A window kit can be a bit of a faff to install the first time – especially as very few windows are a uniform size so a generic kit can sometimes fall short – but once installed you can leave it in place for subsequent use. A unit with Smart functionality can also offer the means to control the unit when you're away from home. I tested the Wave 2 on the same hot day, in the same room as the AEG unit above and while both worked, the big German machine was much more effective.

BTU Portable Air Conditioner for Cooling HOMCOM 7000 BTU Portable Air Conditioner for Cooling

At night it performed better, but did make a great deal of noise, even on the lowest of three speeds, making earplugs a must. It’s a brand everyone has heard of… so you’ll pay a premium, but you can see why you’re paying extra. If you have a larger space to cool then the brand also offers a 12000BTU model that can cool spaces of 24-36m².The good news is that there is a wide range of BTU numbers when it comes to portable air conditioners.

Portable Air Conditioner 9000 BTU 4-in-1 Dehumidifier

However, it's the 12000 BTU that remains the brand's bestseller, with its capability of cooling a large space of up to 51m2.As such, we've rounded up the key features to look out for when sourcing the best portable air conditioner for your home.