There are now propane heaters safe to use in the house, “Mr. Heater”. It uses small propane bottles. I got one in case power goes off. I have sleeping bags good down to 5 below zero. I would use them in the house and Texas doesn’t get to less than 5 below zero and very seldom goes to that. I have a gas fireplace but if power went off for a while, the gas would eventually stop.
I also have warm clothes to wear.