Houses covered in snow

Preventing Heat Loss in the Aftermath of Total Grid Failure

There is unsettling loneliness that creeps into a person’s heart in the depths of winter. Maybe because the streets are cemetery quiet; not a car passes, no dogs bark in the distance, and there is no wind to rustle through the ice-laden trees.

All are dead, silent, dark and dreary: The grid went down in August—victim of the perfect combination of an aging, faulty infrastructure and a serious security hole in the system. The lights blinked out on a Tuesday afternoon, and by Friday, there was no water pressure, no gas and no phone service … just silence.

In the wake of lawlessness, civil unrest and near urban warfare, most people have left the cities for the suburbs and points beyond. But you stayed, certain the power would return. It didn’t. And now, winter’s chilled grip is tightening its fist.


You’re a tropical organism stranded in a temperate environment. You don’t have the fat, the stamina or the evolution to naturally cope. Your body has not developed sufficiently to deal with heat loss, even briefly. The longer you and your lineage have inhabited warmer climates—hundreds of years for most of us—the harder it will be for you to adjust when the thermostat drops, even if it is just a single winter lasting only four or five months.

With a complete loss of services, especially during the temperature extremes of summer and winter, the first few days are crucial to your survival.

Have you planned ahead? (Blankets, firewood, propane.) Do you have your living strategies laid out? (Sleeping bags, generators, heating elements.) Are you prepared to shut up most of your house and live only in a room or two? Do you have an exit plan in case all your contingencies fail or your supplies run out?

Here are some concrete ways to keep your house, family and yourself warm when the power grid has been rendered useless.


With the grid down, the conventional way of preventing heat loss—boiler, furnace, et al—is out. No electricity to power the pumps means no gas for the heater.

One British Thermal Unit (BTU) is the amount of heat necessary to raise 1 pound of water 1 degree Fahrenheit. The capacity of a heater, for example, is given in BTUs per hour. To properly heat a house (under normal circumstances), you’ll need approximately 20 BTUs per square foot of space. For example, a 2,000 square-foot house will require 40,000 BTUs per hour. The farther from the equator you live or the colder the exterior temperature is (not to mention insulation, number of people, quality of the building, etc.), the larger this number will be.

“A small fire will heat an average-sized room quite nicely, so use your wood sparingly.”


There is no need, however, to heat your entire house, and it would be a foolish waste of resources to do so. In an emergency situation or a long-term grid failure, create an “Alamo” in one of the rooms of your house. Ideally, that room will have the least amount of windows, be as close to the center of your house as possible, be the farthest away from where the wind is coming from and contain no doors that lead to the outside. If your house has a fireplace, your Alamo should be that room. If you have a basement, it is easier to heat than a surface-level room, and it isn’t susceptible to heat loss via wind.

logs burning in a fireplace.
A fireplace doesn’t provide the same amount of heat as a stove, nor does it use fuel as efficiently as a stove. Nevertheless, that efficiency can be improved with the addition of convection tubes.

In whichever Alamo room you chose, the object is to conserve as much heat in the room as possible to prevent heat loss. Hang blankets over the doors and any windows. Further, insulate the windows by duct taping the seams. Add layers of newspapers, towels, down pillows or clothes over the glass and seal it with tape, a tarp or plastic wrap. If this room is on the ground floor, layer blankets, tarps and towels on the floor of the room above it.

Heat loss can happen when it seeps out through the floor, especially in a slab house, so put blankets, rugs or towels down to create a layer of insulation. Drag your mattress from your bedroom, and use it to sleep on. Better yet—set up a tent in the room and sleep in that. Your body heat (and that of your family) will keep a tent warmer than it will the whole room. In addition, a tent can provide an element of “fun” to distract children from the direness of the situation.


A refrigerator works best when the door is closed; similarly, a room will stay warm longer if cold air isn’t allowed to enter or warm air to escape. In a small room, opening and closing an exterior door and subjecting the space to a blast of cold air will result in having to use a great deal of energy and time to recoup any heat loss.

Hanging a blanket over the door and choosing a room that doesn’t open to the outside will reduce the amount of heat loss. The blanket will act as a windbreak while you slip behind it to open the door. This is why it is a good idea to enter and exit through a door that doesn’t directly connect to your warm room. Like an air lock, it will act as a buffer from the cold outside. To prevent drafts from slipping in under that door, roll up a towel and jam it between the door and the floor. In a severe cold snap, also duct tape the seams of the door, itself.

Feet being warmed by car heater
A great source of emergency heat is your car’s heater. However, if your car is parked in an enclosed space, such as a garage, properly ventilate the engine exhaust before turning on the car’s motor. A typical car at idle uses about a ⅓ gallon of gas an hour.

