ANN ARBOR—California may be an expensive place to live, but when it comes to energy demands, it’s more sustainable than the Midwest, according to a University of Michigan study.

Michael Sivak of the U-M Transportation Research Institute examined the combined energy demand per person for residential heating and cooling in the 50 largest metropolitan areas in the United States, based on statistics from 1971 to 2000.

His analysis used data on “heating and cooling degree days”—units that relate to the amount of energy needed to heat and cool buildings—to produce a combined index of total energy demand for climate control. One heating (cooling) degree day occurs for each degree the average daily outdoor temperature is below (above) 65 degrees Fahrenheit.

Sivak found that San Diego and Minneapolis—the two extremes on the combined heating and cooling index—had a fourfold difference in total energy demand. The average annual number of heating and cooling degree days was 1,072 in San Diego and 4,764 in Minneapolis.

Joining San Diego among the cities with the fewest total energy demands were Los Angeles, San Francisco, San Jose, Riverside and Sacramento, all in California. Right behind were the Florida cities of Jacksonville, Orlando and Tampa. New Orleans rounded out the Top 10. Miami had the greatest demand for air conditioning—2,423 cooling degree days—but only 83 heating degree days. Overall, it came in at No. 12, sandwiched between Houston and San Antonio.

On the other end of the scale, Minneapolis was joined by Milwaukee, Chicago, Rochester, Buffalo, Detroit, Hartford, Denver, Cleveland and Salt Lake City as the cities with the greatest demand for energy, all primarily because of heating demands. The two cities synonymous with desert living—Phoenix and Las Vegas—were in the middle of the pack.

“The results indicate that the differences among the cities are large and that the total energy demand tends to be dominated by heating demand,” Sivak said. “The recent sharp increases in energy costs and sustainability concerns have served to emphasize the differences in demand for climate control in different parts of the country. It’s likely that such differences will be an increasingly important factor in individual decision-making about where to live in our mobile society.”

Sivak’s study appears in Cities: The International Journal of Urban Policy and Planning.