Before a heatwave, start with a fan instead of a mobile air conditioner

A hot bedroom can make a mobile air conditioner feel like an urgent purchase, but it is rarely the cheapest Dutch cooling story. Milieu Centraal compares the electricity use plainly: for the same 110 hours, a fan uses about 5.5 kWh while a mobile air conditioner can use about 110 kWh. Mobile units also have to deal with warm exhaust air and noise. For many homes, the more comfortable sequence is daytime shade, cooler-night ventilation and a fan.

• Useful number: a mobile unit can use around twenty times the electricity of a fan over comparable hours; compare running cost, not only shelf price.
• Best for: renters, small-bedroom households and anyone trying to sleep better without a sharp electricity bill.
• Before you buy: close blinds or curtains in daytime, ventilate when outdoor air cools, and aim the fan at people rather than an empty room. Use professional installation for a split system.

Hokimi field note: Keep heat outside first and move air where people are. That small change is often the most reliable comfort upgrade.