[Equest-users] Modeling Typical IT Rooms AC Units

[Rob Hudson]

To add to all the fun and confusion, i had this same conversation a few
weeks ago with other LEED people in my office.  My interpretation is that
equipment rack room and IT closets fall into an exception of 90.1, more
specifically Section G3.1.1 Baseline HVAC System Type and Description:

Exception b.  If the baseline HVAC system is type 5, 6, 7 or 8, use separate
single zone systems ... for any spaces that have occupancy or process loads
or schedules that differ significantly. ... Examples where this exception
may be applicable include, but are not limited to, computer server rooms,
...

Per this statement, you need to model the IT HVAC equipment as its own
system type 3/4 and give it the appropriate efficiencies.  Unfortunately
this means that most LEED models with IT spaces that are small get penalties
due to the equipment, as everyone has suggested.

Hope this sheds more light!

--Rob

On Tue, Jun 28, 2011 at 1:39 PM, Nick Caton <ncaton at smithboucher.com> wrote:

>  I should be quick to emphasize:  I’m only relating some personal
> experience here for others’ benefit and to constructively add to the
> discussion.  I appreciate James’s perspective and accept there are probably
> a few good reasons for the way things are in the world of DX data center
> cooling, considering the environment and physical limitations.  It seems
> obvious to me that 90.1 was not built to consider minimum efficiencies for
> this sort of equipment/environment, but that won’t stop others from trying
> to enforce the standard in spite of my opinions.  The section 2.3  reference
> is starting to make a lot of sense from this angle…****
>
> ** **
>
> That said, I don’t think it’s entirely unreasonable to expect some progress
> from the commercial industry either.  For smallish IT closets these days,
> perhaps a residential split with a high EER/SEER is really the way to go.
> For larger cases requiring high-static distribution or heavier capacities,
> I’m only advising that it never hurts to take stock of who/what’s out there
> and what might fit the budget/performance/efficiency requirements for the
> situation at hand.  If nothing truly “fits the bill,” at least we can rest
> easy knowing that’s the case and not wonder whether we missed a better
> option.****
>
> ** **
>
> An extra bit for Will and others considering HVAC systems as “process
> loads:”  this isn’t always so tricky as it might seem =)!  Rather than
> construe a custom fractional schedule to approximate the system’s energy
> consumption (like a plug load), there’s another approach:  submeter these
> systems and report separately on the LEED template…  Report PS-B will show
> the monthly consumptions/demands for the submeters after setting it all up.
> Following are some quick/rough screengrabs illustrating the concept/setup:
> ****
>
> ** **
>
> ****
>
> ****
>
> ****
>
> ** **
>
> ~Nick****
>
> [image: cid:489575314 at 22072009-0ABB]**
>
> * *
>
> *NICK CATON, P.E.***
>
> SENIOR ENGINEER****
>
> ** **
>
> Smith & Boucher Engineers****
>
> 25501 west valley parkway, suite 200****
>
> olathe, ks 66061****
>
> direct 913.344.0036****
>
> fax 913.345.0617****
>
> www.smithboucher.com* *****
>
> ** **
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Andy Phelps
> *Sent:* Tuesday, June 28, 2011 10:56 AM
> *To:* Will Mak; equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] Modeling Typical IT Rooms AC Units****
>
> ** **
>
> Will:****
>
> ** **
>
> I couldn’t agree more with you on Section 2.3.  However, what matters is
> not what I think, but the LEED/USGBC review team.  ****
>
> ** **
>
> In my experience, I’ve modeled data rooms in offices as a System 3/4 for
> the baseline and as scheduled for the design case.  I’ve modeled small rooms
> with a mini-split DX unit, and also for larger rooms with CRAC style units
> (Liebert, DataAire, etc).  I haven’t had any issues with this in the review
> process.  In addition, from some internet research, it appears that
> architects/engineers are getting large-scale data centers certified, so they
> must be wanting us to split data center HVAC usage from server/process
> usage.  ****
>
> ** **
>
> Sorry that I do not have any more insight than this, but I do understand
