How and where do you save energy in the household?

The frozen mass lying in the kitchen extracts thermal energy from the surrounding air, which the heating system will compensate for.

The trick is to put the frozen item in the refrigerator. Then you have cold transfer freezer -> refrigerator and the building heating is completely out of the picture.

Do not preheat the oven

Popular tip but the pizza simply turns out different if you have it in the oven for 15 minutes without preheating instead of 10 minutes at the right temperature. You probably don't save much either, because the expensive part is heating the oven up in the first place, not maintaining the temperature (unless you keep opening it constantly).

Well, a bed lasts 20, 25 years? A mattress lasts 10, 15 years? It's not a car with 10-15,000 parts installed.
A waterbed consumes around 7,500 kWh in 10 years, and that doesn’t just fall from the sky. Wind turbines have to be built or coal shipped from Venezuela or Australia for that.

If someone is worried that the freezer compartment uses more energy when you take the frozen goods out in the morning, they should put a piece of Styrofoam inside.
You can also do that in the fridge...
The building heating is definitely more efficient than the oven.

The warm air generated in the kitchen while baking is also quite humid. You have to air that out. So, a zero sum.

You should basically turn off the lights when you don’t need them. Thanks to LEDs, that’s no longer a problem, nothing breaks even if you turn it on and off 500 times during the day. You also don’t leave the car running when you park and go into a store for 5 minutes...

Popular tip but the pizza simply turns out differently when you bake it for 15 minutes without preheating instead of 10 minutes at the right temperature.

You are right. But what is a slightly different pizza compared to our energy situation? These are the small steps that everyone could take in their own mind... and not use the word "but". The slightly different (better) pizza is anyway just a frozen food version of fast food and has little to do with the real pizza from the Italian place.

So I have always put the frozen pizza straight from the fridge into the cold oven. I want to eat it eventually and not wait forever. My wife says the product is rubbish and pizza should always be homemade, but sometimes I like it this way.

my wife always says "we have LED anyway, so it costs nothing^^"

Which she is right about. Except of course the saved consumption amount is compensated again by the number of LED lights.

... You also don't leave the car running when you park it and go into a store for 5 minutes...

But this has not yet been understood by everyone. I actually still see it occasionally. By the way, there is a lot of nonsense in the other, non-quoted text.

BUT that hasn't caught on with everyone yet. I actually still see that occasionally.

I recently had that happen in front of the daycare. A mother had parked her car with the engine running on a hill and left the sibling in the child seat while she went to pick up the other child. That wouldn't have occurred to me for various reasons. Not least because anyone could just get into the car and drive away with my child. o_O

My wife says that the stuff is rubbish and pizza should always be made yourself, but sometimes I like it like that.

Sometimes I can appreciate that too. A kind of slightly soggy frozen discount store pizza from the oven that hasn’t been preheated sometimes tastes really good. Maybe because it gives me student nostalgia vibes or something.