Simple calculation measures house’s efficiency

Dear Jim: I probably need to make energy-saving improvements to my home, but how can I be sure? Also, what are the most common areas to check for inefficiencies in the typical home, and can I do it myself?

– Jerry V.

Dear Jerry: If your home is built using typical construction methods and more than 20 years old, you can be pretty certain it is not as energy-efficient as it should be. Investing in some energy improvements would be wise and probably provide a reasonable economic payback.

You can do a simple rule-of-thumb calculation to estimate how energy-efficient your home is. If it is inefficient for heating, it is generally just as inefficient when cooling during the summer.

This calculation determines how many Btu of energy your house uses per square foot of floor area adjusted for your climate. Total all the energy you have used for an entire year. Use your gas and electric utility bills, oil or propane deliveries, firewood, etc. Use the following factors to convert to Btu equivalents: 1 kilowatt-hour of electricity: 3,414 Btu, 1 cubic foot of natural gas: 1,025 Btu, 1 gallon of propane: 91,000 Btu, 1 gallon of oil: 138,700 Btu, and 1 cord of wood: 19 million Btu.

Divide the total Btu used by the square footage of your house. Next, divide this by the sum of the heat and cooling degree days for your area. Your local weather service can give you these figures. If the final result is 10 or less, your house is reasonably efficient. If it is between 10 and 20, there is room for improvement. If it is greater than 20, your house needs major improvements.

Each house is unique, but in general ceilings account for 15 percent of losses (gain during summer), windows/doors: 26 percent, walls: 13 percent, basement/slab: 11 percent, and air infiltration (leakage): 35 percent.

Tightening up a home – meaning reducing air infiltration – is a good place to start. Check the weather stripping on the doors by closing each door on a dollar bill. You should feel some resistance when you try to pull it out. Try this in several locations on each door because resistance will vary.

Check the air tightness of your window weather stripping. Wait for a windy day and hold a lighted stick of incense near the weather stripping. Watching the smoke trail will indicate any leaks. Do the same around any ceiling penetrations around ceiling paddle or exhaust fans, recessed lights, etc. If you have a basement, check where the walls rest on the foundation.

Make sure your attic insulation thickness is up to current recommended levels for your area. Since heating and cooling equipment account the majority of your utility bills, have them serviced regularly to be sure they are operating at their maximum efficiency. If they are old, have your contractor do a payback analysis for installing new, higher-efficiency models. This will save energy and generally improve your comfort level.

Dear Jim: I have slider windows, so I could not use a window air conditioner. I thought about installing a swamp cooler like I saw in Arizona. Are those made to fit in slider windows or can I install one some other way?

– Barb D.

Dear Barb: All the major window air conditioner manufacturers do offer tall window air conditioner models designed to fit into slider windows. They are equally efficient to the more common style, which fit single- and double-hung windows. You could install a swamp cooler, but keep in mind, they are effective only in very dry climates. They cool the air by evaporating water. If the air is already humid, as in many regions, there will be very little cooling effect.

Send inquiries to James Dulley, Bangor Daily News, 6906 Royalgreen Drive, Cincinnati, OH 45244 or visit www.dulley.com.