Cut energy use by improving insulation and sealing air leaks

The latest issue of Checkbook magazine shares 32 changes you can make around your home to help save energy. Because heating is by far the biggest energy eater for Twin Cities-area homes, typically accounting for nearly 70% of utility expenses, it makes sense to focus first on cutting that consumption.

For many homes, a big money-saver is to install or add insulation in spots that need it, and to seal cracks and gaps to reduce air leakage.

One little leak might not seem like a big deal but having several can add up to the equivalent of leaving open a small window. It usually costs very little money to identify and fix ways your home passively wastes energy, but it yields significant savings.

A good energy auditor can track down leaks and use equipment to identify leaks you might not find yourself. But you can sleuth out major leaks 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 blows to identify drafts.

Most leaks occur where different building materials meet — brick and wood siding, foundation and walls, and 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 cracks or gaps measuring less than ¼-inch wide and use polyurethane foam sealant for larger ones. To minimize leakage around doors and windows, install weatherstripping. Also add sweeps to the bottoms of all exterior doors to seal gaps there.

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

Next, check whether you need to add insulation. All structural elements enclosing your home's living spaces should be insulated, but it's most practical to add insulation when a home is built or during renovations. Otherwise, accessibility drives costs and often determines what's worth doing.

Because warm air rises, your attic is the front line in the battle to conserve energy during winter. And because most attics are unfinished and contain a lot of empty space, adding a thick layer of insulation is an easy job.

In this region, the U.S. Department of Energy recommends attics be insulated at R-49 or better. Check what type of insulation you already have (loose fibers, granules, batts, etc.) and measure its thickness. To achieve an R-49 rating, loose fiberglass particles should be laid at a thickness of about 20 inches, rock wool particles at 17 inches, cellulose (looks like shredded newsprint) at 13 inches, and batts (blankets that come in rolls) at 15 inches.

How much you will pay for insulation improvements depends on how much you need to add — and whom you hire to do it. For one typical job — adding insulation to increase the rating of an unfinished attic from R-11 to R-49 — area contractors quoted prices to Checkbook's undercover shoppers ranging from $1,400 to $6,781. Until April 7, Checkbook is offering free access to its ratings of local insulation contractors to Star Tribune readers via Checkbook.org/StarTribune/insulation.

Since the work isn't cheap, even if you hire an inexpensive outfit to do it, is it worth it?

Check with your utility companies for programs that can defray upfront costs: Right now, Xcel Energy and CenterPoint Energy offered rebates for insulation improvements. Most attic projects qualified for rebates of $300 to $750.

Unheated areas underneath ground floors, such as crawl spaces and basements, are also cost-effective targets for improving insulation.

If your home was built in the 1970s or later, its exterior walls probably have adequate insulation. If your home is older, it might be worthwhile to install insulation or improve what has deteriorated.