FACT According to the Department of Energy, incandescent lights should be turned OFF whenever they’re not needed. Did you know that 90% of the energy used to power a light bulb is converted to heat, while a dismal 10% is used to generate light? Turning standard incandescent lights OFF will always help you save on energy costs, even if it’s for just a few seconds. The same rule applies to other electronics such as TVs and computers. If not in use, turn them OFF.
A related myth is leaving a ceiling fan ON will cool the room. Not true. Fans cool people (feels up to 5 degrees cooler) by moving the envelope of hot air around them, but they don’t cool rooms, so turn them OFF as well when a room is unoccupied.
For the new Compact Fluorescent Lights (CFLs), it’s a little more complicated. With relatively high prices of electricity, a fairly conservative guideline is that it is cost effective to turn them OFF after about 5 minutes of use. With CFLs (especially the least expensive and older ones), turning them ON and OFF rapidly will shorten their lifespan and may limit your overall savings. Some manufacturers offer models with higher switching cycles; these are ones designated as heavy duty or can typically be found as a standard feature in the newer models. One investigation indicates that a CFL will always provide a savings after 50 hours or so of use.
Myth #2: It takes more energy to cool a house if the air conditioner has been OFF all day rather than keeping it running at a higher temperature (85 degrees, for example).
FACT Cooling a hot house down at the end of the day always takes less energy than leaving the air conditioner running all day, even if it’s running on a high setting. Your air conditioner runs more efficiently when it operates for longer periods compared to short cycles of ON and OFF. One long cycle at the end of the day will save more energy than a number of short cycles during the whole time away. Using a programmable thermostat will allow you to turn the unit OFF and still cool the house down before you arrive home from work or your extended time away.
FACT It doesn’t help speed up the process at all, and if you forget to reset the thermostat to the desired temperature, then you’ll just be wasting energy and money. Setting the temperature lower than the desired end temperature won’t get it there any faster (just like pressing an elevator button a lot of times won’t get you there any faster). Your thermostat is more like a light switch (ON or OFF) than a water hose (opening up the spigot to allow more water to come out). A programmable thermostat will let you plan in advance if you’d like to cool things down by the time you get home.
Myth #4: Buying a highly efficient air conditioner will automatically save me a lot of money on my electricity bill.
FACT Although not completely a myth, if things aren’t done right by the right people, then you could spend more up front than you need to and not save as much as you could over the life of the new unit. A big mistake is automatically replacing your current unit with one of the same size or larger without having an energy audit or other professional analysis done first. Bigger is not always better, especially in this case. The rule of thumb is to have one ton of refrigeration per 500 square feet, and both the inside air handler and the outside condenser unit must have the same tonnage.
If your duct system is leaking, then it needs to be fixed first. More than 60% of all homes experience leaks in their duct system; leaks can often times account for roughly 20 – 30% air loss (either heated or cooled air). Improper installation of a unit also can produce large amounts of energy being wasted due to leakage. Once the leaks are fixed and with the proper design by a quality company, it wouldn’t be surprising if they’re able to recommend a smaller unit than what is currently installed. The same design and installation concerns are apparent in the replacement of windows, adding insulation and/or a radiant barrier, and the purchase of other energy efficient items.
FACT Through experience and laboratory testing, it has been clearly shown that duct tape is not the right solution. Unless it is just for a temporary, very short-term fix that you intend to replace, do not use duct tape. Contrary to its name, duct tape is great for hundreds of uses, but definitely not for repairing leaky ducts! In laboratory testing with 31 other sealants, duct tape was the only one that failed and failed consistently. In the typical hot Texas attic, duct tape has very low durability and will dry out and separate from the ductwork the tape is being applied to. The best choice is mastic, a gooey glue-like substance that is painted on and hardens. A second choice would be a tape that is certified as UL 181A compliant for rigid ducts, or 181B for flexible duct work.
Myth #6: The largest source of air leakage in the home is around windows and doors. Therefore, replacing older windows will save a bunch of energy and money.
FACT Although air leakage is one of the largest sources of energy loss in your home, the amount around windows and doors accounts for about 15% of the total loss. The largest amount is usually found in air duct leaks and holes in your ceiling and attic. Installing weather-stripping and caulking around doors and windows is always a good idea to save home energy. This will save you money, but replacing old windows with energy efficient ones is an expensive proposition and is very hard to justify on energy savings alone. If you have other reasons to replace your windows, besides to save on energy, then definitely replace them with Energy Star rated ones. You’ll see some savings in addition to having a new look and feel around your house.
FACT With today’s air-forced central cooling systems, closing too many air registers completely and closing the doors to those rooms increases the air pressure in your ducts. It can also cause or increase leaks or otherwise damage the system (freeze the coils, for example). According to a 2003 study by the Lawrence Berkeley National Laboratory, “The reduction in building thermal loads due to conditioning only a part of the house was offset by increased duct system losses, mostly due to increased duct leakage.”
Another potential problem from air pressure imbalance is the buildup of mold. For example, if the attic entrance isn’t well sealed, the increased air pressure can draw hot, humid air from the attic which can then condense on a cool surface where mold can grow. Partially closing some registers, especially those closest to the unit is fine, but depending on the size and design of the house and ducting system, completely closing more than one or two will not be helpful to save home energy and could be harmful.
FACT Unless there are only a few dishes, then this is one case where the appliance wins out: washing by hand usually uses more hot water than using a dishwasher. According to a recent study at a university in Bonn, Germany, it was found that the dishwasher will use only one-half the energy and one-sixth of the water (and less soap, too)! Just follow some good practices with your dishwasher, and you’ll save those hands as well as some money. Most modern dishwashers do not require pre-rinsing; this saves water and energy, and you also need not bother with the Rinse & Hold cycle. Wait to wash a full load, and don’t use the heat cycle to dry the dishes. If your dishwasher has a pre-heater, then you can also set your water heater temperature lower.