I found a surprising number of people on my thread about AC not being an all-in-one solution with some very optimistic ideas about the cost of operating AC, specifically in Europe, which is not the cheapest place around for electricity overall.
So, I'm going to break down some data and share some personal experience.
2025 data had Hungary as one of the cheapest markets with retail prices around 10 Euro cents per kilowatt hour and Germany on the high end of around 39 cents. Spain, where I am, is on the higher end as well, but less than Germany at around 24 cents, but not as high as France's 29 cents or Italy's 31 cents.
So, right up front, we can see how expensive it is to run AC is going to vary considerably by country.
My apartment is equipped with five Daikin inverter mini splits that have a peak draw of a bit over 1800w and a typical draw of around 1400w, according to the electrical data. As they are inverter units, they can ramp up and down as needed. Three of the units are in bedrooms while the two others are in the living room and dining room, which adjoin and do not have a door between them.
The master bedroom, dining room and living room all have western exposure to the sun and thus considerably greater heat load than the rest of the house.
Let's imagine that running one mini split consumes an average of 1 kWh to keep one room at a tolerable, but not frosty temperature. Running it for a whole day would be:
Spain
0,24€ x 24 hours x 1 kWh = 5,76€ / day
5,76€ x 30 days = 172,80€ / month
France
0,29€ x 24 hours x 1 kWh = 6,96€ / day
6,96€ x 30 days = 208€ / month
Italy
0,31€ x 24 hours x 1 kWh = 7,44€ / day
7,44€ / day x 30 days = 223,20€ / month
Germany
0,39€ x 24 hours x 1 kWh = 9,36€ / day
9,36€ x 30 days = 280,80 / month
Now, some might argue the cost is worth it. That's a personal issue, but I cannot countenance any argument these numbers don't represent a significant financial hit to ordinary households, especially since they're pretty conservative. If the heat load in the home was greater, insulation worse or the air sealing poor, the cost would go up and the effectiveness would go down. If a space larger than one room or multiple rooms needed cooling, then the cost would be multiplied.
I have a sister in Italy who straight up said this year she wasn't running AC more despite the heatwave because it was imply too expensive.
A few years ago, before I discovered embraced evaporative cooling, we ran the AC at night to be able to sleep comfortably but not during the day in order to save on costs. My MiL though, very reasonably, had to run the AC most of the day if she was home as her room is thermally the worst and she's elderly. The electrical bill was still an issue even with those limits, which was one of the reasons that drove me to look for alternative cooling options. The summer bill was over 300€ more than the cooler seasons and this was using inverter units.
So really, kindly no one tell me that running AC in Western Europe isn't costly.