[Equest-users] Modeling infiltration from an adjacent zone

[Nick Caton]

Hi Mike!

 

Like many things, I’d adjust my approach depending on how accurate/critical this infiltration is to the whole picture.  

 

Most simple approximation:

Assign/bump up the infiltration inputs at the corridor space (detailed edit) to draw additional quantities of raw outside air.  Assign a custom infiltration schedule (applied only to this space) to approximate when and to what extent infiltration occurs.  This is a few steps back from reality, for reasons that will hopefully become clear after reading the rest of this reply.

 

Time-allowing / closer to reality:

1.       Model the loading dock as a space adjacent to the corridor.  Exterior perimeter construction should account for loading dock door thermal performance in the closed position (or else model explicitly as opaque doors).

2.       Estimate an elevated infiltration flow rate/schedule to represent normal levels of infiltration in the dock on a day-to-day (not “design,” necessarily) basis. 

a.       Consider prescriptive loading dock weatherseal requirements in 90.1 and similar, as may apply in the actual design

b.      If this dock is of the “open service garage” variety where modest winds will “flush” the space with multiple bays left open, you might want to consider a substantial wind-driven ACH quantity as well, to capture that behavior

c.       Keep in mind this is not something to dwell hours on – you are just looking to get a fair approximation of actual dock space temps.  Use the space temperature reports (or custom  hourly reports) to track and QC the resulting space temperatures – adjust your inputs as necessary.

3.       The above efforts will result in a zone with a realistic annual space temperature profile, tempered relative to the outside air temps.  Thermostats in the dock space (if conditioned) and the interior constructions bordering the dock will likely need attention in turn to avoid unmet hours for the dock and any all thermally connected conditioned zones.

4.       The above will capture the hourly conductive transfer effects on the corridor, and may be a good stopping point if the construction of the corridor/dock wall is tight and doors between them are not actively opened.  

5a.  Assuming the adjacent corridor transitions are “active” and/or leaky wall construction, with doorways routinely left or propped open, you could *approximate* the associated infiltration by specifying a section of air wall under the corridor space (interior surface, NEXT-TO dock) equal to the free area between the spaces.  Note this approximation can’t “schedule” when the doors are open/closed.

5b.  A more in-depth model could alternatively set up the dock as a sunspace,  permitting you to define an interior wall construction assigned wall parameters to simulate natural convective heat transfer between the two zones when doors are open.  At the associated sunspace zone, you could further define an SS-FLOW-SCH to account for normal door operation behavior (i.e. doors remain closed on holidays and in the evening hours).  

 

~Nick

 

From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Michael Campbell
Sent: Thursday, November 20, 2014 8:30 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Modeling infiltration from an adjacent zone

 

Hi,

 

I have a corridor next to a loading dock. And the corridor is experiencing infiltration from the loading dock.  Is it possible to model this, and if so, how?

 

Thanks,

 

Mike Campbell, E.I.T., LEED AP O+M
Sustainability Specialist
Sustainable Solutions Corporation
Office: 610-569-1047 <http://610-569-1047/> 

Mobile: 609-923-1743 <http://610-569-1047/> 
www.SustainableSolutionsCorporation.com <http://www.sustainablesolutionscorporation.com/> 
Sustainable Solutions Corporation is WBENC and BCorp Certified.

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