Energy and energy savings myths get passed around surprisingly rapidly, often with little scrutiny. But you should always think critically when you hear a "tip" on how to save energy–and dig a little deeper to separate the myths from the facts.
MYTH: Buying an efficient air conditioner will automatically reduce your energy bill.
TRUTH: 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 one-third 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.
MYTH: The bigger your furnace or A/C, the better.
TRUTH: Oversized HVAC systems don’t run as efficiently, control humidity as well, or last as long as ones that are sized properly for the house. In most cases, smaller is better.