What’s Cool about Air Conditioning

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By Elisa Wood

July 24, 2008

Conservationists often mock Americans for their love affair with the car. But the air conditioner appears to be a growing rival for our affection.

Twenty years ago only about one-quarter of US residences had central air conditioning; by 2005 it was up to 62%, according to the United States Census Bureau. http://www.ahrinet.org/ARI/util/showdoc.aspx?doc=703.

As a result, for a handful of hot days, we use enormous amounts of electricity. We must build expensive power plants to ensure that we have enough electricity to run the air conditioners, even though the power plants aren’t needed for the rest of the year. Our grid operators usually use the least expensive power first. But with demand so high, even the dirty and high priced plants are called upon. With everything running full tilt in the heat, the system is vulnerable to outages.

The problem reveals itself again and again each summer, most recently last weekend in New York City, where Consolidated Edison found itself delivering dry ice to keep Brooklyn customers cool after they lost power. A heat wave sent demand for electricity soaring to the second highest level on record.

I live in the southeast, so I am as enamored with the air conditioner as anyone. The good news is that the energy efficiency marketplace is spurring innovation to help avert grid problems brought on by our use of central air conditioning.

One rapidly growing innovation is demand response, which offers businesses payment to limit electricity use when the grid is under strain, reducing the likelihood of power outages. Companies might dim lights, delay expensive manufacturing processes until a time of day electric demand is lower, or engage in other energy reduction strategies. The approach is becoming so popular, hardly a week goes by without word of new major demand response deal. For example, EnergyConnect, an Oregon-based demand-response provider recently signed up Yahoo! As a result, when demand peaked July 10 on the PG&E system, Yahoo! reduced power its electricity use at its corporate headquarters and data centers in northern California by 1 MW, enough power to serve 750 homes. http://energyconnectinc.com/news/press-releases/2008/07/microfields-energy-connect-launches-relationship-with-yahoo/

On the other side of the country, in New England, demand response is also becoming increasing important. In fact, ISO New England reports that demand response makes up 10% of its resources (the majority of other resources are power plants) and the number could grow to 13% by 2011. http://www.iso-ne.com/nwsiss/nwltrs/outlook/2008/outlook_july_2008.pdf

In addition, central air conditioners are being built to better and better efficiency standards. Their efficiency has increased a minimum of 30% over the last two years, according to the Air-Conditioning, Heating, and Refrigeration Institute. This efficiency, however, can be lost if the air conditioners are not installed and maintained properly and used conservatively. To help solve this problem AHRI, utilities, energy efficiency groups and others recently created the 2 Degree Pledge http://www.2degreepledge.org/. The campaign encourages consumers to reduce thermostat temperatures two degrees in the winter and increase them by 2 degrees in the summer. The site also offers customers a zip code search of certified air conditioning technicians.

It looks like our love affair with the air conditioner isn’t going away any time soon. Eighty-nine percent of new houses completed in 2006 had central air, according to the U.S. Census Bureau. Air conditioners, like computers, cell phones and other electric gadgets are bringing about a new round of electrification in our society. They make life easier and more productive. Let’s make more of them – and more ways to use them efficiently.

Visit energy writer Elisa Wood at www.realenergywriters.com and pick up her free Energy Efficiency markets Newsletter and podcast.

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About Elisa Wood

Elisa Wood is the chief editor of MicrogridKnowledge.com. She has been writing about energy for more than three decades for top industry publications. Her work also has been picked up by CNN, the New York Times, Reuters, the Wall Street Journal Online and the Washington Post.


  1. Which is more energy efficient and cost effective, running a portable air conditioner or the old fashioned box fan?