Making simple repairs or improvements and changing wasteful habits will yield enormous energy savings for most families. Before spending thousands of dollars on new windows, a furnace, or solar energy system, take basic steps toward fixing common sources of waste. Because heating costs are by far the biggest source of home-energy expense, most of our advice focuses on cutting that consumption.

Check for Leaks

Assess how your home passively wastes energy by looking for areas in outside walls, windows, and doors that allow conditioned indoor air to escape.

Most homes have holes, cracks, and gaps that let cold air in and warm air out in the winter—and do the reverse in the summer. One little leak might not seem like much, but the cumulative effect of several can add up to the equivalent of leaving open a small window. Finding and plugging leaks costs very little money yet yields significant savings.

If you feel drafts in the winter, that’s an obvious sign of leaks. If you consistently feel chilled between furnace cycles, that’s another sign.

A good energy auditor can track down leaks for you. But you can sleuth out major ones on your own. Turn off your furnace on a cool, very windy day; shut all windows and doors, turn on all exhaust fans that blow air outside, such as bathroom fans or stove vents; light an incense stick and move around your house, watching where smoke is blown to identify drafts.

Most leaks occur where different building materials meet—brick and wood siding, foundation and walls, and between the chimney and siding. Other common problem areas are around windows and doors; mail slots; points of entry for electrical and gas lines, cable/internet wiring, and phone lines; outdoor water faucets; where vents pass through walls; cracks or gaps in siding, stucco, masonry, and all foundation materials; and around window air-conditioning units.

Use caulk to seal any cracks or gaps measuring less than 1/4 inch wide and polyurethane foam sealant for larger ones.

To minimize leakage around doors and windows, install weatherstripping. Open-cell foams are inexpensive and relatively inefficient but easy to apply and suitable for low-traffic areas. Vinyl is more expensive and lasts longer. Metals last for years and provide a decorative element for older homes. Also add sweeps to the bottoms of all exterior doors to seal gaps there.

Prevent drafts around outlets and light switches located inside exterior walls by adding insulating receptacle gaskets, which cost less than $5 each.

If you have window A/C units, remove them during the winter, or insulate them from the outside with an A/C cover ($20-$60). During summer, install units so they fit tightly within windows.

Cost: $25-$1,500+, depending on scope of work and what you DIY.

Energy savings: Combined, these measures can save five to 20 percent of your heating and cooling costs.
 

Deal with Ductwork

According to the U.S. Department of Energy, leaky ducts can add 20 percent or more to a home heating bill. Check for holes or gaps in exposed ductwork in any unfinished attic, crawlspace, and basement, and seal them with mastic tape or HVAC foil tape. Also seal gaps where ductwork connects to registers.

Don’t worry about having your ducts regularly cleaned; despite claims from cleaning companies, very few homes need their services, and it likely won’t impact energy usage.

Cost: $20 to $40 (it’s an easy DIY job).

Energy savings: Five to 20 percent of your heating and cooling costs.
 

Insulate Poorly Located Pipes and Ducts

If you have a crawlspace or unheated basement, check whether any furnace ductwork or pipes that supply hot water run through it. Wrap pipes in foam insulating sleeves; ask HVAC contractors for advice on the best way to insulate ductwork.

Cost: Less than $20 for materials to insulate pipes; $100 to $400 to hire someone to insulate ductwork.

Energy savings: This work isn’t needed in most homes, but if your ducts run through an uninsulated area you’ll likely save five to 15 percent of heating and cooling costs.

 

Fix Fireplace Flues

Chimneys are designed to pull smoke upward and out of homes. As long as the temperature outside is different than inside your house, this draft continues, pulling out air that you paid to heat or cool, and wasting one to three percent of your bills.

When you’re not using a fireplace, make sure to tightly close its flue damper. Still, even closed flues are notoriously leaky; seal yours completely with a chimney plug—basically a balloon that inflates to fill up the space between the firebox and the damper.

Cost: Plugs cost less than $50.

Energy savings: One or two percent of your heating and cooling costs.
 

Dial Down the Thermostat

This is an obvious strategy, and many of us refuse to leave our cozy-comfort zones, but you’ll realize big-time savings if you can handle a change in climate. If you—or your cohabitants—refuse to chill out, at least use a programmable thermostat.

Cost: Free.

Energy savings: In most areas, setting the thermostat at 68 degrees instead of 70 during the winter and 75 instead of 73 during summer can save save 10 to 20 percent on heating and cooling costs.
 

Lose Inefficient Lighting

Somehow, lightbulbs have become part of our culture wars. But using efficient LED or CFL lights instead of incandescents will save an average U.S. household about 35 percent off lighting costs each year.

For most uses, you’ll want bulb-shaped, A-type LEDs. But they sometimes don’t cast light evenly in all directions, so look for omnidirectional bulbs for lamps or shaded light fixtures. Can or recessed lights are best fitted with cone-shaped reflector models that only cast downlights.

Cost: Nearly free, now that energy-efficient bulbs sell for about the same prices as less-efficient incandescent models that remain on the market.

Energy savings: Typically $50 to $80 per year.
 

Pull Some Plugs

Most plugged-in devices consume electricity even when not in use. For a typical family, it costs $200 to $300 per year to power their TVs, computers, chargers, and other assorted tech and small appliances. So yank the cord to that VCR and other electronics you rarely, if ever, use anymore. Check the settings for other tech to see if they have low-power standby options. An even better option is to buy smart power strips, which automatically cut off juice to stuff plugged into them if they haven’t been used in a while or allow you to do so remotely via WiFi connection to your phone or computer.

