My house has central air conditioning, but again this year I’m not turning it on.

The reason is simple: there are better, cheaper ways of making the place comfortable during summer’s heat.

The big air conditioner is something on the order of 30 years old. A lot of things have changed in the last three decades, and a few of those changes have been good. One of the improvements is that air conditioners have gotten more efficient.

Several weeks ago I did a little research and discovered that my central air, though well made and robust, uses so much electricity that it would be illegal to market it today.

That makes sense to me, because the overhead is high for central air conditioning. Outside is a large compressor/condenser unit, with its fins, coils and powerful fan motor, that squeezes and chills the gaseous coolant from inside the home, turning it from a hot gas into a cooler liquid, while a powerful fan expels heat energy into the air. The coolant is then pumped to the air handler/evaporator unit indoors, usually part of the furnace but sometimes (as in a heat pump) a separate unit. There, the coolant, as it evaporates into a gas, absorbs heat energy from the air, effectively cooling it. Another powerful fan blows the now-chilled air through ducts to cool the house.

It’s pretty easy to conclude, accurately, that this process just gulps electricity. There are innovations in whole-house air conditioners and the modern ones are more efficient than the one at my place, but the price of admission is high. I’d rather be comfortable on the cheap.

As with my switching the entire house to LED lighting a couple of years ago, this does not mean that I embrace it all as a kind of religion, the way some people have. My motives are simple: why pay more than I must? And as then, one of the goals was to avoid a big investment at the beginning that I hoped would get amortized in savings over the years, perhaps decades, to come.

Seeking to save money, a few years ago I installed a single dinky window air conditioner in my bedroom. I figured that inasmuch as I wasn’t home most of the day, it made little sense to cool the whole house, and turning on the central air when I got home simply had to be inefficient, running it full-tilt to make the place go from very hot to comfortable.

But then one night I left the bedroom door open. When I awakened the whole place was pleasantly cool. I did an experiment and learned that it stayed comfortable throughout the hot summer day, with the bedroom door open and that little air conditioner turned on. The window air conditioner is upstairs, and hot air rises, so the cool air circulated nicely. And the lowest level, where I have my office, never gets very hot anyway.

This cheap ($150) little air conditioner was doing almost as much as the whole-house installation did. And my electric bill dropped.

That, as I said, was several years ago. The window air conditioner was the cheapest I could find at the time. It remained on all summer, each summer. It still works, though the compressor now sounds a little like the engine of a Piper Cherokee airplane, reminding me of being in a cheap motel.

(I should explain this: Many years ago a friend and I rented a Piper PA-28 – Cherokee – and flew it from New York to Florida. Impenetrable weather ahead forced us to land in northern Florida to wait for it to clear. That meant an overnight stay, and during the night we both awakened with a start each time the air conditioner compressor turned off: it sounded exactly like the airplane’s engine failing.)

So this year I surveyed the current range of little air conditioners, with an eye toward replacing the now-noisy one. The cost of admission is still low, and the efficiency has gotten better. For $200 I was able to get a unit that gave me 1000 BTU more than the old one. The little yellow tag that came attached to it said that its electricity cost will be $48 for the entire season. (That’s a government figure, and I suspect that it’s about as trustworthy as the EPA fuel efficiency ratings for cars, but it’s a good point of comparison.)

By my calculations, using this little air conditioner will save me money over using the central air – and that includes the price of the air conditioner itself! It will be entirely amortized this year, and then some. And the unit should be good for five years or more before it begins imitating airplanes.

Now, there are a few things that need to be pointed out here. The first is that this won’t work for everyone. The way my house is built allows for the circulation which lets a little window air conditioner in the bedroom upstairs keep the living room downstairs comfortable; on especially hot days a little boost from the ceiling fan in the upstairs hallway helps.

The second is that I’m comfortable when the indoor temperature is in the mid-70s. Not everyone is. Some people want their houses colder in the summer than they’d be willing to tolerate in the winter. (Some people get in their cars and drive three blocks to the gym, too.)

The third is that the normal method of installing a window air conditioner is just about as inefficient as it could possibly be. You raise the window, stick in the air conditioner, and pull down the window to hold the appliance in place. To fill the gap on each side you extend a flimsy plastic filler that offers next to no insulation. This year I went into a bit of insulation frenzy, going outside to add a layer of foam insulation on each side, using a lot of weather stripping and caulk (the caulking is easily removed should I ever uninstall the air conditioner; I think I’ll cover it for the winter instead).

I’m also putting reflective film on the inside of my western-facing windows, which reduces the blast from the afternoon sun. That would be a story all its own, but it shall go untold – the rules of the newspaper prohibit the volume and intensity of profanity necessary to accurately tell the tale. The stuff does not install as easily as they’d have you think.

Now, if they’d only come up with highly efficient and inexpensive solar panels, and cheap, low-loss battery storage, the weekly (sometimes daily) power blackouts would get less exciting, too.

Editor's note: Dennis E. Powell’s column appears on Mondays. You can reach him at dep@drippingwithirony.com.

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