How to Heat a Room Without Electricity: Safest and Cheapest Ways
The safest ways to heat a room without electricity are an indoor-rated propane heater, a gas fireplace or wood stove, and trapping the heat you already have by closing off one room and sealing it. The cheapest is the last one: it costs nothing and, with two or three people in a small room, it can hold a livable temperature for hours. The one rule that matters more than any tip: never burn anything indoors that isn't rated for indoor use, because carbon monoxide from grills, camp stoves, and unvented heaters kills people every winter.
Keep reading to see what not to do, what does work (with what each costs per hour), how to keep the heat in one room, and what to do overnight. If you're reading this during an internet outage, check the outage map for restoration estimates first, then pick the option that fits what you already have in the house.
What should you never use to heat a room without electricity?
Never use a charcoal or gas grill, a camp stove, a generator, a kerosene or propane heater that isn't labeled for indoor use, or your gas oven or stovetop burners to heat a room. All of them produce carbon monoxide, which is odorless and builds up fastest in exactly the small, sealed room you're trying to keep warm. The CDC warns that CO poisonings rise during winter storm outages for exactly this reason: people bring outdoor fuel sources inside.
Two rules before any flame comes indoors: have a battery-powered carbon monoxide detector in the room (they cost about $20 and run for years on batteries), and crack a window an inch, even with an indoor-rated heater. Generators stay outside, at least 20 feet from any window or door.
What's the cheapest way to heat a room without electricity?
The cheapest way is to stop heating the whole house and heat one room with what's already there: close every door to that room, hang blankets over the doorways and windows, and let the people, sun, and any flame-free heat you have do the work. It costs nothing and it's the first step regardless of what else you use.
Here's what a small, sealed room gets you. Two adults give off roughly the same heat as a 400-watt heater. A south-facing window on a clear winter day adds more than that while the sun is up. In a 10-by-12 room with the door closed and the windows covered, that's enough to hold the temperature in the 50s or low 60s in Chattanooga's typical winter outage weather, and to keep it there overnight under blankets.
If you're willing to spend a little, the cheapest fuel is propane from a 20-lb tank (the grill tank), burned in an indoor-rated heater: roughly 40–50 cents an hour on high, less on low.
Does gas heat work without electricity?
Usually not for your furnace, but often yes for a gas fireplace and a gas water heater. A gas furnace needs electricity to run its blower and controls, so it shuts down in an outage even though the gas is still flowing. A gas fireplace or gas log set with a standing pilot light (or a battery-backed ignition) works fine with no power and is one of the best emergency heat sources there is. A tank-style gas water heater with a standing pilot also keeps working, which means hot showers and hot-water bottles.
If you have a gas fireplace, test it now: turn the thermostat off, flip the wall switch or remote, and see if it lights. If it does, you have your outage heat source. If it doesn't, a service tech can usually add battery backup to the ignition for under $100.
Which heaters work without electricity, and what do they cost to run?
Indoor-rated propane heaters, vented gas fireplaces, and wood stoves all work without electricity. Here's how they compare, best options first.
Indoor-rated propane heater
Safe indoors: Yes, with a window cracked and a CO detector in the room.
Heat: 4,000–18,000 BTU per hour, enough for a bedroom on low or a living room on high.
Cost: About 20–90 cents an hour on a 20-lb grill tank; $1–2 an hour on the small 1-lb canisters. This is the most practical option for most homes. Look for "indoor safe" on the box and an oxygen-depletion sensor that shuts it off automatically. A 20-lb tank lasts 20–40 hours.
Gas fireplace or gas logs
Safe indoors: Yes; it's vented.
Heat: 20,000–40,000 BTU per hour, enough for one large room.
Cost: Roughly 40–80 cents an hour of natural gas. It needs a standing pilot light or battery-backed ignition to light without power. Test it before winter.
Wood stove
Safe indoors: Yes.
Heat: 20,000–60,000 BTU per hour, the most of anything on this list.
Cost: Roughly 50 cents to $1.50 an hour in firewood. If you have one, it's your outage heat. Keep the flue open and the door closed.
Wood-burning fireplace
Safe indoors: Yes.