The problem with modern houses is that the internal walls don’t contain any insulation, so heat loss between rooms can be expected. If you are building or remodeling your home, keep this fact in mind and add some insulation to the walls and ceiling of your likely Alamo room. Barring that, keep on hand enough aluminized Mylar emergency blankets to cover all the walls and ceiling. While it is not insulation, Mylar reflects heat and will prevent heat loss by keeping it in the room.

Even though you are hunkered down in one or two rooms, it is a good idea to close all the doors and blinds, curtains and shades all over your house, whether you are using them or not. Bedrooms usually have exterior walls, so by closing them off, these rooms will add to the layers of insulation between your Alamo and the frigid outdoors.

Because your HVAC system isn’t being used, cover all vents that lead into your warm room. Duct tape, towels or a blanket placed over the vents will keep cold air from other rooms entering and warm air from your Alamo from exiting.


With the traditional method of home heating out of the question, consider a host of alternative methods available that will provide you with enough heat to survive a winter’s night.

Foremost, if you have a fireplace or a wood-burning or pellet stove, use it. Make sure you open the flu and keep the chimney clear of any snow buildup or debris. Ben Franklin proved 250 years ago that his Franklin Stove is much more efficient at heating a room than a fireplace because much of the heat of a fireplace merely goes up the chimney. If you have a fireplace, consider installing convection tubes to direct some of that heat back into the room.

If you have a limited wood supply, keep the fire low. A small fire will heat an average-sized room quite nicely, so use your wood sparingly. If it comes down to it, there are many, many things in your house that can be burned: books, papers, old clothes, cardboard boxes and furniture (but only burn unvarnished wood, because most furniture paints and glues can be toxic when burned).

Thick towel against a wall covering gap between door and floor.
To keep cold air from drafting in under your door, roll up a towel or rug and wedge it between the door and the floor.

There are several companies that offer portable heaters designed for indoor use. Many models use bottled propane; some can be fitted to 5-gallon propane tanks.

Dyna-Glo’s 25,000 BTU convection heater can keep a 600-square-foot space toasty, and its 360-degree design means it can radiate heat from the center of the room. Another option is a gas catalytic heater; it emulates the efficiency of the sun by generating infrared heat from the ground up that warms whatever is in its path. Camco produces the Olympian Wave-3, a 3,000 BTU catalytic heater that runs on propane and is safe for indoor use.

If you lack a fireplace or another source of indoor-rated heat, light a candle or two. Make sure not to burn anything larger than a candle inside without proper ventilation. Carbon monoxide can build up quickly, proving quite deadly. Run a bathtub of hot water—if you are able to—because it will heat the bathroom temporarily. Then, you can drink the water or drain it before it freezes.

Wall covered by blanket
Cover all your walls and ceilings with blankets, towels or heat-reflecting Mylar emergency blankets.

If you are cooking outside on a barbecue or open-pit fire, consider heating some stones in a pan and bringing them inside. (This was a popular way of warming a room in the 18th century.) In addition, bring inside all cooking pans and let them cool down naturally; that will radiate heat into the room.

If your vehicle still works, pile yourself and family into it and run the heater for a while, but make sure the exhaust gases are properly vented to the outside (duct tape a dryer vent hose to the tailpipe) before starting the engine.

During the day, if the sun is out, use it to your advantage by laying out dark-colored blankets to absorb the heat. Bring them inside in the late afternoon, and they might retain heat into the evening.


Wool is an amazing insulator, so combining a wool blanket and a cotton sheet (wool can be itchy) with even a summer-season sleeping bag makes for a very warm bed. Consider fur or fleece if you have them because these worked well keeping their original owners warm.

When going to sleep, put on warm socks and wear gloves. A wool watchman’s cap or ski cap pulled down over your ears will prevent heat loss through your exposed head. In addition, sleeping in a close group will allow you to share body heat, especially if you are using a tent indoors.

Freezing to death

Despite scores of years of research, neither scientists nor statisticians can accurately predict how quickly hypothermia can strike and who is more susceptible.

Your core temperature must be maintained in order to survive, but many people have had theirs dip to precarious levels—and they still pulled through. The lowest recorded core temperature in a surviving adult is 60.8 degrees (F).

For a child, it’s lower. For instance, In 1994, a 2-year-old girl in Saskatchewan, Canada, spent five hours outside in -40 (F) temperatures. She was found the following morning, limbs frozen solid, and her core temperature chilled to 57.6 degrees. Yet, she lived.

