by Hedda Haning

We live in WV where we tend to require heat only from the end of October through early March, with the largest gas bills limited to January and February. We have a small, very well insulated home with triple glazed windows, have the heat ducts turned down in areas we use least, and set the turn-off point for the furnace at 67 degrees. Sweaters are great. That being said for winter, the rest of the discussion will be limited to cooling efficiently.

First we have a whole house exhaust fan, thermostatically controlled. It begins to be useful in early spring and then again in the fall when the air can be quite warm during the day, but cool to cold at night. We even use it in the middle of summer (turning off the air conditioning at that time) when temperatures allow. The temperature control mechanism was specifically installed at our request and is quite unusual: most are on timers. To allow for an exhaust fan the house must have adequate venting in the attic to avoid over-pressurizing it, causing damage.

We have the exhaust fan set for a low of 65 F. We turn it on only at night, just as we are going to bed, after first opening enough of our windows to allow for passage of the demanded air. It runs until it brings the house temperature down to 65 F and then turns itself off. Even if it is cold outside, temperatures will be comfortable inside as air will move little when the fan is not running. At any time the inside temperature rises enough (1 or 2 degrees), the fan automatically goes on again. Often, as the temperature is not quite cool enough (say it only gets down to 67 F outside) it does not turn off at all. Still it cools the house considerably, maybe even more thoroughly for constant running; and with only a fan motor, and no condenser, it uses much less electricity than the air conditioner. We turn it off and close up the windows in the morning, leaving the warming air outside.

I consider a large advantage of the fan the fact that it turns over in-house air such as cooking odors or off-gassed products of house construction or furniture that apparently can impact health and go on for years.

Here is how we use our air conditioner: we run it principally at night.

We keep the windows tightly closed all the time in hot weather. I have to sit outside or work in the yard for the summer air. We have a programmable time-temperature control for the air conditioner, and set the turn-on temperature at 80 degrees F during the day. At about 9 pm or an hour before bedtime, its temperature set changes to 77. At 3 or 4 in the morning it goes down again to 73. Whenever it is on, It removes humidity from our in-house air (WV can be very humid) making it more comfortable, and by wake up time the house temperature is 73 degrees. Obviously, all of the cooling occurs at the coolest times outside so the conditioner can work at its most efficient. Because of our excellent insulation, in house temperatures rarely rise above 80 during a single day even at 90+ outside, so the air conditioner rarely goes on. As the air has been de-humidified at night, there is little water in the air during the day, so the higher temperatures are more comfortable than you might think.

Obviously, there is room for individual variation in terms of specifics. I would say that key to lower costs are avoiding extreme temperature demands on your system, excellent insulation including windows and doors, a temperature control whole house exhaust fan, a programmable air conditioner, and doing most of the cooling at night when outside temperatures are at their lowest.