Heat: Low net heat; most of it goes up the chimney, but you'll be warm in front of it.
Cost: Firewood. Close the damper only when the fire is completely out, never before.
Kerosene heater
Safe indoors: Only if labeled for indoor use, and only with real ventilation.
Heat: 10,000–23,000 BTU per hour.
Cost: Roughly 60 cents to $1.20 an hour. Use 1-K kerosene only. The fumes are strong, and it doesn't belong in a bedroom.
Camp, catalytic, and alcohol heaters
Safe indoors: No, unless the label specifically says indoor.
Heat: Low. Most are outdoor-only. Don't improvise.
Candle and terra-cotta pot "heaters"
Safe indoors: Safe enough, but useless.
Heat: About 80 BTU per hour per candle, roughly 1/50th of the smallest propane heater. Good for light, not for heat.
Rules of thumb: 4,000 BTU per hour warms a small bedroom, 9,000 warms a living room, and a whole floor needs 20,000 or more. A 20-lb propane tank holds about 430,000 BTU, so at 9,000 BTU per hour it lasts about 48 hours.
How do you keep the heat in one room?
Pick the smallest room that fits everyone, ideally one with a south-facing window and no exterior doors, and treat it like a tent. In order of impact:
- Close the door and block the gap under it with a rolled towel. A single closed door can be the difference of 10 degrees.
- Cover the windows at night with blankets, quilts, or bubble wrap taped to the glass. Uncover south-facing windows during the day to let sun in (the Department of Energy's window guidance recommends the same day/night routine for any home in winter).
- Hang a blanket over the doorway if the door doesn't seal, or over the hall side of the door.
- Seal drafts you can feel: towels along window sills, tape over the keyhole and mail slot. If you weatherstripped your doors before winter, this step is already done.
- Get off the floor. Cold air pools low. Sit and sleep on the bed or a couch, not on the floor, and put a rug or cardboard down if you must.
- Skip the ceiling fan. It won't run without power anyway, and in an unheated room moving air makes you colder.
How do you stay warm overnight without electricity?
Sleep in the sealed room, together, in layers, with heat you can hold. Body heat is your biggest free source, so put everyone in one room. Wear a hat and socks to bed; you lose a surprising share of heat through your head and feet. Layer a sleeping bag under the blankets, or use a mylar emergency blanket as the top layer to reflect heat back.
Fill hot-water bottles or sealed jars from a gas water heater or a propane heater's kettle and put them at your feet under the covers; they stay warm for hours. Chemical hand warmers work the same way and last 8–10 hours. Eat something before bed, and keep warm drinks going if you have a way to heat water. Don't run a propane or kerosene heater while you sleep unless it has an oxygen sensor, the CO detector is in the room, and a window is cracked.
What can you do before winter so an outage is less of a problem?
The cheapest heat is the heat you don't lose. Before the first cold snap: replace the weatherstripping on exterior doors, seal window drafts with rope caulk or plastic film (the Department of Energy's winter checklist starts with the same two steps), put a battery CO detector on every floor, and test your gas fireplace. If you're an EPB customer, Home Uplift covers insulation and air-sealing for qualifying homes at no cost, and the EPB Energy Pros can point you to rebates on the rest. And if you want a heat source you can count on, an indoor-rated propane heater and one 20-lb tank cost about $120 together and sit in a closet until you need them.
Frequently asked questions
How do you make a homemade heater without electricity?
The safe "homemade" options are hot-water bottles, a sealed room, and body heat. If you want real heat, an indoor-rated propane heater costs about $80.
What's the cheapest way to heat a cold room?
Seal it and heat only that room. Close the door, cover the windows, block drafts, and keep the people in it. If you need more, a small indoor-rated propane heater on low costs about 20 cents an hour on a 20-lb tank, which is cheaper per hour than most electric space heaters.
Will my heat pump or furnace come back on by itself when the power returns?
Most do, once the thermostat has power. Heat pumps can take 30–60 minutes to bring a cold house up to temperature, and some will run on backup electric strips first, which is normal. If the system doesn't restart within an hour of the outage map showing your area restored, check the breaker and the thermostat batteries before calling for service.
