Seeing the Light on Energy Efficiency

by Pete Geddes

The excellent Roger Pielke Jr. asks:

Advances in efficiency might presage greater energy consumption?!

Yep. Here’s how it works:

Common sense tells us that increasing energy efficiency reduces energy use. But this is not so. William Stanley Jevons first identified this paradox in his 1865 book, The Coal Question. Jevons observed that England’s consumption of coal soared after James Watt introduced his coal-fired steam engine, which represented a vast improvement on Thomas Newcomen’s inefficient design.

Jevons pointed out that efficiency gains reduce the cost of energy, allowing the steam engine to penetrate other industries, i.e., textiles. This lead to an increase in the total energy consumed. Jevons wrote, “It is wholly a confusion of ideas to suppose that the economical use of fuel is equivalent to a diminished consumption. The very contrary is the truth.”

The increase in the use of household appliances bears this out. As appliances become ever more energy efficient, we use more of them. Survey data for 1980 and 2001 shows increases in microwave ovens from 14 percent to 86 percent, dishwashers from 37 percent to 53 percent, and central air conditioning from 27 percent to 55 percent.

Even though energy efficiency has improved in almost every aspect of our society, overall energy consumption continues to grow. Improvements in energy efficiency are good for the economy and for people’s lives, but it doesn’t mean we’ll use less energy overall. We’ll use more, especially in the developing world. In their 2005 book, The Bottomless Well, Peter Huber and Mark Mills wrote, “Efficiency fails to curb demand because it lets more people do more, and do it faster—and more/more/faster invariably swamps all the efficiency gains.”


  1. The Jevons Paradox is not very useful when making policy decisions. It seems to argue that the more efficient we are the more we use. Really, however, it says that some of the benefits of increased efficiency are clawed back by prosperity. But how that plays out is not straightforward. For instance, Alan Greenspan notes in his book that the total weight of everything we made in 2005 is roughly similar to what we produced in the US in 1950. Our GDP was many times higher. Efficiency didn’t lead to increased resource use, it simply squeezed more from less. So, energy efficiency might not increase energy use, but incremental improvements in energy efficiency aren’t fully recovered, because some of the reduction is reallocated. For this reason, the Jevons Paradox isn’t really the dramatic rule some make it out to be. I don’t think it indicates increases in energy use, but indicates the energy savings will be less than exptected.