Smart Living Conference Preparation

I am giving a talk Saturday at the first annual Smart Living Conference (www.smarthome.duke.edu) to be held at Duke University’s Smart Home. In preparing for my talk, I have been reading this section of my book Occam’s Energy.

“About 20 percent of the energy used in the U.S. is consumed in our homes. Up until the 1950s, coal was the predominant fuel used in homes; but then its use dropped rapidly. Now coal is used mostly to create the electricity we use in our homes. Petroleum usage grew slowly to its peak in 1972, and then it also subsided. Natural gas became an important resource, growing strongly until 1972 when its growth essentially stalled. Electricity, only an incidental source in 1949, has increased in almost every year since then.

The amount of energy we use at home is usually proportionate to the size of it. It takes more energy to heat and cool a big house and even more to pay for the cost of transportation and energy to get from that big house in the suburbs to work in the city. As the size of our homes has grown the amount of energy we used has grown.

For instance, in 1900 the average new house size ranged from 700 to 1,200 square feet with two or more bedrooms and one or no bathroom and consisted of two stories.[1] Well over 20 percent of the nation’s population lived in crowded units, with entire families often sharing just one or two rooms. Most existing houses were small rural farmhouses that lacked the basic amenities, such as complete plumbing and central heat, standard in housing today. In fact, even in 1950 more than 35 percent of the nation’s homes lacked complete plumbing facilities (hot and cold piped water, a bathtub or shower, and a flush toilet), according to the Census Bureau.[2]

In the past thirty years, the size of the average house has increased 33 percent and the number of people living in those houses has decreased almost 20 percent, from 3.1 to 2.6 persons (one fewer person for every two households). Now, nearly 40 percent of new single-family houses are over 2,400 square feet in size, double the percentage in 1987.

It costs more to build, furnish, operate and maintain a large home. The growth of electricity use is a result of the increased use and variety of electrical appliances and systems. In 1997, a total of 99 percent of U.S. homes had a color television and 47 percent had central air conditioning. Eighty-five percent had one refrigerator; the remaining 15 percent had two or more. New products continue to enter the market; for example, in 1978 only 8 percent of our homes had a microwave oven, but 83 percent had one by 1997. In 1990, a total of 16 percent of U.S. households owned one computer or more. By 1997, the number had more than doubled, to 35 percent. As a result of our bigger, appliance-filled houses that need to heated, cooled, and lit, in 2007 the average American consumed almost 60 percent more energy than they did in 1949.

On average we use more natural gas at home than we do electricity—47 percent versus 39 percent, with the remaining 14 percent coming from fuel oil, propane, and wood. When you look overall at how we use energy at home, the largest use is for space heating (47 percent), followed by appliances (29 percent), water heating (17 percent), and air conditioning (6 percent). The bulk of the natural gas is burned for space heating. It is also used for cooking and water heating.

We have many uses for electricity. Almost 13 percent of the electricity we now expend at home keeps the food in our refrigerators cold, 12 percent keeps us cool running our air conditioners, 12 percent fires up the coils in our space heaters, 11 percent warms our water, 9 percent lights up our rooms, 3 percent cooks our food, 3 percent energizes the tube in our color television, 4 percent freezes our food, 4 percent dries our clothes, and the remaining 28 percent we use for everything from running our PCs, Playstations, X-Boxes, and rotisseries to blending drinks, ironing clothes, charging cell phones, and running fans.”

Next up, the energy we use for driving.

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[1] A Century of Progress: America’s Housing 1900-2000, National Association of Home Builders, April 2003, p. 3.

[2] A Century of Progress: America’s Housing 1900–2000, National Association of Home Builders, April 2003, p. 3.