Is your refrigerator eating you out of house and home?

Chances are, if it's more than 10 years old, it's gulping enough energy to put a serious hurt on your wallet.

Now that the federal stimulus bill is funneling $300 million into rebates for energy-efficient appliances, perhaps it's time to consider upgrading.

Even though the money isn't available now and the rules haven't been set up, common sense says that whenever the program begins, you'll want to be ready. With 112 million households in the country, that $300 million won't go far.

Over all, the trusty fridge is one heck of a guzzler, using anywhere from 5 percent to 8 percent of household energy, more than any other appliance.

But technological advances have been swift and steady.

Gerry Gerhard, co-owner of Gerhard's Appliances in Glenside, has watched it all happen. The insulation, compressors, and gaskets have all improved. Even a switch to LED lighting - it uses less energy and is cooler - helps.

In general, a new efficient refrigerator uses about half the energy of its 10-year-old cousin, federal statistics show.

"People use the word hog," lamented Jill Notini of the Association of Home Appliance Manufacturers. "I feel terrible for this appliance that has made such strides."

Still, a fridge is a big-ticket item to replace. So most don't. According to the Energy Information Administration, in 2005 there were 135 million refrigerators in the United States, and 104 million were considered inefficient.

The nonprofit advocacy group Alliance to Save Energy estimates that if the older gluttons were replaced, Americans would save $866 million a year in utility costs.

How to know when to buy? Uncle Sam's efficiency program, Energy Star, has a refrigerator calculator on its Web site: www.energystar.gov.

All refrigerators manufactured in the United States must meet minimum efficiency standards, but Energy Star-certified models are at least 20 percent more efficient.

Plug in your electric rate and the model number of your fridge, and it will tell you how much energy it uses. Then it compares that to what a basic Energy Star model would use.

What it doesn't factor in is the impact of making and transporting a new refrigerator. But environmentalists agree that if the energy savings are significant, it's worth making the switch. Plus, 95 percent of the materials in the old ones are recyclable.

At least one rule is hard and fast: If you buy a new one, get rid of the old one.

When a friend of mine moved into a new home about 20 years ago, her old fridge went into the garage. Handy for beer and parties.

But she was aghast when we plugged in the numbers. Her main refrigerator, just a few years old, was costing $82 a year to run. The garage unit was sucking electrons at a rate of $227 a year.

I think she banished it from the premises last weekend.

So reviled are those second refrigerators that PacifiCorp, a Western power company, launched a project - "See ya later, refrigerator" - that pays its customers $30 to $35 per fridge. The idea was to reduce strain on the grid. Since 2003, they've picked up 100,000 in Utah alone.