Air velocity in Airflow-network

asked 2016-03-13 22:01:14 -0600

Jevin
197 ●7

updated 2017-04-16 11:24:03 -0600

__AmirRoth__

4446 ●5 ●17 http://bleedinggreenna...

Greetings everyone,

I am currently modelling a residential house with an airflow-network set-up for natural ventilation in energyplus. I am using the adaptive thermal comfort standards to evaluate the various design strategies.

The velocity field can be input from a schedule which i'm planning to control using EMS.

My question is : What is the right sensor for zone air velocity in an AFN?

Should i mix some sensors and create a formula in EMS for this ? IF so what is recommended?

Thanking you in advance, Jevin

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Are you talking about using the room air models with AirflowNetwork, or something else?

Jason DeGraw ( 2016-03-14 10:51:21 -0600 )edit

Greetings Sir,

I didn't use the room air models with the airflow network. Simple set-up and airflow network and using the AFN node temperatures as reference temperatures for the comfort estimations.

Jevin ( 2016-03-14 11:08:58 -0600 )edit

Then I'm a little confused about the "velocity field" you mention. Are you talking about the air velocity schedule in the People object documented here

Jason DeGraw ( 2016-03-15 09:22:27 -0600 )edit

Kind of . I created a thermal comfort for my needs from an onsite survey. I'm using the EMS to report the number of hours where comfort is reached but the parameter is depended on various air velocities. According to the documentation this is a user input value through a schedule.

I don't know if i'm right but i'm guessing that without a mechanical fan these values should be low but i would just like to know if there's actually a way to get a value from energyplus in an Aiflownetwork .

Jevin ( 2016-03-15 10:31:06 -0600 )edit

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answered 2016-03-15 12:06:19 -0600

Jason DeGraw

2208 ●6 ●10 https://github.com/jasondegraw

I'm no expert on EMS or E+'s thermal comfort calcs, but per a quick discussion just now with @Edwin, if you define the proper outputs (see here) you can connect to them using these objects. Maybe you already know that.

Whether you should do this or not is an entirely different question. AirflowNetwork solves for bulk airflow, so it gives mass/volume flow rates. While that can be used to determine the average velocity through a window (for example), what that means for the air velocity that occupants experience is a bit harder to quantify and should be highly dependent on geometry. A quick literature search hasn't turned up too much, but there is probably more there.