Updated: May 18, 2021
Learn how to evaluate your home for energy performance, and then read about the energy saving tips that will make your home more comfortable.
If you wince every time a gas or electric bill arrives in your mailbox, take heart. You can easily reduce energy use in your home. And we don’t mean by wearing three sweaters, taking cold showers and shuttering the windows. Energy efficiency and a pleasant indoor environment work hand-in-hand. You’ll not only reduce the drain on your bank account but also find your home more comfortable.
In this article, we’ll give you the BIG picture on how to evaluate your home’s energy performance, determine where the biggest savings lie and maintain a healthy indoor environment. Other articles in this section deal with the specifics: simple steps you can take to save energy and money, sealing up attic bypasses and weatherstripping windows and doors.
We’ll tell you right off that big energy savings aren’t as easy to get today as they were years ago. During the energy crunch of the 1970s, many homeowners added insulation and caulked around windows and doors to capture the biggest savings. And since then, new homes have been built to higher energy-efficiency standards. Still, if you follow these simple steps, you’ll find plenty of savings still out there.
Figure A: How Energy is Lost
The biggest culprits are air leaks (infiltration) and poor-performing windows. But every home is unique. An energy auditor will tell you where the biggest savings lie in your home.
Hire an energy auditor
It’s worth hiring a pro to evaluate your home and help you sort out the many possible energy-saving strategies. Call your local utility company to find energy auditors. It may supply this service for free or recommend an auditor.
An energy audit may cost several hundred dollars, but sometimes community programs subsidize the bill. The energy auditor will inspect your home and rate its current performance in terms of insulation levels, air leakage, condition of heating or cooling equipment and other criteria.
The auditor can then tell you which upgrades are cost effective and estimate your energy savings. Cost effectiveness is the key. You can spend thousands of dollars for upgrades that won’t save you much, and a good auditor will steer you away from those. For an improvement to be worthwhile, the estimated savings should cover the cost of the improvement in about seven years. For example, adding $200 of insulation to your attic will be worth it if the estimated savings are about $30 per year ($210 after seven years). But installing a new efficient window for $200 won’t be worth the cost if you save only $10 per year ($70 after seven years). The auditor’s report should clearly specify the estimated savings.
Keep in mind that as energy costs go up, more retrofit ideas become cost effective.
Tip: Tell the auditor which improvements you can do yourself. That eliminates the labor cost and makes many more upgrades cost effective.
Reduce air leakage
Think of the warm air leaking out through gaps, cracks and holes in your home’s walls and ceilings as your energy dollars floating away (Fig. A). Sealing these openings is one of the most cost-effective ways to save energy.
Stopping air leaks in the attic is usually the most important task see How to Seal Attic Air Leaks. You don’t necessarily have to work your way through every room caulking every crack, inside and out. Just get the largest and worst offenders, which are almost always in the attic.
You’ll notice that your house feels more comfortable too, because you’ll have fewer drafts. The less warm air that leaks out, the less cold air that leaks in to replace it.
There are hundreds of energy-saving steps that cost little or nothing. Some ideas involve a small investment of time and money, for example, installing a programmable thermostat or caulking around windows. Others involve a small investment of energy—yours. These simple steps include lowering the temperature setting on your water heater and closing the curtains.
Figure B: Where Energy Goes
About half of the energy consumed in the average home goes to space heating and/or air conditioning. But all areas are targets for energy improvements, especially as energy costs rise.
Buy high-efficiency windows (when it’s time to replace them)
Windows are the weakest link in your home’s outer defenses against heat loss, accounting for about 18 percent of the heat loss in the typical home. But windows are also expensive, so it isn’t cost effective to replace them just to save energy. If they’re worn out, however, it’s cost effective to upgrade to double-pane windows with low-E coatings. Your window specialist will help you choose the type of coating that works best, depending on whether you mostly need to slow heat loss or reduce solar gain.
For information on installing a new window, see How to Install Replacement Windows, How to Install Vinyl Replacement Windows and Proper Window Installation.
Add 6 in. of insulation to an uninsulated attic and you’ll reap substantial energy savings. Add 6 more inches and you’ll get additional energy savings, but to a lesser degree. To find out how much insulation is recommended in your part of the country, consult your local building department. You can also just search “How much insulation” on your computer. The recommended values are based on climate, fuel costs and other factors. Adding more than the suggested amounts will result in a longer payback period for your investment.
For more on insulation, see Insulating Walls.
Shade your home
Shading is the best way you can save energy dollars in the summertime with your own sweat equity. Shading saves energy because it blocks out the direct sunlight that is responsible for about 50 percent of the heat gain in your home. Most of it strikes the roof and works its way through the attic, then down through the ceiling; the rest comes in mainly through windows. If you upgrade your attic insulation to at least 12 in. thick (about R-38) and make sure to buy light-colored roofing next time you reroof, you’ll stop most of that roof heat. And steps like planting trees, attaching awnings and extending roof overhangs will shade the most vulnerable south-facing windows as well as those facing east and west. Most of these are low-cost, do-it-yourself strategies.
Stop duct leakage
Studies have shown that an average duct system loses 10 to 40 percent of the cool or warm air through gaps in the duct joints. This cooling and heating is wasted when the ducts run outside the interior conditioned space, in an attic or a crawlspace. While sealing ducts is a common practice now, few older homes have had this done. Sealing ducts is difficult. You’ll have to rely on professional HVAC services to test the ducts for leakage and to retest to show the effectiveness of their work.
Protect your health and the health of your home
Energy-efficiency improvements can increase the risk of carbon monoxide (CO) poisoning. This can occur in homes with devices that burn gas, oil or wood and in homes with attached garages. At a minimum, install a CO alarm.
Watch your windows for excessive condensation. Most energy-saving measures reduce air leakage, allowing excessive moisture to build up inside. This moisture can cause mold and rot and an unhealthy indoor environment. Condensation on windows is common at the beginning of the heating season but should largely disappear except during cold snaps. Usually the best prevention strategy is to find the moisture sources (some of the worst culprits are improperly vented dryers, bath fans and the rooms they’re in) and eliminate them or improve ventilation.