Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page
Ask Your Question

fan schedule not working

asked 2022-01-10 05:00:26 -0600

Cold wong gravatar image

updated 2022-01-17 07:42:02 -0600

I'm doing research about heat recovery in data center, sensible heat from datacenter was tranported to rooms in winter to saving energy. Fans: VariableVolume have been added between OA Mixing box in datacenter and Plenums in occupied rooms. But when I changed the schedule of fans, output data shows a same energy consumption as before. Then I checked the system node mass flow rate, which is constant when I revised the schedule of fans. Where could the error occur in my model?Any suggestions will be appreciated.

The SVG and IDF file was there. Origin file based on PNNL Large Office building.

edit retag flag offensive close merge delete


@Cold wong could you include a diagram of the HVAC system that you're modeling, and/or some tables/plots to show what output data is the same between runs? It looks like the Fan:VariableVolume object only has one schedule input field for availability, so perhaps the fan only needs to run during the periods you've set in both runs.

Aaron Boranian gravatar image Aaron Boranian  ( 2022-01-10 10:27:15 -0600 )edit

Thanks @Aaron Boranian, question has been revised.

Cold wong gravatar image Cold wong  ( 2022-01-10 22:23:33 -0600 )edit

@Cold wong your Drive link requires access permission. Consider changing to a public link, and include the IDF. But based on the information so far, I'd guess that your air handler is operating based on load, and there is a 24-hr load in the data center, so the air handler needs to operate continuously to meet the space setpoint. Even if your setpoint schedule has night time setbacks, if the equipment loads are continuous, and you have night cycling on your AHU, then the AHU will operate through the night to meet setpoint regardless of fan schedule.

ericmartinpe gravatar image ericmartinpe  ( 2022-01-13 11:27:05 -0600 )edit

1 Answer

Sort by ยป oldest newest most voted

answered 2022-01-17 17:31:25 -0600

The fans are not operating at all, flow rate is zero for the entire year. The fan inlet node is the OutdoorAir:Mixer's relief/exhaust air node. Relief/exhaust air flow will always equal outdoor air flow (conservation of mass), and since no outdoor air is required for the data center, the outdoor air flow is zero and therefore relief air flow is zero. All of the data center's zone air is returned to the UnitaryHeatPump, none of it reaches the mixer's relief air node.

I think you may have better luck using ZoneMixing rather than trying to direct zone exhaust air through a fan into another airstream's return air plenum.

edit flag offensive delete link more

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Training Workshops

Question Tools

1 follower


Asked: 2022-01-10 05:00:26 -0600

Seen: 251 times

Last updated: Jan 17