RE: [EnergyPlus_Support] How does Airflow Network really work?

---In EnergyPlus_Support@xxxxxxxxxxxxxxx, <solomonyp@...> wrote :

I am currently using AirflowNetwork with AirLoopHVAC:UnitarySystem to predict the energy consumption of a residential house at different duct pressures. The reason I am choosing AirflowNetwork is because I have to calculate duct leakage at different duct pressures. The AF model needs to obtain airflow rate, temperature, and humidity conditions from the Fan object. Without linking the fan object to AF model, you may end up with a severe error.

Solomon

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: EnergyPlus_Support@xxxxxxxxxxxxxxx
Date: Tue, 7 Oct 2014 16:14:36 +0000
Subject: RE: [EnergyPlus_Support] How does Airflow Network really work?

I have used the AirFlowNetwork with IdealLoads. I think the assumption is IdealLoads can provide heating and cooling that does not change space pressure at all (perfectly balanced). A defined mechanical system (supply or exhaust) is going to interact with building pressure and change the air flow pressure relationships. I havenâ??t tried it yet (Iâ??m working on calibrating a building now that has a constant exhaust), but having an outdoor air supply or exhaust form a space should change the AirFlowNetwork results.

Ned Lyon, P.E. (MA, WV)
Staff Consultant

SIMPSON GUMPERTZ & HEGER
781.907.9000 main
781.907.9350 direct
617.285.2162 mobile
781.907.9009 fax
www.sgh.com

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
Sent: Tuesday, October 07, 2014 11:30 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] How does Airflow Network really work?

Hello all,

It seems that Airflow Network has some things that "Cannot Do or Restricted".
For example, IOReferece says specifically:
"The model is restricted to using a constant volume fan (Fan:ConstantVolume and Fan:OnOff) and cannot model variable volume fan equipment."

However, it seems that AirflowNetwork:Distribution:Component:Fan admits a Variable Fan.

Is IOReference outdated?

Also, what happens if you define an AirLoopHVAC but do not "connect" its definition to the AirflowNetwork (e.g. you define a Fan:VariableVolume but don't define the corresponding AirflowNetwork:Distribution:Component:Fan)

Or if you use IdealLoads systems, which do not have any connection to the Airflow Network definition?

What aspects from the HVAC systems are considered somehow in the Airflow Network simulation and which are not?

I think this is not clear in E+ reference.

Regards,

GermÃ¡n Campos