As your core temperature drops just a degree or two below 98.6, the muscles on your shoulders and back between to tighten. The capillaries in your arms and legs begin to constrict, forcing blood back into your torso and head. Your hands and feet turn numb. If you lack a layer of fat, heat escapes your body faster. With a 3-degree loss
of your core temperature, you’ve slipped onto the cusp of hypothermia. Your shivers can be described as trembling. Your muscles don’t work properly, and your mind is beginning to cloud. Movement becomes exhausting.

In -30-degree weather, a well-dressed person’s core temperature will drop 1 degree every 45 minutes. For every 1-degree drop of your core’s temperature below 95, your ability to reason, think and understand drops by 5 percent. Your body heat is now escaping into the air like wisps of smoke from a dying campfire.

By 91 degrees, you have developed penetrating hypothermia. Three more degrees, and your body begins to give up. It stops shivering. Apathy about your situation overwhelms you, and the desire to save yourself vanishes. The only feeling you have is the urge to go to the bathroom, because your kidneys have been working overtime since your capillaries constricted all fluids (blood, waste, oxygen, etc.) into your torso.

At 87 degrees, you won’t recognize friends and family. When your body’s core temperature falls to 86 and below, your heart becomes arrhythmic, pumping less than two-thirds the blood it would normally. This causes a lack of oxygen to your cells and your brain. You hallucinate and hear sounds that don’t exist. Your brain triggers memories, incongruent thoughts and placid assurances. It’s telling you that dying is okay and to let go.

Right before death, a person freezing to death will tear off their clothes. Called “paradoxical undressing,” one of the last sensations is the immense flow of warm blood back into the extremities near the skin’s surface, giving the impression of extreme heat against the skin. You slowly lose consciousness and slip into a coma from which you will never awaken.


An often-misquoted myth says 90 percent of your body heat is lost through your head. Go outside in the winter wearing just a hat, and you’ll notice that your endothermic body, much like a Franklin stove, radiates heat from every surface.

It is important to keep those surfaces covered and also regulate your body temperature. When in cold environments, the worst thing you can do is work up a sweat. Wet skin will get cold much faster than dry skin because of evaporation. Wet clothing will lose its insulation properties.

You should also change damp clothing such as socks, gloves, hats and any layers that are next to your skin with dry clothing.

Regulate your body temperature by layering your clothing. This creates pockets of trapped air between the clothing and your body, as well as between the layers of clothing. Plus, three or four layers of clothing will provide more heat and trap more warm air than one big coat. Your layers should be lightweight and loose-fitting; tight-fitting clothing reduces circulation and does not insulate well.

The most effective approach is to have a light base layer that insulates and transports sweat away from the skin. Follow this layer with an insulating layer to prevent heat loss and then an outer layer to protect from wind and rain.

By constructing a simple tealight heater, you are harnessing the power of four small candles into a very effective convection heater that can reach temperatures of more than 150 degrees (F).

When selecting a cold-weather clothing system, the four layers you should pay close attention to are: underwear, mid-layer(s), insulation and shell.

Underwear: The first layer should be high-quality long underwear. It should fit close to your skin and be made from a non-absorbent material so it wicks away any moisture to keep your skin dry. Synthetic fabrics such as polypropylene work well, while natural fibers such as wool and silk are also effective. Avoid cotton, because
it absorbs water.

Mid-layer(s): The next layers are important because they serve to absorb the moisture out of your long underwear and transport it to the environment through evaporation. Again, synthetics are best, but there’s nothing wrong with a thick wool shirt and pants.

These layers should be loose to trap a layer of heat against your underwear.

Insulation: Down, Polarguard, Holofill, Thinsulate and Primaloft are types of insulation that are found in quality outer jackets. However, down loses its loft when wet and takes a long time to dry, so synthetic insulation is a better choice if you think you might get wet.

Shell: A waterproof and/or windproof outer shell will prevent heat loss while simultaneously keeping out the water and wind. It can also increase your body temperature by dozens of degrees. Waterproof fabrics don’t allow moisture to escape, so consider a wind shell only if you plan to be in a dry climate (remember, arctic air is just as dry as a desert’s).

Extras: Just as important as long underwear are hats, gloves, scarves, boots and socks. Aside from preventing heat loss, these items should help wick moisture away from you, as well.

Even in the depths of winter, with a cold wind blowing just outside your house, consider yourself lucky: You have a roof over your head and walls to stave off storms. If food and water are plentiful, surviving a winter off the grid will be a manageable challenge. Remember: the home furnace wasn’t invented until 1885, and steam-heated radiators were in use for just a few short years. Prior to that, people used the resources they had to prevent heat loss in even the coldest of winters. If they could stay warm, so can you.

William Jeffries


Editor’s note: A version of this article first appeared in the February 2017 print issue of American Survival Guide. 

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