A portable air conditioner is the only cooling most renters can install, and it is also the most misunderstood appliance in the house. What follows is what a 34-unit test programme found: which three are worth buying, why monoblocks cannot match a fixed split system, and what running one actually costs you in electricity.
The short version
- Top pick: De'Longhi Pinguino PAC EX105 — solid cooling on remarkably little power, so heavy users recoup the higher purchase price.
- Smart pick: AEG Comfort 6000 — the first genuinely recommendable app-controlled unit in the test.
- Compact pick: Dreo 318S — a small 7,500 BTU/h machine for a bedroom or a small study.
Top pick: De'Longhi Pinguino PAC EX105
The PAC EX105 is not cheap to buy, but the outlay can be worth it. High energy efficiency means it draws remarkably little power — around 570 watts — despite thoroughly solid cooling, so the higher purchase price is recovered over time. That maths works best for people who run the machine a lot rather than for a few days a year.
Build quality is good and the design is genuinely attractive, which matters more than it sounds for an object this size living in your sitting room.
The drawbacks are honest ones: it is expensive, it is big and heavy, and there is no window kit in the box — you will be buying sealing separately.
Smart pick: AEG Comfort 6000
The Comfort 6000 is the first app-controlled portable air conditioner in this test programme that is genuinely worth recommending. The app is very good, and the connectivity and everyday operation are the point of the machine.
Cooling performance is good and the build is solid. Two things hold it back: high power consumption, and accessories that are not exactly generous — including no remote control, which is an odd omission on a unit sold on convenience.
Compact pick: Dreo 318S
The 318S is not a "mini" air conditioner. It is a very compact conventional machine with an exhaust hose and everything that goes with one — the physics are the same, only the box is smaller.
At 7,500 BTU/h it does not have the power for a living or dining room. In a bedroom or a small study, though, it is an excellent answer, helped by low operating noise and smart control. The one reservation is that its power consumption is proportionally a little too high for the cooling it delivers.
How much power does a room need?
Cooling capacity is quoted in BTU per hour, and matching it to the room is the single decision that determines whether you will be satisfied.
As a rough guide, around 7,000 BTU/h suits a small room, and about 10,000 BTU/h a medium one. The Dreo's 7,500 BTU/h places it firmly in the first category — which is why it is recommended for bedrooms and warned against for living rooms.
Going larger is not free. More powerful machines are heavier, louder and thirstier, and stronger units readily draw over 1,000 watts.
What running one actually costs
Air conditioners are, unavoidably, heavy consumers of electricity, and the bill can be a surprise if you have been enjoying a cooled flat all summer.
The source's worked example gives the shape of it. Take a 770-watt machine, a typical figure for a smaller portable unit, and run it for ten hours a day across a 90-day summer. That is 693 kilowatt-hours of electricity over the season — multiply by whatever your own tariff charges per kilowatt-hour and you have your answer. Longer running or a more powerful machine raises it proportionally, and units drawing over 1,000 watts are common at the larger sizes.
The reason we give you the working rather than a figure is that electricity tariffs differ by supplier, by region and by month, and a number quoted here would be wrong for most readers within weeks.
Why monoblocks cannot match split systems
Every portable unit here is a monoblock: one box, indoors, with a hose to the window. A fixed split system puts the compressor and condenser outside, and that architectural difference is why a split will always cool more effectively for the electricity it uses.
The monoblock's problem is that it expels hot air through a hose while standing in the room it is cooling. Warm air is drawn in from elsewhere in the home to replace what goes out of the window, which works against the machine continuously. It cools genuinely — but it is fighting itself in a way a split system never does.
The window problem
This is where most portable air conditioners disappoint, and it has nothing to do with the machine.
The exhaust hose has to go through a window, and the tilt-and-turn windows common across much of Europe are the worst possible case: they leave a large opening that lets the heat you have just expelled come straight back in. Without a proper seal, you are running an expensive machine against an open window.
Some units, such as the De'Longhi AP130I for sliding windows, include usable sealing; many, including our top pick, do not. Budget for a good fabric tilt-window seal as part of the purchase rather than an afterthought, and treat any bundled kit with suspicion until you have seen it.
