Skill guide · Energy & Heat

Staying Warm Without Power

This is currently three separate fragments across the site: one-room heating gets a single bullet in the Energy & Heat chapter, hypothermia recognition lives in Sanitation & Medical, and carbon monoxide safety lives in Fire-Starting & Generator Safety. This guide is the one place that actually walks through staying warm, start to finish, cross-linking the other two rather than repeating them.

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Layer correctly, since it does most of the work for free

Three layers, each doing a different job:

Base layer: moisture-wicking material against the skin. Not cotton; wet cotton actively pulls heat away from the body instead of insulating it.
Insulating layer: wool or synthetic fleece, which traps warm air close to the body.
Shell layer: blocks wind and moisture from getting to the layers underneath.

A hat matters more than it sounds like it should: any uncovered skin loses heat, and once you're otherwise dressed in layers, your head is usually the largest patch of skin still exposed, not because heads are uniquely lossy the way the old "you lose 40-45% of body heat through your head" claim suggests, but simply because it's what's left uncovered. Stay dry; damp clothing or bedding pulls heat away far faster than dry material, even at the same temperature.

Pick one room, and seal it

Choose the smallest interior room with as few exterior walls as possible. A room with one exterior wall loses heat far more slowly than a corner room with two or three; an interior bathroom or closet-adjacent bedroom often beats a room that looks more comfortable but bleeds heat through multiple walls.
Close the door and hang a blanket over it as a second seal.
Cover windows with plastic sheeting or heavy blankets; this is one of the biggest heat-loss points in most homes. A shrink-film window insulation kit, sold at any hardware store, works better than a loose sheet: tape the film to the window frame with the kit's own adhesive tape, leaving about an inch of overlap on all sides, then run a hairdryer on low heat over it to shrink out wrinkles and pull the seal drum-tight. Done well, this alone can cut a room's heat loss by 10-30%.
Stuff towels or rolled blankets against the bottom of the door and any obvious drafts.
Move the whole household into this one room rather than trying to heat the house. Concentrating people and heat sources in one small space is far more effective than spreading the same heat across a larger area.

Warning

A sealed room still needs fresh air if you're running a combustion heater in it

Every sealing step above assumes the room is unoccupied by an open flame or fuel-burning heater; the moment a propane or catalytic heater is running in it, that changes. An oxygen-depletion sensor shuts the heater's gas off once oxygen falls to roughly 18% (normal air is about 21%), which is a safety backstop, not a substitute for ventilation, it doesn't prevent carbon monoxide from building up in an airtight room before that point. Keep a window cracked open at least an inch and the door to the rest of the house open whenever a combustion heater is running, per CPSC's own winter heating guidance; never run one in a fully sealed space, even with an oxygen-depletion sensor and a CO detector both present.

Aim to keep the sealed room at 68°F or above where you can manage it. Below roughly 65°F, sustained indoor cold raises real hypothermia risk for older adults and anyone with reduced mobility; below about 61°F, resistance to respiratory illness drops too. The World Health Organization sets 64°F as a general minimum indoor temperature and recommends 68-70°F for a room with an elderly or sedentary occupant specifically.

Tip

Protect the rest of the house's pipes while you're sealed in one room

Leave a cold-water faucet in the coldest part of the house, often a kitchen or bathroom on an exterior wall, running at a slow trickle. Moving water is harder to freeze than still water, since a trickle keeps drawing in slightly warmer supply water instead of letting the pipe sit static. It also relieves the pressure that actually bursts a frozen pipe: freezing itself doesn't split the metal or plastic, the pressure trapped between the ice blockage and a closed faucet on the other side does. It costs a little water for real insurance against a repair that costs far more.

Insulate from the floor, not just the air

This is the detail most people miss. A hard floor, tile, wood, laminate, conducts heat directly out of a body in contact with it, regardless of how warm the air in the room is. Put down a layer of clothing, blankets, or a mattress between anyone and the bare floor before worrying about anything else; sitting or sleeping directly on a hard floor undoes a meaningful share of everything else in this guide.

