Between fans, portable air conditioners and cooling units running all day through these weeks of intense summer heat, the next electricity bills are set to go through the roof. Look closely at your consumption, though, and you may spot unusual figures that even a permanently running cooling system doesn’t explain.

The truth is that plenty of other things quietly push the final amount higher. Think of devices left on standby, or appliances with a poor energy rating that consume far more than a recent A+++ model. But there is one unsuspected habit in particular, one we all repeat every day, that ranks among the main culprits behind steep bills.

Why you shouldn’t leave the fridge door open

Few people think about it, but the refrigerator is one of the appliances that consumes the most electricity over the course of a year, because it runs nonstop, 24 hours a day. Opening the door even for a few seconds changes its energy use. The reason? With the door open, the cold air stored inside escapes and is replaced by warmer air coming from the kitchen.

The cooling system detects that temperature swing and fires up the compressor to bring the interior back down. That process requires more energy, and if it is repeated frequently the motor has to work accordingly.

In the hottest months the effect intensifies further. If the kitchen sits at, say, 28 to 30 °C (82 to 86 °F), the gap with the inside of the refrigerator is wider than it is in winter. That is why leaving the door open lets in far more warm air, increasing the strain on the compressor and therefore consumption.

What this habit costs you

Opening the fridge repeatedly and leaving the door open for long stretches translates into a meaningful increase in monthly electricity costs, and it also accelerates wear on the motor. According to figures compiled by IDAE, Spain’s Institute for Energy Diversification and Saving, prolonged openings can cause waste equal to up to 7% of total energy consumed.

This single appliance can account for an average of 18% of a household’s annual consumption, a share that rises significantly during the warmer months. The real cost may look small, but in practice it contributes — and not marginally — to the amount you end up paying.

To minimize the impact, the first step is to plan what you are going to take out before you open the refrigerator, so you cut down the time food spends exposed to warm air. Another excellent tip is to gather everything you intend to eat or drink in a single trip. Finally, organize your food so that it stays visible and easy to find, without having to hunt for it with the door hanging open.

Editor’s note

This article was originally published in Italian on money.it by Pasquale Conte on August 15, 2026 as «Questo semplice gesto giornaliero potrebbe essere la causa nascosta delle bollette salate». It has been translated and adapted for an international audience by the Money.it International desk.