released detailed acoustic specifications. A unit operating in a living room during the afternoon faces different expectations from one running beside a bed throughout a hot summer night.
There are also questions about humidity. Octopus says its system prevents condensation on existing radiator pipework, but has not explained whether the indoor unit actively removes moisture from the air. Conventional air conditioners often provide dehumidification alongside cooling, an important contributor to comfort during humid weather. The extent to which Cosy Cooler offers the same benefit remains to be established.
Compatibility and installation flexibility will matter too. Many existing homes have complicated radiator circuits, multiple heating zones and thermostatic valves that can restrict water flow. How Octopus intends to manage those arrangements during summer cooling will be worth examining, particularly where several indoor cooling units are operating simultaneously.
The company says trials are already underway in homes and offices, with additional participants being recruited ahead of the planned commercial launch in 2027. Those trials should provide an opportunity to establish how effectively the system performs under real summer conditions rather than relying solely on laboratory testing or theoretical efficiency calculations.
Beyond the product itself, the announcement reflects a potentially important change in how heat pumps are marketed to British homeowners.
For years, the sales proposition has concentrated almost entirely on replacing fossil fuel heating, lowering carbon emissions and potentially reducing running costs. Cooling has generally been a secondary consideration, despite air-to-air heat pumps providing both functions in homes across much of Europe and elsewhere.
That distinction is becoming increasingly difficult to ignore as British properties experience more frequent periods of uncomfortable indoor temperatures. Modern homes with extensive glazing and high insulation levels can be particularly susceptible to overheating if solar gains, shading and ventilation have not been adequately considered.
Mechanical cooling should not become a substitute for sensible building design. External shading, appropriate glazing, ventilation and measures to limit unwanted solar heat remain important. But there will inevitably be periods when passive measures are insufficient and homeowners want active cooling.
Octopus is attempting to address that demand without requiring households to invest in an entirely separate system.
There is also a wider commercial implication. By developing accessories that work specifically with its Cosy range, Octopus is extending its offering beyond the original heat pump installation. Homeowners could gain additional functionality from equipment they already own, although that also makes compatibility, long-term support and dependence on the manufacturer’s ecosystem more important considerations.
From a Renewable Heating Hub perspective, the concept deserves attention. Making better use of equipment already installed in a property is sensible, particularly where it avoids unnecessary duplication and additional disruption.
But the engineering and economics need to stand up to scrutiny. The decisive questions are relatively straightforward: how much cooling can a homeowner expect, how much electricity will it consume, how noisy will it be and how effectively will it operate during genuinely hot weather?
Octopus has demonstrated a willingness to develop products specifically around the needs of British households rather than simply importing established heating solutions. The Cosy Cooler represents another attempt to make the domestic heat pump more versatile, although its commercial proposition remains to be proven.
If the company can deliver useful cooling for £500-£600 without significant installation work or excessive running costs, it could make heat pumps more attractive to households weighing up their next heating system.
For now, however, the Cosy Cooler remains a promising development rather than a proven alternative to conventional air conditioning. Its real value will become clearer when the first homeowners can demonstrate how much cooler their rooms become and what it costs to keep them that way.
Indeed. They teased this earlier in the year and there is a (possibly) similar Dutch product already. If it’s what they hinted it will be much more efficient (and probably more effective) than one of those standalone Aircon units.
As you say we need to know the specifics. I guess it needs a tee on a pair of rad tails. There are such things as self cutting tees which don’t require draindown so it’s potentially a DIY job, but this (or professional installation) all adds to the cost.
That’s a very interesting development. For those with an existing Octopus Cosy heat pump that want air-conditioning, this could be a cost effective way to go. The Octopus article suggests that it can be fitted in around 3 hours and two or three Cosy Coolers can be connected depending on the Cosy heat pump model.
Not needing an additional outdoor unit (heat pump) is potentially a useful gain in terms of costs and also planning permissions, since only one unit is permitted development on properties that are not detached houses (two for detached).
Octopus comparison of a £500 to £600 price point for a single Cosy Cooler compared to £2000 to £6000 for traditional air-conditioning systems seems a little exaggerated. A premium single-split install is indeed around £2000. Whereas £6000 would pay for a premium multi-split system installed with indoor units in multiple rooms.
The Octopus article says that the Cosy Cooler is freestanding and 72cm tall (width 43cm, depth 36cm, weight 28kg). That is perhaps not ideal for cooling, since cooler air tends to descend and sit at floor level, which is why indoor units for air-to-air systems are typically mounted high on the wall. That said it is similar to the approach taken with portable AC units.
It is not clear where the condensate ends up. In humid weather the indoor unit of an air-to-air system can extract a litre an hour of water that runs out of the condensate pipe. It would seem there are two viable solutions to this, either a condensate pipe through an outside wall, or a catch tank that the householder then has to empty.
In terms of running costs, I don’t think achieving really high efficiency will be that much of an issue for most households. The reason being that the amount of heat energy needing to be removed via cooling is typically far less than the amount of energy needed for heating. In the case of my property, the exceptional summer of 2026 required 640 kWh of heat removing compared to annual heating of around 13,000 kWh, i.e. 1/20th of the energy. Even if the efficiency on cooling (SEER) is much lower than that achieved by a good air-to-air system in cooling mode, then that will still hardly make a difference to annual bills.
It will be interesting to see how the competition in this area turns out. The alternative approach is to have a heat pump that does both air-to-water and air-to-air (via refrigerant lines) such as the Samsung Quint. That technology has the advantage of heat recovery; instead of dumping heat outside, it can use it to heat hot water instead. The air-to-air indoor units can also help to heat rooms up very quickly in heating mode.