Anytime someone tells you how to save money on your energy bill, you might want to consider what Evan Mills, a staff scientist with Lawrence Berkeley National Laboratory, has to say. Many of the tips on how to save energy around the house should be treated with some healthy skepticism.

"Sometimes the basic premise of the myth is correct," says Mills, "but the energy savings are much smaller than people realize. In other cases, the myth is based on factors that were once true but have subsequently resolved through better design or manufacturing of products."

Here’s what Mills has to say about some common energy myths.

Myth. Buying an efficient air conditioner or furnace will automatically reduce your energy bill.

Fact. This is true to some extent, but you won’t realize all the possible savings if the equipment is not sized or installed properly. Studies show that typical air conditioner and duct systems are improperly installed, wasting one-third or more of energy used by the air conditioner. Air conditioning, insulation, windows and many other energy efficient upgrades need to be properly designed and installed to work at their maximum efficiency.

Myth. Energy efficiency and energy conservation are the same.

Fact. Energy efficiency means getting the same job done while using less energy. Energy conservation means reducing the level of services, such as reducing lighting or comfort or turning up the temperature of your fridge. You can improve energy efficiency by buying better appliances or reduce service levels by turning off unused lights, but lowering your quality of life is not a prerequisite for reducing energy demand.

Myth. Duct tape is good for sealing ducts.

Fact. Research shows duct tape has very low durability when used to seal ducts. It often falls off because it is applied to dirty or dusty surfaces or as it ages and the adhesive dries. Instead of duct tape, seal ducts with mastic.

Myth. An appliance that’s turned off, is off.

Fact. Most devices continue to consumer power when they’re switched off. Sometimes this is as much power as when they’re on. Many electrical products from air conditioners to VCRs cannot be switched completely off without unplugging them. If you want to save power, consider grouping several appliances on one power strip that you turn off when you leave home.

Myth. Cleaning refrigerator coils saves energy.

Fact. While this may seem logical, any actual savings are very small. But this is a good way to cut down on dust and dirt in your kitchen. Just don’t expect to lower your utility bills as a result.

Myth. Installing foam gaskets in electrical outlets will significantly reduce air leakage.

Fact. Less than 1 percent of a home’s air leakage results from electrical outlets. Of course, lots of little holes equal one big hole. If you’re sealing a really big house with lots of light switches, gaskets can’t hurt. But do this last in case you run out of time, energy or both.

Myth. Leaving lights, computers and other appliances on uses less energy than turning them on and off repeatedly and makes them last longer.

Fact. The small surge of power created when some devices are turned on is vastly smaller than the energy used by running the device when it’s not needed. This used to be the case with cycling appliances, but better design has largely eliminated that problem. When you don’t need something, turn it off.

Myth. Fluorescent lighting is unhealthy.

Fact. Fluorescent lighting has changed dramatically in the last few years. Today’s fluorescents have greatly improved color quality, and annoying hum and flicker have been eliminated. Because they require less power, fluorescents generate less pollution. Fluorescent lights do contain small amounts of mercury and must be disposed of properly.

Myth. Halogen lighting is super efficient.

Fact. It is true that halogen lights use slightly less energy than standard incandescent bulbs. But many halogens require transformers that can use extra energy, even when the light is off. They also tend to generate heat, which may add to the cooling load during hot weather. By comparison, compact fluorescent lights are nearly three times as efficient and put off far less heat. Many new models are dimmable, like halogens.