Myth #1: Closing the Vent Saves Energy
Though it seems that closing vents in unused rooms would save energy, the energy consumed by the system is at the unit itself, and restricting conditioned air at a vent termination redirects it to other locations in the house or through leaks in your duct system. Closing vents also puts backpressure on the fan that pushes the air through the system, causing it to work harder, use more energy, and wear out faster.
Myth #2: New Windows = Significant Energy Cost Savings
Replacing single-pane windows for Energy-Star rated dual-pane windows will save energy. That energy savings, however, is a function of the size and number of windows in your home, their orientation and overhangs, and the location of your house and the climate zone you are live in. This typically amounts to a small fraction of your total energy use, and given the expense of replacing windows, there are typically much more cost-effective ways to reduce your energy bills.
Myth #3: Setting Thermostat Higher Heats a Home Faster
A furnace will provide heat at its max power (or a fraction of max power for multi-stage units) when it is first turned on. So, setting the temperature higher will have little effect in how quickly a home heats. Setting the thermostat higher does have the potential to increase the run-time of the heating system, using more energy and potentially making your home uncomfortably hot.
Myth #4: Using an Electric Space Heater Saves Money
Given that electricity is typically between four and 10 times the cost of natural gas, running just two electric space heaters can cost the equivalent of heating an entire home with a gas-powered system.
Myth #5: Leaving a Light on Uses Less Energy Than Turning It Off, Then on Again
Some people actually believe that if leaving the light on when they leave the room for a few minutes to take a restroom break, for example, is better than turning it off and then on again when they return. There is no significant additional power draw when turning on a light bulb (other than the calories you use by flipping the switch). So, turn off the lights each time you leave a room, even if for just a couple of minutes.