We check the power used by each portable air conditioner against the cooling energy it produces, to see which unit can help you save on your power bills.

Our priority is comparing the models you'll see in stores and major online retailers. To do this, we check current market data to see what's most popular. We'll also look at models that a lot of members have requested.

We rate portable air conditioners based on their cooling performance, as well as energy efficiency, estimated running costs and noise levels. Using our ratings, you should be able to work out the model that's best for you.

Portable air conditioners work the same way as built-in air conditioning. They suck in warm and humid air, cool and dehumidify it, then blow it back into the room. Single-duct models (with a duct connected to an open window) draw the air from the room to cool it and vent some of it outside. These units also condense water from the air while cooling. Generally, this is collected in a tank or drained away in a tube. A venting kit is usually included so you can seal the gap around the duct to stop the cool air escaping out the window.

While they're convenient and often comparatively cheaper than split-systems, single-duct portable air conditioners aren't as effective or efficient. They're only really worth considering if you're a renter and can't make modifications to your building, or if you can't afford the upfront costs of the built-in option. If you use your air conditioner a lot, a split-system model is likely to be more cost-effective in the long run.

Portable air conditioners can cost about twice as much to run as a split-system air conditioner of a similar size. We found the average running cost for portable air conditioners over a summer was $172, compared with $61 for a small split-system. That's based on running the cooling mode for four hours a day, over three months, at an electricity cost of 40c/kWh.