7. Replacing the windows
Cause: Those big pieces of glass get so darn cold. They must be the reason your house is so drafty.
Effect: You could spend a lot of money to only take care of part of the problem. Windows must be installed properly to avoid drafts, gaps and leaks. Moreover, more heat is typically lost through poorly insulated walls and ceilings than through windows.
8. Replacing the furnace first
Cause: You blame high energy bills on an old, inefficient furnace.
Effect: Your energy bills will still be higher than necessary if you don't start with cheaper, smaller upgrades to improve the energy efficiency of your home, such as caulking around windows and doors and adding insulation.
9. Upgrading to the most efficient furnace on the market
Cause: You want the sleekest, most energy-efficient furnace available because it will be the most cost effective as well.
Effect: You may end up replacing an oversized furnace with another (albeit more efficient) oversized furnace. The U.S. Department of Energy reports that most U.S. homes have oversized HVAC systems. Again, insulate and weatherize to maximize efficiency, then get the smallest system that will comfortably meet your heating needs, which will be substantially reduced. Also make sure it is professionally installed.
10. Using incandescent light bulbs for heating
Cause: Incandescent bulbs give off more heat than light, so they must be warming up the house.
Effect: It is hard to see this logic as anything but a weak excuse for holding on to the Edison bulbs rather than switching to CFL and LED lighting. In fact, one German entrepreneur is marketing incandescent bulbs as "heat balls" to skirt EU laws against the old-style bulbs. However, I doubt he is keeping cozy this winter simply by sleeping with the lights on.