We seek shelter in the snug coziness of home. But how snug is it? Does your home’s warmth begin to sneak away the moment the furnace cycles off? Where is that warmth going, and how can we entice it to stay awhile? Short of an expensive weatherizing remodel, there are plenty of simple, affordable (or free) tricks to make your indoor refuge tighter and more fuel-efficient.

Many of these tips apply equally to all types of indoor heating. A few have special application for forced-air furnaces. If you heat with wood, also take a look at our article Wood Heating Tips detailing wood-stove efficiency techniques, as wood can be an exceptionally clean-burning sustainable fuel if used wisely.

1. Use blinds or curtains for strategic window insulation

Maximize solar gain by leaving your south-facing windows uncovered during any sunny days – even the winter sun makes a real difference. Consider pruning any foliage that blocks the sun on the south wall. Cover all windows after dark to create a simple but effective insulating layer. The thicker the coverings, the more effective the insulation. Window treatments can also reduce heat gain in summer by up to 45%, slashing air conditioning costs. If you buy dual shades (reflective white on one side, heat-absorbing dark on the other) they can be reversed seasonally to soak up that winter sun and repel summer heat.

Double up your curtains for even better insulating properties (and an attractive layered look), or use lined curtains. For greatest benefit, hang window coverings as close as possible to the glass, sized so that they rest upon the windowsill or floor when closed. For an easy DIY project, use velcro or magnetic tape to attach the edges of your curtains to the wall or window frame at the sides and bottom, and even where the drapes come together. If done with a heavy closed-weave curtain fabric, you can reduce heat loss up to 25%.

Northern-facing windows can be left covered day and night all winter for maximum insulation, provided you’re not sacrificing quality-of-life-enhancing natural light (you shouldn’t need to compensate with electric lights during the day). Yet another option is rigid foam-board window inserts, which are cut to fit your windows and simply pushed in place when light is not needed. These are a great option for seldom-used rooms such as guest or storage spaces, with the added advantage of protecting rugs and upholstery from photo-degrading.

2. Stop heating an empty or sleeping house

Install a programmable thermostat. If you’re still adjusting your heat by hand and trying to remember to turn it down when you go to work every day — who needs another task to remember when you’re rushing out the door? Your new thermostat should last for decades, saving you money every day. If you program your thermostat down 10 degrees during the time you’re sleeping or not home, you will save up to 15%. Yes, the furnace has to briefly work hard to return to the target “comfort zone”, but the down-time while you’re sleeping or absent more than offsets those short bursts.

And when you’re home, consider challenging your usual comfort-zone habits. Within the 60-70F zone, each degree you lower your thermostat setting will save you about 2% on your yearly energy bill: that’s 10% between 65 and 70F! More Americans are choosing to wear an extra sweater around the house as energy-conservation awareness grows, not to mention tighter budgets in many homes. Warm slippers and comfortable fleece are some of the best energy-savers you can wear. The fuel we save today will be there to keep us warm tomorrow.

3. Use a space heater: make a warm heart in a cool house

We may associate space heaters with the singed drapes and cheap rented rooms of our college years, but take another look: they’ve come a long way. The results are in, their targeted use will save you real money. Luckily, many modern space heaters are far more efficient (and more attractive) than their predecessors. You can find one that suits your budget and performance specifications for as little as $40, to add welcome flexibility to your heating routine.

How does it work? Place the portable heater in the room your family uses most during the hours everyone’s home (often a living room in the evening). If you work from home, this zone may be your home office during the day. The smaller the room, the bigger the savings! Ideally, isolate this room as much as possible by closing all doors — this is more challenging in many modern open-plan living spaces. Then turn your thermostat down to a reasonable sleeping temperature in the rest of the house, which is typically 10-15 degrees cooler than your preferred living temperature. To make the system even tighter, use foam pipe insulation to reduce draft through your interior doors.

The space heater will create a haven of coziness in the home, encouraging togetherness and shared relaxation, while saving your furnace lots of work. Take care to follow all the heater’s safety instructions, particularly not placing it close to or in direct contact with furniture or other household items.

