Zone Multiplier and Airflow Rates

asked 2016-07-22 03:23:37 -0600

updated 2016-07-22 03:29:29 -0600

Similar to this question, I'm adding a number of objects to zones that have a multiplier attached to them. These objects are either Fan:ZoneExhaust and ZoneVentilation:DesignFlowRate as well as ZoneMixing (transfer air).

I basically want to model exhaust of $200 \ CFM$ in a trash room, with make up coming from the adjacent corridor. I have a floor that gets multiplied by two: I added a Zone Multiplier of 2 for all zones on this floor.

Should I enter $200 \ CFM$ or $ 2 \times 200 = 400 \ CFM$ for the aforementioned objects?

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answered 2016-07-22 11:19:36 -0600

ericringold

10637 ●32 ●8 https://www.nrel.gov/b...

updated 2016-07-22 11:35:04 -0600

The 'FanCoil_HybridVent_VentSch.idf' example file is a good one to use to test whether ZoneVentilation:DesignFlowRate and ZoneMixing are affected by zone multipliers, since it is set up with both those objects (and output variables). Let's science this:

Hypothesis: ZoneVentilation:DesignFlowRate and ZoneMixing object inputs are unaffected by zone multipliers.

Method:

Run unmodified example file
Change the multiplier for 'North Zone' in the example file, run modified file.
Verify that the zone design loads were affected as expected.
Check if the output variables 'NORTH ZONE:Zone Ventilation Standard Density Volume Flow Rate' and 'NORTH ZONE:Zone Mixing Total Heat Gain Energy' remained unchanged.

Conclusion: Hypothesis verified. ZoneVentilation:DesignFlowRate and ZoneMixing object inputs are unaffected by zone multipliers, and should be adjusted accordingly.

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answered 2016-07-22 08:20:52 -0600

Julien Marrec

29706 ●94 ●76 http://www.effibem.com/

For Fan:ZoneExhaust, to get the appropriate electricity consumption at least, you should multiply the airflow rate of a single zone by the multiplier. In the example I gave, that means inputing $400 \ CFM$.

Source: I've tested this by assigning a unique End-Use Subcategory and checking the html versus calculating the fan electricity consumption manually.