Our priority is testing 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 test models that a lot of members have requested.

Our testing takes place in an accredited laboratory. Air conditioners are tested in a 4.5m x 4m room with a 2.4m insulated ceiling, surrounded by a room or 'shell' which is kept at a constant temperature and humidity. When both rooms are at a stable 27ºC and 70% relative humidity, the air conditioners are turned on full for an hour. The test is repeated at 32ºC and 70% relative humidity. The testers rate the air conditioners' cooling effectiveness based on their ability to reduce the temperature and lower the humidity in the test room. They also assess how evenly the models cool the test room.

Unlike other product review sites, we don't accept free test models from manufacturers. This allows us to be independent and review without interference. Instead, we buy products anonymously from a variety of retailers, then bring them into our labs. This means we get what you'd get, and can be sure the model has not been potentially 'tweaked' for better performance.

We rate the portable air conditioners we test based on their cooling performance, measuring each air conditioner's ability to reduce the temperature and lower humidity in a room, as well as how evenly it cools the room. We also measure energy efficiency, estimated running costs and ease of use in set up and ongoing use and maintenance. Using our ratings, you should be able to work out the model that’s best for you.

While they're convenient and often comparatively cheaper than split-systems, single-duct portables 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 cons work the same way as built-in air conditioning. They suck in warm and humid air, cooling and dehumidifying it, then blowing 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.

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 $136, compared with $70 for a small split system. That's based on running the cooling mode for 4 hours a day, over 3 months, at an electricity cost of 30c/kWh.