I had read in the past that the single largest home energy use is something that would be even harder to live without than refrigeration...
hot water.
May be true, maybe not.
Water heaters are the biggest draw on electric. Unless you have electric heating. To either turn on or off a light bulb is about 1% of your electric bill. Instant water heaters are very nice, but the price tag is still way too high right now.
I don’t know how common these are in the States, but I have an electric hot water heater that is attached to the wall in the laundry room. When one turns on a hot water tap, water runs through some heating coils (or something). There is endless hot water throughout the house. There is no tank of water, which is heated and reheated 24 hours a day, and wasting one’s money.