[Equest-users] Chiller ROI - HELP!

[Brett Sanicola]

I've been attempting to calculate a simple ROI for a new 250 ton chiller
our client wants to install to replace his older chiller.  I ran the
simulation for the default "high rise hotel" construction which, to my
luck, is quite similar to the actual building.  The detailed results,
however, are not making sense to me.  Specifically, when I look at
Equipment Loads and Energy Use for the Chiller, the Elec Use and Cool
Load don't coincide given the default Chiller efficiency of .67kw/ton.
For example they give a Chiller Elec Use of 535453 KWH and a Cool Load
of 3294 MBTU.  However, according to my calculations, at .67KW/TON,
535453 KWH should give me closer to 9590 MBTU.  I see most of the hours
are in part load range, but does the efficiency drop off that
dramatically at part load that it would explain the discrepancy?  Which
numbers should I base my analysis on, the Cool Load number or the Elec
Use number.

 

Also, on the same page (Equipment Loads and Energy Usage), it gives me a
peak load of 2436 KBTU/HR.  However, when I go to the section titled
"Building Peak Load Components" the peak cooling load is significantly
less (1619 KBTU/HR)

 

At this point, I have no idea what any number represents, since I don't
know how it was calculated.

 

I greatly appreciate any help!  Thanks.

 

Respectfully,

 

Brett Sanicola

Engineer

ASB Engineering

(516) 785-4200

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