To begin,
it all depends.
In particular is it summer or winter and are you using direct electric heating, e.g. electric heater as opposed to a heat pump system.
For instance, turning off the lighting in a room that is being heated with an electric fire makes little sense, so would many of the tips. It may well be the case that leaving a gas oven on low all day might be a better idea than using electric heaters.
Do you huddle in the kitchen for warmth? We did, I expect it is a trait likely to catch on once more.
But besides all that:
1) The microwave is generally the most efficient way to heat up and cook food ...
2) Use the kettle to boil water ..
Or use the microwave, I do
3) When using water to boil anything in atr pan, make sure that you only use as much water as is needed to cover the amount of food you’re cooking ...
Don't try this with pasta!
FWIW I commonly cook some types of pasta in the microwave, but I would.
4) Slow cookers are also an energy-efficient cooking appliance ...
5) Cook as much as possible in the oven in one go ...
Compatible items only
6) Keep the oven door closed while you're cooking.
Once the oven is turned off, it makes no difference.
7) Defrost frozen food in the fridge overnight
8) It’s helpful to know how long your oven takes to pre-heat.
Err doesn't the little light go out? Sometimes the noise changes.
9) When cooking potatoes, boil them in a saucepan before roasting them ...
More to do with taste than efficiency I think.
10) Use glass or ceramic dishes in the oven. They retain heat better than their metal counterparts, making them the most efficient to use in the oven. You can even set the heat lower than needed (if you’re confident enough to do so) because of the increased efficiency provided by these dishes.
Consult an expert! On the face of it, the above is all a bit contradictory.
I thought that you turned the oven down to avoid uneven cooking and thereby cooked more slowly for longer.
11) Some people think that inserting stainless steel skewers into baked potatoes and joints of meat can help to speed up the cooking process because the heat is more quickly and evenly conducted throughout the food while it’s in the oven.
Heat pipes work and have been used for more than fifty years but they are a lot more sophisticated than a skewer.
12) If you’re cooking large food like a joint of meat, it can be worth cutting it into smaller pieces ...
13) Invest in a fan-assisted or convection oven, which uses fans to circulate heat around the food as it cooks. This is a more energy-efficient way of cooking because it means the heat doesn’t have to be as high as it would in a conventional oven.
Do they mean heat or do they mean temperature or what do they mean? Easier to say that they tend to be more efficient in most circumstances
14) When using an electric oven, turn it off ten minutes before the food’s finished cooking. ...
Err, follow the recipe.
And ovens tend to be thermostatically controlled and are not heating continually once both the oven and food are hot.
15) Always use a pan which is the right size for the amount of food you are cooking ...
Or just do one pan cooking, and own just one pan.
16) Similarly, when you’ve selected your pan, make sure you use the right size hob for it.
See above answer!
17) Sometimes the instructions on a recipe may mean that it’s not a good idea to put lids on pans but, if not, use lids in order to keep the heat in.
18) Use a double steamer to cook vegetables so you can layer vegetables on top of each other and still use one ring.
See one pan cooking above.
19) Turn down the level of the ring or burner once the cooking temperature or state is reached; most dishes need to simmer, not boil.
20) It can often be worth using a pressure cooker to cook beans, meats, whole meals or stews. The pressure cooker’s sealed lid traps steam and ensures that the food cooks more quickly and efficiently than it would in a pan, therefore saving energy.
Or use the microwave if the amounts are small, soak dried food before cooking .
21) If you're using an electric hob, choose flat-bottomed pans so the pan is in full contact with the ring and the heat spreads through it as evenly as possible.
Provided that the base is reasonably flat over the area of the ring, I doubt this makes a lot of difference.
See Baz's wok above.
22) Certain pan types are better at conducting and retaining heat. Copper-bottomed pans heat up more quickly than stainless steel, and cast-iron pans retain heat more efficiently, so you won't need the heat to be turned up so high.
That is all very well but what are we meant to do with this information. That is even if the inferences were true which I sincerely doubt.
23) Keep heating rings as clean as possible - any food that sticks to the ring will absorb heat, making it less efficient.
Excuse me while I clean my mouthful of coffee off this computer. What have they left on the ring? A leg of lamb?
ETA:
FWIW One dish microwave cooking, vegetarian at least, can be done with little or no added water. One dish is a lot cheaper to wash up than all the various vessel combinations the authors seem to prefer.
FWIW(2) How common it is for such experts to be vague to the point meaningfulness when it comes to all things thermodynamic, e.g. temperature, heat, energy, and the thermal properties of materials.
