What’s the most common mistake people make in trying to save energy around the house?

Common mistakes people make include:
– letting the furnace or air conditioner salesperson sell them a unit that’s much bigger than they need,
– not getting the ducts checked for leakage when installing a new heating and cooling system,
– thinking that “since heat rises, we only need to insulate the attic.” Floors over a basement or crawlspace, walls and windows also matter.
– not using ceiling and portable fans to improve comfort in the cooling season. They use very little electricity. Use them to circulate air in the house, to make the house feel cooler by doing this, the thermostat setting for your air conditioner can be raised to 85?F, and still maintain the same comfort as the lower setting.

What’s the single biggest user of electricity in my house?

If your house has central air conditioning, the air conditioner will probably be the biggest user by far. Although used only a few months of the year, the annual cost can be much greater than the annual cost of your refrigerator, which is typically the next largest user. In hot climates, the annual air conditioner cost can exceed a thousand dollars. You can get a very rough idea of what your air conditioner is costing you by subtracting the electric portion of your bill in a spring month when you aren’t using your air conditioner from the electric portion of the bill in the summer when you do use it. This gives you the monthly cost. Multiply this by the number of months you use your air conditioner to arrive at your approximate annual cost.

We have an older house. Which should we do first?

Insulate or replace the furnace? Whether you should insulate or replace your furnace first depends on the situation in your house. Factors that influence this decision are the age and efficiency of your furnace, and the amount of insulation currently present in the house. In general it is more cost-effective to upgrade insulation than it is to upgrade your furnace. However, if your furnace is old, and you are planning on replacing it anyway, you might want to upgrade the furnace if you have to choose between the two options. The average lifetime for a furnace is between 15 and 20 years. The efficiency of furnaces has increased over the years, so the older a furnace is, the more likely that furnace is to be inefficient. The average efficiency of new furnaces has increased from 63% in 1972 to 83% in 1995. Older furnaces, and furnaces which are used a lot are more cost-effective to replace than newer or infrequently used furnaces. Also, if you insulate your house at the time of furnace replacement, you might be able to buy a smaller capacity furnace and save money on the price. The same holds true for A/C and other heating and cooling equipment.

Air-sealing ducts

Measurements of heat pump performance indicate that duct leakage wastes 10 to 30 percent of the heating and/or cooling energy in a typical home. It’s one of the most severe energy problems commonly found in homes because the leaking air is 20? to 70?F warmer than indoor air in winter and 15? to 30?F cooler in the summer. Duct leakage may cause some minor comfort problems when ducts are located in conditioned areas. But when leaky ducts are located in an attic or crawl space, the energy loss is often large. Some of the worst duct leakage occurs at joints between the air handler, and the main supply and return air ducts. Some main return ducts use plywood or fiberglass duct-board boxes. These boxes frequently leak because their joints are exposed to the duct system’s highest air pressures. Heating and air-conditioning contractors often use wall, floor, and ceiling cavities as return ducts. These building-cavity return ducts are often accidentally connected to an attic, crawl space, or even the outdoors, creating serious air leakage. Fiberglass ducts and flex ducts are often installed improperly. These ducts may also deteriorate with age, leading to significant supply-duct leakage. The best heating and cooling contractors have equipment to test for duct leakage. Testing helps locate duct leaks and indicates how much duct sealing is necessary. Do not use duct tape for sealing – its life span is very short, often less than 6 months.