Safe heat sources, and what's never safe indoors

Source	Safe indoors?
A propane or catalytic heater with an oxygen-depletion sensor and tip-over shutoff, used with a working CO detector	Yes, this is the standard safe choice for indoor emergency heat
Body heat, sleeping close together, or a small tent pitched inside the sealed room	Yes, and free; a tent creates an even smaller air volume to warm than the room itself
A fireplace or wood stove that's properly installed and vented	Yes, if the chimney/flue is already in good condition; see the seasonal chimney-sweep guidance in the Energy & Heat chapter
A gas range or oven	Never. Not designed for space heating; produces dangerous carbon monoxide levels
A generator, propane camp stove, or charcoal grill used indoors, in a garage, or near a window or vent	Never. Same carbon monoxide risk as running it in a closed room

Full detail on CO risk, detector placement, and generator safety is already covered in Fire-Starting & Generator Safety; this guide isn't repeating it, just flagging where it applies here specifically.

Warning

The viral flower-pot candle heater doesn't work, and it's a real fire hazard

A widely shared trick claims stacking terracotta pots over lit tea candles "amplifies" their heat into real room warmth. It doesn't, and the physics explains why: a tea candle puts out roughly 30-40 watts regardless of what's sitting over it, a clay pot only redirects that heat's distribution, it can't create more of it, and heating even a small room takes somewhere around 1,000-1,500 watts, the output of 30 or more candles burning at once, not one or two. Fire departments have specifically warned against this setup for the more serious problem it actually creates: multiple unattended open flames indoors, often left burning overnight for a "heater" that isn't doing meaningful work, a real house-fire risk for essentially no heat benefit.

Sleeping warm

A sleeping bag rated for the actual temperature holds heat far better than loose blankets, since it's a sealed shape rather than something that shifts and gaps overnight. Read the tag carefully: most bags print a "Limit" rating, the temperature at which an average sleeper can survive the night curled up without waking from cold, not a "Comfort" rating, which is the temperature an average cold-sensitive sleeper actually sleeps comfortably at. Buy 10-15°F below the coldest temperature you actually expect, and know the printed rating assumes a base layer of clothing and a sleeping pad underneath, not a bare or thinly padded floor.
Keep a hat on overnight; heat loss doesn't stop when you're asleep.
Everyone in the sealed room, together, concentrates body heat that would otherwise be lost to separate cold rooms.

Warning

Infants need extra care, not bed-sharing for warmth

Infants under one year old lose body heat much faster than adults and should never sleep alone in a cold room, but the right response is room-sharing, not bed-sharing: keep the infant's own crib or bassinet in the same room as an adult, not in the adult's bed, since bed-sharing raises the risk of suffocation and SIDS regardless of the cold. Dress the infant in one more layer than an adult would wear in the same room, and use a wearable sleep sack rather than loose blankets, which are a suffocation hazard in a crib. Check on them more frequently than an older child or adult in the same room.

Recognize the warning signs

Know the early signs of hypothermia, shivering that eventually stops, confusion, slurred speech, before they progress; full recognition and response steps are in First Aid Basics. Confusion or loss of coordination in a cold environment is a medical emergency, not something to wait out.

Sources

CDC, winter storm safety and power outage guidance (never use a gas range/oven for heat, carbon monoxide risk): CDC; CDC
CDC, infant susceptibility to cold and carbon monoxide: University of Washington DEOHS (CDC-sourced)
One-room heating strategy, floor insulation, and catalytic heater safety features: PowerOutage.us; Popular Science
CPSC, winter heating ventilation requirements and oxygen-depletion sensor mechanism: CPSC
AAP, infant room-sharing (not bed-sharing) and safe sleep clothing guidance: HealthyChildren.org / AAP
Window insulation kit technique and heat-loss reduction: ENERGY STAR
Minimum safe indoor temperature for older adults and general WHO guidance: National Institute on Aging
Sleeping bag Comfort vs. Limit temperature rating (ISO 23537): Backpacking Light
Head heat-loss myth correction: Cleveland Clinic
Dripping-faucet technique for preventing frozen pipes, and pressure buildup (not the ice itself) as the actual cause of a burst pipe: American Red Cross; Consumer Reports
Flower-pot candle heater myth debunked (real wattage output, fire risk warnings): FOX 5 Atlanta; The Prepared