[Bldg-sim] thoughts on App G system type for mixed use building

Wed Mar 10 12:48:38 PST 2010

James,

It has been awhile since I have really looked at 90.1-2007, but your space type has no bearing on what the system type is going to be.  You just need to know whether your building type is res or not, this should be whole building.  Seeing that you reference 2004 and assuming your project is 2.2 (also you should be referencing the actual standard not the manual for finality), you should be using system 5 or 6 due to the square footage.  I got jammed up on the square footage vs. number of floors once myself.  I got reviewed on a job where the building was one floor and 80k sqft but I had used system 3.  When I changed to system 5 the savings doubled, I resubmitted and since the project was on the cusp of silver to gold, they got gold instead of the expected silver.  I am assuming everyone was just glad things worked out there.

Secondly, I don't think whether the space is conditioned or not matters either. G expects all spaces to be conditioned.  I say again, it has been awhile since I have thoroughly looked at this standard and I know a few people have quarks about the whole space conditioning expectations (just trying to get some good discussion going) seeing as how us HVAC/energy guys are so stuck on carbon-based realties.  But, in reality (and to answer your question), the entire charade is all up to interpretation anyways :)

________________________________
From: James Hansen [mailto:JHANSEN at ghtltd.com]
Sent: Wednesday, March 10, 2010 2:39 PM
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] thoughts on App G system type for mixed use building

I can't find an addenda on this, but which publication is correct for defining the baseline system of a non-residential building less than 3 stories?

The base 90.1-2004 document says that if the building is 3-stories or less AND < 75,000 sq ft, System 3 and 4 are to be used.
The User's Manual, on the other hand, says "For smaller non-residential buildings that are less than 75,000 ft2 (any height) OR less than three stories (any area)"...the baseline system is PSZ (System 3 or 4)

Which is correct?

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<http://www.ghtltd.com/>

From: James Hansen
Sent: Wednesday, March 10, 2010 12:45 PM
To: 'Gregg Liddick'; bldg-sim at lists.onebuilding.org
Subject: RE: thoughts on App G system type for mixed use building

Thanks Greg, but based on the heating density, I can't classify these as semi-heated.

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<http://www.ghtltd.com/>

From: Gregg Liddick [mailto:gliddick at theepstengroup.com]
Sent: Wednesday, March 10, 2010 11:21 AM
To: James Hansen; bldg-sim at lists.onebuilding.org
Subject: RE: thoughts on App G system type for mixed use building

Hi James,

It sounds like the storage and workshop area may be semi-heated as defined by Section 3.  I'd recommend looking into that.  If the spaces are semi-heated then they should be modeled only with heating in the baseline case and the requirements of Table G3.1.10 don't apply.  It's also worth noting that if the spaces are semi-heated they should be modeled with different envelope values in the baseline case (based on the semi-heated in Table 5.5).

Best Regards,

Gregg Liddick, EIT, LEED(r) AP

The Epsten Group, Inc.
429 Edgewood Avenue
Atlanta GA 30312
Phone: 404-577-0370  ext. 102
Fax: 404-577-1739
www.theepstengroup.com<http://www.theepstengroup.com>

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From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of James Hansen
Sent: Wednesday, March 10, 2010 11:02 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] thoughts on App G system type for mixed use building

I've got a 92,000 square foot Industrial building that I am modeling.  If you went by Table G3.1.1A, the baseline system type would be System 5 - Packaged VAV with reheat.

However, of the 92,000 square feet, approximately 16,000 sq ft is conditioned to standard 75/72 degrees, while the remainder is a mixture of storage, manufacturing, etc, and is heated to 55 and cooled to 120 (no actual cooling in proposed model, but you've got to insert some sort of cooling system per App G).

So I really have 16,000 sq ft that is fully conditioned, and 76,000 sq ft that is only partially conditioned (ie the peak thermal load differs by 10 Btu/h-ft2).

Any guesses how I configure this?

Do I have a packaged VAV system for the 76,000 sq ft of shop/storage and isolate the 16,000 ft2 of real conditioned space as system 3 per the Exception to G3.1.1?

Or do I have a packaged VAV system for the 16,000 ft conditioned space and isolate the 76,000 sq ft as system 3?

To further complicate things, since the 76,000 sq ft is split between storage and manufacturing, where there is theoretically an operating schedule that differs by 40 hours or more a week between these two different use types, do I actually just end up with ALL system 3 even though the total net building area is above the 75,000 sq ft cutoff where we're supposed to go to System 5?

I'm confused!  Any help would be appreciated.

To recap:

16,000 sq ft office, heated/cooled to 72/75
30,000 sq ft of storage with basically no operating hours per week, heated/cooled to 50/120
36,000 sq ft of manufacturing / workshop area that is used approximately 50 hrs a week, heated/cooled to 50/120

Mixture of System 3 and System 5, or ALL system 3?

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<http://www.ghtltd.com/>

________________________________
The information contained in this communication is confidential, may be privileged, and is intended only for the use of the addressee.  It is the property of GHT Limited.  Unauthorized use, disclosure or copying of this communication or any part thereof is strictly prohibited and may be unlawful.  If you have received this communication in error, please notify me immediately by return e-mail or by e-mail to ght at ghtltd.com<mailto:ght at ghtltd.com>, and destroy this communication and all copies thereof, including all attachments.  Thank you.

________________________________
The information contained in this communication is confidential, may be privileged, and is intended only for the use of the addressee.  It is the property of GHT Limited.  Unauthorized use, disclosure or copying of this communication or any part thereof is strictly prohibited and may be unlawful.  If you have received this communication in error, please notify me immediately by return e-mail or by e-mail to ght at ghtltd.com<mailto:ght at ghtltd.com>, and destroy this communication and all copies thereof, including all attachments.  Thank you.
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