How Long Will Your Home Stay Warm Without Power?


Our family had a winter power outage this year, and we were unprepared to go without heat; I wondered how long our house would stay warm without power as our central heat is electric. I want to share what I learned about dealing with no heat in a power outage to help with your preparation.

How Long Will Your Home Stay Warm Without Power?

If your power goes out in cold weather, you may lose your heat source. Your house will start to cool immediately but will remain warm for 8 to 12 hours. If well-protected, your home will stay above 0° F for one day to many weeks.

Factors that will affect how long your home will stay warm without power:

  1. Outside air temperature The colder it is outside the faster your home will cool.
  2. Inside air temperature The warmer it is inside compared to outside, the faster your home will cool down. Overnight you could lose 15° F. This cooling effect will slow from that initial temperature drop.
  3. Wind speed If your home is poorly insulated, the wind will affect heat loss at a higher rate.
  4. Home Insulation Insulation keeps the warm air in and the cold air out.
  5. South-facing Glass Passive solar heating can warm a space.
  6. Basement or crawl space, the ground is warmer under and around your house. A basement or crawl space slows the cooling of your home.
  7. Body Heat

Canadian Mortgage and Housing Corporation: Cooling Rates of Houses During Extended Power Failure. Click here to read the PDF.

The power is out, and you know your home is going to get cold! You probably want some suggestions for what to do now or how to prepare for future outages. Check the 9 to-do lists for a power outage.

9 To-Do Lists for a Power Outage And Loss Of Heat In Your Home

  1. Dress like your going out to shovel the driveway
  2. Pick A Room For Your Warm Space
  3. Gather Your Emergency Light Sources
  4. Plan What You Are Going To Eat And How You Will Cook
  5. Plan for Drinking Water
  6. Follow Safety Tips
  7. Prepare Before Your Power Goes Out
  8. Learn The Basics of First Aid
  9. Know Tips for Emergency Communication

1. Things To Do: Dress like your going out to shovel the driveway

If you are facing blizzard-like conditions or just cold weather without home-heat, staying as warm as possible is essential. Once you get cold, it will be hard to raise your body temperature.

  • Dress like your going outside into the cold. It is much easier to stay warm than it is to get warm.
  • Dress in layers. If possible, wear a wicking layer as an undergarment. A wicking layer will move moisture away from your body and keep you from getting cold. Suitable materials for a wicking layer: wool, polyester, polyethylene, and microfiber
  • Cotton Kills. Once cotton is wet from sweat, it no longer provides insulation to the body.
  • Cover your head with a stocking cap or beanie, 10% of your body heat can exit through your noggin.
  • Wear heavy socks to keep your feet warm.
  • Cover your hands; mittens are better than gloves, hands stay warmer when your fingers are together.
  • Cover your neck and face with a scarf or a balaclava.
  • Don’t take a shower; you may not get warm again.
  • Don’t do anything strenuous enough to sweat. A wet body cools core body temperature. 
  • Use chemical, hand, and foot warmers (e.g., Hot Hands), if you have them.

2. Things To Do: Pick A Room For Your Warm Space

One of the first steps to take when the heat goes out, and the house starts to lose heat is to pick a warm room where everyone will hang out. You do this to retain as much heat as possible. Think of it as winter camping.

  • Choose a room to keep warm. Close that space off by shutting the door or hanging blankets or a tarp in the opening. Close all the other entries in the house. Compartmentalization makes it easier to retain heat in your chosen warm-room.
  • Eliminate as much draft as possible by covering windows with cardboard, old newspaper, bubble wrap, blankets, couch cushions, or anything you have available.
  • Use towels, old blankets, or rugs to cover cracks at the bottom of the door, window sills, and to insulate the floor.
  • Set up a tent or a blanket fort to retain body heat. Pretend you’re indoor camping.
  • Huddle together for warmth.
  • Don’t open doors unless necessary since open doors allow cold air into your space.

3. Things To Do: Gather Your Emergency Light Sources

If you are in an emergency, you will need light sources that do not rely on electric power. It’s a good idea to plan and have all of these in one place.

  • LED flashlights with batteries.
  • Rechargeable flashlights once the charge is gone, you won’t be able to recharge them.
  • LED Headlamps Good for hands-free tasks, they automatically point to where you are looking—my personal favorite.
  • LED Battery Operated Lanterns. These are great during a power outage for your warm room or gathering space. They will allow you to play board games, read, or add ambiance where you are hanging out.
  • Batteries: Gather your extra batteries.
  • Solar lighting, you are exiting the house to charge them, and letting in cold air.
  • Chem-lights are a great light source to hang in every room you are using: kitchen, bathroom, and your warm-space. It’s like having a nightlight in every room. Chem-lights last up to 12 hours.
  • Candles You are limited by where you can safely use candles. If you use candles, place them in a jar and leave them in place. Open-flame light sources are a fire hazard.
  • Oil and grease lamps are super dangerous; if not used properly, they can explode. Drop them or knock them over, and the oil spreads the flame.

4. Things To Do: Plan What You Are Going To Eat And How You Will Cook

You don’t have power, and your house is losing heat, but you still need to eat. Use this list to plan or to gather what you need. Proactive planning is always the best, but it’s not always possible.

