The UK is currently experiencing some prolonged windy weather and my all-renewable energy provider offers dynamic pricing. That means cheap energy and even negative-cost energy. This is where my HA instance shines and saves me a fortune on my power bill. Thanks again to the HA devs for this incredible project.
For the curious, I'm using bottlecapdave's excellent Home Assistant Octopus Energy integration via HACS.
Flip side of heating could be to lower the temperature of freezers. If the energy is free anyways.
In my old place I actually did this: replacing my fridge and freezer's thermostats with an ESP Home controlled relay and thermometer. This place has a fancy integrated unit that I don't want to play with too much.