Machines that use a lot of energy like water boilers, vacuum cleaners, etc.
Use a water boiler where you can limit the temperature. I personally like to drink my tea right away. We surely can discuss how this is also about my personal impatience. But on the scope of sustainability, it’s a good coincidence.
Reduce using the vacuum cleaner by using a broom instead. I personally don’t like the noise a vacuum cleaner produces. My broom is just ready on the balcony. For a quick swipe of the kitchen floor, using the broom is not just quicker it also consumes less power. Within half a minute the job is done. Completely noiseless.