Many people make a final pass through their homes before heading to work turning off lights and, perhaps, unplugging appliances in an effort to conserve energy and save money.

But few actually know how effective this ritual is in saving energy, reports a new study on people s perceptions of energy savings from researchers at Columbia, Ohio State and Carnegie Mellon universities.

But wait, didn t everyone say turning off the lights would save the planet and our checking accounts? For years, people have been bombarded with ads on television, in print, in train cars and even on the sides of buses that practically promise turning off the lights and unplugging your cell phone charger will help global warming and lower your power bill. And those campaigns, funded in part by utility companies, have largely been successful, with 25% of people in the study reporting they engage in one of those much-touted habits as their primary energy-saving measure.

But, it turns out all that light-switch flipping and unplugging gadgets does little to conserve energy or save money for individual households.

What savings that come are small. Lighting accounts for about 11% of a household s energy bill, according to the Department of Energy. And while calculating the exact savings gleaned by flipping a few switches is complicated light bulbs have different wattages and people use lights for different amounts of time turning off one 40-watt conventional bulb for eight hours saves about three cents if you re paying the typical rate of 10 cents per kilowatt hour of energy use. That s less than a dollar in savings over 30 days.

Compare that with the savings to be had from insulating a home and sealing its cracks, which improves energy efficiency by up to 20% year round, according to the Alliance to Save Energy. Your savings on heating and cooling bills would be as much as $16 per month more if you own a larger home.

But marketers rarely tout those stats and instead have largely used the gateway drug theory that if you can get people to do the little things it will encourage bigger steps, says Suzanne Shelton, president and chief executive of the Shelton Group, a Knoxville, Tenn.-based advertising agency specializing in energy efficiency and sustainability. Shelton Group s clients include Energy Star, a joint program of the Environmental Protection Agency and the Department of Energy aimed at helping households save money and the environment with energy efficient products and practices.

Shelton says that the lights-off campaign hasn t necessarily led to bigger conservation efforts or savings. I don t think we re seeing that, she says. I don t want to say we ve duped consumers, but maybe we ve given them a false sense of accomplishment.

Con Edison, which serves roughly nine people million in New York City and Westchester County, says it has spent under $10 million this year on advertising, most of it geared toward energy conservation campaigns. The company says it uses ads that both encourage turning off the lights and buying Energy Star appliances. Why bother with some tips that don t save that much energy? What we really want to do is educate our customers about energy efficiency," says a Con Ed spokeswoman. "It s about whatever piques a customer s interest."

So why the hype around shutting the lights off? It provides people with the emotional benefit that their action has helped them save money and energy without inconveniencing them and without making them uncomfortable or requiring them to spend money.

It s true that many of the big energy and money savers will cost more upfront. For example, re-insulating a 2,000-square foot house will cost anywhere from $400 to $800. But most households could recoup those savings within two years.

Here are four other ways to save big on energy costs.

This may come as a surprise, but the air conditioners that go into windows or walls are more energy efficient than the central air conditioner that pumps cool air through the vents in a house.

The study s researchers reported another group's findings that central air uses about 3.5 times more energy than an individual A/C unit, in part because it has to cool more air, says Shahzeen Attari, a post doctoral fellow at Columbia University s Earth Institute and the Center for Research on Environmental Decisions and lead author of the study. And replacing an old air conditioner made before 1998 with a new Energy Star-qualified model at a cost of between $200 and $500 for each unit will lower cooling bills by $30 per year per unit, according to the Department of Energy.

Install compact fluorescent light bulbs

Replacing incandescent light bulbs with compact fluorescent Energy Star-qualified light bulbs decreases energy usage by 75%, according to the Department of Energy. A 60-watt incandescent light bulb, for example, which costs 96 cents at Lowe s, left on for three hours a day will add $7.64 per year to your home s energy bill, according to the Alliance. But a 13-watt CFL bulb that produces the equivalent light, which costs $6.14, will tack on just $1.66. The costs appear to be about the same, but CFLs last up to 10 times longer than incandescent light bulbs, says Ronnie Kweller, a spokeswoman for the Alliance to Save Energy.

Soon there won t be much of a choice on which bulbs to buy. In January 2012, inefficient light bulbs will start to be phased out of the market, beginning with 100-watt light bulbs and then replaced with even more efficient bulbs, including CFLs.

Look for Energy Star-qualified appliances

Energy Star labels are found on a variety of appliances, including refrigerators, dishwashers and computers. A product with this label will use energy more efficiently than older or less-efficient models.

For example, a new Energy Star-qualified refrigerator uses at least 40% less energy than conventional models sold in 2001, according to the DOE.

And there s little difference in cost. At Lowe s, a Hotpoint 25 cubic-foot refrigerator with a side freezer and ice dispenser costs $999 the same price as a similar Frigidaire model with the Energy Star label. But your monthly energy bill will be about $15 lower with the Frigidaire.

Tap into the energy tax credit

There are incentives available for consumers who make energy-efficiency improvements to their homes. Tax credits for up to 30% can be had for things like adding insulation or new windows. The products must meet government qualifications, found at Energy Star s web site, and consumers must keep receipts and plenty of proof of the efficiency improvements to file with their tax returns. But in return consumers can get a one-time credit of up to $1,500. It s available through the end of this year (and is higher than the $500 offered in previous years).

The credit is extended through the end of 2016 for homes that make larger energy-efficient installations like geothermal heat pumps and solar energy systems.