Cooking

boil water with lid - according to this:
Does placing a lid on a pot affect the rate of boiling?
time of heating until water boils will shorten when we put the lid on the pot. So we save cooking time and therefore energy as well.

According to konsumentenschutz.ch - Wie spare ich Energie beim Kochen ? there are a lot of energy saving tips. E.g. it is better to use an energy-efficient kettle instead of a pot to heat water for tea or coffee.