Residential Dishwashers

How many homes in the U.S. are actually equipped with automatic dishwashers? The American Housing Surveys for the U.S. (1985 to 2003) confirm an increasing trend in the installation of these appliances. According to AHS, 58 percent of all housing units possessed automatic dishwashers in 2003. At the same time, 88 percent of all new housing stock (4 years old or less) was being equipped with them. Trends are upward, as noted below:

dishwasher-chart

While independently developed water use data does not yet exist for the wide array of automatic dishwashers now in the marketplace, sufficient data does exist from industry to allow stratification of water use and development of performance metrics for water use efficiency programs. All of this data is reported by the manufacturers.

State of Oregon

The Oregon Department of Energy maintains a list of dishwashers that meet its maximum water use threshold of 6.5 gallons per cycle. The following tables of products and performance assume 215 cycles per year of residential dishwasher operation.

Energy Star Canada

As correctly pointed out by Doug Bennett (Southern Nevada Water Authority) in his Waterwiser posting on March 20, 2006, the Energy Star Canada website makes available the water use data for residential dishwashers available in North America. Doug’s posting:

“We have petitioned DOE/Energy Star to make dishwasher water use information available so it may be used by state and local agencies that would like to establish requirements for rebates or program certification (such as Southern Nevada's Water Smart Home Program and State of Oregon's energy rebate program). Although EnergyStar has this information, it has not been published on their web pages. Water use is not a criterion for Energy Star dishwashers, however, publishing the data would have been consistent with how Energy Star handled washing machine water factors years ago. One of my staff discovered that the water use information is published on Canada's Office of Energy Efficiency website”

For the most current data and the ability to search their database, visit Natural Resources Canada's website:
http://oee.nrcan.gc.ca/residential/personal/appliances/dishwashers-tips.cfm?attr=4

Doug goes on to state: “We have verified that ‘Hot water use per cycle’ is total water use (since dishwashers only connect to the hot water line). We have also verified that Canada and the US have the same energy efficiency requirement for Energy Star dishwashers. Thus, if the Canadian site says it is Energy Star Qualified, it is qualified in the states. Product model numbers also appear to be identical.”

OR, download the Canadian listing of residential dishwashers (updated to December 10, 2006), which we have re-sorted according to gallons per cycle and with local energy costs deleted: Canadian Ratings (PDF)

Water Factors of Machines in Today's Marketplace

Using the Canadian data, we plotted the water factors of the 1,817 different dishwasher models currently available in the North American marketplace. The following chart reveals that 87% of all AVAILABLE residential dishwasher models meet the Oregon criteria of 6.5 gallons per cycle. (NOTE: This does NOT mean that 87% of all dishwashers SOLD meet those criteria. Sales volumes of machines within each of the different WF classifications are not currently available.)

dishwasher-wf-chart

Energy Star U.S.

The Energy Star program does not publish water use data for individual dishwashers. Instead, refer to the Canadian data above, which covers the same dishwasher models.

However, for information on the U.S. Department of Energy's current information and initiatives relating to residential dishwashers, as well as stakeholder comments to the DOE, go here:

Consortium for Energy Efficiency (CEE)

Much to the dismay of water use efficiency professionals, the CEE's list of "efficient" residential dishwashers provides no information whatsoever on water use (even though, as noted above, such water use data exists). The list of dishwashers that can be downloaded from this site, lists machines in two tiers of energy efficiency, Tier 2 being more efficient than Tier 1.

The CEE also issues a so-called "specification". However, this document provides no information on test protocols, measurements, tolerances, reporting procedures, or other metrics normally found in a product specification:
http://www.cee1.org/resid/seha/dishw/dw-spec.pdf

In view of the above, water use efficiency professionals and water providers are strongly advised to use the water factor data and product listings offered above by the State of Oregon and Energy Star Canada to structure their efficiency programs.

Residential Dishwashers as a Potential Best Management Practice

Should water-efficient residential dishwasher installations qualify as a Potential Best Management Practice for water providers? That question is addressed in this 2006 study:
- PBMP Report- Residential Dishwashers (PDF)