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

Wed Mar 10 12:11:01 PST 2010

90.1-2007 says "or", so I suspect that's the updated / corrected
understanding.  (Makes more sense, too.)

The Building Performance Team
James V. Dirkes II, P.E., LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653

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 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)

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

 <http://www.ghtltd.com/> 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, LEEDR AP

The Epsten Group, Inc.

429 Edgewood Avenue

Atlanta GA 30312

Phone: 404-577-0370  ext. 102

Fax: 404-577-1739

 <http://www.theepstengroup.com> 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)

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

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