4. Reduce ventilator fan use

In our modern kitchens and bathrooms, we have grown to appreciate the efficient action of built-in fans. They provide crucial air circulation to remove fumes from cooking and excess humidity from showering. In winter, though, these fans can act as silent heat thieves. You’d be surprised how much of your warm indoor air these fans will quickly transfer to your backyard: a whole houseful of expensive heat can be whisked away in as little as an hour. Teach all members of your household to use fans only as needed, and turn them off religiously. If this seems difficult to accomplish, you can add an automatic timer to fans controlled by wall switches.

5. Raise your humidity

Here’s a surprising tip. Winter air is often parched, especially indoors. The seasonal increase in chapped lips and dry skin reveals that our home heating is sucking all the moisture out of our bodies — surprisingly, dryness makes the air feel colder, too. Not only do we feel colder in dry air, but adding some moisture will actually allow your indoor air to retain the heat longer.

Do you get a little shock of static electricity every time you pet the cat? By increasing your home’s humidity to a comfortable level, you can make 68F feel as comfortable as 75F. You’ll also be decreasing your susceptibility to winter colds and sinus infections: dry air makes your mucus membranes more vulnerable.

Easy non-technological ways to increase humidity include adding (well-watered) houseplants, using indoor drying racks for laundry (adding to your savings by reducing dryer use), and placing shallow containers of water on heating elements such as radiators and wood stoves. Even leaving a water-filled baking dish in an unobtrusive spot such as on top of the refrigerator will help — you might be surprised how quickly evaporation empties the vessel.

Run kitchen and bath fans only as needed to prevent window condensation: if the moisture buildup is not visible on glass surfaces, it’s being absorbed into the air to enhance your home humidity. If you start seeing visible window condensation (not immediately explicable by a recent shower or dishwashing), you’ve raised the humidity too high and should reduce your efforts. The target zone is between 30-50% humidity: you can test it yourself with a home hygrometer if you’re not sure.

6. Eliminate drafts

A bottle of insulating foam sealant is another great way to make a few dollars go a long way toward saving fuel. Combined with your handy tube of weatherizing silicone caulking (you’ll need one of these too), you have an approachable home improvement project that needs few tools or expertise, only a little patience and enthusiasm for energy conservation. Time to start hunting for cracks and heat leaks! Use your senses, feeling for tell-tale cool spots as well as looking for visible gaps. Here are a few good places to start:

• Attic access door: Even if your attic already has an insulated floor to keep heat in the living spaces where it belongs, the pull-down hatch is often left without protection. A surprising amount of heat gets whisked away through those leaky portals: heat naturally rises to the top of the house, and the drafty hatch can create a chimney effect. The internet has lots of “how-to’s” illustrating this insulating project, which uses foam board insulation or fiberglass batting. Make sure to attend to any gaps causing drafts around the edges of the door while you’re at it: weatherstripping can help.
• Electrical outlets: Place a hand in front of an outlet on a cold day. Is there any perceptible coolness emanating from the holes? Does the plastic itself feel cold? If so, carefully remove the cover with a screwdriver to insulate your outlets. Use caulking to fill gaps around the outside of the box, and insert a foam gasket specially made for insulating outlets, available from home stores.
• Door thresholds: Can you see daylight under any exterior doors? Some thresholds are adjustable with screws: turn them counterclockwise to raise the threshold until you can’t see daylight. Or try a quick fix requiring no tools at all: buy or make a “draft snake”, a flexible tube of fabric filled with something heavy (a stocking or knee sock filled with dry rice is probably the simplest version), placed across the draft at the bottom of a closed door or window. Surprisingly effective! Check the weatherstripping around your doors and replace if it looks worn — 7-12% of home heat loss occurs around doors and windows.
• Plumbing entrances: The places where pipes enter and leave your living space need to be sealed with foam or caulk — builders sometimes neglect this step. Bugs and little critters can sneak in through these gaps too, so eliminating them serves two purposes. Check in your basement ceiling and inside cabinets, as well as exterior walls.
• Window frames: Windows are essential for the light and view they admit, but they are also the weakest points in your home’s energy armor. Remove old cracked caulking and replace it with fresh caulk. Combined with lined drapes or blinds, this will address one of your home’s greatest points of heat loss.
• Chimney: Most of us know to close the damper on our fireplace whenever it’s not in use, to reduce the draft going up the chimney — but a lot of warm air still escapes up there. Some dampers fit poorly and provide little protection from draft; a snug-fitting damper may save 8% of fuel costs. Even more effective is the ingenious “chimney balloon” http://www.chimneyballoon.us/chimneyballoon.html, which inflates to fit snugly, keeping out insects and bats too — it will pay for itself many times over with consistent use. Don’t forget to remove it before lighting the fire!

