How to Heat Your Home During a Power Outage

The thing most likely to kill you in a heating outage isn’t the cold — it’s carbon monoxide. Every fuel-burning heater, whether it runs on propane, kerosene, or diesel, produces CO as a byproduct. The gas is odorless, and its early symptoms (drowsiness, a dull headache) are indistinguishable from being exhausted and cold in an emergency. People fall asleep instead of recognizing the danger. This is the trap buried in every “indoor-safe” label: that rating assumes active ventilation. It does not mean safe in a sealed room.

Before anything else in this guide — before heater types, generator sizing, or passive tricks — the safety system is this: a cracked window and a battery-powered CO detector. Not accessories. The primary system. Everything else in emergency heating is secondary to keeping that in place.

Carbon Monoxide: The Invisible Failure Mode of Every Combustion Heater

Any heater that burns fuel — propane, kerosene, diesel — consumes oxygen and produces CO. The faster the burn rate (higher BTU output), the faster CO accumulates in an unventilated space. “Indoor-safe” ratings are conditional, not absolute. They mean the unit was tested in conditions that included airflow. Run the same heater in a sealed room and the rating is meaningless.

The practical rules are straightforward, but they are not optional:

• Keep a window cracked while any combustion heater is running. The ventilation needed scales with the heater’s output — a bigger unit needs more airflow — but no source provides a precise formula. Treat “a crack” as the floor, not the spec.
• Never run a fuel-burning heater while sleeping or unattended. The drowsiness that’s a symptom of CO poisoning is what stops you from waking up and acting on it.
• Place a battery-powered CO detector on every floor and test it monthly. Battery-powered is non-negotiable here — the power is out.
• Keep children and pets away from the heater, and run it on a hard, fireproof surface well away from flammable materials.

One more hazard that belongs here, even though it shows up later in the sizing discussion: generators are CO producers too, and must be run outdoors and well away from windows and vents. The instinct in a cold outage is to pull the generator close to the house. That instinct kills people. The same CO rule that governs your kerosene heater governs your generator — and a generator in a garage with the door cracked is not outdoors.

Active Heat Sources: What Actually Works and What the Labels Don’t Say

Propane and Kerosene Heaters

Portable propane and kerosene heaters are the most practical combustion options for a home outage. They don’t require electricity, produce substantial heat output, and are widely available. Both require the ventilation protocol above, full stop.

For kerosene heaters specifically: use only 1-K (K-1) grade kerosene. This is standard guidance across manufacturers and isn’t a preference — lower-grade kerosene (2-K) contains more sulfur and contaminants that increase soot and raise the levels of harmful combustion byproducts. In a sealed or poorly ventilated space, that difference matters. Don’t substitute diesel or gasoline for kerosene in a unit not designed for it.

Generators and Electric Heat

A generator lets you run your existing electric heating system, which sidesteps the indoor-combustion problem — but introduces its own CO hazard outdoors, and introduces a sizing problem that the wattage ratings on the box won’t fully solve.

The retail category bands from Consumer Reports give a rough frame for sizing:

These are retail category descriptions, not measured performance specs from independent testing — treat them as ballpark orientation, not purchase specs. The bigger problem is what the wattage rating doesn’t tell you: a furnace blower motor can momentarily draw two to three times its steady running watts when it first starts up. A generator sized to the furnace’s running load alone may trip or fail to start the heating system entirely. Before you buy or borrow, find your furnace or heat pump’s starting wattage — not just the running wattage — and size the generator to that number. Electric furnaces and heat pumps draw heavily enough that a recreational unit is a non-starter for them.

Diesel Air Heaters

One forum community has reported good results with 12V battery-powered diesel air heaters — compact units that run their fan and pump from a car-style battery and produce substantial heat for their size. This is a single anecdotal claim from a Facebook group, not verified by independent testing or product specifications, so treat it as a direction to research rather than a recommendation to act on.

The more important point is about the “battery-powered” framing: these are combustion appliances. The 12V battery runs the controls and fan; the heat comes from burning diesel. They require an exhaust line ducted to the outside, the same as any other combustion heater. An unducted or leaking exhaust indoors is a CO hazard identical to any other fuel-burning unit. If you pursue this option, the exhaust installation is not the place to improvise.

Pellet Stoves — Read the Footnote First

Pellet stoves are sometimes pitched as an emergency heating solution because they don’t require a traditional masonry chimney — they can vent through a smaller horizontal flue. That’s accurate. What the pitch tends to omit: standard pellet stoves require electricity to run their auger (which feeds pellets) and their blower. In a power outage with no generator or battery backup, a pellet stove is a storage unit, not a heater. If you already own one and have backup power, it’s a legitimate option. If you’re shopping for emergency heating specifically, confirm the unit can operate without grid power before you buy.

Passive Heat: What Layering and Blankets Actually Do

Passive methods — layering, thermal mass, reflective blankets — conserve heat. They don’t generate it. That distinction matters when temperatures drop hard.

Layering works better than one heavy garment because trapped air between loose layers insulates more effectively than compressed fabric. Staying dry is as important as staying warm: wet clothing loses insulating value, and sweating inside a heavy layer defeats the purpose. The principle is loose layers, adjusted before you’re soaked.

Thermal mass like soapstone can absorb heat from a nearby source and then radiate it slowly after the source is turned off or moved. Warming it for around 30 minutes before cutting off the heat source gives you a slow-release radiator. It won’t heat a room, but it can keep a small space or a sleeping area more comfortable.

Reflective emergency blankets address radiant heat loss — the heat your body radiates outward. They work when the problem is radiation loss in still air. They don’t address conductive loss to a cold floor or cold air moving around you, which is why they often underperform expectations in genuinely cold conditions. They’re worth having in a kit; they’re not a substitute for an active heat source.

One group-specific caveat: young children and older adults reach dangerous hypothermia faster than healthy adults in the same conditions. Passive methods that might keep an adult reasonably comfortable for a long outage may be insufficient for them. If vulnerable people are in the household, that raises the priority of having an active heat source — and all the ventilation rules that come with it.

The One Thing to Keep Straight

Every practical option for heating your home in an outage — every one that actually moves the needle against serious cold — involves burning fuel somewhere. The CO risk doesn’t go away when you step up to a bigger unit or add a generator. It travels with the combustion. The ventilation window and the battery CO detector aren’t the details you sort out after you’ve figured out the heater — they’re the condition under which any of this is safe to use at all. Get those two things in place first, and the rest of the decisions get a lot simpler.