California: efficient, but ...

• Author: Mitchell, Cynthia
• Position: FROM READERS - Letter to the editor

Energy efficiency is indeed the fastest, most cost-effective way to reduce greenhouse gas emissions and combat global climate change. Your article ["Energy Efficiency, Rediscovered," January/February] points to California as "probably offer[ing] the most notable example" of significant success in harvesting this low-hanging fruit via utility programs and state appliance and building efficiency standards. The proof: "[California] has the lowest per-capita electricity use in the United States, and this has remained flat over the last 30 years. ..."

Because so much is being made of California's success story, in 2008 we undertook a series of statistical analyses to better understand how energy savings and consumption are linked. We found that while energy efficiency has played a part in holding California's per-capita consumption relatively constant, the rising price of electricity is also a significant, and likely much greater, factor. Less than 20 percent of the annual variation in per-capita consumption can be explained by changes in the level of efficiency savings, while energy prices explain 40 percent of the annual variation. These findings are in keeping with the national data on residential energy prices and residential per-capita consumption that we analyzed: those states with higher energy prices have lower per-capita consumption and vice versa. Also, other factors in California, such as weather, are strong drivers of per-capita use, at about 20 percent. In other words, while there is a trend in California historical energy savings and per-capita consumption--as savings go up, per-capita consumption stabilizes and remains relatively constant--we did not find a strong cause-and-effect statistical relationship between annual changes in the level of savings and per-capita consumption.

Further, our work indicates that there are a number of distinctions between California and the rest of the United States that are most likely influencing the state's overall consumption trend. The effects of household size, other demographic variables, and shifts in underlying economic structure (from industrial to service) appear at least as important as state energy-efficiency policies. While we assume the article is referring to total per-capita electricity use as remaining flat over the last 30 years, California's residential per-capita consumption...