Data Center Baseline System Questions
We are modeling a large data center for LEED V4 using the ASHRAE 2010 appendix G as the baseline. The selection of baseline system is not completely clear to me and I was hoping for some guidance. By number of floors (1) and area (very large) alone the building would be system type 8.
The building can further be broken down into an admin portion (typical spaces types of an office/PDR type building) and data center portions, each of which is over 150,000 ft2, though the data center dominates in area by far.
How should exceptions a and b to G3.1.1 be applied in this case?
We are currently applying system 8 to the data center portions and system 4 for all other zones. In my mind it would be more appropriate to essentially treat the admin and data center spaces as if they were on different floors (i.e. give each a system 8 and remove individual zones form those systems based on load/schedule diversion).
It seems like this has been cleared up in 2013 with an additional exception, but I would love to hear from anyone who has had success submitting whole building energy models of large data centers for LEED v4.
Two somewhat related questions:
1) Table G3.1.1B gives systems 1 - 4 as CV, should this have an note saying something like "unless system meets requirements of 6.4.3.10 a or b," in which case it would have a variable or 2 speed fan?
2) When removing systems that differ in the average load according to exception b to G3.1.1, does the average need to be recalculated every time after a zone has been removed? e.g. zone loads (Btu/h ft2) = 100, 40, 10, 10, 10, average load = 34, so remove zone with 100. Now if average of all zones remaining on the system is calculated, ave = 17.5, so zone with 40 should also be removed?
Thanks.
