Cooking uses less energy than the attention it receives

Getting the size of the thing right first

Heating a house and heating its water are the two large items in most households, and everything electrical put together is generally the smaller part of the bill. Cooking sits inside that smaller part, alongside lighting, refrigeration, laundry and everything else, and it is not the largest item within it either.

This matters because the advice available about cooking energy is out of proportion to what is at stake. There are real differences between appliances and real savings available, and they are the sort of savings that come after the heating system, the insulation and the hot water have been addressed.

Which isn’t a reason to ignore the subject. It’s a reason not to start with it.

Where the heat goes on a hob

The energy that matters is the energy that ends up in the food. A gas flame heats the base of the pan and a good deal of it goes past the sides into the room, which is why a kitchen with gas cooking is noticeably warm. A conventional electric element heats itself, then the pan, then the food, and retains a lot of heat when switched off.

Induction changes the mechanism rather than improving the same one. A coil under the surface generates a rapidly changing magnetic field, and that field induces currents directly in the base of a ferrous pan. The pan is the heating element, and the hob surface stays comparatively cool.

That directness is why the response is quick and why less energy is wasted heating the surroundings. It also requires a pan that responds magnetically, which rules out some aluminium and copper cookware, and a hob with a suitable electrical supply arrangement.

Lids, pan size and water quantity beat appliance choice

Boiling water with the lid off means supplying latent heat to steam that leaves the pan, which is far more energy than raising the water to temperature in the first place. A lid is the single most effective adjustment available in a kitchen and it costs nothing.

A pan smaller than the ring wastes the surrounding heat, and a pan much larger than it heats unevenly and slowly. Filling a kettle to boil one cup wastes the energy that went into the rest. None of these individually amounts to much, and collectively they are worth more than the difference between two hob technologies.

It is the same pattern seen elsewhere in a house. How the equipment is used usually matters more than which equipment it is.

Ovens heat a large volume to cook a small one

An oven brings a substantial insulated cavity up to temperature and holds it there, and the food inside is a small part of what is being heated. That is inherently less efficient than heating a pan, which is why a small quantity cooked in an oven is the most energy-hungry way to prepare it.

Fan ovens circulate air so heat reaches the food faster and more evenly, allowing a slightly lower temperature and a shorter time. Smaller countertop ovens and air fryers apply the same principle to a much smaller cavity, and their advantage is the volume they are not heating rather than any superior technology.

Preheating for dishes that do not require it, and opening the door repeatedly, both undo the benefit. Batch cooking recovers it, since the cavity is already hot.

The measures that are not worth the trouble

Replacing a working hob or oven on energy grounds alone does not stand up. The consumption difference is applied to a small base, and the manufacturing and disposal of a replacement appliance is a real cost of its own. When the existing one fails, choose deliberately — that’s the moment the decision is free.

Elaborate routines around cooking energy are similarly poor value for attention. A household that has draught-proofed, insulated the loft and sorted out its heating controls has achieved more than a decade of careful kettle filling could.

And there is a comfort dimension that deserves respect. Cooking is something people enjoy, and optimising it into a chore to save a small quantity of energy is a bad trade that nobody should feel obliged to make.

Where cooking does interact with the rest of the house

In winter the waste heat from cooking is not entirely wasted, since it warms a room the heating system would otherwise have warmed. In summer it is a genuine cooling load, and a kitchen is often the hottest room in a house for exactly this reason.

Extract ventilation is the other connection. A hood removes moisture and cooking products and it also removes warm air, and running it longer than needed exports heat you paid for. Running it too little leaves moisture in the house, which is the more expensive mistake.

For a household with an array, cooking is one of the few substantial daytime loads that can sometimes be moved into generating hours. That is a modest gain and it is the most relevant thing cooking has to do with a solar roof.