1  Buying an efficient air conditioner or furnace will automatically reduce my energy bill.

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 have shown that typical air conditioner and duct systems are improperly installed, wasting 1/3 or more of the energy used by the air conditioner. New and replacement equipment (and ducts) need to be properly designed and installed to realize all the possible savings. The same caveats about proper installation hold true for insulation, windows and many other energy-efficiency upgrades.

2 Duct tape is good for sealing ducts.

Unfortunately, laboratory research has concluded that duct tape has very low durability when used to seal ducts. On new installations, tape may fall off due to poor surface preparation, because ducts are installed in dirty and dusty locations and conditions. On older systems, the tape falls off as it ages and the adhesive dries out and tends to wrinkle.

3 When my appliance is turned off, it is off.

In fact, we’ve found that most devices continue to consume power when they’re switched off, sometimes as much power as when they’re on!

4 Cleaning refrigerator coils saves energy.

While this seems intuitively logical, and very small savings may indeed arise, the few efforts to actually measure this effect have typically come up empty-handed. This is a classic example of a widely held belief based on assumptions rather than measurements.

5 Dimming my incandescent lights by 50% will cut my lighting bill in half.

Actually, the relationship is not linear and savings will be less than expected. As the voltage drops, the filament cools, the wavelength spectrum of the light output shifts further in to the infra-red, and efficacy thus suffers. Interestingly, fluorescent dimming is more linear and the savings for dimming are proportionately higher.

6 Turning up (down) the thermostat will make your home get warm (cool) faster.

It’s tempting to think of a thermostat like a water tap, i.e. the wider you open it the more water (heat/cool) will come out. In reality, it works more like a light switch in that if it’s “on” the same amount of light (heat/cool) will come out.

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

Measurements have shown that less than 1% of a home’s air leakage is due to outlets.

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

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. While it used to be the case that cycling appliances and lighting on and off drastically reduced their useful lifetimes, these problems have been largely overcome through better design.

9 Fluorescent lighting is unhealthy.

Fluorescent lighting has changed dramatically in the last few years. Today’s fluorescents have greatly improved color quality. And the annoying flicker and hum have been eliminated from fluorescents that use electronic ballasts. Because they require less electricity, fluorescents generate less power plant pollution, emissions which have many known health effects. Fluorescent lights also contain small amounts of mercury and should be disposed of properly. However, additional mercury releases are avoided thanks to reduced use of mercury-containing fossil fuels used to generate electricity. If it’s been a while since you tried fluorescent lights, you might give them another chance.

10 Electric heating is more efficient than fuel-based heating.

It’s true that all, or almost all, of the electricity that goes into an electric heater is transformed to useful heat in your home. However, making electricity is an inefficient process, with as much as two-thirds of the input energy (coal, natural gas, etc.) being lost in the process. This is why electricity is so much more expensive for the consumer than direct fuels.