Fixed vs portable air conditioning: which should you choose?

What fixed and portable air conditioning mean

Fixed air conditioning, also called fitted air conditioning, usually means a split system. A slim indoor unit sits high on the wall, and a small outdoor unit holds the compressor and the big fan. Two refrigerant pipes, a cable and a drain run between them through one small hole in the wall behind the indoor unit. It's fitted by an F-Gas certified engineer and stays put.

A portable air conditioner is one box on wheels. Everything is inside it, compressor included, and it gets rid of the heat it collects through a wide hose that you lead out of a window. You plug it in and move it from room to room.

There's a third type, the through-wall unit, which is fixed but has no outdoor unit. Our guide to air conditioning without an outside unit covers it.

How a portable air conditioner works, and its hidden catch

Inside, a portable runs the same refrigerant cycle as any air conditioner. A cold coil cools the room air that blows out of the front. A hot coil carries the heat away, and air passing over it is pushed out of the room through the hose. Most portables are single-hose models: the energy rules define a single duct unit as one that takes the air for its hot side from the room it's in and blows it outside.

That's the catch. Every cubic metre of air the hose pushes out has to be replaced, so warm outside air is drawn back in through gaps around the window kit, under doors and from the rest of the house. The US Department of Energy studied this when it rewrote its portable test in 2016. It found that the negative pressure from the exhaust pulls in outside air, that most of it comes straight in around the window, and that a portable's real cooling is generally significantly lower than the lab figure suggests, mainly for this reason.

Dual-hose portables draw outside air in through a second hose to cool their hot side. The same study found that single-hose units typically pull in more outside air than comparable dual-hose ones, but that dual-hose units usually take some of their air from the room too.

Fixed vs portable air conditioning at a glance

A premium fixed 2.5 kW wall unit against a 9,000 BTU portable (about 2.6 kW), sized for a bedroom or small living room.

Fixed figures from Daikin and Panasonic UK spec sheets. Portable figures from Meaco's product page for the MeacoCool MC Series Pro 9000 CH, checked October 2026. Manufacturers measure noise in different ways, so treat the noise figures as a guide. Electricity at the Ofgem cap, 26.32p per kWh.

Energy labels: why an A portable isn't an A split

The energy labelling rules that apply in Great Britain use two different scales. Split systems are rated on seasonal efficiency (SEER), measured across a typical cooling season. To earn A++ a split needs a SEER of at least 6.1, and A+++ needs 8.5. Panasonic's value-range 2.5 kW TZ has a SEER of 7.0, and its premium Etherea 9.5.

Portables are rated on EER, the cooling given per unit of electricity at one test point. On their scale, an EER of 2.6 is enough for an A and 4.1 for A+++. Meaco's 9,000 BTU model, about 2.6 kW of cooling for 1,005 W, works out at about 2.6: an A, at the bottom of the band.

The test also flatters single-hose units. Under the rating conditions in the ecodesign rules, a single duct unit is tested with the room and the air it breathes both at 35°C, so the warm outside air that leaks back in at home isn't counted. That's the effect the US regulator chose to subtract in its own test.

Running cost per hour at the Ofgem cap

Electricity at 26.32p per kWh, the Ofgem price cap for 1 October to 31 December 2026. A night is 8 hours.

Fixed figures are Panasonic's TZ (value) and Etherea (premium) from Panasonic UK spec sheets, as in our running costs guide. Seasonal means full output at the unit's SEER, closer to a normal hour once the room has cooled. The portable figure is its full power draw from Meaco's product page. Because warm air leaks back in, a portable's real cooling is lower than its box figure, so each hour buys less cooling than the fixed unit gives.

Noise: the compressor is the difference

In a portable, the compressor and both fans run in the room with you. Meaco lists 52 dB on the lowest fan for its 9,000 BTU model, and 54 dB at the top. A fixed split leaves the compressor outside, so premium 2.5 kW wall units from Daikin, Mitsubishi Electric, Panasonic and LG list 19 dB(A) on their quietest setting and 23 to 27 dB(A) on low.

