[Equest-users] [Bldg-sim] ASHRAE 90.1 - Appendix G - Parking Garages

Dahlstrom, Aaron ADahlstrom at in-posse.com
Wed Jan 19 07:26:07 PST 2011


Fred:

I imagine the key question, like all the others, is whether the garage is enclosed and conditioned (or semi-heated).

If it's unconditioned and open to ambient, then its walls do not count as part of the exterior envelope.

If it's enclosed and conditioned, then its walls do count as part of the exterior envelope.

I could also imagine a situation where a garage was enclosed and had no heating / cooling system, but it was adjacent to conditioned space, in a way that made it an indirectly conditioned space.

Probably the most helpful resource I've found when trying to make these decisions is the ASHRAE User's Manual discussion of spaces and envelopes (pp 5-2 and 5-3 etc from the 2004 User Manual). Making the determination about indirect conditioning would require a careful parsing of where the insulation is and the overall relative u-a  heat transfer factors between the enclosed spaces and the potentially indirectly conditioned space. This is more fully described in the definition of conditioned space in the standard.

Basically, the key to this is figuring out what spaces in your building are conditioned and semi-heated, then drawing the line of the "envelope" around them, as per the User Manual.

What's in the envelope then becomes the basis for the window to wall calculation.

Aaron Dahlstrom , PE, LEED(r) AP
In Posse - A subsidiary of AKF| 1500 Walnut Street, Suite 1414, Philadelphia, PA 19102
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From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Fred Betz
Sent: Tuesday, January 18, 2011 11:14 PM
To: Bishop, Bill; Nick Caton; Richard Auffermann; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] ASHRAE 90.1 - Appendix G - Parking Garages

A semi-related question on parking garages.

If the parking garage is part of a high rise, does the surface area count towards the overall window to wall ratio calculation?

Please advise,

Fred

Fred Betz  PhD., LEED AP
Sustainable Systems Analyst



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

P: 608.236.1175 | F: 608.238.2614
fbetz at aeieng.com<mailto:fbetz at aeieng.com>  |  www.aeieng.com<http://www.aeieng.com/>



From: Bishop, Bill [mailto:wbishop at pathfinder-ea.com]
Sent: Tuesday, January 18, 2011 9:16 AM
To: Nick Caton; Richard Auffermann; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] ASHRAE 90.1 - Appendix G - Parking Garages

While parking garages may not be considered "spaces" per ASHRAE, I think lighting should still be modeled differently for baseline and proposed per Appendix G, and not considered a process load. "Lighting power for parking garages and building facades shall be modeled" per Table G3.1, and baseline lighting is determined per Section 9.2, where values for parking garage lighting power appear in both the Building Area and Space-by-Space Tables. You could attach these (different) lighting loads directly to a meter, as Nick suggests, if you don't model the parking garage as a space in the model.

~Bill

William Bishop, PE, BEMP, LEED(r) AP | Pathfinder Engineers & Architects LLP
Mechanical Engineer

[cid:image001.jpg at 01CBB7C2.1E7BCF40]134 South Fitzhugh Street                 Rochester, NY 14608
T: (585) 325-6004 Ext. 114                F: (585) 325-6005
wbishop at pathfinder-ea.com<mailto:wbishop at pathfinder-ea.com>           www.pathfinder-ea.com<http://www.pathfinder-ea.com/>
P   Sustainability - the forest AND the trees. P
________________________________
From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Nick Caton
Sent: Monday, January 17, 2011 6:07 PM
To: Richard Auffermann; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] ASHRAE 90.1 - Appendix G - Parking Garages


These definitions came up during review of one of my recent LEED projects.  For future reference, 90.1 questions may be seen by a group more keen to respond if you post to the [bldg-rate] list.



I've got a definite position if you'd like to hear:



1. As you point out, per the definition of "unconditioned space," parking garages are "...not considered enclosed spaces."  Whether in design it's actually conditioned or not has no bearing on this statement.



2. All of the definitions for space classifications, and indeed the definition for "space," start with "an enclosed space..."  Therefore no parking garage can be considered "conditioned" or "semiheated," or even as a "space."



3. This also means by extension (re: section 5.1.2): There are no envelope requirements for parking garages, as they are not "spaces" of any classification.



If you reject this approach and instead assert a parking garage can be a "conditioned space," you'd be forced down a path of assigning identical heating/cooling systems to parking garage spaces in both proposed and baseline models, per Table G3.1.1.b, regardless of whether it's actually conditioned or not.  Things might get hairy if you're only heating or only cooling (I believe the other would need to match the baseline serving the rest of the floor/building, as may apply).  I'd only suggest that requiring heating/cooling of parking garages in all climates seems odd for an energy efficiency standard - you'd have to explain that one to me ;).



If you do have heating and/or cooling for a parking garage design, I'd personally stick with points #1/#2 above and simply model such energies as a process load alongside any mechanical ventilation systems, identical in both models.



I personally use eQuest, and prefer to model parking garages as simply as a series of building shades with a series of process/lighting loads attached directly to the meter.



All this is my take on the situation.  I think it's pretty defensible, but there may have been CIR's I'm unaware of to the contrary - not that precedent matters anymore...



Hope that helps you and others,



~Nick


[cid:image002.jpg at 01CBB7C2.1E7BCF40]

NICK CATON, E.I.T.
PROJECT ENGINEER
Smith & Boucher Engineers
25501 west valley parkway
olathe ks 66061
direct 913 344.0036
fax 913 345.0617
www.smithboucher.com


-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Richard Auffermann
Sent: Monday, January 17, 2011 3:44 PM
To: bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] ASHRAE 90.1 - Appendix G - Parking Garages



I have a questions about the modeling of Parking Garages for ASHRAE 90.1 Appendix G energy model



As I was looking up the definition of a conditioned and semi-heated space in Section 3 of ASHRAE 90.1 I noticed that under the definition of an "unconditioned space" it states that "Crawlspaces, attics, and parking garages with natural or mechanical ventilation are not considered enclosed spaces." In addition the definition of "ventilation" is "the process of supplying or removing air by natural or mechanical means to or from any space. Such air is not required to have been conditioned." Since the air is not required to be conditioned then the air can or cannot be conditioned, does that mean that any parking garage conditioned or unconditioned is not considered an enclosed space? If that is true then how do you model a parking garage since all spaces are defined as being enclosed?



Richard Auffermann

Design Engineer

DAGHER ENGINEERING, PLLC

29 Broadway, New York, NY 10006

T. 212.480.2591 x122

F. 212.480.2654

rauffermann at dagherengineering.com

www.dagherengineering.com



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