Humidity Control - LB/HB 1.2

1

I am unable to get the reheat to kick in when I change the dehumidification set point in the model. Any idea what I am missing/doing wrong?

100% RH

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50% RH

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2

Hey @ApoorvGoyal ,

That’s because humidity control for a VAV system isn’t really dictated by the humidistat but is instead set by the temperature of the air loop setpoint manager. If you want to set a maximum humidity, I recommend lowering this setpoint from its default value of 12.8C (corresponding roughly to 60% humidity at typical room temperature setpoints). I realize that there’s no direct way to change this setpoint from grasshopper but you can do it manually with the OpernStudio application. Or you could use an OpenStudio measure (that you can load up into Grasshopper). Or you can build the HVAC with IronBug, in which case you will have ful control over the setpoint manager.

3

Thanks, @chris, I knew about the VAV system requirement - but assumed that the new HVAC template took care of that. So if I were to do a parametric analysis to study the reheat energy based on humidity control etc. the best way would be to add the Ironbug template in the OSM file at the end and run again?

4

Yes, either of the following options could work right now:

  • Use IronBug to make a custom HVAC with a setpoint manager at the desired dewpoint temperature
  • Write your own measure that grabs the setpoint manager temperature schedule and changes it

If either of these workflows become annoying I am also not totally against trying to auto-adjust the setpoint in the translation from honeybee → OSM whenever a dehumidification setpoint is found. But, if I were to go this route, I would want to find a good means of communicating which systems support such dehumidification since not all of them can do this.