[Bldg-sim] LEED Kitchen/Laundry HVAC Systems

[Reba Schaber]

I don't have anything from USGBC, but I have some history from ASHRAE.  There are a series of interpretation requests to ASHRAE 90.1 about how handle AC systems serving primarily process loads.  It is clear that ASHRAE considers AC systems serving primarily process loads exempt from requirements of ASHRAE 90.1.  Since they don't have to meet minimum efficiencies, they need to be modeled the same when demonstrating compliance with ASHRAE 90.1.  See interpretation 4 about a theoretical central plant that is used mainly for IT cooling.

"The central plant is exempt from the requirements of Standard 90.1 and should be identical in both the Proposed Building Design and Budget Building Design."

The interpretation is worded for Chapter 11, which is another means to show compliance to the standard.  However it is interesting to note they are no longer applying this interpretation to Appendix G of 90.1-2007.  This seems like a logical progression sense Appendix G is meant to show energy efficiency not compliance.

"This interpretation also applies to Section 11 of 90.1-2007 as well as Appendix G of 90.1-2004 but does not apply to Appendix G of 90.1-2007."

Perhaps that knowledge may be helpful.

~Reba

From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Rob Hudson
Sent: Thursday, October 27, 2011 1:58 PM
To: Fred Betz
Cc: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] LEED Kitchen/Laundry HVAC Systems

I completely agree with you Fred.  This is the same logic that i followed.  Unfortunately my superiors do not agree with this logic, even though I have shown them the same exception that you mention.  Their logic states that process loads shall be the same in both models, and anything associated with process loads (such as cooling for a data room or exhaust/make up air for a kitchen) do not serve any purpose except for process and therefore is also process.

Does anyone have anything from USGBC clarifying this issue?  I have looked through the interpretations and nothing speaks to the HVAC equipment of process loads.

Thanks for the input so far,

Rob
On Thu, Oct 27, 2011 at 4:51 PM, Fred Betz <fbetz at aeieng.com<mailto:fbetz at aeieng.com>> wrote:
HVAC energy consumption caused by process loads cannot be called process loads. Nor would you want it to be a process load, because then you can't take credit for savings or at least not as easily.

Correct, your electrical or IT room with 90kW baseline is a system 3, and your Proposed can be an efficient design. ASHRAE 90.1-2007 G3.1.1 exception b allows you to apply system 3 for zones with large process loads.

This can be a huge source of energy savings. Enjoy it now, because rumor has it that the next version of 90.1 will set an alternate baseline for IT rooms and the like, and system 3 will no longer be applicable because the energy savings can be ridiculously large.



Fred Betz  PhD., LEED AP
Sustainable Systems Analyst



AEI | AFFILIATED ENGINEERS, INC.
5802 Research Park Blvd. | Madison, WI  53719

P: 608.236.1175<tel:608.236.1175> | F: 608.238.2614<tel:608.238.2614>
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From: Rob Hudson [mailto:rdh4176 at gmail.com<mailto:rdh4176 at gmail.com>]
Sent: Thursday, October 27, 2011 12:54 PM

To: bldg-sim at lists.onebuilding.org<mailto:bldg-sim at lists.onebuilding.org>
Subject: [Bldg-sim] LEED Kitchen/Laundry HVAC Systems

In the situation that a design is utilizing an efficient exhaust/make up air system, the LEED book says that an exceptional calculation may be used to help quantify savings.  This leads me to believe that the kitchen cooking equipment is process, but the HVAC equipment is not.  My office has been having a "discussion" about whether HVAC equipment that conditions air for process equipment is considered process as well.

Another example that is plaguing me:  an electrical rack room has 90 kW of stuff and requires 25 tons of cooling.  If i use an efficient design, can i take credit for it by comparing my design to a baseline of system 3 (PTAC w/ DX cooling and furnace heating)?  I believe that this HVAC system should be allowed to get credit, but others argue that because it serves process equipment, then it is "process" heating/cooling.

Any thoughts from LEED AP out there? (i'm still working on getting my LEED AP).

Thanks,

--
Rob Hudson



--
Rob Hudson
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