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NC-2009 EAp2:Minimum Energy Performance

Pumps: Balancing Report HPs vs Design

Hi there

Can we use our pumps Balancing/Start Up Report Hp's rather than the Design? Or does LEED/Ashrae require us to model at design conditions (since Balancing/Start Up Report are instantaneous operating conditions)?

Many thanks

 

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Marcus Sheffer
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7group / Energy Opportunities
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Fri, 05/18/2018 - 13:09

You should use the BHP in the design or the BHP of the installed if it is known and there is a difference.

Sat, 05/19/2018 - 15:54

Hi Marcus Thanks for the reply, appreciated. A follow on thought, if you dont mind. When we fully balanced the system, the HPs are less than the Designed/Installed (Pumps that are correctly designed have additional HP to ensure that the pump is not undersized). Meaning all heat pumps were full open and balanced to receive design flow. So at any given point in the year, the pumps will not exceed the power provided on that balancing report as that is indicative of the entire building being operational. So cant we use the HP within the Start-Up/Balancing reports or does LEED not allow that? Or are we being thick :-) ? Very much appreciated

Sun, 05/20/2018 - 10:15

Dear Gaston, I think, you always need to model your proposed building as per actual information/data available. What is the HP required by the pump at 100% load? what is the efficiency of your motor at that HP? Dividing this HP by the motor efficiency, is the maximum electrical power input that your pump will consume. Here motor size does not matters. (unless you have plan to change the pump in future). You have to consider this input power in W/gpm. Someone else may have better answer than this ;)     
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Marcus Sheffer
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Mon, 05/21/2018 - 16:41

Gaston and Pawan what you are both describing sounds like the brake horsepower (BHP) to me. So the short answer to the original question is that you can use this testing information as I would assume that it gives you the BHP.

Wed, 06/20/2018 - 16:31

Hi Marcus Apologies for the delay, super appreciate/appreciated your input (and Pawan). We benched this item but we now need to get it back on the field to attain the potential savings. Yes, thats correct, the balancing test gives the BHPs for the pumps in question. So our plan here is to deploy the BHPs from the tests as its ''real'' data (as opposed to our spec data). Just to confirm, in your opinion we can do this right? Lastly, there is one more hurdle on this. When we model in eQuest the BHPs, the efficiencies for some go greater than 1. We think by adding the norm 15% capacity (saftey margin, losses etc) to the BHPs will generate the efficiency that these pumps should have given their spec (c90%), which allows the model to run and generate the savings we need to get this build over the Min. line. Any comments/thoughts on this? Again, super appreciated Best Gaston
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Marcus Sheffer
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7group / Energy Opportunities
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4454 thumbs up

Wed, 06/20/2018 - 19:01

Yes you can use the installed data instead of the design data. Sounds odd that the efficiency would go above 1. You should definitely not increase the capacity as then you would not be modeling the BHP as installed. As I recall you should have some choices about the pump efficiency, standard, premium, etc. and should select the one that applies. This should be an input where you enter the actual efficiency or it assumes an efficiency based on a selection like standard/premium. 

Wed, 06/20/2018 - 19:54

Hi Marcus Again, huge thx for your time in responding, appreciated. Ok great, we were getting mixed responses on this one. Re the >1, yes, an odd one indeed.  Given what you have said on that, we will deep dive back into the Why this is happening...probably something opaque and maybe stupid on our part. If it still exits, you points are strongly not to add in a % overhead capacity (to account for safety margin, VFD losses etc), right? We couldn't do that and supply a strong narrative as to why we did as it would be rejected by the reviewer? Big thx again Gaston  
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Marcus Sheffer
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7group / Energy Opportunities
LEEDuser Expert
4454 thumbs up

Wed, 06/20/2018 - 20:11

Regarding the use of installed data I can tell you with certainty that it will be accepted by the reviewer. In fact if you do an energy model based on the design, technically you are supposed to make changes to it if anything happened during construction that would significantly affect the energy use. The reason I say you should not add capacity is because the proposed model must be modeled as designed/installed. You should never be adding additional capacity to the proposed systems like you do in the baseline. If I was your reviewer I would reject such an argument.

Wed, 06/20/2018 - 20:16

Hi Marcus Ok noted, will explore the odd eQuest item then. Many thx again  

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