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Is efficient sufficient?

Physical limits in the atmosphere’s ability to absorb additional greenhouse gas emissions without causing fundamental changes in the earth’s climate lend a new urgency to efforts to reduce energy consumption. Central to those efforts is the art of defining, testing, and specifying the energy efficiency of particular products such as appliances, televisions, homes and vehicles that account for the majority of consumer energy use.

Read the report Is efficient sufficient? (pdf), published 22 March 2010


Go to the workshop "Is efficient sufficient?" to find presentations and a summary of the event.


Thus far, most governments have defined energy efficiency in a way that allows power consumption or annual energy use to rise steadily (and typically linearly) with product performance, size, amenity, or functionality. This helps consumers locate the least consumptive among a range of similar products, but does little to prevent absolute energy consumption from rising over time as products naturally migrate toward higher performance, larger size, and greater amenity and functionality. We have slowed the rate of growth compared to a business-as-usual scenario, but have not consistently turned absolute energy consumption or greenhouse gas emissions downward. Yet the capacity to do so clearly exists; we can do better.

Given the steady growth in population and affluence, technology has been ineffective, by itself, in stemming that tide. Examples from past efforts in Europe and the United States to improve the efficiency of refrigerators, vehicles, and homes illustrate why present approaches to defining, encouraging, and regulating particular levels of efficiency are no longer achieving the energy savings we need.

What is needed instead is a more comprehensive view of the range of factors at work, so that more product attributes can be specified than merely efficiency, and so that the efficiency specifications themselves can be tailored to be more effective.

In turn, this prompts consideration of overall sufficiency limits on total annual energy use or greenhouse gas emissions from a particular product type, regardless of its size or performance.

Progressive efficiency specifications can in many cases be crafted where the allowable power consumption approaches those sufficiency limits and ceases to increase, no matter how much more performance or amenity is provided. ENERGY STAR has proposed exactly that in its version 5.0 television specification, which will help to reduce energy use and greenhouse gas emissions even as televisions continue to grow in size. Such specifications, when employed by programs that also recover and recycle the energy-using products consumers are replacing, reduce the greenhouse gas intensity of fuels, increase product durability, and minimize hours of use, have the potential to finally bring overall energy use and greenhouse gas emissions downward.

Progressive efficiency standards alone will not be enough to turn down energy consumption, however. A range of changes are required in the way voluntary and mandatory efficiency policies and programs are implemented to systematically implement sufficiency and progressive efficiency concepts, keep specifications up to date, and discourage excessive consumption through price and information signals. Long term, such profound changes are our only hope for reversing the extraordinary global risks of climate change.

sufficiency column höger

eceee report

  • Is efficient sufficient? The case for shifting our emphasis in energy specifications to progressive efficiency and sufficiency (pdf), 22 March 2010

Background reading

eceee Summer Study papers

ACEEE Summer Study papers

Energy Efficiency

  • Jeffrey Harris et al: Towards a sustainable energy balance: progressive efficiency and the return of energy conservation, Energy Efficiency 2008 (available for eceee members from Energy Efficiency, online version, Issue No. 3, August 2008)

Other links & documents

  • Jack Barkenbus: Putting Energy Efficiency into a Sustainability Context: The Example of Refrigerators (pdf), Environment, October 2006
  • Linda Baker: Great big green monster mansions, salon.com, 7 July 2004
  • Martin Holladay: Raising the Bar for Energy Star Homes, 29 April 2009