[Equest-users] FW: Number of systems required by 90.1?

[Paul Riemer]

James,
I agree addendum u seems is the only big direction in Appendix G, and LEED-NC 2.2 applicants can elect to follow it or not.  Addendum u changed G3.1.1 but not its exceptions.  In 90.1-2007, G31.1 includes addendum u and some changes to the exceptions.
I think the exceptions to G3.1.1 should also be reviewed from which ever version.  I have pondered occasionally if they are allowed exceptions or dictated/mandatory exceptions,  and I am leaning more toward the latter recently.
(If by some odd chance you were referring to the ECB method, I prescribe a baseline system for each proposed system.)
If you have to or choose to have different system alignments, then be conscious of keeping OA constant and all those parameters that vary by system size like fan power, heat recovery, economizer, package cooling efficiency,  etc.
Paul Riemer
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Bill Talbert
Sent: Wednesday, December 10, 2008 12:01 PM
To: James Hansen; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] FW: Number of systems required by 90.1?

James,
90.1-2004 addendum u includes the 'one system per floor' wording for systems 5 thru 8, but floors can be grouped when the thermal blocks are similar. For LEED, it is optional to use addenda. 90.1-2007 adopts the same wording.
Regards,
Bill


Bill Talbert, PE, LEED(r) AP
Mechanical Systems
Phone: (608) 441-6677
E-mail: btalbert at aeieng.com

Affiliated Engineers Inc.
5802 Research Park Blvd.
Madison, WI. 53719
Tel. (608) 238-2616
Fax. (608) 238-2614

>>> "James Hansen" <JHANSEN at ghtltd.com> 12/10/2008 11:45 AM >>>
Thanks for your response Richard.

Can anyone confirm whether ASHRAE 90.1-2007 specifically says that your Baseline model MUST have a system per floor?

I can't seem to find it in 2004, or the user's manual, or in the LEED-NC reference guide.

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://console.mxlogic.com/redir/?IKnspLtASC--ZtVVMS028AVDPgVv3t-LtxYQsLTjvhdTd-bd_iptKDNEn8lrxrW0E-l9QWIf8dOfgB0zM04SCCUqem3qaqrNEVpjhKedLCzAS2_id41Fr6xpLWjbJQ-d3iWq81s1kzh0q80oSGg-9EwGWq8a5GjZmxEwzUITafE6y0wmd41EVLO98TfM-u0USyrjdFLLLnuuudQ0SQnqYMFSB->

From: Richard Ellison [mailto:REllison at southlandind.com]
Sent: Wednesday, December 10, 2008 11:53 AM
To: James Hansen
Subject: RE: [Equest-users] Number of systems required by 90.1?

I interpret ASHRAE to suggest one should use 5 AHUs for just the reason you mentioned.  They are different because of different exposures.  One has slab and one has roof.  The external load would be different as would the return plenum temperatures.  One might be able to group floors 2-5 energy wise but I recall reading, perhaps in 2007 where they specifically meant on per floor for the baseline.  I always have at least one AHU per floor in my baseline models.  Using only one AHU would be cheating a bit.  This would be the same logic that says one must zone rooms with different occupancies or schedules separately.

RICHARD ELLISON
Energy Engineer
Southland Industries
22340 Dresden Street, Suite 177
Dulles, VA 20166
Office: 703.834.5570
Direct: 703. 834.2438
Fax: 703.834.5572

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of James Hansen
Sent: Wednesday, December 10, 2008 11:40 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Number of systems required by 90.1?

I'm working on a model of a 5-story building - my Proposed system is floor-by-floor chilled water AHUs connected to a water-cooled chiller central plan.  Airside is shutoff VAV boxes with hot water reheat.

For the size of the building, the baseline model is almost identical.  It is System 7 - Packaged rooftop VAV system with reheat boxes, chilled water, hot water boilers.

My question is whether or not the Baseline model has to have a single system for the building, or should it have 5 separate RTUs (doesn't really make any sense) since my proposed building has 5 systems?

I'm pretty sure the answer is that the Baseline should just have one packaged RTU for the building, but it actually makes a big difference on energy use.  By breaking the systems down into one-per-floor, as is the case with the proposed model, I end up saving a LOT of energy, possibly because the 1st floor is slab-on-grade, and the 5th floor has a roof.

Just wanted to make sure I have the correct number of "systems" for the Baseline model.

Thanks!

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://console.mxlogic.com/redir/?IKnspLtASC--ZtVVMS028AVDPgVv3t-LtxYQsLTjvhdTd-bd_iptKDNEn8lrxrW0E-l9QWIf8dOfgB0zM04SCCUqem3qaqrNEVpjhKedLCzAS2_id41Fr6xpLWjbJQ-d3iWq81s1kzh0q80oSGg-9EwGWq8a5GjZmxEwzUITafE6y0wmd41EVLO98TfM-u0USCrjdFLLLnuuudQ0SQnqYMFSB->
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