Shocked like me by your latest electricity bill? Before you resign yourself to paying a fortune to stay cool this summer, it’s worth trying a few simple changes that could make a noticeable difference.

When my latest electricity bill landed, it came as a bit of a shock. More than €400 for a single month, compared to an average of €160 over the previous ten months. The culprit was obvious: a prolonged heatwave and heavy use of air conditioning in a flat with three aircon units (for three different zones).

Like many people, my strategy had always been simple. Set the air conditioning to the lowest possible temperature—18°C—turn the fan up to maximum, and let it run until the flat became comfortable. The problem was that it often took hours to cool down, and the electricity meter was spinning the whole time.

It never really occurred to me to experiment with the other operating modes until now.

De-humidify

One feature I’d largely ignored was the “Dry” mode. Rather than aggressively cooling the air, it removes moisture. That might not sound like much, but if you live on the coast, where humidity is a big part of what makes summer uncomfortable, it can make a surprising difference.

I tried running the system in Dry mode at around 22°C. The flat never became as cold as it would in full cooling mode, but it felt perfectly comfortable. Based on some informal testing, it also appeared to use around 20–25% less electricity than standard cooling.

This won’t be the answer everywhere. In humid coastal areas like Barcelona, Valencia or Málaga, reducing humidity can make the room feel much cooler. In inland cities such as Madrid or Seville, where the heat is much drier, Dry mode is likely to be far less effective.

The other change I made was to stop thinking of air conditioning as something that has to run continuously. Instead, I’d cool the living area for an hour or two, switch it off, and then only turn it back on once the flat started to warm up again. I found I could stay comfortable without having the compressor running for hours on end. However, having to manually turn on and off different units, and remembering to do so, it’s a lot more work.

Used together, these two approaches—making greater use of Dry mode where appropriate and cycling the air conditioning on and off instead of leaving it running constantly—could plausibly reduce air conditioning costs by anything from 25% to perhaps 50%, depending on your home and how disciplined you are.

I’m not claiming this is a scientific study, and every home is different. But if you’ve never looked beyond the standard cooling setting, it’s well worth experimenting. A small change in how you use your air conditioning could make a noticeable difference to your electricity bill without leaving you sweating through the summer.

If anyone has any suggestions or comments on this topic, please let me know. You can use the contact form below.