You may have received an email this morning from RESNET titled, "Interested in the RESNET Emerging Leadership Council, But Wasn't Able to Participate in the Webinar?".  I did too.  When you open it, however, you will see a very important announcement about RESNET's formal standards interpretation regarding how to handle the water heater UEF or Uniform Energy Factor.  This has happened to all of us...oops!  What did I just do?  We have all sent out emails that were not quite ready for prime time and regretted it as soon as it was too late.  The classic one is an email that was sent from my office in which auto-correct decided that the word "inconvenience" needed to be changed and the email left with the last line reading, "We apologize for any incontinence this may have caused."  But I digress...

You may have noticed on your AHRI Water Heater certificates where you used to see EF you now see UEF.  The Federal Government changed the method of calculating efficiency for water heaters and the new standard when into effect in June of 2017.  This is why you are seeing the nomenclature change.  However, HERS Raters did not have a method of determining the difference between UEF and EF so that the correct information could be modeled.  The Technical Committee has been very hard at work on this issue and developed a spreadsheet to help HERS Raters enter the appropriate value into their modeling software.  Then the Standard Development Committee 300 adopted that spreadsheet, effective December 9, 2017.  Here is the official verbiage:

The RESNET Standard Development Committee 300 has adopted the following standard interpretation No. 301-2014-12 "Water Heater UEF":

Where RESNET Accredited Rating Software requires Energy Factor (EF) as input for water heater efficiency, the EF may be calculated from the Uniform Energy Factor (UEF) using the spreadsheet calculator titled RESNET EF Calculator 2017_10_30.xlsx

So now the question is, where is this spreadsheet?  If you follow the link in the email, you will not find it.  If you google the name, you will find an old one which was created for commercial water heaters.  It does not look like the tool is uploaded to the site yet.  Stay tuned and I'll share the details when I get them; but for now it seems that our friends at RESNET really need to have that cup of coffee before they send their morning email!

UPDATE: 

You can access the interpretation here: http://www.resnet.us/blog/wp-content/uploads/2017/11/Interpretation-301-2014-012-Water-Heater-UEF-v.f_posted.pdf

and the spreadsheet here: http://www.resnet.us/blog/resnet-consensus-standards/  To find the spreadsheet, scroll down to Interpretations and click on the link named: RESNET EF Calculator 2017_10_30.