A Question about chilled water usage

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I'm looking at utility data for a building on a college campus that has a central utility plant. They list cooling energy in ton-hrs and It seems really high for all buildings across the board.

However - if you assume that ton-hrs is the metered chilled water usage and not the chiller energy, its not that bad. For example if the chilled water usage is 1 ton-hrs, that's 12,000 BTU's of cooling energy delivered. However, if whats being measured is chilled water usage (and not chiller energy), then 1 ton-hr is not the energy consumed by the chiller - that should be 12,000BTU/COP of the chiller. So if the chiller COP is 4 - then that's only 3,000 BTU's of energy consumed to deliver that ton-hr.

So - to get to the point - does anyone know if campuses monitor their chilled water usage (in ton-hrs) as chiller energy or cooling delivered?

(I hope this makes snese)

Vikram Sami, LEED AP

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I've usually seen this metric as chilled water usage at the building vs.
chiller energy. This goes in line with installing a Btu meeting for a
campus chilled water system, so you can define the chilled water energy
used at the building, similar to district steam.

Mark Nieman, PE, CEM

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Dear Vikram,

I think that the definition of ton-hours is inherently an "cooling energy
delivered" or "useful energy", metric.

James V. Dirkes II, P.E., LEED AP

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Vikram:
?
I agree with James. Chiller energy would be measured in electric or gas units
(energy input)..
?
Ton-hours is a load (useful energy) function.
?
John R. Aulbach, PE, CEM

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