If your fridge seems to hum more in a heatwave, it is not your imagination. A fridge or freezer does not make cold so much as move heat, pumping it out of the cabinet into the room around it, and the hotter that room, the harder it has to work. Since the fridge-freezer runs around the clock all year, that extra summer effort quietly adds to the bill. The good news is that the fixes are simple and free.
The short answer. A fridge or freezer cools by pumping heat out into the room, so the hotter the room, the harder it works and the more it costs. A kitchen in a summer heatwave can push its running cost up noticeably. The fixes cost nothing: keep it out of direct sun and away from the oven, leave ventilation gaps around it, keep the door shut, let warm food cool before it goes in, and do not set it colder than it needs to be.
Why heat makes it work harder
A fridge works by the same principle as an air conditioner: it gathers heat from inside the cabinet and dumps it out of the back, usually through the coils you can see or feel there. To do that it has to push the heat into the surrounding air, and that is only easy if the surrounding air is cooler than the heat being shed. In a warm kitchen the job gets harder, because the room it is dumping heat into is itself hot, so the compressor runs longer and more often to hold the inside cold. That is why the same appliance, holding the same temperature, costs more to run in a heatwave than in a cool month: not because the food is warmer, but because the room it lives in is.
Where you put it matters most
Because the fridge is fighting the temperature around it, its position is the biggest thing you control. Keep it out of direct sunlight, which can fall on it through a window and heat the cabinet directly. Keep it away from heat sources, above all the oven, but also a dishwasher, a boiler or a radiator, since standing next to something hot makes the fridge work against that heat all day. Avoid sites that bake in summer, like a conservatory or an unventilated garage. And leave a gap around the back and sides so the heat it sheds can actually escape, because a fridge crammed tight into a unit with no airflow ends up re-breathing its own warm air. While you are back there, brushing the dust off the coils now and then helps them shed heat efficiently, and a quick check that the door seals still grip keeps the cold where it belongs.
The right settings
It is tempting to crank the dial up in hot weather, but a fridge only needs to be cold enough to keep food safe, and every degree colder than that costs more to maintain. The table shows the sensible targets. Setting it colder than these wastes energy without keeping the food meaningfully safer.
| Setting | Aim for |
|---|---|
| Fridge temperature | 3 to 5C |
| Freezer temperature | -18C |
| Gap around back and sides | a few centimetres for airflow |
| Position | out of sun, away from the oven |
A fridge thermometer costs little and takes the guesswork out, since the numbered dial is not a temperature. A well-stocked freezer also holds its cold better than an empty one, as the frozen mass acts as a buffer, so it cycles on less.
Hot-weather habits
A few small habits ease the load further when it is hot. Let warm leftovers cool to room temperature before putting them in, so the fridge is not asked to chill a hot dish in an already hot kitchen. Open the door less and close it promptly, because every opening lets cold air spill out and warm, humid summer air rush in to be cooled again. If the freezer has iced up, defrosting it helps, since a thick layer of frost makes it work harder. And resist over-filling the fridge so tightly that air cannot circulate inside, which leaves warm spots and makes the appliance run more to compensate.
The numbers, and when to replace
A fridge-freezer is one of the few appliances that never switches off, so it is a steady year-round cost, somewhere in the region of a couple of hundred kilowatt-hours a year for a modern one, more for an old or poorly placed model, and summer nudges that figure up. To see your own, the running cost calculator and the appliance's rated annual consumption tell you roughly what it costs at your unit rate. If yours is an old unit running hot and often, it is worth knowing that a tired fridge-freezer from twenty years ago can use several times the electricity of an efficient modern one, so when it finally needs replacing the energy label and the fridge and freezer efficiency guide are the place to start, since for an always-on appliance the running cost dwarfs the difference in purchase price.
The bottom line
Your fridge and freezer cost more in summer because they shed their heat into the room, and a hot room makes that harder, so the compressor runs more to hold the same cold. The cure is all about position and habits: keep the appliance out of the sun and away from the oven, give it room to breathe, set it no colder than it needs, let food cool before it goes in, and keep the door shut. None of it costs a penny, and together it keeps the one appliance that never rests from quietly costing you more than it should through the warm months.