Hi LEED experts,
I just received LEED reviewer comment. They said "It appears that each Baseline pump has been modeled with a power of 22 W/gpm. ASHRAE Interpretation ASHRAE/IES IC 90.1-2007-14 indicates that the Baseline pump power of 22 W/gpm from Section G3.1.3.10 is inclusive of all baseline chilled water pumps. This ruling is confirmed by LEED Interpretation 10299. The Baseline pump power shall be evenly distributed between the Baseline primary and secondary chilled water pumps. Alternatively, if the proposed case has primary/secondary chilled water pumps, the Baseline pump power may be distributed between the Baseline primary and secondary pumps consistent with the proposed design"
I'm struggling to understand how to distribute the baseline pump power. When they said baseline pump power will be 22 W / gpm for all pumps. Does the gpm here mean the total flow rate of both primary and secondary pumps? And will the power of primary and secondary pump be equal (as said evenly distributed)? It's quite different in the excel calculator, which recommend to distibute one-third power for primary and two-third power for secondary pumps. So what proportion should I use, (1/2 and 1/2) or (1/3 and 2/3)?
The reviewer also mentioned on alternative way. My proposed case has both primary and secondary pumps, so does it mean that the power of primary and secondary pumps for baseline will be exact those of proposed case? (then 22W/gpm is not applied for baseline pumps in this case). Thank you.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
November 10, 2017 - 1:26 pm
The flow rate is auto-sized in the baseline.
FOr the distribution of the baseline pump power I think the most logical way to do it is the 1/3 - 2/3 but you can model is any one of the three ways and it should be acceptable.
Jorge Torres-Coto
Building Systems Commissioning EngineerEmpirical Engineering, LLC
17 thumbs up
December 2, 2017 - 11:28 pm
This is a simple math problem that due to the interpretation and possible set up of the baseline can cause confusion. Basically all you have to do is either put every pump (primary and secondary) with 22 W/gpm efficiency. You can also add up all the gpm and make sure the total watts for the pumping is equivalent to 22 W/gpm. As I mentioned before, if you have auto sized the pumping and made sure that flow is the same for primary and secondary, it does not matter if you have 1/3, 2/3 or everything together. Mathematics is always precise and tells us that the order of the factors will NEVER alter the product. THE ONLY ISSUE YOU WILL HAVE IS EXPLAINING IT TO THE REVIEWERS. As long as you present it in a manner that is logical clearly explains that you are meeting the ASHRAE requirement of distributing evenly the flow on all pumps. And yes, that means total flow for primary and secondary added up will be 22W/gpm.
JamieDamon Damon
May 8, 2020 - 5:32 pm
Either you distribute one-third power for primary and two-third power for secondary pumps or if you use, the second option , it’s exactly the same thing. But keep in mind that the total flow will be 22W/gpm for both pumps. My situation is a little bit different than yours, and I ordered a water pump from https://www.grabe.com.br/ but I didn't receive it yet. My brother purchased industrial equipment from them for his plantation. I can't wait to receive it and put it to the test because I've heard only positive reviews from him about this company.