How Do You Measure Energy Savings? The Rosenfeld Unit


How do you capture the significance of a life’s work? Writers deliver stories, teachers prep students for the world, scientists – if their work is truly path-breaking – might have their seminal discovery enshrined in a term that bears their name.

Last week, some 400 academics, business leaders, and government officials, including California Public Utilities Commission President Michael Peevey and Susan Kennedy, chief of staff to Gov. Arnold Schwarzenegger, gathered at the Mondavi Center, on the campus of UC Davis, to honor a man who, over the past 35 years, birthed and then guided not just a new industry, but a new way of thinking. To those assembled, he is simply a “one man institution.”

Arthur H. Rosenfeld, who recently completed the second of two five-year terms as a commissioner at the California Energy Commission (CEC), is, with justification, called “the father of energy efficiency.” After a mid-career pivot prompted by the oil crises of the 1970s (had he not changed course he likely would have won the Nobel Prize in physics), Rosenfeld spent the next three decades helping to build California’s world-leading energy policy, first as founder and leader of the Center for Building Science at Lawrence Berkeley National Laboratory, and later as a commissioner at the CEC.

Much of the California energy story – rigorous appliance and building energy efficiency standards, championing the CFL, “decoupling” electricity sales from revenues, altering the state’s energy loading order so that energy efficiency is the first priority – stems from policies advocated by Rosenfeld.

Time and again at the Rosenfeld Symposium, the speaker noted Rosenfeld’s penetrating ability to make the abstract clear. There is no better illustration of this tactic than one that became a Rosenfeld trademark: the avoided power plant. Rosenfeld intuitively sensed that to successfully mobilize public opinion in favor of saving energy, fuzzy concepts like kilowatt-hours, especially large, opaque numbers such as the output of a mid-sized coal plant (3 billion kilowatt-hours annually), would have to be made concrete. Rosenfeld argued that if you told consumers that their wise choices could together help prevent the need for more power plants – massive, expensive assets easily visualized – you could alter their behavior.

Rosenfeld was right. Per capita electricity consumption has remained flat in California for three decades, despite breakneck population growth, even as it increased by 40 percent nationwide.

It’s a stunning achievement. To recognize it properly, Chris Calwell of Ecos Consulting and Jonathan Koomey of Stanford University collaborated on an audacious gesture: they conspired to ensure that Art Rosenfeld’s legacy would live on in his name – just as the terms Volts, Watts, and Joules honor their discoverers. Calwell and Koomey, joined by nearly 50 of Rosenfeld’s peers in the energy industry, such as Ralph Cavanagh of NRDC, Amory Lovins of the Rocky Mountain Institute, and Dan Kammen at UC Berkeley, co-authored a paper, published the day of the Davis symposium, in the peer-reviewed journal Environmental Research Letters, proposing a new unit of measurement for energy savings called the “Rosenfeld.”

The Rosenfeld unit represents the energy savings required to replace the output of one existing 500-megawatt coal-fired power plant – 3 billion kWh annually (the hard-to-grasp metric I mentioned above) – and its associated planet-warming emissions, 3 million metric tons of CO2.

“Art has already won many awards, but we feel that his stature and accomplishments in the scientific and policy communities are worthy of something a bit more permanent,” said Koomey, who, like many of the speakers and presenters at the symposium, studied under Rosenfeld. (John DiStasio, CEO of the Sacramento Municipal Utility District, joked that Rosenfeld was the Kevin Bacon of the energy industry in California.)

“The Rosenfeld unit immortalizes Art’s most enduring and important contribution to society: the recognition that energy efficiency is the fastest, cheapest, and most reliable way to save money and reduce pollution at the same time,” said Koomey.


Brad Bergman

What’s wrong with this sentence: “Per capita electricity consumption has remained flat in California for three decades, despite breakneck population growth…”?

A: “per capita” takes population growth out of the equation. You can argue that per capita energy use remained flat in the face of rapid technological advances, or in spite of huge increases in the size and usage of home appliances, but to say it remained flat despite population growth only points out that you don’t know what per capita means.


To be fair, maybe some Californians have more than one head.

Ravindra Datar

Actually per capita energy must fall with higher population based on the economy of scale principle.
On the other hand per capita would susbtentially increase over a period of 40 years due to enhancement of life style.

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