  • High-energy, no-cook foods are your best option: granola bars, nuts, nut butter, trail mix, cheese, beef jerky, dried meat sticks, freeze-dried backpack meals, or Meals Ready to Eat (MREs). 
  • Warm drinks are good for morale; they warm you from the inside out, and they cheer you up. Good choices are broth cubes, hot cocoa, coffee, or tea. 
  • Do not use propane camp stoves or outdoor grills inside the house, or any enclosed space. *They give off deadly carbon monoxide. 
  • Cooking food indoors can be done safely in a wood fireplace, with canned heat (like Sterno) or with a backpacker style alcohol stove. Open flames consume oxygen, so be cautious.
  • Cooking outdoors with a camp stove or a campfire is not the best option, but it may be the only option you have. Every time you go outside to cook, you are reducing your body temperature and letting cold air into your space.

5. Things To Do: Plan for Drinking Water

Drinking water is more important than food. The “Rule of 3s” states that you can survive for 3 weeks without food but only 3 days without water.

  • Water Storage a minimum of one gallon of drinkable water per person per day for a 72-hour Emergency. This amount of water is the minimum suggested by the Center for Disease Control (CDC).
  • Fill your bathtub and sinks with water. Use the water to flush the toilets. Do not drink this water unless you treat it or know it’s safe.
  • Treat drinking water with bleach. Use ⅛ teaspoon (or 8 drops) of unscented bleach to treat one gallon of water; stir after adding the bleach; wait 30 minutes. If there is no bleach smell, treat again until you have a slight bleach smell as per CDC guidelines.
  • Treat drinking water by boiling it. Below 5000 ft., boil water 1 minute to treat, above 5000 ft., boil water for 3 minutes, per the Environmental Protection Agency (EPA) Guidelines.
  • Filter your water by purchasing some form of water filtration. Even backpack filters are excellent in a pinch.

6. Things To Do: Follow Safety Tips

Remember to keep safe during blizzard conditions!

  • Do not use propane camp stoves or outdoor grills inside the house, or any enclosed space. *They give off deadly carbon monoxide. 
  • Oil and grease lamps are super dangerous; if not used properly, they can explode. Drop them or knock them over, and the oil spreads the flame. I advise against using these unless necessary, and you know what you are doing.
  • Unplug large appliances and electronics or turn off breakers, so they don’t get burned out if there is a power surge when the power goes back on.
  • Let faucets slow-drip to avoid freezing pipes. Moving water doesn’t freeze as quickly.
  • Stay away from power lines hanging or lying on the ground. They may be hot or electrified, don’t guess. If you see them, notify the power company.
  • If a power line is down, don’t touch anything the power line is touching. Electricity travels from the hot power line through the object and into your body.
  • Stay off of the streets to avoid downed power lines, falling or fallen trees, and accidents. Depending on your situation, this may be a judgment call you will have to make. Don’t take it lightly. If you get hurt, there may not be access to emergency assistance.
  • Check-in with your neighbors to see if they need anything.
  • Keep your car exhaust free and clear do avoid deadly carbon monoxide poisoning, if you will be driving or using your car’s power. Do not run it in an enclosed space, like a garage.

7. Things To Do: Prepare Before Your Power Goes Out

There is no substitution for preparation. Learn how to do things around the house that will mitigate damage and keep you safe.

  • Know how to raise and lower your electric garage door manually
  • Know where your water valves are and how to shut them off in case of a frozen pipe burst.
  • Plan for medications. Know ahead of time, how you will store medicines that require refrigeration, contact your pharmacist for direction
  • During the winter, keep your vehicle’s gas tanks no lower than 2/3rd full in case you need to start your car to get warm or charge smartphones. Make sure the exhaust is free and clear of obstruction and that you run the vehicle in an open, outdoor space.
  • Winterize your home before winter arrives
  • Plan for an alternative heat source and fuel (woodburning stove, outdoor generator, etc.)
  • Make a 72 Hour Emergency Preparedness Kit suggested by the Federal Emergency Management Agency

8. Things To Do: Learn The Basics of First Aid

It’s good to know the basics of first aid and the specific risks to the human body in a cold environment. You don’t know how long your house will be without heat so be prepared.

  • Take an online first aid course with the American Red Cross
  • Know the signs of frostbite and seek medical attention: cold skin and a prickling feeling numbness, red, white, bluish-white or grayish-yellow skin, hard or waxy-looking skin, clumsiness due to joint and muscle stiffness, blistering in severe cases. Mayo Clinic  
  • Know the Signs of hypothermia and seek medical attention: shivering, slurred speech or mumbling, slow, shallow breathing, weak pulse, clumsiness or lack of coordination, drowsiness, or low energy, confusion or memory loss, loss of consciousness. Seek immediate medical attention. Mayo Clinic
  • Maintain hygiene. You can use liquid hand sanitizer, baby wipes, or sanitary wipes. *Don’t take a shower if you cool down you may not be able to warm back up.

9. Things To Do: Know Tips for Emergency Communication

Communication in a winter power outage:

  • Conserve battery life on your smartphone for when you need it: close all running applications, turn the screen brightness down, and put the phone in airplane mode.
  • Charging your mobile phone in a winter power outage may not be possible. If you don’t have an emergency battery pack, you can use your laptop and a USB cord to charge it, or you can use a car charger and a vehicle.
  • Battery Operated Emergency Radio This is my top choice for power outage communication. A good emergency radio runs on batteries, can be hand-cranked or charged with solar. Emergency radios keep you up to date on weather alerts, local news, and they entertain.  

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