Cost: Free; decent smart power strips cost less than $25 each.

Energy savings: Typically $20 to $75 per year.
 

Replace HVAC Filters

A dirty filter makes your system work harder than it should, reducing performance and energy efficiency—plus it could spread dust. This chore won’t save much energy—probably less than two percent of heating and cooling costs—but is an important maintenance task regardless of green considerations.

Check your filter monthly until you see how quickly it gets dirty at different times of the year. When a filter has a matting of dirt, it’s time to replace it (usually four to six times a year). Click here for more advice on maintaining your system, plus ratings of HVAC contractors for quality and price.

Cost: $5 to $40 per filter, or $25 to $200 per year if you change it five times.

Energy savings: Less than one percent of heating and cooling costs, but it's an important maintenance task you should do regardless of cost considerations.
 

Get Rid of Extra Fridges and Freezers

Many of us have extra refrigerators or freezers sitting in garages or basements to handle overflow items. While it’s great to buy in bulk without having to play Tetris to fit everything into a single appliance, extra storage comes at a steep price—especially if your fridge or freezer annex is an old model: Ten-year-old fridges cost about $75 a year to run; 25-year-old models about $100 a year; and your parents’ indestructible 40-year-old one can drain away more than $200 a year.

Cost: Free; some communities and utilities offer recycling incentives and/or free pickup.

Energy savings: Typically $50 to $200 per year.
 

Make Your Water Heater Chill Out

Lowering your water heater’s thermostat from 140 degrees to 120 will cut its energy use by three to five percent. Although 120 degrees is sufficiently hot enough to prevent bacterial growth, if someone in your household has a suppressed immune system or respiratory disease, keep it set at 140 to play it safe.

Cost: Free.

Energy savings: Typically $5 to $30 per year.
 

Wrap It Up, Too

Wrap your water heater in a fiberglass insulating blanket to save about 10 percent of its energy usage. Skip doing this if your model was made in the last 10 years or so, as it likely was built with foam insulation; wrapping it won’t provide much additional benefit. Not sure if you need additional insulation? If the outside of your heater feels warm to the touch, a blanket will benefit you.

Cost: $25-$40.

Energy savings: Typically $10 to $25 per year.
 

Give Windows the Treatment

When it’s warm outside, close curtains and blinds to reduce heat from the sun. When it’s cold, open curtains on sun-facing windows for free warmth—but keep curtains closed to block drafts from windows that don’t get rays. Thermal shades provide the most benefit. Make sure curtains don’t block HVAC vents. Click here for our advice on buying window treatments.

Cost: Free if you already have window treatments; $100 to $400 per window for professionally installed blinds (be sure to shop around for the best price).

Energy savings: Typically $10 to $80 per year.
 

Turn Out the Lights!

Channel your father and constantly roam your home yelling “Who left this light on?!” Annoying your family is a small price to pay to help the environment.

You can install motion-detecting switches that automatically turn off lights when no one is in the room—or if you sit still for too long. Occupancy sensors are less frustrating: They turn on lights when someone enters and then off again when they leave.

Cost: Free, or $15 to $25 for each occupancy sensor.

Energy savings: Typically $10 to $40 per year.
 

Wash Clothes in Cold Water

According to Energy Star as much as 90 percent of the energy used to wash clothes comes from heating water. In Consumer Reports’ tests, cold water sufficiently cleans most loads.

Cost: Free.

Energy savings: Typically $20 to $30 per year.

Reduce Drying Times

Use trial-and-error to figure out how long your model takes to dry loads so you don’t run it longer than necessary. Don’t do small loads, but don’t overstuff it, either. If your dryer has a cool-down setting, enabling it will use remaining heat in the drum at the end of the cycle to finish drying clothes while expending very little energy. Before drying, use the highest spin setting on your washer to remove as much moisture as possible. By cutting drying times, you can likely save 20 percent of your appliance’s energy usage.

Option B: Go old school and buy drying racks or an outdoor clothesline for free evaporation and, during wintertime, your wet wardrobe will improve humidity.

Cost: Free.

Energy savings: Typically $20 to $40 per year.
 

Do Dishes Wisely

Consumer Reports’ tests indicate most newer dishwashers clean well if you skip a pre-rinse or scrub. Dishwashers also use less water than handwashing, which means your water heater uses less gas or juice. Just scrape off leftovers and load ’er up.

After your dishwasher finishes a load, open its door. The remaining heat inside will speed evaporation, rather than consuming electricity to generate heat to do that job.

Cost: Free.

Energy savings: Typically $20 to $40 per year.
 

Don’t Be a Drip

Although you don’t pay for it via monthly electric and gas bills, it takes a lot of energy to treat water and pump it to your home. The EPA estimates that running your faucet for five minutes uses about as much energy as keeping a 60-watt lightbulb burning for 14 hours. And if you paid to heat wasted water, you’re buying more gas or electricity than necessary.

Our article on conserving water provides simple ways to conserve H2O, many of which are no-cost and no-hassle, from eliminating obvious and hidden leaks to installing low-flow faucets and aerators to harvesting rain to water your landscaping.

Cost: Free.

Energy savings: Typically $20 to $30 per year.