It is widely believed that improved energy efficiency results in saved energy. An Englishman named William Stanley Jevons challenged this idea in the 19th century — long before Energy Star and CAFE standards. His idea became known as “Jevons’ paradox.” Tim Harford — aka the “Undercover Economist” — writes about this in his essay Energy efficiency gives us money to burn. It is worth the read.
Jevons’ paradox appears to be at work in commercial buildings — particularly those that are achieving LEED certification. NYC energy benchmarking data released last fall reveals that NYC office buildings have Energy Star scores that suggest they are more efficient than office buildings nationally. But here is the rub — they use no less energy? Their gross energy intensity — either site or source — is no lower than national averages, even though their average Energy Star scores is 68. If you look at just the LEED-certified office buildings in the data the results are even more striking. NYC LEED-certified office buildings have an average Energy Star score of 78 — yet, like other NYC office buildings, use no less energy (site or source) than national averages.
Is this evidence that supports Jevons or does it, instead, suggest problems with the Energy Star and LEED scoring systems? Time will tell.
After writing the above I was reminded of an article published some time ago by Andrew Rudin that addresses the failure of energy efficiency to reduce energy use in US buildings. The article is titled “Energy efficiency’s false hope.” I definitely recommend it.