Where the Northwest
shapes energy efficiency


Northern Climate EF calculator

Created 6/28/2011 by Dave Kresta
24 views • 0 comments
1)      Space heating interaction is not dealt with yet (and likely won’t be in this version)

2)      Currently the calculator uses the DOE EF figure (at 67 ambient), and either EF40 or EF50.  The thinking is that manufacturers can choose either one, but not have to do both.
a.       Dave question for Ben: why not just require the EF50 test to simplify things? Extrapolate lower temperature performance with a  straight line, and simply step down to resistance at the compressor cutoff. Is there an advantage to a manufacturer to choose EF40 or EF50?

3)      The test scheme that we run for EF40 or EF50 will not be a full 24-hour test (this is too onerous). We will propose a specific draw patter-based test, but this may need to be changed to keep track with changes in test standards at the DOE level.

4)      Testing/verification of compressor cutoff temperatures were discussed briefly with no resolution. We must determine an approach to this.
a.       Proposal from Dave: use the manufacturers’ published compressor operating range –OR—test data if available? That way we reserve the right to test it, but can also just use mfg data for expediency.  The specific test mode for determining the compressor cut off is perhaps not something we have to make a part of this spec, since there are multiple ways to get at it and we don’t want to mandate a separate test for it since mfgs have to publish the spec anyways.

5)      Testing must be in default (out of the box mode).

6)      Some discussion on whether we should use temperature data in the early mornings (when most hot water is used).
a.       Unclear resolution on this: Ben can you do a little research to see if this has a non-trivial impact? Suggest we use 6am to 10am temperature data.

7)      The different climate profiles were discussed. It was agreed that a representative Northern climate sample (Seattle, Chicago, Boston) was best, as opposed to a NW-centric one. 8)      Warm/cool basements and warm/cool garages were discussed.
a.       Agreed that some combination of basement and garage profiles was required. Dave proposal: use warm basement (basement with little to no insulation) and cool garage (garage with insulation between garage and house).  This provides a good spectrum of potential applications. Average the two together.
Log in to comment, rate, and share.
Comments (2)
Stephanie Vasquez-Pettit on 06/28/11 on 02:26 PM (Pacific Time)
Thanks for setting this up, Dave.  Sorry I couldn't make the meeting, but I have a question: Will there be an EF provided for each operating mode?  Consumers (such as myself) will be interested in performance of all operating modes, in addition to the out of the box spec. This is especially true if efficiency mode for unit A is better than for B, though B has a better out of box setting.
Dave Kresta on 06/28/11 on 04:12 PM (Pacific Time)
At this point we've only talked about the default mode, which in all models we've seen is the "hybrid" mode in which the heat pump and the electric elements are both available for heating water. We are mimicking the Federal test standard approach by focusing only on the default mode, and the thinking is that we will follow their lead.  We are already under pressure to simplify the Northern Climate test procedure as much as possible...I'm afraid that adding test for other operating modes would really make the test regime to onerous. Those are my thoughts, at least.

This resource is Public

Sector: Residential
Function: Emerging Technology

Associated Groups:

Heat Pump Water Heater Collaboration

Add to My Groups