Pull Out the Pin

How Air Conditioning Works
When the scorching Texas sun is overhead and you can see the heat shimmering off the asphalt, you know there’s only one escape from the summer weather: air conditioning. Even the hardiest Texan can find it hard to sleep when the mercury is pushing 90 degrees in the middle of the night. While most of us could live without cold-conditioned air in our homes, cars and workplaces, it certainly is comfortable having an oasis from the summer outside. For those of us lucky enough to have air conditioning, that humming box outside our homes also represents something else: a large part of our Texas electric rates bill.

Mechanical engineer Willis Haviland Carrier pioneered much of the early work in air conditioning. At first, regulating temperature and humidity wasn’t about keeping people comfortable. Carrier was trying to assist a printer who had trouble crisply applying ink to paper during hot, moist days. With the ability to constantly regulate conditions in the plant, the printer’s paper would no longer expand or contract due to change.

Anyone who has walked into a meat cooler on a hot day can attest to how good it feels to step out of scorching conditions for a little while. Department stores, movie theaters and other consumer businesses soon equipped their businesses with air conditioning units and saw their traffic increase, often advertising how comfortable their showroom or auditorium was. (This practice continues today; who doesn’t like escaping the heat while seeing a film at the local multiplex?)

It didn’t take long for Carrier (and his company) to produce appliances designed for home use. According to Mary Bellis, writing for about.com, the first residential air conditioner was put on the market in 1928. The practice of cooling one’s home during the summer, however, didn’t catch on until after World War II, when there were time and resources enough for American industry to bring air conditioners to the masses.

While the efficiency and power of air conditioners have changed a great deal over the decades, the principles of how they work are relatively unchanged. The California Energy Commission describes the process as identical to that of a refrigerator, but on a much larger scale. There are three components of an air conditioner: a compressor, a condenser and an evaporator. The compressor takes the air inside your house and turns it into a high-pressure, hot gas. This allows the condenser to easily remove the moisture from the air. The evaporator facilitates heat transfer between this air and outside air; the result is the cool, dry air that feels so satisfying after working outdoors.

There is a down side, of course. When you flick on your air conditioner, you are drawing electricity, and this will have an effect on your monthly power bill. How much will that effect be? The Public Service of New Hampshire notes that a 7,000 BTU (British Thermal Unit) air conditioner that is in operation 200 hours each month will add approximately .95 to your bill when it is time to pay. This is the middle range; a 5,000-BTU air conditioner used for the same amount of time will cost just over and a 10,000-BTU unit will ring up costs of almost .

The Energy Information Administration reports that central air conditioning accounts for half of the energy Americans use in their homes. In fact, 60% of American homes have central air conditioning. These statistics indicate that the upward trend in air conditioning saturation is not going to subside any time soon. What can you do to minimize your use of air conditioning and keep your bills as low as possible?

*Ensure that your home has adequate weatherstripping. Weatherstripping is the material you use to plug the open spaces in your home that allow that valuable cool air to escape. Make sure your doors and windows are protected.

*Limit the square footage the air conditioner is responsible for. If you have central air, shut the vents in rooms that you are not using. If you have a single-room air conditioner, keep the door closed as much as possible to keep the cool air inside.

*Take advantage of (and protect your home from) the weather. Try to close your blinds or curtains when the sun is beating on them. The radiant heat can make your air conditioner work much harder; it’s the same principle that keeps a greenhouse hot and humid.

*Use the timer settings on your home’s climate control panel (if you have one). It doesn’t make much sense to cool your house to your favorite temperature when you will be out of the house. Setting the timer will ensure you have one less thing to remember before you head out to work.

*The most important thing to do with air conditioning is to enjoy the relief from the summer sun. Before you know it, the weather will be too cold and you’ll be thinking about your home’s winter Texas electricity bill instead!