How Long Will a House Stay Warm Without Power? 

Most homes rely on electric heating systems to stay warm in the winter because they’re more reliable than gas in most cases and much safer. In the case of small power outages, your house should maintain the heat until the power comes back. However, in the case of unexpectedly prolonged power outages, your home will gradually cool down. 

Your house will likely stay warm for at least eight to 12 hours without power, after which it will begin to cool down. How long your house stays warm will often depend on the house’s design, insulation system, type of heating system, outdoor temperature, and how many people are inside it. 

This article will explore the average duration a house will stay warm without power. It will also look at the factors that affect your house’s heat retention ability and give you tips on conserving heat during a power outage. 

What Affects Your House’s Heat Retention Ability? 

Several factors will affect how long your house retains heat. These include: 

  • Your house’s insulation system 
  • The house’s design 
  • The weather outside
  • How many people are inside the house 

Let’s look at each of these factors in detail: 

Your House’s Insulation System 

Your house’s insulation system is the biggest factor that determines how long your house stays warm without power. Without roof insulation, your house could lose 25% more heat than with roof insulation. Even slight variations in the type of insulation you use may significantly affect how long your house stays warm. 

Insulation helps prevent heat loss and will keep your house naturally warm, even if you’re without power. Always insulate the floor, roof, windows, and doors to prevent hot air from escaping. Also, ensure there are no cracks in the windows or underneath the doors where cold air can come in from. 

If you notice cracks or damages, fill them or cover them as soon as possible. The longer you allow air to seep in through cracks and damaged areas, the more energy you’ll be wasting in trying to cool your house.

If your house cools down too quickly when you switch the heating system off, it’s a sign of poor insulation. Luckily, you don’t have to tear into the walls and add insulation just to further insulate your house. Instead, you can make simple changes to your interior decorating that will make a big difference. 

For example, you can insulate your home with simple items such as thick curtains or area rugs. These materials are natural insulators and will prevent cold air from mixing with the hot air inside. Adding plastic sheeting over windows will help, as well.

Read: How To Keep A House Warm In Winter?

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The House’s Design

Home architecture plays an essential role in the ability of a house to retain more heat. Modern engineers take natural factors into account to keep a house cool in summer and warm in the winter. To design an energy-efficient house, they may look at wind direction, sunlight patterns, and other climate factors. 

If your windows are placed correctly, they will let sunlight in during the winter months and block it out in the summer. Similarly, the ventilation design also affects the humidity levels and heat retention. A good ventilation system will help circulate fresh air in winter without causing the house’s temperature to drop. 

While older houses weren’t designed to make the most of natural heating and cooling systems, modern houses are. So, if your house’s design is energy-efficient, it will retain heat for longer without power. 

If you live in an older house, talk to someone about energy-efficient upgrades. Although they can sometimes be costly, they often save you lots of money in the long run. Furthermore, you can sometimes get tax breaks and rebates for upgrading your home to a more environmentally friendly, energy-efficient house.

Read: How To Heat An Apartment Efficiently?

The Weather Outside 

While you can control how well your house is designed, you can’t control the weather outside. Unfortunately, the colder the weather is, the sooner your house will lose heat without power. However, it’s not entirely dependent on the temperature. 

Humidity levels also play an important role in how cold your house feels during winter. Houses in drier climates won’t retain heat as well as those in wetter climates. Fortunately, you can increase your house’s humidity levels by heating water or with a humidifier. 

Houses in windy climates will lose heat much faster. The cold drafts can cool down the house, even if it’s adequately insulated. However, you can block the effects of cold wind by using door stoppers and window wraps to seal the windows. If all else fails, stuff a towel in the bottom of your exterior doors! 

Read: How To Keep A House Humid In Winter?

How Many People Are Inside the House?

Have you ever noticed that a room becomes much warmer when more people are inside? The same principle applies to your home’s heat retention. Houses with more people inside will stay warmer for longer since each individual gives off body heat. 

When you breathe, you release water into the air. If several people stay in a room for a few hours, the humidity levels will increase significantly, and the room will heat up. So, if you’re in for a few hours without power, try and get everyone in the house to share one or two rooms. 

How To Keep a House Warm Without Power? 

If there’s no power during the middle of winter, there’s no need to panic. An average house will stay warm for at least eight to 12 hours without power, but you can retain the heat for longer with simple tips. 

To keep your house warm without power, insulate it properly, use thick curtains and carpets, and exercise indoors. If you’re in for the long haul, increase the house’s humidity levels by heating water or lighting candles and cuddling together in a single room. 

Let’s look at some of these tips in detail: 

Insulate Your House 

Proper insulation is your primary shield against the cold when there’s no power. Roof insulation is the first thing you should check, but don’t ignore wall and floor insulation. Spray foam is the best insulator, although you can use fiberglass to equal effect. 

If you want to go the extra mile in home insulation, insulate the doors and windows. Tinted glass windows, reflective coated windows, and triple glazed windows are the best for keeping the warmth in. 

Read: How Do You Keep A Poorly Insulated House Warm?

Use Thick Curtains and Carpets 

Thick curtains can be a shield against the cold drafts that come in through the windows. Since the windows will get colder faster than the walls, insulating them with wool curtains is best. Thick woolen carpets are the perfect floor insulation and can retain heat for much longer during the winter. 

While you can get cheaper cotton rugs, these don’t have the same heat retention ability as wool rugs. You don’t need to install floor carpets either; small area rugs in different spots will keep your floors well insulated. 

Exercise Indoors 

If your power is out for several hours, try exercising indoors. Your sweat and faster breath will increase the humidity levels, keeping your house a few degrees warmer. You’ll also stay warm with physical activity, and you’ll have less need for heating appliances. 

Staying active is also a great way to keep your mind off the cold weather, and you won’t even notice if your house becomes a few degrees colder. 

Increase the House’s Humidity Levels 

Increasing indoor humidity is the best method of heat retention. You can do this by boiling water and letting the steam drift through the different rooms of your house. Alternatively, you can use a battery-powered humidifier. Just remember to purchase a battery-powered humidifier. An electric one won’t do you much good when the power goes out.

Read: What Type Of Heating Systems Do Apartments Have?

Light Candles and Cuddle Together 

Sometimes the power outages will be longer than expected due to fallen wires or other problems. If you know that the power isn’t coming back for quite some time, you can preserve the heat inside a single room rather than trying to keep the whole house warm.  

Spend as much time with other family members in a single room. The collective body heat will keep the room warmer than other rooms. Also light several candles. Although the flame (and heat) from a small candle wick doesn’t put out a ton of heat on its own, if you light a half dozen, they can help heat up a room.


While the average house will last almost half a day without power, you can keep your house warmer with proper insulation and heat conservation practices. Energy-efficient houses will retain heat for longer, so it’s best to invest in good insulation and energy-efficient house design. 

Also, stay active to keep your body warm and your mind off the cold weather. While you can survive a day or two inside a house without power, you may have to move if the indoor temperature drops below freezing.