Dear All,
My proposed model includes a 250 sq.ft. server room with 11,44 kw of
installed equipment (nameplate power). I assume that these will be running
24/7/365 with full power and giving away 100% sensible heat (noting these
to get your reactions on my assumptions as well).
This space is cooled by a 25 kW precision cooler with a COP of "1". With
such performance, this is a big time loser against what I am modeling for
the same space in the baseline with System 3. Actually, the SSH report
tells me that the precision cooler is using 90000 kWh p.a. for cooling
compared to 32600 kWh in the baseline model. However, we all know that in
real life such systems will never be used for server rooms.
Isn't this unfair? I am still considering whether this cooling energy
should be part of the process energy. There is actually a CIR from 2003:
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4/11/2003 - Credit Interpretation Request
Kelley Engineering Center is in design as a 144,000 s.f. university
research and teaching building. This project includes a 2200 s.f. data
center with racks of servers, and a uninterruptible power supply room.
This area has dedicated cooling equipment to extract the heat produced by
all of the electronics. Given the nature of the space, and the purpose of
the cooling equipment, it appears to meet the definition of a process
load, and can be excluded under ASHRAE 90.1 from the energy cost budget
for this credit. Do you agree with this interpretation?
5/5/2003 - Ruling
Yes, as described the dedicated server room air conditioning equipment
fits the ASHRAE 90.1-1999 definition of "process load." As such it can be
excluded from the project's Energy Cost Budget.
------------------------------
What do you think about this? What are your experiences with server room
air conditioning and modelling for LEED?
Thanks for all the answers and happy weekend,
Omer Moltay, LEED AP
As far as assumptions go you'll have to evaluate for yourself if the nameplate power consumption is the appropriate value for 24/7 operation.
That CIR is from LEED 2.1 which used ASHRAE 90.1-1999 and the energy cost budget method, where process energy (at whatever percentage) was not included in the savings calculation. Personally I agree that cooling provided only for a process, could also be treated as process energy. However the newer versions of LEED specifically include process energy in the savings calculations. If you are using LEED 2.1, go ahead and stop here.
This CIR and methodology do not apply to LEED NC 2.2 or 3.0 which include all process energy. 25% is a minimum, and the project should include the expected amount of process energy if it is greater than 25%. Treatment of the server cooling system as process energy won't gain you anything...the percentage calculation will be the same under 2.2 or 3.0.
The part of your question that I don't understand is if your project is using LEED, why select cooling equipment with a COP of 1.0? Regarding your cooling system, it sounds like the equipment selection is not in line with the project goals rather than receiving a penalty from the rating system. If the selected precision unit is really the only option, it will have to be made up for elsewhere in the project.
David Eldridge, PE
As far as assumptions go you'll have to evaluate for yourself if the nameplate power consumption is the appropriate value for 24/7 operation.
That CIR is from LEED 2.1 which used ASHRAE 90.1-1999 and the energy cost budget method, where process energy (at whatever percentage) was not included in the savings calculation. Personally I agree that cooling provided only for a process, could also be treated as process energy. However the newer versions of LEED specifically include process energy in the savings calculations. If you are using LEED 2.1, go ahead and stop here.
This CIR and methodology do not apply to LEED NC 2.2 or 3.0 which include all process energy. 25% is a minimum, and the project should include the expected amount of process energy if it is greater than 25%. Treatment of the server cooling system as process energy won't gain you anything...the percentage calculation will be the same under 2.2 or 3.0.
The part of your question that I don't understand is if your project is using LEED, why select cooling equipment with a COP of 1.0? Regarding your cooling system, it sounds like the equipment selection is not in line with the project goals rather than receiving a penalty from the rating system. If the selected precision unit is really the only option, it will have to be made up for elsewhere in the project.
David Eldridge, PE
Hi David,
Thank you for taking the time to answer. Well, I was also curious about
the COP of "1", double checked it with the manufacturer's representative
and it turns out that they misprinted the brochures with EER instead of
COP. (EER = 3,41 when they wanted to say COP = 3,41).
Now we are not penalized any more.
Thanks,
Omer Moltay, LEED AP
As far as assumptions go you'll have to evaluate for yourself if the
nameplate power consumption is the appropriate value for 24/7 operation.
That CIR is from LEED 2.1 which used ASHRAE 90.1-1999 and the energy cost
budget method, where process energy (at whatever percentage) was not
included in the savings calculation. Personally I agree that cooling
provided only for a process, could also be treated as process energy.
However the newer versions of LEED specifically include process energy in
the savings calculations. If you are using LEED 2.1, go ahead and stop
here.
This CIR and methodology do not apply to LEED NC 2.2 or 3.0 which include
all process energy. 25% is a minimum, and the project should include the
expected amount of process energy if it is greater than 25%. Treatment of
the server cooling system as process energy won't gain you anything...the
percentage calculation will be the same under 2.2 or 3.0.
The part of your question that I don't understand is if your project is
using LEED, why select cooling equipment with a COP of 1.0? Regarding
your cooling system, it sounds like the equipment selection is not in line
with the project goals rather than receiving a penalty from the rating
system. If the selected precision unit is really the only option, it will
have to be made up for elsewhere in the project.
David Eldridge, PE