Do Portable Air Conditioners Work?

Yes, portable air conditioners do cool a room, and on a hot day they do more than a fan. But they have real limits. Before you buy one, or if you are wondering why yours does not seem to make much difference, this is what you need to know.

How a Portable Air Conditioner Works

A portable unit contains everything a fixed system does, including the compressor, in one box on wheels. It cools the air in the room and pushes the heat it removes out through a hose, usually fitted into a gap in a window.

Most are single-hose models. The air they push outside has to be replaced, so warm air is drawn back in through gaps around doors and windows. Some of the cooling is lost straight away.

The Limits of Portable Units

• Noise. The compressor is in the room with you. Testing by the consumer group CHOICE found portable units running at 57 to 74 dB(A) on a high setting. The quietest fixed wall units, with the compressor outside, are rated at 19 dB(A) on their lowest setting.

• Efficiency. CHOICE describes single-hose portable units as quite inefficient compared with split systems, giving you less cooling for each kilowatt of electricity.

• The hose. It has to go out of a window or door, which then cannot be closed or locked properly. The hose itself also gets warm and gives some heat back to the room.

• Water. Some models collect water in a tank that needs emptying.

• Space. They take up floor space and need to sit near a window.

• Cooling power. Many struggle in a large room or on the hottest days.

When a Portable Unit Makes Sense

• You rent and cannot make changes to the property.

• You only need cooling for a few days a year.

• You need a short-term solution while a fixed system is arranged.

If you do use one, choose a model sized for your room and seal the window gap with a proper kit. Keep the hose short and straight, and keep the curtains closed on the sunny side.

Portable vs Fixed Air Conditioning

• Noise: portable units are loud in the room. Fixed systems are far quieter inside because the compressor is outdoors.

• Efficiency: fixed systems are much more efficient.

• Heating: fixed systems heat efficiently in winter. Many portable units only cool.

• Windows: a fixed system leaves your windows closed and secure.

• Cost: a portable unit costs a few hundred pounds. A fixed single-room system typically starts from around £2,500 installed.

Fixed air conditioning is an investment, and it is not for everyone. If you want a room that stays cool on the hottest nights without the noise, or a system you can use for heating as well, it is worth considering. See how our home air conditioning installation works.

Frequently Asked Questions

Do portable air conditioners use a lot of electricity?

They use more electricity for the cooling they provide than a fixed system, because single-hose units are less efficient. The exact cost depends on the model, how long you run it and your tariff.

Can I use a portable air conditioner without a window?

Not properly. The hot air has to go outside, so the hose needs an opening such as a window, a door or a vent through the wall. Without one, the unit just moves heat around the room.

Are dual-hose portable units better?

They draw less warm air into the house, so they are a little more effective, but the compressor is still in the room and the noise is similar.

Is there an option with no hose and no outdoor unit?

There are through-wall units with no outdoor unit, each with its own trade-offs. We explain the options in air conditioning without an outdoor unit.

What else can I do to keep a room cool?

Start with the free measures in our guide on how to cool down a room.

Call 01772 288651 or use the form below to book a free survey. We will measure the room, recommend the right system and give you a clear written quote.

Last updated: November 2026.