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?
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.
HI,
The type and number of chillers for system 7 & 8 (G3.1.3.7) states that you shall model the chillers as indicated on the table. The table shows if you have a peak building load of more than 600 tons you need to have 2 water cooled centrifugal chillers minimum with no chiller over 800 tons.(see attachments)
[G3.1.3.7.png]
[table g3.1.3.7.png]
For the kw they are simply taking the COP=Work done/Work input. So they are converting the cooling tons to kw and dividing it by the COP to obtain chiller demand.
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
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
The IP edition states "2 Water Cooled Centrifugal chillers minimum with
chillers added so that no chiller is larger than 800 tons, all sized
equally"
Byron D. Burns, EIT, BEMP
HI,
The type and number of chillers for system 7 & 8 (G3.1.3.7) states that you shall model the chillers as indicated on the table. The table shows if you have a peak building load of more than 600 tons you need to have 2 water cooled centrifugal chillers minimum with no chiller over 800 tons.(see attachments)
[G3.1.3.7.png]
[table g3.1.3.7.png]
For the kw they are simply taking the COP=Work done/Work input. So they are converting the cooling tons to kw and dividing it by the COP to obtain chiller demand.
Thanks,
Matthew J. Baron
Yes, thank you. Left that out of the transcription.