Decibels rise on a logarithmic scale, so a gap of more than 25 decibels is a big one. It's most noticeable at night, which is why we rarely suggest a portable for a bedroom you use every summer. The fixed unit's noise moves outside instead: about 46 dB(A) for a typical 2.5 kW outdoor unit in cooling, by the manufacturers' figures, and in England a permitted development install must keep it to 37 dB(A) at a neighbour's window by the MCS 020(a) calculation.

Heating, security and the window

Every fixed system we fit heats as well as cools. At the October to December 2026 cap a modern split gives heat for about 5.1p to 5.7p per kWh, against 26.3p for a plug-in heater. Some portables heat too: Meaco's heating model lists 8,100 BTU of heat (about 2.4 kW) for 940 W, roughly 10p per kWh of heat at its rated point. Many portables only cool, so check before you buy.

A portable needs its window held part open, with a window kit sealing the gap around the hose. The window can't be shut and locked while it runs, which matters on a ground floor and if you want to leave it on while you're out. A part-open window lets in more street noise too. The hose is also short: Meaco's is 1.8 metres, so the unit has to stand close to the window. With roof windows in a loft, the hose is awkward to fit at all.

When a portable is the right answer

We fit fixed systems, but a portable is genuinely the better buy in some cases.

• You rent and your landlord won't agree to a fixed system
• You want to get through one heatwave or a few hot weeks a year
• You can't drill: a listed wall, or a freeholder who hasn't agreed yet
• The room is used now and then, not every day
• You're moving soon and want to take the cooling with you
• You need cooling now while you wait for consent or a survey

When fixed air conditioning is the better answer

• A bedroom you use every summer, where noise at night matters
• You want heating as well, especially to replace plug-in heaters
• You'd rather keep windows shut and locked, for security or street noise
• You want the floor space back and nothing to store each winter
• More than one room: a multi-split cools and heats two to four rooms from one outdoor unit
• A loft with roof windows, where a portable's hose is hard to fit
• You own the home, or your landlord agrees in writing

Is a portable air conditioner worth it?

For occasional use, often yes. It costs a few hundred pounds, needs no installer and takes the edge off one room. For a room you cool most of the summer, it's a poorer deal than the price tag suggests: louder, weaker in real use and dearer per hour.

In money, fixed doesn't win on cooling costs alone. Energy labels assume 350 hours of cooling a year, which costs £24 to £33 for a 2.5 kW fixed unit at today's cap. By our sums, 350 hours on a portable drawing 1,005 W costs about £93. The difference won't repay a fitted system quickly. People choose fixed for the quiet, the heating, the shut window and the space, and because heating with it costs far less than plug-in heaters.

Renting? Check before you buy either

A fixed system means a hole through an outside wall and a unit on the building, so a tenant needs the landlord's written permission, and in a flat the freeholder usually has to agree too. A portable is usually fine because nothing is fixed, but check your tenancy agreement. Our guide to air conditioning in a rented home covers who has to say yes and what to put in the request.

Planning: only fixed systems need it

A portable isn't fixed to the building, so planning doesn't come into it. A fixed system on a house in England is usually permitted development under Class G, with no application, if every rule is met. A semi-detached or terraced house can have one heat pump, a detached house two, and a block of flats one for the whole block.

The outdoor unit can be up to 1.5 m³ on a house (0.6 m³ on a block of flats), it must pass the MCS 020(a) noise calculation of 37 dB(A) at a neighbour's window, and since 29 May 2025 it must not be used solely for cooling. The systems we fit all heat, so they qualify. Conservation areas, World Heritage Sites and listed buildings add limits. Our planning permission guide has every rule.

What fixed air conditioning costs with us

Starting prices, fitted, with 5 m of pipe. Home prices include VAT. Every system heats and cools, and a free survey confirms the size and price.

• A bedroom or study

  2.5 kW wall unit, 5 m pipe, fitted in a day

  from£1,850inc. VAT

• A living room

  3.5 kW wall unit

  from£2,050inc. VAT

• Open plan or a loft

  5 kW wall unit

  from£2,450inc. VAT

• Floor-standing unit

  2.5 kW console

  from£2,350inc. VAT

• Two rooms, one outdoor unit

  Multi-split

  from£3,650inc. VAT

Fixed vs portable questions