[Bldg-sim] [Equest-users] Precision Cooler - Big Disadvantage in Comparison to Baseline?

[David S Eldridge]

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
____________________________________________________________________________________________________________________

David Eldridge, PE
LEED(r) AP BD+C, HBDP

Grumman/Butkus Associates | 820 Davis Street, STE 300 | Evanston, IL 60201 | Ph: (847) 328-3555, ext 224 | Fax: (847) 328-4550

Energy Consultants and Design Engineers
____________________________________________________________________________________________________________________





>
> 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:
>
> --------------------------
> 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.
> ------------------------------