[Equest-users] Modelling Parking Garage Exhaust CombinedwithJetFans

[Amber Welsh]

I think they are asking for you to reference if this is required by local code.  For instance, the city of San Francisco will require CO sensing for parking garage exhaust.  In which case the methodology is explained.  If it is not required by code, then I would ask GBCI if you include the selection of code relevant to parking garage ventilation to back-up your baseline model.  

Baseline is always based on baseline code, not anyone's personal base design strategies.  This is the whole point and benefit of having a standard.

Amber

-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Nick Caton
Sent: Tuesday, August 02, 2011 11:28 AM
To: James Hansen; Ömer Moltay; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Modelling Parking Garage Exhaust CombinedwithJetFans

Great heads up - I haven't run into that one yet!

While I don't disagree with what the reviewer is getting at (standard practices do evolve), I think he/she is crossing a line by putting the burden of proof for a baseline practice on the modeler... 

What's potentially unfair about this situation is that it artificially punishes those who try to design above and beyond the prescriptive minimums.  Measures like CO sensing controls are ultimately 
either done because (A) you have to, or (B) because you want to do more than is required.  If LEED reviewers today are taking it upon themselves to NOT reward those going above and beyond code requirements, then to be even-handed I'd expect in turn they're making a point to punish those who do the bare minimum.  

If the new mandate is that baseline garage ventilation should always include CO sensing, then come out and say it (and define how it's to be modeled exactly while you're at it).  Write it into 90.1 or the next version of EAc1.  Don't arbitrarily punish owners and designers who are trying to do more than the minimum.

~Nick

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 


-----Original Message-----
From: James Hansen [mailto:JHANSEN at ghtltd.com] 
Sent: Tuesday, August 02, 2011 10:08 AM
To: Nick Caton; Ömer Moltay; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] Modelling Parking Garage Exhaust Combined withJetFans

Please also note that if this is for a LEED project, one of the "default" review comments now for CO-based control of garage fans is that the design professional must demonstrate that this is not a "standard practice" for new base-building projects in the area.  I personally think this is a ridiculous comment, but regardless, be prepared to provide a list of new projects in the area that you've worked on that have not had CO-based control of the parking garage fans, otherwise you might have to include it in both the baseline and proposed models.  I would love to hear how other people have addressed this comment.

GHT Limited
James Hansen, P.E., LEED AP
Senior Associate
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Arlington, VA  22201-4749
703-243-1200 (office)
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-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Nick Caton
Sent: Tuesday, August 02, 2011 11:01 AM
To: Ömer Moltay; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Modelling Parking Garage Exhaust Combined withJetFans

Hi Ömer,

A1: If you're not conditioning the fresh air, then there's no reason to try and model this ventilation as a SYSTEM.  Assign a direct load to your meter.  Assign to a submeter if you wish to separately track its energies easily.  Further discussion in the archives if you need to ask how.

A2: A fractional schedule is necessary to model CO sensor-based controls.  If you're doing this under LEED:  90.1-2007 users manual, which offers specific schedules for specific occupancies (adapted from 90.1-1989, also used in the Washington State energy code IIRC)... has a table for parking garages.  Rather than provide an hourly fraction as with most other cases, it says Parking garage HVAC shall be "Based on likely use."  I interpret this as a prescriptive latitude to define and assign schedules appropriate to your system's behavior on a case-by-case basis.

A3: "Model the airflows" is a fairly vague query... Are these operating for user comfort?  If they're tied to a thermostat, it might be easiest to set them up as a system with a thermostat.  If they're just circulating/directing ventilation air alongside the main exhaust fan, then I'd treat them identically as a direct load to the meter, per A1.  I'd use an identical or modified schedule from that used for the exhaust fan, depending on whether they operate identically.

~Nick

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 


-----Original Message-----
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Ömer Moltay
Sent: Tuesday, August 02, 2011 6:05 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Modelling Parking Garage Exhaust Combined with JetFans

Dear All,

In a building with 6 underground parking storeys, air is exhausted 
through a shaft and a single fan, while outside air is brought in 
through natural flows on another shaft. This is achieved by jet fans 
operating in each parking garage. The exhaust fan is variable speed 
controlled by CO sensors in the parking areas.

Q1: How can I assign 6 underground zones to a single exhaust fan? As far 
as I know, exhaust flows are assigned on a zone basis in eQuest?
Q2: How to model the speed variation of the exhaust fan? Any other way 
other than using schedules?
Q3: Can eQuest model the airflows caused by jet fans? Or should I just 
assign these as electric loads so that their electric consumption is 
taken into account?

Thank you,

Ömer Moltay, LEED AP BD+C, BREEAM Assessor
Mimta Ltd.
Hekimsuyu Cad. 559. Sk. No:39
34255 Kucukkoy Istanbul Turkey
Tel: 90-212-617-2296
Fax: 90-212-617-2297
www.mimtarch.com
www.mimtasolar.com
www.eko-yapi.net
www.servogas.com

Sürdürülebilir Binalar Blog
http://surdurulebilirbina.blogspot.com

Green Building in Turkey on LinkedIn
http://www.linkedin.com/groups?gid=2278249


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