7,000–9,000 BTU air conditioners compared

A 9,000 BTU unit often weighs under 25 kg, fits next to the bed and runs on a normal socket at around 1 kW. In a 20 m² bedroom it reaches the target temperature quickly and can then carry on in quiet night mode. A 12,000 BTU unit would keep switching on and off there – which is louder and no more efficient.

In the bedroom, noise matters more than capacity. Look at the dB figure in night mode (below 50 dB is good), a sleep timer and whether the display can be dimmed. If you are very sensitive to noise, consider a mobile split, or run the unit for an hour before going to bed and then switch it off.

Monoblocks dominate this class: the Comfee Breezy Cool and MPPH series, the smaller versions of the De'Longhi Pinguino PAC EM and EX, the Trotec PAC 2010 to 2610, plus entry-level units from Suntec, Tristar and Klarstein. Mobile split units below 12,000 BTU barely exist – if you want to cool a bedroom especially quietly, choose either a small monoblock with night mode or go straight for the PortaSplit, which throttles down in silent mode anyway.

Prices in this class are well below the larger units; off-season, 9,000 BTU monoblocks are often available for a low three-figure sum. More important than the last euro is whether a window seal is included and whether the unit can also dehumidify – on muggy nights that adds more comfort than one degree less.