Re: [EnergyPlus_Support] airflow network influenced by zone controls? ventilation setpoint does not work

[Lixing Gu <gu@xxxxxxxxxxxx>]

Astrid:

The answer to the first question (Tzone< 22C and windows are open) is that 
the report frequency may be hourly, instead of "detailed". The 
AirflowNetwork model works at every system time step, which is equal or less 
than the zone time step given in the input file. When the report frequency 
is greater than the system time step, the average airflows are reported. It 
is possible that the zone temperature may be higher than 22C in a system 
time step during the report frequency, so that you may see airflows or other 
report variable values are not zero due to average.

The answer to the second question is that you may try to use the 
AvaiabilityManager:HybridVentilation object. One of purposes for this object 
is to prevent simultaneous natural ventilation and HVAC system operation. 
The detailed descriptions are given in both Input Output Reference and 
Engineering Reference. An example input file, called 
HybridVentilationControl.idf, may give a guide how to use this object.

Please let me know if you need more information.

Thanks.

Lixing
----- Original Message ----- 
From: <astroid8@xxxxxxxxxxxxxx>
To: <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Sent: Tuesday, March 03, 2009 10:52 AM
Subject: [EnergyPlus_Support] airflow network influenced by zone controls? 
ventilation setpoint does not work


Dear all,

I got stuck with two questions regarding the airflow network system:

I am modelling an airflow network system for natural ventilation,
using the ventilation control mode "temperature". my setpoint
temperature above which the windows should be modelled open is 22°C.
However if I look at the output (zone/sys air temperature) I can also
find hours with opened windows even if the zone temperature is
slightly below 22... What is my mistake?

Additionally I want to calculate the cooling loads to a certain
setpoint, so I use dual setpoint with deadband at zone control
thermostatic. How is it possible to switch off the natural ventilation
(i.e. assume closed windows) defined in airflow network system while
the cooling system is running?

I would be happy about some help,

Regards, Astrid



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