It’s only the start of July, but the UK has already faced a number of record-breaking warm days. Our heat-retaining homes have quickly become desperately uncomfortable, and don’t get us started on those long, sweaty commutes. And according to forecasters, there’s more of this to come in the coming weeks.
So, it’s no surprise that sales have been rocketing for essential items like portable air conditioners, fans and air coolers. Weather like this is so rare that air conditioning isn’t part of everyday life here, which means many people aren’t really sure how it actually works. We know you switch it on and the room cools down, but what’s it really doing behind the scenes?
To understand how these pieces of kit work, I spoke to Tom Houlker, air conditioning installation and service expert and director at Houlkair.
Read more: Fans vs air conditioners, which to buy
How does an AC work?
An air conditioner doesn’t actually make cold air, explains Houlker. Instead, it moves the heat from inside a room to outside. He says warm room air is pulled across a cold evaporator coil, where the refrigerant absorbs the heat, before the system pushes that heat outdoors via the compressor and condenser. In simple terms, the cooling effect comes from heat being removed from the room rather than colder air being created.
Read more: Boxt air conditioner review
How energy efficient are air conditioners?
The efficiency of an air conditioner really depends on usage. It comes down to “how many British thermal units of cooling you get for each kilowatt hour of electricity you pay for,” Houlker explains. “Energy labels are the best starting point, since they show efficiency class and energy use.”
He also advises checking SEER or EER ratings where available. However, he stresses that real-world performance also depends on correct sizing, a sealed exhaust hose and clean filters.
Read more: Portable vs fitted air conditioning units
How to make the most of your air conditioner
Houlker recommends keeping usage simple but consistent. He says to “keep the filter clean, seal the window kit properly, shut blinds in direct sun, close doors to unused rooms and do not set the unit colder than you need.” He adds that lower temperatures don’t cool rooms faster; they just make the system run longer, and that steady airflow and humidity removal are what actually improve comfort.
How does an air conditioner move air around the room?
"The indoor fan creates the circulation loop. It pulls warm air into the unit and pushes cooled and dehumidified air back across the room. It keeps mixing the air so you do not end up with one cold corner and one hot corner,” Houlkar explains.
“The system works best when you keep the supply air path clear and avoid placing the unit where furniture, curtains or a bed blocks the airflow."
Read more: Best handheld fans
The portable air conditioners to buy
If you’re looking for respite from the heat, home appliance expert Joanne Lewsley has reviewed the best portable air conditioners. While lots of them are flying off the shelves, these models are currently available and well-rated.
Blyss A018I-09C 9000BTU portable air conditioner
Rating: 4/5
In her review of the best portable air conditioners, Joanne Lewsley called the Blyss A018I-09C 9000BTU portable air conditioner a “no-fuss air conditioner that still gives you a bit of flexibility.”
She added, “This Blyss model is a solid option. It covers the basics well, with cooling, fan and dehumidifier modes, plus three fan speeds and a 24-hour timer to fine-tune things depending on how you’re using it – and it’s good value.”
Buy now £269.99, Screwfix.com
Meaco meacocool MC series pro 8000 BTU portable air conditioner
Rating: 4/5
“If you’ve struggled with awkward window setups in the past, this MeacoCool model is one of the easiest I tested to get up and running,” Lewsley wrote in her review. She notes things like the window kit with extra-long panels and visual appearance for making it stand out more than many other options.
Buy now £380, Argos.co.uk
Meet the expert
- Tom Houlker: Air conditioning installation and service expert and the director of Houlkair
