Sorry that I jump in to your discussion, because I do not seem to understand the purpose of these two diagrams.
A Zone has four ports for air flow. The two inlet ports are connected in the zone. The total zone air is split into two outlet ports, when there are more than one air paths. I called them ports, because I am an EE. A branch has two ports. A node is usually a connection between two or more components or ports.
The middle of a zone is a node. It is between a internal mixer and splitter.
For node naming purposes, EPlus is using the outlet name as the node name for the nodes in templates. The inlet connection is now using the outlet port name of the preceding branch.
When connected to the OD air, one of the outlet ports is connected to the OA mixer or exhaust to OD directly.
When using inter-zone mixing, the zone node exchange heat between the zones, and there may not be any air flow.
If you are using the node number for AFN, there will be five external OD nodes, 4 sides and the roof. The inter zone path direction will follow the external air pressure direction. For air to flow through a building, there must be at least two OD air nodes. Inter zone openings are required to complete the air path.
The external pressure determines the air flow. The exhaust air is not ignored, as the heat in minus heat out is the net heat gain in the building, which is related to temperature difference and air volume. Exhaust volume is the same as the inlet volume.
One OD air node cannot create a pressure difference, therefore no air flow through windows mounted on the same wall. Node1 for the zone is not effective for AFN. There must be another OD air node on the other side or another side of the building.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
CC: lisa.ng@xxxxxxxx
From: vaibhav.energyarchitect@xxxxxxxxx
Date: Thu, 5 Jul 2012 15:58:27 +0200
Subject: Re: [EnergyPlus_Support] Re: Actual Air flow ?
I will now put the picture (more a diagram) inline with text in this email. You should be able to see it now. Thanks!
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A Zone has four ports for air flow. The two inlet ports are connected in the zone. The total zone air is split into two outlet ports, when there are more than one air paths. I called them ports, because I am an EE. A branch has two ports. A node is usually a connection between two or more components or ports.
The middle of a zone is a node. It is between a internal mixer and splitter.
For node naming purposes, EPlus is using the outlet name as the node name for the nodes in templates. The inlet connection is now using the outlet port name of the preceding branch.
When connected to the OD air, one of the outlet ports is connected to the OA mixer or exhaust to OD directly.
When using inter-zone mixing, the zone node exchange heat between the zones, and there may not be any air flow.
If you are using the node number for AFN, there will be five external OD nodes, 4 sides and the roof. The inter zone path direction will follow the external air pressure direction. For air to flow through a building, there must be at least two OD air nodes. Inter zone openings are required to complete the air path.
The external pressure determines the air flow. The exhaust air is not ignored, as the heat in minus heat out is the net heat gain in the building, which is related to temperature difference and air volume. Exhaust volume is the same as the inlet volume.
One OD air node cannot create a pressure difference, therefore no air flow through windows mounted on the same wall. Node1 for the zone is not effective for AFN. There must be another OD air node on the other side or another side of the building.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
CC: lisa.ng@xxxxxxxx
From: vaibhav.energyarchitect@xxxxxxxxx
Date: Thu, 5 Jul 2012 15:58:27 +0200
Subject: Re: [EnergyPlus_Support] Re: Actual Air flow ?
Hi Lisa,
Vaibhav Jain
On 5 July 2012 15:10, lisacng <lisa.ng@xxxxxxxx> wrote:
Vaibhav,
How do I see the attached picture? Is there a link?
Thanks!
Lisa> On 3 July 2012 15:54, Jean marais <jeannieboef@...> wrote:
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Vaibhav Jain <vaibhav.energyarchitect@...> wrote:
>
> I have this picture (attached) I made for myself to remember the
> terminology. Might save us time, because: a picture = many words :)
>
> Vaibhav Jain
> www.vaibhavjain.co
>
>
>
>
>
> > **
> >
> >
> > Bidirectional flow is also calculated depending on what object you are
> > using (AirflowNetwork models such two-directional flow, but only for
> > vertical openings).
> >
> > I think you may be right that only infiltration is considered in load
> > calcs, but then exfiltration is usually less interesting (has very small
> > impact on building energy usage). This is the case for TrnSys.
> >
> > However,
> > the io ref states that exfiltration is better handled with an exhaust
> > componant and that AFN can "16) Determine the impact of zone exhaust fans
> > on air flows, pressures, air temperatures/humidity levels and energy
> > consumption."
> >
> > I've not checked the engineering ref on this.
> >
> >> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "lisacng" <lisa.ng@> wrote:
> > >
> > > 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:
> > > >
> > > >
> > > > Don't worry.
> > > >
> > > > 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.
> > > >
> > > > Let me know if you need more help.
> > > >
> > > > 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,
> > > >
> > > >
> > > >
> > > > Sorry to bother you again but , regarding the air flow network, how do
> > > >
> > > > I know the direction (from inside to outside and vice versa) of the
> > > >
> > > > flow in the window?
> > > >
> > > >
> > > >
> > > > Thanks for your help.
> > > >
> > > >
> > > >
> > > > Alberto
> > > >
> > > >
> > > >
> > > > Citando oscar hernandez <oscarhernandez_81@>:
> >
> > > >
> > > >
> > > >
> > > > >
> > > >
> > > > >
> > > >
> > > > > THe value 1 to 2 or 2 to 1 is the flow rate. You have to inside or
> > > >
> > > > > to outside.
> > > >
> > > > > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> > > >
> > > > > From: ahneto@
> > > >
> > > > > Date: Fri, 29 Jun 2012 13:54:19 -0300
> > > >
> > > > > Subject: [EnergyPlus_Support] Actual Air flow ?
> > > >
> > > > >
> > > >
> > > > >
> > > >
> > > > >
> > > >
> > > > >
> > > >
> > > > >
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> > > >
> > > > >
> > > >
> > > > > Dear Forum,
> > > >
> > > > >
> > > >
> > > > >
> > > >
> > > > >
> > > >
> > > > > I modeling a room with the AirFlowNetwork object. I would like to
> > > >
> > > > >
> > > >
> > > > > confirm the following:
> > > >
> > > > >
> > > >
> > > > >
> > > >
> > > > >
> > > >
> > > > > When I set as output variable AirflowNetwork Mass Flow Rate from Node
> > > >
> > > > >
> > > >
> > > > > 1 to 2 and AirflowNetwork Mass Flow Rate from Node 2 to 1 for a
> > > >
> > > > >
> > > >
> > > > > exterior window, the difference between these two variables will give
> > > >
> > > > >
> > > >
> > > > > the actual flow rate and the direction will be set verifiying which
> > > >
> > > > >
> > > >
> > > > > variable is greater?
> > > >
> > > > >
> > > >
> > > > >
> > > >
> > > > >
> > > >
> > > > > Regards,
> > > >
> > > > >
> > > >
> > > > >
> > > >
> > > > >
> > > >
> > > > > Alberto Hernandez Neto
> > > >
> > > > >
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> > >
> >
> >
> >
>
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Primary EnergyPlus support is found at:
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The group web site is:
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