[bldg-sim] Turning one number into four..

Aulbach, John jaulbach at nexant.com
Thu Feb 8 14:54:10 PST 2007

Hi all:

The infamous "one equation, four unknowns".  Namely, IPLV (or NPLV, if
you are of that persuasion).

Utility incentive Programs and LEED say to use an ASHRAE 90.1-2004 code
chiller with a COP of xx and an IPLV of xx. As I understand it, IPLV is
a curve created as a standardization to compare chiller part load
characteristics, one to another.  However, no analysis program that I
know of (certainly not of the DOE-2/eQuest flavor) can extract such a
curve from a single number.

I believe you are losing out if a new high efficiency chiller with a 4
mile long condenser (just kidding) happens to perform quite well at part
load. You will not get a fair comparision, only the default program

Is there some accepted ASHRAE magic that will take an IPLV number and
make the 75%, 50%, and 25% kW/ton numbers, so that a true "apples and
apples" comparison between a code chiller and a super chiller can be

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