Condensation: the litre nobody expects
Cooling air removes moisture from it, and that water has to go somewhere. Several machines in the test will leak condensate onto the floor if they are set up carelessly or used incorrectly — the comparison notes flag exactly that for more than one unit.
Read the manual on drainage before the first hot day, not during it.
Noise, honestly
These are not quiet appliances. Across the test field, operating noise clusters in the high fifties to high sixties of decibels: the De'Longhi AP130I GentleJet Inverter measured about 59 dB, the Bosch Cool 5000 also around 59 dB, and the Klarstein Breeze Box 9K 63 dB, while the loudest units in the field pushed past 67 dB.
That range matters most in a bedroom, which is precisely where the compact Dreo earns its recommendation on low operating volume.
Elsewhere in the tested field
De'Longhi AP130I Pinguino GentleJet Inverter. A big, powerful and characteristically premium machine at 30 kilograms, with handsome design, integrated sealing for sliding windows and 13,000 BTU of capacity. It drew 937 watts and measured about 59 dB, and from a 25 °C start it reached 22.4 °C against an 18 °C target.
De'Longhi Pinguino AP98 GentleJet. Rated for rooms up to 50 square metres at 11,500 BTU, drawing 690 to 700 watts, and weighing 34 kilograms — it moved the room three degrees, and ranged from 53 dB to 60 dB depending on setting.
Bosch Cool 5000. 12,000 BTU, between 823 and 1,100 watts, around 59 dB.
Klarstein Breeze Box 9K. 9,000 BTU covering a claimed 32 square metres, though 20 square metres is the realistic figure, at 776 watts and 63 dB.
Cheaper relief first
Before buying any of this, consider whether you need it. A fan costs a fraction as much, uses a fraction of the electricity and makes a hot room genuinely more bearable by moving air across your skin. Tower fans do the same in less floor space.
So-called air coolers — the evaporative units marketed as cheap air conditioning — are the ones to be sceptical about. They add humidity to the room while barely lowering its temperature, which in a European summer is often the opposite of what you want.
If a fan is enough, it is the better purchase by a wide margin. Only when it genuinely is not should you take on the cost, weight, noise and window problem of a monoblock.
How the machines were tested
34 portable air conditioners have been through the programme, run one after another under conditions kept as identical as possible in the same room. That room measures 29.7 square metres with a ceiling height of 2.50 metres.
Each test starts from 25 degrees Celsius, with the target set to the lowest available setting — 16 degrees on almost every machine, with a few exceptions that stop at 18 degrees. Build quality and everyday handling are assessed alongside the cooling measurements.
Frequently asked questions
How many BTU do I need? Roughly 7,000 BTU/h for a small room and about 10,000 BTU/h for a medium one. Under-specifying means the machine runs constantly without ever winning; over-specifying costs you weight, noise and electricity.
Why does my portable unit not cool as well as a proper air conditioner? Because it is a monoblock. The compressor sits in the room it is cooling and vents heat through a hose, which draws warm replacement air in from the rest of the home. A split system puts that hardware outside, which is why it will always be more effective per unit of electricity.
Do I need a window seal? Yes, and it is the most-skipped purchase in the category. A tilt-and-turn window left ajar around a hose lets the expelled heat straight back in. Some units include usable sealing; our top pick includes no window kit at all.
Are they expensive to run? They are among the heaviest domestic consumers. Work it out from your own tariff: a 770-watt machine for ten hours a day over a 90-day summer is 693 kilowatt-hours, and larger units draw over 1,000 watts.
How loud are they? Expect somewhere between the mid-fifties and high sixties of decibels — around 59 dB for several of the tested machines, and past 67 dB for the loudest. That is the figure to weigh most carefully for a bedroom.
Would a fan do instead? Often, yes. Fans and tower fans cost and consume far less and make a room genuinely more bearable. Evaporative "air coolers" are the weak option: they add humidity without meaningfully lowering the temperature.