> your frustration with data rooms/centers and applicability to 90.1.  ****
>
> ** **
>
> I would also point you to some addenda for 90.1 that does mention data
> centers and outlines some requirements (addenda BU).  It looks like these
> Liebert units would meet the requirements for efficiency in this addenda.
> For the purposes of LEED certification, I would caution to read all addenda,
> since LEED doesn’t let you pick and choose addenda, there may be some
> addenda out there that might hurt your energy savings percentage.  ****
>
> ** **
>
> Andy****
>
> ** **
>
> ** **
>
> *From:* James Hansen [mailto:JHANSEN at ghtltd.com]
> *Sent:* Tuesday, June 28, 2011 10:36 AM
> *To:* Will Mak; Nick Caton
> *Cc:* equest-users at lists.onebuilding.org
> *Subject:* RE: [Equest-users] Modeling Typical IT Rooms AC Units****
>
> ** **
>
> Liebert is no less efficient than any of the other computer grade
> self-contained units out there.  The problem is that the units have to fit
> the niche that has been created for them.  They need to be no more than 3’
> deep to work with typical server room design, they have to generally have
> high static fans to pressurize under floor systems, and they have to be
> fully serviced from the front of the unit.  All of these have implications
> on the evaporator / condenser coil layout, and thus efficiency.  ****
>
> ** **
>
> There are certainly things that you can do to improve computer grade AC
> unit design (like using the ECM motors that have been popping up for a lot
> of manufacturers, and playing around with higher space temperatures), but
> ultimately, you’re never going to have a Liebert (or Stulz, etc) unit with
> an EER of 18. ****
>
> ** **
>
> Also, in almost all cases, the efficiencies you are getting from the
> manufacturer or manufacturer’s rep are probably based on the abnormal
> operating conditions of a server room (68, 70, 72 degrees) – make sure you
> are properly accounting for this in eQuest, as these are not ARI
> conditions.  ****
>
> ** **
>
> *GHT Limited
> **James Hansen, PE, LEED AP*
>
> *Senior Associate*
>
> 1010 N. Glebe Rd, Suite 200****
>
> Arlington, VA  22201-4749****
>
> 703-338-5754 (Cell)****
>
> 703-243-1200 (Office)****
>
> 703-276-1376 (Fax)****
>
> www.ghtltd.com****
>
> ** **
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Will Mak
>
> *Sent:* Tuesday, June 28, 2011 8:47 AM
> *To:* equest-users at lists.onebuilding.org
> *Subject:* [Equest-users] Modeling Typical IT Rooms AC Units****
>
>  ** **
>
> Hey all,****
>
> ** **
>
> I’m working on a LEED energy model for an office building that has a couple
> standard sized data rooms for server storage. They will be served by a
> couple air cooled Liebert units. I started inputting information about the
> units in the proposed design model and requested EER information from our
> vendor. The EER value was provided but also pointed me towards ASHRAE
> 90.1-2007 Section 2.3 as the reason why EER values aren’t typically provided
> for these types of units (he claims the cooling of the server rooms would be
> considered process cooling):****
>
> ** **
>
> ASHRAE 90.1-2007 Section 2.3 - The provisions of this standard do not apply
> to:****
>
> a.       Single-family houses, multi-family structures of three stories or
> fewer above grade, manufactured houses (mobile homes), and manufactured
> houses (modular)****
>
> b.       Buildings that do not use either electricity or fossil fuel, or**
> **
>
> c.        *Equipment and portions of building systems that use energy
> primarily to provide for industrial, manufacturing, or commercial processes
> *.****
>
> ** **
>
> I’ve typically model the scheduled units on the proposed design model and
> System Type 3 or 4 on baseline model. However, if the above Section 2.3
> applies, should we be modeling the systems that serve IT rooms in an office
> building as “process energy” and be equal?****
>
> ** **
>
> *William Mak, LEED AP BD+C*
> Mechanical Design Engineer
>
> *EPSTEIN*
> Architecture
> Interiors
> Engineering
> Construction****
>
> Sustainability
>
> 600 West Fulton Street
> Chicago, Illinois 60661-1259
>
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> F: (312) 429-8800****
>
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-- 
Rob Hudson
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