How to Stay Warm Without Power in Winter (Safely)

In short

Heat people, not the house. One small room, doors closed, everyone together.
Most furnaces stop without electricity, even gas ones. Find out what yours needs.
Never use a generator, barbecue, camp stove or gas oven for heat indoors. Carbon monoxide has no smell.
Have a battery-powered CO alarm near where people sleep.
Decide in advance how cold is too cold, and where you will go.

Know what your heating needs

Find this out today. Almost every modern heating system needs electricity, even when it burns something else.

Heating	Works with no power?
Gas, propane or oil furnace	No. The blower, igniter and controls are electric.
Electric baseboards, heat pump	No.
Boiler with radiators	Usually no. The pump and controls are electric.
Pellet stove	No, unless it has a battery backup.
Wood stove or fireplace insert	Yes, if the chimney is clean and it does not rely on a fan.
Some gas fireplaces	Sometimes. Models with a standing pilot or battery ignition can run. Check the manual.

A furnace blower can be run from a generator or a large battery, but only through a proper connection installed by a licensed electrician. Never rewire it yourself.

Shrink the space

Pick one room. Small, few windows, on the sunny side if you can. An inside room is best.
Close every other door. Roll a towel along the bottom of the door.
Cover windows at night with blankets or cardboard. Open the sunny ones during the day.
Put everyone in it. Each adult gives off about as much heat as a 100-watt bulb.
A tent indoors works. A small tent or a blanket fort on a bed traps body heat well.

Dress for it

Several loose layers, a hat, dry socks. Wool and fleece stay warm; cotton does not once damp.
Sleeping bags rated for the cold, with a blanket or mat underneath. Cold comes up from below.
Eat and drink regularly. Your body needs fuel to make heat.
Stay dry. Change out of damp clothes straight away.

The shortcuts that kill

Do not do any of these. Opening a window does not make them safe.

Running a generator inside the house, basement, garage or on a balcony. Keep it outside and at least 20 feet (6 metres) from doors, windows and vents.
Bringing a barbecue, charcoal grill, camp stove or outdoor patio heater indoors.
Using a gas stove or oven to heat the room.
Running a car in an attached garage, even with the door open.
Building a candle or flowerpot heater.

All of these make carbon monoxide (CO), a gas you cannot see or smell. Early signs feel like the flu: headache, dizziness, weakness, nausea, confusion. If anyone has them, or the alarm sounds, get everyone outside into fresh air and call 911.

Every home needs a CO alarm that works without mains power: either battery-only or plug-in with battery backup. Put one near where people sleep and test it. See battery CO alarms on Amazon.

Heaters made for indoor use

Some portable propane heaters are sold as "indoor-safe". That label has a narrow meaning, the rules differ between the US and Canada, and many buildings ban them. Read the indoor-safe propane heater guide before you buy or light one. A wood stove that was professionally installed and is cleaned every year is still the most dependable heat there is with no power.

Watch the people

Babies, older people and anyone who is ill lose heat faster and may not say so. Signs of hypothermia are hard shivering, confusion, slurred speech, fumbling hands and unusual sleepiness. It is a medical emergency. Call 911, get the person somewhere warmer, and replace wet clothing with dry.

Decide when to leave before you need to

Set the rule while you are warm and thinking clearly. For example: "If the room we live in falls below 10 °C (50 °F) and we cannot bring it back up, we go." Know where: a relative, a friend with a wood stove, a public warming centre. The page on −30 with no heat covers how fast a house cools and when to go.

Sources

Official guidance this page was checked against. If your local authority says something different, follow them.