Anything that burns liquid fuel uses up oxygen and creates water as a byproduct of combustion. You would need to crack a window a little bit when using them and then you'll have to watch to make sure it doesn't get too cold from the open window or too hot from the heat source.
It's difficult to prepare for an emergency if you only have one day. The best bet is to get a generator but if you shop local stores you will pay out of the nose. The cheapest place to get one is e-bay or Amazon.com. You can get a larger one for about $300 shipped if you shop around, but I really love my little 'Earthquake' generator. I paid $311, looks like the newer version is about $400. It always starts in just a couple pulls and you don't have to mix gas and oil. It's very compact and pretty quiet. All you would need are a few extension cords and power strips. Best to be prepared before the storm comes. For a heat source in a small room you could run a halogen lamp to this generator.
https://www.amazon.com/Porta-Source-...b_title_garden
If you want more power and a cheaper price you could get this one, less than $300 with free Amazon shipping. It's going to be heavy though and you'll probably need two people to load it in the back of a pickup to move it a distance from your house. I actually have one of each, a big one and a small one. If one won't start I have a backup.
https://www.amazon.com/dp/B004918MO2...&pd_rd_w=kwFEB
My next big investment for my house is going to be an all house backup generator. Even with this I would have one or more backup portable generators, especially if you have quite a few valuable reptiles at stake.
https://www.amazon.com/Briggs-Stratt...ouse+generator