Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
Answering my own question, in the hopes it may help someone else in the future....
I found that a couple of things were happening here:
First, the ppm target (1100 ppm) that I had set was not reasonable for this high occupant density (exhibit hall) space occupancy. For information on how ventilation requirements correspond to ppm at steady state conditions Appendix A to ASHRAE 62.1 is helpful. Additionally, this article from Trane is helpful.
Second, neither the zone terminal supply air flow, nor the system supply air flow will increase in response to ppm exceedance at a zone, although the Controller:Outdoorair and the Controller:MechanicalVentilation will increase the outdoor air flow fraction to 100% of system flow.
| | 2 | No.2 Revision |
Answering my own question, in the hopes it may help someone else in the future....
I found that a couple of things were happening here:
First, the ppm target (1100 ppm) that I had set was not reasonable for this high occupant density (exhibit hall) space occupancy. For information on how ventilation requirements correspond to ppm at steady state conditions Appendix A to ASHRAE 62.1 Users' Manual is helpful. Additionally, this article from Trane is helpful.
Second, neither the zone terminal supply air flow, nor the system supply air flow will increase in response to ppm exceedance at a zone, although the Controller:Outdoorair and the Controller:MechanicalVentilation will increase the outdoor air flow fraction to 100% of system flow.
| | 3 | No.3 Revision |
Answering my own question, in the hopes it may help someone else in the future....
I found that a couple of things were happening here:
First, the ppm target (1100 ppm) that I had set was not reasonable for this high occupant density (exhibit hall) space occupancy. For information on how ventilation requirements correspond to ppm at steady state conditions Appendix A to ASHRAE 62.1 Users' Manual is helpful. Additionally, this article from Trane is helpful.
Second, neither the zone terminal supply air flow, nor the system supply air flow will increase in response to ppm exceedance at a zone, although the Controller:Outdoorair and the Controller:MechanicalVentilation will increase the outdoor air flow fraction to 100% of system flow.
Additional note which may be helpful: you can set a zone terminal outdoor air requirement, which will modulate the terminal minimum flow if needed, using the DesignSpecification:OutdoorAir field at the air terminal object, as mentioned in this post. (The modulation would not be based directly on CO2 concentration though.)
| | 4 | No.4 Revision |
Answering my own question, in the hopes it may help someone else in the future....
I found that a couple of things were happening here:
First, the ppm target (1100 ppm) that I had set was not reasonable for this high occupant density (exhibit hall) space occupancy. For information on how ventilation requirements correspond to ppm at steady state conditions Appendix A to ASHRAE 62.1 Users' Manual is helpful. Additionally, this article from Trane is helpful.
Second, neither the zone terminal supply air flow, nor the system supply air flow will increase in response to ppm exceedance at a zone, although the Controller:Outdoorair and the Controller:MechanicalVentilation will increase the outdoor air flow fraction to 100% of system flow.
Additional note which may be helpful: you can can set a zone terminal outdoor air requirement, which will modulate the terminal minimum flow airflow if needed, needed,(which will also impact total system airflow), using the DesignSpecification:OutdoorAir field at the air terminal object, as mentioned in this post. (The modulation would not be based directly on CO2 concentration though.)
