Gas Fireplaces
So, we recently rediscovered the gas fireplace in our house. Once it warms up the fake log and starts radiating heat, it works nicely to keep downstairs warm (versus central heating, which keeps downstairs cold and upstairs hot). The fireplace is convenient - just flip the light switch on the wall, and the gas starts flowing and gets ignited.
However, when the power goes out.. the valve defaults to closed without power applied. Which means, no gas fireplace. Which means, no redundant heat.