The overall Which? test score is made up of the following star ratings, all determined by our rigorous lab tests.
How we test water extraction at room temperature
We run each dehumidifier twice at its maximum setting for an hour at normal room temperature. From these two tests, we work out the average amount of water pulled from the air - we then compare these results to other dehumidifiers to generate our star rating. We run the same test in colder conditions as well - the sort of temperature you might expect in an unheated caravan or conservatory.
How we test quietness
Our expert lab testers subjectively rate how noisy each dehumidifier is. Some dehumidifiers have variable speeds so we check how much noise each one makes at its highest and lowest settings.
How we test energy efficiency at room temperature
During our water extraction at room temperature test, we measure the energy consumption of each dehumidifier at normal room temperature. A less energy efficient dehumidifier will cost you more to run than a more energy efficient one.
How we test ease of use
This star rating reflects a combination of different ease-of-use tests, including how simple it is to use the controls, whether emptying the water tank is likely to cause any problems, and whether it's easy to move the unit around.
