While the following discussion (originally published in Climate Progress) extends to energy opportunities well outside the residential sphere, it's the latest example an overstatement of the so-called "Rebound Effect". Although there are certainly times that a portion of the energy savings may be taken back in the form of elevated comfort or some other form of energy service, Re-bounders would have us think that the true savings are negligible. I just can't imagine an innocent homeowner, upon getting their premium-efficiency air conditioner, would then proceed to ratchet down their summertime thermostat setting to 60 degrees.... Let's account for the rebound effect, but let's do so realistically.

Misreading of a new Sandia National Laboratories study on efficient lighting has led The Economist into the dark. In the process, they inverted the researchers’ findings, perpetuating the myth of the “energy rebound effect,” which has been postulated in theory but never shown empirically to be significant. The assertion is that the too-cheap-to-meter energy savings from energy-efficient lighting will induce people to become ravenous light hogs, increasing their demand for lumens to such an extent that lighting energy use will grow despite factor-ten improvements in efficiency compared to today’s incandescent lighting.

Perhaps a new species of “Efficiency Deniers” will be born of all this…. I can hear it now: Energy efficient technologies will fuel global warming and other scourges of the earth.

The authors of the underlying Sandia study have already pointed out one of many egregious flaws in the article: Comparing today’s mixed-source lighting energy use with that projected for three and a half decades downstream (larger population, GDP, etc.) and attributing the predicted increase to LEDs (solid-state lighting):

SIR – Your surprisingly negative article on energy efficient lighting technologies (“Not such a bright idea”, August 28th) appears to have resulted from a misunderstanding of our paper in the Journal of Physics.

Unfortunately, your writer’s reasoning erred by comparing today’s per capita mixed light consumption with the projected 2030 consumption for all-solid-state lighting (SSL), rather than comparing the projected 2030 consumption with and without SSL. Because of this “apples and oranges” comparison, you drew a number of erroneous conclusions. For instance, you stated that in 2030 a tripling of electricity prices would be required before energy consumption for lighting declined. In fact, our paper shows that, for the two 2030 scenarios (with and without solid-state lighting), a mere 12% increase in real electricity prices would result in a net decline in electricity-for-lighting consumption. This “green” result is obtained while at the same time enabling consumers in 2030 to use three times more light with SSL than without it. Your amusing but hopefully tongue-in-cheek conclusions about the “greenness” of incandescent lighting would be, if serious, off-base and in our view potentially harmful.

Jeff Tsao
Harry Saunders
J. Randall Creighton
Michael E. Coltrin
Jerry A. Simmons
Sandia National Laboratories
Albuquerque, New Mexico

It would indeed be worrisome if the energy savings from this game-changing technology were gobbled up by a penchant for cheaper lumens. However, the significant stipulated growth in demand for lighting services is based on an extrapolation of the growth that took place three centuries ago (in the days of whale oil lamps), without regard for contrary indications in the recent and far more relevant past.

Consider the highly analogous case of compact fluorescent lamps (CFLs), which are today replacing Edison’s incandescent lights hand over fist while reducing energy use by five-fold (about the same improvement that LEDs will eventually offer over CFLs on a per-delivered-lumen basis). CFLs have made a major dent in the overall lighting market in the U.S., replacing about one in four incandescent lamp sales in just a decade’s time. Importantly, this has been accompanied by no visible change in the overall number of light bulbs sold or illumination desired by their users. By both of these measures (sockets and lumens), the speculative rebound-effect of consumer behavior is invalidated by the facts. And other well-demonstrated strategies for improving lighting systems – e.g., dimming coupled with controls for daylight harvesting – actually reduce light levels by better tailoring light output to what is needed by users and not otherwise provided by daylight. These kinds of strategies must figure big in any serious scenario for 2030, irrespective of the underlying lighting technology mix.

Source: U.S. Department of Energy

More is not always better. For rich and poor alike, the sky (i.e., a burning sun in every living room) is not the limit for lighting demand. Illuminating engineering societies around the world have actually been reducing their lighting-level recommendations for many years running, as overzealous guidelines have been seen to create excessive glare and other problems. Even granting some pent-up demand for more lumens, LEDs can save energy because their light can be more precisely directed to end-use needs and more easily controlled.