Modeling Ceiling fan or circulation fan in Designbuilder or EnergyPlus

Hello,

I am a student doing research on Mixed-mode ventilation (including fan-assisted ventilation). Which tools I am using are DesignBuilder and EnergyPlus.

So, What I make as mixed-mode ventilation is divided into three types of ventilation: 1) Natural ventilation using single-sided window 2) Forced natural ventilation assisted by ceiling fan/circulation fan. 3) Air Handling unit operation and window opening.

There is much research on mixed-mode ventilation related to hybrid ventilation (fan-assisted). But, the authors didn't provide information about ceiling fan (or circulation fan).

The followings are what I am asking:

1) In a single thermal zone, Is it possible to install the fan without dividing room air? What I mean is some people divide a single room into a thin air space with a large hole and the main room. But I don't want to use these kind of modeling methods.

2) Is there any other example of EnergyPlus or Designbuilder about modeling ceiling fan or circulation fan? I found the youtube video that has contents to model ceiling fan in EnergyPlus. But it did only address making Zone:equipment object which does not influence indoor air pressure or velocity.

3) Using a circulation fan can rise the pressure in a single room?

Please help me. Also, If there is a file example and you don't mind sharing, please share the link

131

Selma Inger

asked 2023-05-11 20:24:20 -0500

14.1k

Aaron Boranian

updated 2023-05-12 09:58:48 -0500

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Hi Selmar, After reading your post, it is not obvious to me that you have used the existing DesignBuilder help and tutorials on Mixed-mode ventilation. So, I'll link some here for you: https://designbuilder.co.uk/helpv7.0/...

https://www.youtube.com/watch?v=FRuhH...

I think a ceiling fan simply mixes the air in a zone. If you want to study this, I think a CFD tool is needed.

Greg Estep (2023-05-13 17:53:54 -0500) edit

@Greg Estep Thank you for providing me with those links. Actually, I am not using the mixed-mode option in designbuilder. I just needed to air-circulation fan when natural ventilation cannot chill the room even if fenestration surfaces are fully opened. (for assisting natural driving force) Also, I am working on BES + AFN model. Hence, CFD is too precise for my case.

Regards Selma

Selma Inger (2023-05-16 04:38:26 -0500) edit

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EnergyPlus assumes zone air is well-mixed by default, so the addition of a ceiling fan would not aid in air circulation or prevent stratification any more than is already assumed. One workaround to the well-mixed assumption is to model two separate zones on top of each other with a hole (or ZoneMixing) to represent stratification within a single zone.

Adding a fan to the zone would also not affect zone pressure in the model. That's why the video you referenced only accounts for the electricity of the fan using an ElectricEquipment object, but does not account for any air circulation or increased air velocity. For the purpose of calculating thermal comfort, your assumed air velocity can be independent of the fans and equipment specified in the model.