Best portable air conditioning units

Every summer the "best portable air conditioning units" league tables reshuffle the same dozen machines, and every summer buyers discover that the ranking mattered less than the specification. This is not another review roundup. It is the buying guide underneath the roundups: the six criteria that decide whether any portable unit — whatever its badge — will actually work in your room. Get these right and most reputable machines will serve you well; get them wrong and the best-reviewed unit in Britain will disappoint.

Start with size: kW and BTU per room

Cooling capacity is quoted in kilowatts or BTU (roughly 3,412 BTU per kW). Undersize and the unit runs flat out without reaching temperature; oversize and you pay more for capacity the room never uses.

Treat the table as a starting point, not a verdict. Big glazing, a south-facing aspect, a loft room under a hot roof, or lots of occupants and equipment all push the requirement up a band — sometimes beyond what any portable can deliver. The room size guide explains the variables in the same way an installer's heat-load survey weighs them.

Single hose or dual hose

This is the specification the league tables gloss over, and it matters more than brand.

A single-hose unit uses room air to cool its condenser and blows that air outside. The room ends up short of air, goes slightly negative in pressure, and pulls warm replacement air in through every gap — including around the hose seal itself. Part of the unit's work is spent cooling air it is simultaneously importing. A dual-hose unit draws its condenser air from outside through a second hose, largely avoiding the problem, and typically cools the same room faster for similar power draw.

Most portables on sale in the UK are single-hose because they are cheaper to make. If you see a dual-hose model from a reputable brand at a price you can stomach, that is usually the better machine. The full physics is set out in our portable vs fixed comparison.

Noise: read the dB(A) figure like it is the price

Every portable keeps its compressor in the room with you. Specifications quote noise in dB(A), usually at the lowest fan speed and measured at a distance — real-world experience is louder. As a rule of thumb, the low-50s dB(A) is conversation-level sound, which many people cannot sleep through; anything quoted in the 60s will dominate the room.

For a bedroom, prioritise the quietest low-fan figure you can find, a genuine sleep mode, and a compressor that ramps gently rather than clunking on and off. Our noise guide explains what the decibel numbers mean in practice, and the bedroom guide covers why night-time cooling is the hardest test any unit faces.

Dehumidify mode is quietly the most useful button

British summer discomfort is as much humidity as temperature. Most portables include a dedicated dehumidify mode that removes moisture with less noise and power than full cooling, and on muggy-but-mild days it is often all you need. Check how the unit handles the water it collects: a tank you must empty, a continuous-drain spigot for a hose, or — best — self-evaporation that exhausts most moisture out with the hot air.

Energy labels and what an hour actually costs

Portable air conditioners carry an energy label with an efficiency ratio (EER) — the cooling delivered per unit of electricity consumed [2]. A higher EER means cheaper cooling, and between two similar machines it is the better tiebreaker than a review score.

Running cost is simple arithmetic: input power in kilowatts multiplied by your electricity unit rate. Typical portables draw somewhere between 0.8 and 1.2 kW while cooling, so at a price-cap unit rate — check the current figure with Ofgem [1] — an evening's use costs tens of pence per hour, and a hot fortnight of long days adds up faster than most buyers expect. Energy Saving Trust guidance is blunt on the cheapest first step: shade the room and shut out daytime heat before you switch anything on [3]. Our running costs guide compares portables with fixed systems over a full summer.

Venting: the window kit is part of the product

A portable is only as good as its exhaust path. Most units ship with a window kit — a sliding panel or fabric seal that closes the opening around the hose. Check the kit suits your windows before you buy: sash, casement and tilt-and-turn all need different solutions, and a badly sealed window lets the hot air straight back in. The tidier alternative is a through-wall vent: a cored hole with a fitted grille that the hose couples to, sealing the room properly. It needs a drill and a landlord's blessing, but it fixes the biggest single weakness of portable cooling.

R290: the refrigerant question answers itself

Most current portables run on R290, a hydrocarbon (propane) refrigerant with a very low global-warming potential. Because R290 is not a fluorinated gas, it sits outside the F-gas regime that restricts split-system refrigerant work to certified engineers [4] — which is precisely why a portable can be a sealed, plug-in appliance while a wall-mounted split must be professionally installed. From a buyer's perspective R290 is a mark of a current design; walk past old stock on legacy refrigerants.

Brands worth shortlisting

The UK portable market has a reliable core of names: Meaco and De'Longhi at the quality end, AEG among the appliance majors, and Igenix and ProBreeze in the value tier. We deliberately name no models and quote no product prices — ranges change every season, and a model number that tops a league table in June is superseded by August. Apply the criteria above to whatever is on sale when you buy: correct capacity for the room, dual hose if you can get it, the quietest credible dB(A) figure, a decent EER, and a venting kit that fits your windows.

What the league tables won't tell you

Every portable air conditioner — the best included — is an engineering compromise built around one constraint: the whole machine, compressor and all, is in your room, breathing through a hose. The review sites rank the compromises; they rarely say that the category itself is the limitation. A well-chosen portable is genuinely right for renters, for rooms cooled a few weeks a year, and for anyone needing cooling this week rather than this month.

But if you are buying for a bedroom you sleep in every summer night, or a room you will cool daily from June to September, the honest comparison is not portable versus portable — it is portable versus fixed. A split system at £1,800–£3,000 installed puts the compressor outside, cools the room properly with no hose and no open window, and heats it efficiently all winter as well. The full comparison sets out where the line falls; the home units overview walks the whole ladder if you want to see every option in one place.

Best portable air conditioning units FAQ

What size portable air conditioner do I need? Roughly 2.6–2.9 kW (9,000–10,000 BTU) for an average double bedroom or lounge of 15–25 m². Go up a band for big glazing, loft rooms or south-facing spaces — and question whether a portable is enough at all for a conservatory.

Are dual-hose portable air conditioners better? Generally yes. They avoid depressurising the room, so more of their rated output reaches you as cooling. They are scarcer and cost more in the UK, but the premium buys real performance.

How much does a portable air conditioner cost to run? Input power times your unit rate. A unit drawing around 1 kW costs roughly one unit-rate's worth per hour — check the current price cap rate with Ofgem [1] — so long daily use through a hot month is a material cost.

Can I use a portable air conditioner without a window? It must vent somewhere. A through-wall vent kit is the usual window-free answer; venting into another room simply moves the heat. If no vent path exists, a portable cannot work in that room.

Are portable air conditioners quiet enough for sleeping? The quietest models are tolerable for some sleepers; many are not, because the compressor is in the room. If sleep is the whole point, a fixed unit is markedly quieter — compare the two before you buy.

When you are ready to compare the fixed route

If this summer's portable is a stopgap rather than the plan, get the real number for the alternative: run the cost estimator for an indicative installed price, or request an installer match to have the room surveyed properly.