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New Residential Clothes Washer Energy-Efficiency Standard

In January 2001, the U.S. Department of Energy promulgated a new minimum efficiency standard for residential clothes washers. The new mandated efficiency levels will become effective in two stages: in the years 2004 and 2007. In 2004, the standard will mandate an energy reduction of 22% and in 2007, 35%, as compared to the current minimum efficiency standards in effect since 1994. Manufacturers may achieve these reductions in laundry energy use by selecting any design options they like. Many manufacturers are introducing new energy-efficient washers that meet future minimum efficiency requirements even before the required date. These energy savings are being met by modified vertical axis or top-loading designs with a spray wash, as well as by front-loading, horizontal axis washers, sometime referred to as tumble washers.

The new metric for clothes washer efficiency, the Modified Energy Factor, MEF, is expressed as cubic feet of basket capacity divided by energy use, in kilowatt-hours per cycle. MEF includes the energy to heat the water for the clothes washer, as well as the motor energy and a calculated dryer energy.

Most of the energy used in a typical clothes washer is used to heat the water. Therefore, efficiencies are primarily being met by reducing hot water consumption. When hot water energy is reduced, total water use is often reduced as well. Other methods to increase efficiency are to use auto-fill features, better temperature control, and faster spin speeds. The latter spins out more water in the washer so the dryer needs less energy to complete the drying. Data collected from manufacturers show that, on average, they expect to reduce the washer energy by approximately 68%, and the dryer energy by 11%, to achieve an overall laundry energy reduction of 35%.


The Energy Policy and Conservation Act, as amended, mandates that the Department of Energy establish minimum efficiency standards for clothes washers. Researchers in EETD's Appliance Standards Group provide the analysis for the DOE to determine the highest energy-efficiency standard that is technologically feasible and economically justified. EETD's work includes analyzing the impact of technological options on consumers, manufacturers, and the nation as a whole.

Distribution of consumer life-cycle cost impacts due to a new efficiency standard. The distribution is skewed heavily toward consumer benefits (to the right of $0 on the x-axis).

Figure 1. Distribution of consumer life-cycle cost impacts due to a new efficiency standard. The distribution is skewed heavily toward consumer benefits (to the right of $0 on the x-axis).

This analysis includes several methodology improvements including using distributions for the variables needed in the life-cycle cost (LCC) and payback period analysis. In addition, a distribution of marginal electricity prices was used instead of the usual national average price. The marginal price is the actual price a consumer would have paid for the increment of electricity saved. Using all of the input variables in a Monte Carlo analysis allowed the resulting LCC to be presented as a distribution. Rather than just an average change in LCC, we can now show the percentage of consumers that would benefit from a new efficiency standard and by how much (Figure 1).

Cost and savings from clothes washer standards.

Figure 2. Cost and savings from clothes washer standards.

In addition to looking at impacts on the consumer, impacts to the nation as a whole were also determined. Cumulative energy savings to the nation, forecasted to the year 2030, were estimated at 5.5 quadrillion BTUs (Quads). In addition, the standards are expected to save 11.6 trillion gallons of water through 2030. A cost-benefit analysis shows that on a national basis, the reduction in the operating costs of washers compliant with the standard outweighs the increase in the initial cost of the clothes washers. Analysis included a forecast of future shipments based on a decision tree model that accounted for price elasticities, operating cost elasticities, forecasted fuel prices, housing starts, increased sales of used washers, and other variables. The existing clothes washer stock was modeled using a retirement function that provided input into how many new washers would be purchased in future years. Detailed charts were created showing trends in future clothes washer shipments and national costs and benefits to the year 2030 (Figure 2).

In addition to the consumer and national impacts described, researchers analyzed national emissions, employment, and alternatives to national standards.

— Peter Biermayer

For more information, contact:

  • Peter Biermayer
  • (510) 486-5983; fax (510) 486-6996


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