What size portable air conditioner do I need (BTU guide)?
When choosing a portable air conditioner, it’s important to consider the BTU - British Thermal Unit of the appliance and ensure its suitable for your chosen room size. The BTU rating is a measurement that describes how much heat an air conditioner can remove from a room per hour.
As a general rule, the larger your room or office, the higher BTU rating you’ll need:
Small rooms (up to 14m2) - 4000-6000 BTU
Medium rooms (up to 23m2) - 6000-8000 BTU
Large rooms (up to 35m2) - 8000-10000 BTU
Extra large rooms (up to 42m2) - 10000-12000 BTU
You may also want to choose a higher BTU if your room is on the top floor of a 3 story house or gets strong direct sunlight during the day.
Do portable air conditioners need to be vented out of a window?
Yes, portable air conditioners need venting out of a window or patio door to remove the hot air from your room via an exhaust hose.
Most portable air conditioners come with window kits included, with options for both sliding and sash windows. Some window kits are sold separately however, so check the product listings before you buy to avoid disappointment.
Venting can be done in a few easy steps. Grab the hose and connect it to the back of your AC. Here's the important part: make sure the other end of the hose is directed outside, preferably through a slightly open window or a vent hole. This lets the hot air escape while your AC cools things down indoors. Just double-check for any gaps or leaks around the window and hose, and you're good to go. A lot of air conditioners come with a sealing kit so you can maximise its efficiency, too, by blocking gaps in the open window.
Single hose vs dual hose portable air conditioner: what’s the difference?
Single-hose portable air conditioning units exhaust the hot air from your room through one hose, whereas dual-hose air conditioners use two – one to pull in outside air and expel hot air to the outside.
For occasional use in the UK, a single-hose portable air conditioner should be sufficient, but you may want to invest in a dual-hose for continuous use in warmer climates.
How much does a portable air conditioner cost to run per hour in the UK?
The exact cost of running an air conditioner overnight will depend on the type of unit, whether it has an auto shut-off timer and its overall power consumption. You can calculate the energy use by multiplying the wattage, electricity rate and number of hours it's running.
According to recent testing by consumer champion Which?, the average cost of running a portable air conditioning unit is 22p per hour.
Are portable air conditioners noisy - and can you sleep with one on?
Portable air conditioners can be noisy, especially at maximum fan speeds - ranging between 50-65dB on higher settings.
If you plan to sleep with it running, you should look for models with designated sleep modes, which use low fan speeds for quieter 40-50dB operation during use. If you are a light sleeper however, you may prefer to use a timer, or cool the room prior to going to bed.
About the authors
Lucy Cotterill is a freelance writer, who in addition to running an established blog, Real Mum Reviews, writes lifestyle content for a variety of publications in the UK and US, with a focus on detailed and balanced product reviews. She's written about a vast range of products for Mumsnet, including the top ways to beat the heat this summer.
Poppy O'Neill is a Content Editor at Mumsnet and a mother of two. She researches and reviews the products Mumsnet users swear by, with a particular focus on home essentials, laundry and fans.
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