What does a fridge/freezer (main) cost to run?

The main fridge-freezer is the household's steady background load. Modest power, but running 24 hours a day, every day of the year, which makes it a meaningful slice of the annual bill despite never drawing much at once. A modern unit with a good energy rating can cost noticeably less to run than an old one doing the same job.

That around-the-clock duty is the whole story. A modern fridge cycles on and off, so the 150W figure is really the time-averaged draw rather than a constant pull, but averaged or not it never stops. Even a modest wattage adds up when there is no hour of the day or night when the thing switches off.

Most of the savings are about placement and maintenance, not usage. Give it room to breathe, because a fridge crammed against a wall or sitting next to the oven works harder to shed heat. A few centimetres of clearance at the back and sides lets it dump warmth easily instead of fighting to stay cold.

Keep the door seals clean and intact, since a perished seal lets cold leak out and the compressor run more, and do not set it colder than it needs to be, around 3-4C for the fridge and -18C for the freezer. A degree or two colder than that buys you nothing and simply costs power every hour of the year.

The other everyday habits are small but free. Let hot leftovers cool before they go in, keep the door open no longer than you need, and a reasonably full fridge holds its temperature better than an empty one. None of these are dramatic, but on an appliance that runs continuously the little things compound.

An ageing second unit running alongside it is usually the bigger target. See the garage fridge. If your main fridge is a decade or more old and you are replacing it anyway, a good energy rating pays back a little every day. Pop your fridge into the calculator to see how a small constant draw quietly turns into real money over a full year.