[Bldg-sim] Vestibule Modeling (UNCLASSIFIED)

Eurek, John S NWO John.S.Eurek at usace.army.mil
Mon Aug 5 08:32:17 PDT 2013


Classification: UNCLASSIFIED
Caveats: NONE

An interesting variable for a vestibule is the frequency of use.

How do you model a vestibule for a shopping center with a nearly continuous stream of people entering and exiting compared to a vestibule for an office building where the traffic is very low.

I was designing an HVAC system for a 600 sqft guard office in a cold climate. I couldn't find much information on how to model (or design) the system to account for the extremely frequent opening and closing of the door.


-----Original Message-----
From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of RobertWichert
Sent: Wednesday, July 31, 2013 2:36 PM
To: Nick Caton
Cc: 'equest-users at lists.onebuilding.org'; 'bldg-sim at lists.onebuilding.org'
Subject: Re: [Bldg-sim] Vestibule Modeling

In my original post I said "Since LEED requires compliance with ASHRAE 90.1 Mandatory measures...".  I believe this is correct, at least as far as Architectural, Mechanical and Electrical mandatory requirements are concerned.

And yes, I realize that there are exceptions for doors not used as entries (emergency only or exit only?) and for doors leading into spaces less than 3000 sq. ft.  Also for buildings less than four stories under 10,000 sq. ft. in CZ 3 or 4.  And for mild climates.  I do not believe any of these would apply to the building I am working on, but I do appreciate the options.  Including revolving doors!



Robert Wichert P.Eng. LEED AP BD&C
+1 916 966 9060
FAX +1 916 966 9068







===============================================
On 7/31/2013 11:50 AM, Nick Caton wrote:


	I concur with the advice to read the requirements more carefully – in almost no case is a vestibule required at every door, when they are required.

	 

	Take care and recognize that an Appendix G model is NOT a method to show code compliance.  It’s a procedure for benchmarking the building performance for design which exceeds the minimum requirements of the standard.  The first sections of Appendix G provide a concise overview.

	 

	You can evaluate the effect a vestibule or not as already discussed – in function this should simply reduce scheduled infiltration.  That said, I do not believe any Appendix G model should have the proposed and baseline models differing with respect to having a vestibule.  I think table G3.1 is pretty clear that the baseline model is to match the proposed with respect to space/thermal block configuration and arrangement.

	 

	Finally, just to drive an extra wedge into the commentary – while the specified mandatory sections (#.4…) ARE required of the design for a LEED project, to pass EAp2, in my humble opinion it’s incorrect (or at least a stretch) to say LEED requires demonstrating compliance with 90.1. 

	 

	In sum, to the extent vestibules are required (review the sections and exceptions carefully), a LEED project must by design include them in the proposed design.  In turn, the proposed model should incorporate the vestibule in the form of a distinct thermal block (zone/space), to match the actual design.  In turn, the same edits should be applied to the baseline model as it’s supposed to match the proposed model in this regard.  

	 

	If the vestibules will be designed to be conditioned by the same systems handling the surrounding spaces, you might make the case that it’s a reasonable thing to not model them explicitly as a separated space (modeler has the prerogative to identify and assert where such spatial approximations are appropriate), but in preliminary LEED submission I’d advise making that decision and case clear to the reviewer in your documentation so if it isn’t acceptable you have the opportunity to make the corrections per above prior to final submission.  

	 

	~Nick

	 

	cid:489575314 at 22072009-0ABB

	 

	NICK CATON, P.E.

	SENIOR ENGINEER

	 

	Smith & Boucher Engineers

	25501 west valley parkway, suite 200

	olathe, ks 66061

	direct 913.344.0036

	fax 913.345.0617

	www.smithboucher.com 

	 

	From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Jim Dirkes
	Sent: Tuesday, July 30, 2013 10:25 AM
	To: 'RobertWichert'; 'bldg-sim at lists.onebuilding.org'; 'equest-users at lists.onebuilding.org'
	Subject: Re: [Bldg-sim] Vestibule Modeling

	 

	Robert,

	Did you notice the 7 exceptions to section 5.4.3.4?  One of them may apply to you…

	As far as modeling goes, a vestibule is principally an infiltration control technique, so I suppose that you could argue for reduced infiltration when vestibules are present.  I am unaware of any research or other information about how they may affect infiltration.  Since infiltration is such a guessing game, I never apply any special curves for vestibules.

	p.s., the IECC 2012 (Int’l Energy Conservation Code) includes mandatory envelope and infiltration testing and criteria.  This will probably be a game changer for the construction industry in areas that adopt this code and will definitely affect the energy models prepared for those projects.

	 

	James V Dirkes II, PE, BEMP, LEED AP
	www.buildingperformanceteam.com <http://www.buildingperformanceteam.com/>  
	Energy Analysis, Commissioning & Training Services
	1631 Acacia Drive, Grand Rapids, MI 49504 USA
	616 450 8653

	 

	From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Rosenberg, Michael I
	Sent: Tuesday, July 30, 2013 11:16 AM
	To: 'RobertWichert'; 'bldg-sim at lists.onebuilding.org'; 'equest-users at lists.onebuilding.org'
	Subject: Re: [Bldg-sim] Vestibule Modeling

	 

	Any of the mandatory requirements in Standard 90.1 must be included in your building design and cannot be traded off using a performance approach.
	
	
	
	____
	
	______________________
	
	Michael Rosenberg, CEM, LEED AP
	Senior Research Scientist
	ENERGY & ENVIRONMENT DIRECTORATE
	
	Pacific Northwest National Laboratory
	2032 Todd Street
	Eugene, OR 97405
	(541) 844-1960
	michael.rosenberg at pnnl.gov
	www.pnnl.gov
	
	
	
	-----Original Message-----
	From: RobertWichert [robert at wichert.org]
	Sent: Tuesday, July 30, 2013 08:08 AM Pacific Standard Time
	To: bldg-sim at lists.onebuilding.org; equest-users at lists.onebuilding.org
	Subject: [Bldg-sim] Vestibule Modeling
	
	

	I see that ASHRAE 90.1 requires a vestibule in most cases, but I don't
	know if it is modeled or if it is just mandatory.  It would seem to me
	that if it was modeled, showing compliance using modeling, without a
	vestibule, would be OK (you would make it up somewhere else in the
	envelope).  Does anybody know if the vestibule is modeled anywhere, and
	how to take it out or put it in?
	
	Since LEED requires compliance with ASHRAE 90.1 Mandatory measures, this
	makes a vestibule a mandatory requirement unless I can model it with and
	without.  If this is even possible.
	
	Otherwise we must put in a vestibule to comply with LEED.
	
	
	Is this correct?  Does anybody have other thoughts or ideas?  We have a
	very efficient building, modeled without the vestibule in Climate Zone
	3B.  I would think that we could take a heating penalty and not install
	a vestibule AT EVERY DOOR.
	
	
	I appreciate your thinking about this.
	
	
	
	--
	Robert Wichert P.Eng. LEED AP BD&C
	+1 916 966 9060
	FAX +1 916 966 9068
	
	
	
	
	
	
	
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Classification: UNCLASSIFIED
Caveats: NONE




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