Portable air conditioner or a fitted split system?

A fair comparison, using the figures the manufacturers publish, from a company that only fits split systems.

Shameet PatelDirector, NVK Air21 October 2026

REFCOM certified, REF1025662
Daikin registered installer

A portable unit is the right answer if you need cooling this week, rent, or cannot fix anything to an outside wall. A fitted split system is the better answer for a room you will cool every summer: the noisy part sits outside, it uses less electricity for the same cooling, nothing hangs out of the window, and it heats the room in winter as well. As an example from published figures, a common portable has a sound power of 64 dB(A) against 55 dB(A) for the indoor unit of a 2.5kW Daikin split, and draws 930 watts when cooling. A split costs more to start with: ours start at £1,995 fully installed.

How each one works

Every air conditioner has a cold side and a hot side. In a split system the cold side is on your wall and the hot side, with the compressor, sits outside. Two small pipes, a drain and a cable run between them through one hole in the wall.

A portable puts both sides, and the compressor, in one box on your floor. The heat it takes out of the room has to go somewhere, so it blows it out through a hose that goes out of a window or through a panel in one.

Most portables sold in the UK are single hose units. They take air from inside the room to cool their hot side and then blow that air outside. That air is replaced by warm air from outside, coming in under doors and around windows. The US Department of Energy found this effect large enough that it changed how portables are tested there, and it noted the effect is most pronounced in single hose units.

The published figures side by side

One common portable and one split we fit, each from its manufacturer's own data. Sound power is the noise the unit itself gives off, measured the same way for both, so it is the fairest noise comparison.

	Portable example	Fitted split example
Model	De'Longhi Pinguino PAC EL98 ECO RealFeel	Daikin Comfora 2.5kW
Sound power in the room	64 dB(A) maximum	55 dB(A) indoor unit, cooling
Sound pressure in the room	47 to 50 dB(A)	19 to 40 dB(A)
Where the compressor is	In the room	Outside
Efficiency figure	EER 2.6, class A on the portable scale	SEER 7.20, class A++ on the split scale
Electricity when cooling	930W rated	Varies with the load, see running cost below
Heats in winter	Check the model	Yes, it is a heat pump
Takes up	Floor space, plus a 150mm hose to a window	Wall space only

Figures read from De'Longhi's and Daikin's own product data on 21 October 2026. A difference of 9 dB(A) in sound power is a large one: on the decibel scale every 10 dB is ten times the sound energy.

An A rated portable and an A++ split are on different scales

The energy label law gives portables their own scale. A single hose portable needs an EER of 2.6 to be rated A. A split system needs a seasonal efficiency of 6.1 or more just to be A++. So the letters cannot be compared across the two types, and an A on a portable is not close to an A on a split.

What each costs to run

The portable above draws 930 watts when cooling. At the Ofgem price cap of 26.32p per kWh, that is about 24p for every hour the compressor runs.

For the 2.5kW Comfora we work from Daikin's seasonal efficiency figure, which gives about 9p an hour averaged over a cooling season.

These two numbers come from different test methods, so do not read the gap as exact. But every published figure points the same way, and the portable's figure does not count the warm air it pulls in from outside.

When a portable is the right choice

We do not sell portables. These are the situations where we would still tell you to buy one.

You rent

Fixing a unit to an outside wall needs your landlord's consent, and a tenancy might not last long enough to make it worth it. A portable goes with you.

You need it this week

A portable can be bought and plugged in today. A fitted system needs a survey and an install date. In stock now. Fitted within 2 to 3 weeks.

You cannot get consent for the wall

Some leases and some listed buildings rule out an outdoor unit. A portable needs no permission from anyone.

It is for a few days a year

If the room is only uncomfortable for a week or two each summer, the cost of a fitted system may be hard to justify.

When a fitted split is the better buy

You want to sleep with it on

With the compressor outside, the indoor unit of a split is far quieter than a box with a compressor in it. In a bedroom that is usually the deciding point.