Re: [EnergyPlus_Support] Re: Actual Air flow ?

Vaibhav Jain

www.vaibhavjain.co

On 11 July 2012 18:38, YuanLu Li <yli006@xxxxxxxxxxx> wrote:

Attached is a diagram showing what I meant by using the corner zones, etc. to illustrate the flow direction using the numbers in EPlus variables.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: vaibhav.energyarchitect@xxxxxxxxx
Date: Tue, 10 Jul 2012 21:19:10 +0200
Subject: Re: [EnergyPlus_Support] Re: Actual Air flow ?

Dear Dr.Li,

The diagram is a graphical translation/representation of output variable: AirflowNetwork Mass Flow Rate from Node 1 to 2 (or node 2 to 1) as per I/O manual page no. 747, which is copied below. I used it to explain my colleagues in a simple/quick way about what this output variable means, hence shared here for others to see.

AirflowNetwork Mass Flow Rate from Node 1 to 2 [kg/s]
This is the AirflowNetwork linkage mass flow rate output in kg/s in the direction from Node 1
to Node 2. It reports surface airflows through a crack or opening, and through linkages

defined in an AirflowNetwork:Distribution:Linkage object. The surface linkage is divided into
two types of surfaces, exterior surface and interior surface. Node 1 for an exterior surface

linkage is a thermal zone and Node 2 is an external node. The value of AirflowNetwork Mass
Flow Rate from Node 1 to 2 represents the flow rate from a thermal zone to outdoors. The
flow direction through an interior surface crack or opening is defined from a thermal zone

defined by a surface?s Zone Name (Node 1) to an adjacent thermal zone defined by a
surface?s OutsideFaceEnvironment (Node 2). For an AirflowNetwork:Distribution:Linkage
object, the value represents the air mass flow rate flowing from Node 1 to Node 2.

Vaibhav Jain
www.vaibhavjain.co

On 10 July 2012 20:25, Lixing Gu <gu@xxxxxxxxxxxx> wrote:

I would like to clarify what Lisa said in the last paragraph.

All incoming airflows are a part of zone loads, including infiltration,
ventilation and mixing. All outgoing airflows are not a part of zone loads.

Lixing

-----Original Message-----
From: EnergyPlus_Support@xxxxxxxxxxxxxxx
[mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of lisacng
Sent: Tuesday, July 03, 2012 9:36 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Re: Actual Air flow ?

Alberto, Oscar

Just to make things clear, "inside" and "outside" aren't inside the building
and outside the building. It is the inside or outside face of the referenced
surface (AirflowNetwork:MultiZone:Surface // Surface name // Leakage
component name) where your leakage element is.

Also, in the same hour, you are seeing two different values for 1-->2 and
2-->1 in the same window because your time step is smaller than an hour. If
you output detailed or timestep results, you will see that only one flow
should have a value and the other is zero. The hourly output is an average
of the timestep outputs. If using the hourly results is fine, then the flow
of air is the difference of 1-->2 and 2-->1 and the direction is determined
by which is greater.

It should be noted that EnergyPlus only uses the flow into a building from
the outdoors to affect the load on a zone. Exfiltration (air leaving a
building) and mixing of air between zones does not affect load calculations.
Someone out there can correct me if I'm wrong.

Lisa Ng
NIST
IAQ & Ventilation Group

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, oscar hernandez
<oscarhernandez_81@...> wrote:
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> Don't worry.
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> If I remember, 1 to 2 is from outside to inside and 2 to 1 inside to
outside. Look at the energyplus input output manual (airflow network) you
have everything about that.
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> Let me know if you need more help.
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> Oscar.
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> From: ahneto@...
> Date: Sat, 30 Jun 2012 17:44:40 -0300
> Subject: RE: [EnergyPlus_Support] Actual Air flow ?
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> Dear Oscar,
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> Sorry to bother you again but , regarding the air flow network, how do
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> Thanks for your help.
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> Citando oscar hernandez <oscarhernandez_81@...>:
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> > THe value 1 to 2 or 2 to 1 is the flow rate. You have to inside or
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> > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
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> > From: ahneto@...
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> > Date: Fri, 29 Jun 2012 13:54:19 -0300
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> > Subject: [EnergyPlus_Support] Actual Air flow ?
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