[Equest-users] Table G 3.1.3.7

[Hall, Brendan]

I've always thought that this was an error in table G3.1.3.7 in the SI version but I don't know if it was fixed. In the IP version of 90.1 if your building cooling load is over 600 Tons, you should use " 2 water cooled chillers minimum with chillers added so that no chiller is larger than 800 Tons, all sized equally". Notice that the SI table column header says "Building Peak Cooling Load" but then lists areas. Maybe there is a reason for it that I don't know but it seems incorrect to me.



Brendan Hall,  PE, LEED AP BD+C
Engineer, Mechanical
karpinski
ENGINEERING
3135 Euclid Avenue
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From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Rakesh Desai
Sent: Thursday, October 17, 2013 8:58 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Table G 3.1.3.7

Dear All,


1.        I had submitted energy model for certification and have received following reply:

As per table G3.1.3.7, ASHRAE 90.1.2007, "as chiller auto size capacity is more than 600 tons, centrifugal chiller should be considered".

My building conditioned area is < 22296 m2 and as per model my chiller capacity is more than 600 TR and I have to use 2 chillers. I have modeled 2 nos. screw chillers of equal capacity (auto size mode) with 5.5 COP.

I checked the table and no where it is written that we need to model centrifugal chillers.

Can someone help me to understand where I went wrong?


2.        I had submitted PS E report of all rotations of base case and have received following reply:
Peak demand (946.52kW) reported for cooling is not matching with chiller input (For 2*613 TR and 5.5 COP, 783kW). So cooling savings in not justified.

As per first submittal comment, I had changed my chiller to auto size mode and the chiller capacity is selected by model and not by me. Now, I have received above comment. What is the way out?



Thanks,

Rakesh Desai
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