[Bldg-sim] A Question about chilled water usage

[John Aulbach]

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
Senior Energy Engineer

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PartnerEnergy
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________________________________
From: "James V Dirkes II, PE" <jvd2pe at tds.net>
To: "Sami, Vikram" <Vikram.Sami at perkinswill.com>; 
"bldg-sim at lists.onebuilding.org" <Bldg-sim at lists.onebuilding.org>
Sent: Fri, September 10, 2010 2:30:19 PM
Subject: Re: [Bldg-sim] A Question about chilled water usage


 
Dear Vikram,
I think that the definition of ton-hours is inherently an “cooling energy 
delivered” or “useful energy”, metric.
 
The Building Performance Team
James V. Dirkes II, P.E., LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653
 
From:bldg-sim-bounces at lists.onebuilding.org 
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Sami, Vikram
Sent: Friday, September 10, 2010 4:23 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] A Question about chilled water usage
 
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
Sustainable Design Analyst
1382 Peachtree St. NE, Atlanta, GA 30309
t: 404-443-7462    f: 404.892.5823       e: vikram.sami at perkinswill.com   
www.perkinswill.com
Perkins+Will.  Ideas + buildings that honor the broader goals of society
Years of Design Innovation
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