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April 9, 2008
Energy Star Certified Water Heating
Energy Star has released information about the Energy Star Water Heater criteria that will take effect in January 2009. This is exciting news, as water heaters had not been Energy Star certified prior to this, and it will help people make informed decisions about products' energy efficiency and potential long-term cost savings. Depending on the type of water heater, choosing an Energy Star model is estimated to save 7.3 to 55% of typical annual energy use for water heating. This relates to $26 to $277 a year.
The criteria all relate to the Energy Factor (EF), with some added requirements as needed for each technology. The EF more or less relates to the overall efficiency of the unit and higher is better. The highest possible EF for electric resistance or gas heating is 1. The heat pump water heaters can see EF's greater than 1 because of they pull heat from their environment in addition to the electrical power input to produce more heat energy than the electrical energy input.
Most common here in the US are water heaters that utilize some sort of tank storage for the hot water. This allows for the burner or heating element to be smaller, but the tank loses heat to its environment continuously, lowering the efficiency. Most solar thermal systems for water heating of this type also use some sort of thermal storage tank, as do most of the heat pump water heaters I've seen. A lot of advantage can be gained by using an on-demand, or tankless, water heater. There are some disadvantages as well. Check out the Department of Energy's website dedicated to water heaters if you wish to learn more about the different technologies and their advantages/disadvantages.
Here is a rundown of the minimum Energy Factor levels required for Energy Star certification for residential water heaters in 2009:
* Gas storage water heaters: EF of 0.62
* Gas condensing water heaters: EF of 0.80 (plus some other performance caveats)
* Whole-home gas tankless water heaters: EF of 0.82 (plus some other performance caveats)
* Heat pump water heaters: EF of 2.0
Solar thermal water heaters have requirements of a minimum solar fraction of 0.50 and a Solar Rating and Certification Corporation (SRCC) OG-300 certification.
Check out the DOE press release and these two blog entries for details and other ways of looking at this:
DOE press release
groovy green
CleanTechnica
Posted by Eric Helton at April 9, 2008 11:45 AM
Comments
I will be buying a 40 gal water heater within the next year.(Gas)
Posted by: JohnMIller at April 15, 2008 10:19 PM
We have oil - not gas. What about oil hot water tanks????
Posted by: carolyn at April 16, 2008 6:39 AM
I am very interested in a tankless gas hot water heater and information on availibilty
Posted by: Charles Garrod at April 16, 2008 6:44 AM
Can you tell me the differences between gas & electric tankless water heaters?
Posted by: Frank at April 16, 2008 2:08 PM
What wonderful timing! I just finished replacing the storage-tank, electric-resistance water heater with a similar model, fractionally more efficient, because nothing better is sold locally. Gas is not available, propane is outrageously expensive, so on-demand tankless heaters not too likely -or are they? This new heater will be the back-up to a solar setup in the near future.
Posted by: Larry Jean at April 16, 2008 2:41 PM
I need to replace our 40 gal. elec. water heater in central NJ. We have natural gas in the house. What is the best investment vs. economy option for this location?
Posted by: Carol R at April 20, 2008 11:03 AM
