A wood frame house with no insulation won't be comfortable after a 1/2 hour and won't be better than a tent after 2 hours in 0 Degrees F.

A wood frame house with superb insulation and double-pane thermal windows and lots of thermal mass in the right places and windows in the right places doesn't need a furnace to stay above freezing aslong as there is a few hours of sun each day.

The average house doesn't exist.

Don't sit in your car and keep the engine running! Carbon monoxide poisioning is truely a danger. If you are trapped in your car then run the car long enough to heat the interior and turn it off. Don't turn it back on until you are really cold again. Get out every now and again and knock the snow away from the windows and exhaust. A couple of tea-light candles can make a huge difference if you keep at least one window cracked open to let out the Carbon Monoxide. A bag of 50 is $1 at the dollar tree store. Don't need to burn more than 2 at a time tho.

Look into what you would want to have for a winter camping trip - sleeping bag, stove, fuel, tent, food, water, cook-kit, chemical hand warmers, down parka etc... Don't bother with the rope, crampons, snow shoes, ice-ax etc unless you are actually going out. Keep this kit in your car. If you need it in your house you should be able to get it from the car.

For the house heating problem you might want to look at the Alpaca kerosene heater which is available in many places - one being Major surplus and survival online - look under their stoves/ heaters link in thier online catalog. Doug has reviewed this stove and recommended it last I read. Use the Kerosene stove in a room with a window or chimney that leaks a bit to vent the potential Carbon Monoxide and keep that room sealed from the rest of the house with blankets hung on the doorways. Live in that room until things warm up.