You might be a renter, want to wheel your air conditioner around between rooms, or just simply don't have the cash for a fixed option. In any of these and more scenarios, a portable air conditioner is an option to consider, but because of their inefficiency it might be wise to know what you're in for if you get one.
How portable is portable, exactly?
Firstly, 'portable' in our language is slightly different to a manufacturer's idea of portable! While you can install these units without modification to the building, you wouldn't want to lug one from room to room the way you do with a fan. They're heavy, not always easy to manoeuvre and require installation via a window kit. So, there's that.
Okay, so they're not that portable. Got it. How do they work?
Portable air conditioners work basically the same way as built-in air conditioning: sucking in warm and humid air, cooling and dehumidifying it and blowing it back into the room. Single-duct models, with a duct connected to a window to vent heat from the room, can be very effective at cooling most of the room, but they draw the air from the room (in order to cool it) and vent some of it outside.
Venting the hot air outside through the duct results in a net air pressure reduction, so more warm air is drawn into the room from the rest of the house. The portable air conditioner thus faces a continual struggle to cool the room. Portable units are also noisier indoors than most split-systems (which have the advantage of having the noisiest component, the compressor, situated outside).
So while they are convenient and often comparatively cheaper than split-systems, single-duct portables are not as effective or efficient.
The heat extracted from the air is vented through an air duct that you install in an open window. The unit also condenses water from the air while cooling, collecting this in a tank or draining it away via a tube. Dryer air feels more comfortable and enhances the cooling effect. A venting kit is included so you can seal the gap around the duct to stop the cool air escaping.
As of late 2014, there's no Australian standard for portable air conditioners. There are technical hurdles in devising a suitable test method to measure their performance and efficiency. For that reason, portable air conditioners are still not subject to Minimum Energy Performance Standards (MEPS) and don't carry star rating labels. However, a draft standard has been produced for public discussion; once it is approved, MEPS can be expected to follow in the not too distant future. Encouragingly, we have found some models with improved energy efficiency in recent tests.
I read all of that and I still really want one. What should I look for?
Our tests identify the best-performing models. You'll also want:
These are handy in much the same way that a television remote is handy (because we're lazy!), but with the added benefit of information on room temperature. You can also usually set automatic modes and timers to make life simple.
Cool, heat (for reverse-cycle models), dry (dehumidify), automatic or fan only. Automatic or "smart" mode means they can be set for a target temperature and will switch to cooling mode (or heating for reverse-cycle models) as required.
These are useful to program the unit to turn on/off at certain times, for instance to cool the place down before you get home from work. Sleep timers are useful at night as they switch the unit off after a set period rather than running all night, and usually have automatic temperature adjustment. This adjusts the temperature to a comfortable level for sleeping in,so the air conditioner doesn't work as hard (and also more quietly) when you're sleeping.
Louvres to direct airflow
Most have manually adjustable louvres, though a few have only fixed louvres. Other models have automatically oscillating louvres, which enable the cool air to be directed more widely rather than just in a fixed direction.
They range in price from $300 to $1500.