7. Help heat flow freely

Sometimes it’s as simple as rearranging the furniture. If a large piece of furniture is directly blocking an air register, that corner will become very cozy with trapped heat, while the furnace labors to adequately warm the rest of the home. Also make sure the hot air isn’t blowing straight into a billowy curtain, resulting in major loss through the window glass.

If your air ducts are full of dust and debris, a good cleaning will improve your system’s performance. If your system uses radiators, place aluminum foil between the radiator and any exterior wall to reflect more heat back into the room. This trick can work with any heating unit placed near (but not attached) to an exterior wall.

8. Use heat-shrink film over windows and glass patio doors

At first glance, covering your windows with plastic may sound like a view-obstructing last resort. If you have single-pane windows, however, it’s worth a second look. Once installed, you may barely notice! The heat-shrink window films currently available are a quick, inexpensive alternative to storm windows and double-glazing. A hair-dryer easily smooths out the plastic, creating a near-invisible protective layer.

This is one of the most cost-effective measures you can choose: a kit covering up to five windows can be purchased here for under $7. Be sure to choose a product designed for “convection control” rather than “solar control” — the solar control film is best at preventing heat gain in summer, and will shut out precious solar warmth in winter. For best results, the film should be installed less than one inch from the window glass; if this is impossible, it will still provide benefits comparable to a storm window. Bubble wrap is another cult favorite for DIY window insulation, but though it transmits light, you can’t use it on windows you actually like to see through.

9. Don't neglect furnace maintenance

Check your furnace filters monthly, and clean or replace them when they look dirty. Clogged filters greatly reduce furnace efficiency — you should be able to clearly see light through the filter. After the first few years, a new furnace needs an annual cleaning and tune-up to maintain peak efficiency. Also be sure to seal and insulate your air ducts, particularly any which travel through unheated space such as basement, attic, or crawlspace. You can buy mastic sealant or metal tape at any home improvement store and do it yourself if you’re interested.

What’s your furnace’s AFUE (Annual Fuel Utilization Efficiency)? This will tell you the percentage of fuel directly contributing heat to your home — and the percentage uselessly going up the chimney or elsewhere. All new furnaces are required to have an AFUE of 78% or higher (the best are up to 95% efficient), but old models may have an AFUE of as low as 50% when wear-and-tear is accounted for. All-electric furnaces or boilers have the highest AFUE, but heating electrically can be expensive, and it’s important to remember that the source of your electricity (particularly coal burning) can have both a low efficiency and a devastating environmental impact.

You may not be ready to replace your old furnace today, but an inexpensive parts-upgrade can make a big difference: if yours uses a standing pilot light (burning fuel uselessly for hours while your furnace is resting), switch it out for a spark igniter. In an oil furnace, installing a flame retention burner can improve efficiency by 10-15% by itself!

By making our homes more heat-efficient, we’re taking a major step toward being responsible environmental consumers. Heating and cooling accounts for up to 50% of home energy use, and that energy comes with various costs: our personal finances, the impact of its extraction, and the carbon released when it is refined and burned.

In a cold climate, it’s hard to come up with the perfect home-heating solution. But when you spend just a little time taking care of your heat-loss hot-spots, everyone wins. Your fuel costs decline; your home releases less CO2; less burden is placed upon the already-maxed-out fossil-fuel industry; your furnace rests more and lasts longer. Take it one step at a time, and thank yourself later.