Hello everyone,
We are having a datacenter project which requires both cooling and heating as the outdoor temperatures vary from -20 degree C to 45 degree C.
Now, in proposed system, we have air cooled chillers for critical rooms and VRF systems for other critical rooms serving both cooling and heating functions.
I am struggling to understand whether there will be 2 different baseline systems to be considered for cooling and heating as baseline is falling under System 8?
Thanks in advance.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5925 thumbs up
January 29, 2025 - 12:16 pm
Do any of the exceptions to G3.1.1 apply? If so you could end up with two different baseline systems. Make sure to subtract off the area applied in the exception and then reenter table G3.1.1A.
Anurag Ghosh
January 30, 2025 - 12:29 am
Hi Marcus, Thankyou for the reply.
I would request further clarifications on the process loads in exceptions which is asked to differ by 31.2 W/m2 or more from average of other spaces served by the system for System 3 or System 4 to be applicable.
Is this process load talking about equipment power density EPD (W/m2) or the peak cooling loads observed in various zones after cooling load simulation?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5925 thumbs up
January 31, 2025 - 1:08 pm
It is peak thermal load so not EPD. In this case yes it would be peak cooling load. Keep in mind which part of the project you are applying this exception toward. If this is a typical data center it has very large area that contains the IT equipment and a smaller area of office that houses the people. In that case the exception gets applied to the smaller area of the two, so typically it would be applied to the office area and not the IT area for example.
Anurag Ghosh
January 31, 2025 - 10:59 pm
Hi Marcus, thanks for the clarification.
I have 2 things to clarify here now:
1. It is said the thermal loads should differ by 31.2 W/m2 or more from the average of other spaces served by system. What is this average considered as peak cooling load differs for each and every zone
2. I would further like to understand whether the applicability of this exception for additional baseline system types of 3 and 4 (based on thermal loads) depends on the particular functionality of the whole building. Like for example, in hospitals and commercial towers,the baseline exception gets applicable to zones like Electrical/ELV/UPS battery rooms based on the peak cooling loads differing from average of 31.2 W/m2. Am I interpreting it correctly now?
Would appreciate your suggestion on the above 2 points and thanks in advance.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5925 thumbs up
February 2, 2025 - 10:49 am
1. Not sure I am undertstanding your question. Peak is not the average, it is the highest level of cooling load throughout the year.
2. Yes that would certainly be possible. SInce those rooms are small components of the overal building area the exception would apply to them.
Anurag Ghosh
February 2, 2025 - 11:12 am
Hi Marcus,
What I meant by the first point "It is said the thermal loads should differ by 31.2 W/m2 or more from the average of other spaces served by system. What is this average considered as peak cooling load differs for each and every zone" is whether the applicability of the exception for baseline systems 3 or 4 depends upon peak cooling loads in these smaller zones differ by 31.2 W/m2 or more from rest of the bigger space(based on functionality of building)?
Is that what ASHRAE 90.1 trying to say?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5925 thumbs up
February 3, 2025 - 4:34 pm
It is not zones, it is spaces. It is hard to reply to what you are asking without specifics, but I would not try to make it more complicated than necessary. The data center portion of the project has a much greater peak cooling load than other portions of the building so the exception would apply to those other portions. If some portions of the data center are in different spaces you could take the average of the peaks for your determination. Conversely if the other spaces vary slightly you could take an average of those peaks as well.
Anurag Ghosh
February 26, 2025 - 11:13 am
Hi Marcus, I would like to raise a point here.
1. So, we are first asked to segregate the spaces based on functionality and larger area. For example, in a commercial space like mall, we have these machine rooms like UPS/electrical/ELV battery rooms, which occupy a small proportion of area in the whole mall space and hence the exception apply to these rooms.
2. Now secondly, we find the average of peak thermal loads for these rooms. Then find whether the peak thermal loads for each of these rooms differ by 10 btu/hr/sqft from average peak thermal load.
Am I right now in interpreting this exception?
Thankyou in advance.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5925 thumbs up
February 26, 2025 - 12:36 pm
Sounds right to me, also note that the variation can be by schedule difference. So in a multifamily residential building with first floor retail the schedule difference would be the rationale for applying the exception to the retail spaces.
Anurag Ghosh
February 26, 2025 - 8:37 pm
Got it. Appreciate your explanation.