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How to define the infiltration rate in a central zone which is composed by internal walls?

asked 2017-05-29 09:55:12 -0600

gaofeng gravatar image

updated 2017-05-29 11:27:33 -0600

The defination of infiltration is the outside air from the crack of building. So, how to set the infiltration rate in a central zone which is composed by internal walls. Theoretically, there is no direct outdoor air to go into this area, but the mixture of indoor and outdoor air. How about setting a smaller value than common situation? or set zero in this situation?

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answered 2017-05-30 06:08:12 -0600

updated 2017-06-06 03:00:59 -0600

How you define infiltration is your choice. You might want to do it only for perimeter (=exposed to the outdoor) zones, or to put a constant air change in the entire building for example. There are good reasons to choose one or another.

There are several choices in ZoneInfiltration:DesignFlowrate's Calculation Method for example (I'm linking to this object since it's the most commonly used, but there are a few other infiltration objects).

If you use Flow/ExteriorAreaor Flow/ExteriorWallArea, any core/central zones that don't have exterior surfaces will get a resulting infiltration of zero. If you use any of the other methods (Flow/Zone, Flow/Area, AirChanges/Hour) it won't care whether it's a core or a perimeter zone.


Here's an example to set the Flow/Zone to 500 CFM / 0.246 m3/s, with a constant value (not depedent on temperature or wind), where Core Zones is a ZoneList listing all the zones to apply it to, but you could also just use the name of one Zone.

    Core Infiltration,   !- Name
    Core Zones, !- Zone or ZoneList Name
    Always On Sch, !- Schedule Name
    Flow/Zone,      !- Design Flow Rate Calculation Method
    0.246,       !- Design Flow Rate {m3/s}
    ,               !- Flow per Zone Floor Area {m3/s/m2}
    ,               !- Flow per Exterior Surface Area {m3/s/m2}
    ,               !- Air Changes per Hour
    1,              !- Constant Term Coefficient
    0,              !- Temperature Term Coefficient
    0,              !- Velocity Term Coefficient
    0;              !- Velocity Squared Term Coefficient
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Thanks for your answer, but for a non-perimeter zone, how to define its infiltration (flow/zone) value. Have you ever seen such example?

gaofeng gravatar image gaofeng  ( 2017-05-31 07:51:46 -0600 )edit

It's already in my answer, use ZoneInfiltration:DesignFlowRate. The IDF example included in the documentation (which I linked to already), uses Flow/Zone for example.

Julien Marrec gravatar image Julien Marrec  ( 2017-06-06 02:56:20 -0600 )edit

I added a concrete example (a different one) in my answer too. If that solved your problem, please mark the answer as accepted so we know the thread is resolved. Thanks.

Julien Marrec gravatar image Julien Marrec  ( 2017-06-06 03:01:39 -0600 )edit

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Asked: 2017-05-29 09:55:12 -0600

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Last updated: Jun 06 '17