[Equest-users] Baseline Fan Energy Very High

[David Eldridge]

What's the ratio of the kW/cfm for the two cases, and the ratio of total cfm?

i.e. as you are proposing, if the two systems run at the same sequence of operation to get a 6x factor of reduction you'd have to be some combination of 2x the cfm in the baseline and 3x the power use per CFM - if that's not accurate then the likely culprit is the sequence which may be allowing the proposed case to run fewer hours or running much longer at part-load if the proposed case has that capability - maybe add a report to see the load profile for the two cases.

Another check is that unmet hours and temperature plots in the SS-O report were consistent between the two cases providing equal comfort. Reviewing the SS-O can help you find an instance where the temperature control sequence isn't equivalent resulting in more runtime for the baseline case.

A third check - were the two cases showing reasonable increase in efficiency for the proposed case of the other end-uses for cooling, heating, lighting, etc - verify there isn't a stray heat gain causing increased run-time in one case.

David


David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP
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From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Jeff Ross-Bain via Equest-users
Sent: Sunday, July 21, 2019 2:05 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Baseline Fan Energy Very High

Hi All,
To those of you who regularly and graciously contribute your knowledge to this site, we all owe you a huge debt of gratitude. Thank you.

I am stumped. Usually, in my experience, following the standard Baseline process of establishing [ASHRAE max] fan power and applying that value to eQuest in kW/cfm, the resulting difference between Baseline and Proposed is evident but not super big.

In this case, on a small project with 6 x under 5-ton split HP systems, the Baseline fan energy use is, like, over 6 times bigger than the Proposed. I have exhausted every check and iteration I can think of and cannot find out why or how this occurs. As-is, the energy savings is incredible on fan power alone and I know it is not right.

Any thoughts or similar experiences with this circumstance?

Thanks!

Jeff Ross-Bain, BCxP, BEMP, LEED Fellow, MSc
President

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