Venting Availability Schedule of AirflowNetwork:MultiZone:Surface not acting on the AirflowNetwork:MultiZone:SpecifiedFlowRate path element

Issue overview

In the IORef section for Airflownetwork:MultiZone:Surface, it seems that the “venting Availablity Schedule” would have an on/off effect on many types of AFN flow path elements including the new AirflowNetwork:MultiZone:SpecifiedFlowRate one.

However, it was confirmed in the code that the Airflownetwork:MultiZone:Surface does not have an effect to shut off the vent when an AirflowNetwork:MultiZone:SpecifiedFlowRate path element is used. When the schedule has a “zero” value (not a blank schedule), which means “off”. The afn path AirflowNetwork:MultiZone:SpecifiedFlowRate’s flow rate is still per the flow rate specified by its own input, rather than shutting off to zero.

This was further confirmed by checking the EnergyPlus code. The openfactor is correctly set to zero in this case; but it will not be used in the flow path flow calculation for this specified volume or mass flow type element. The impact is not sent in via control or `multiplier’ (or other factors) for this type when doing the path flow calculations, either.

Therefor the first question might be: should the AirflowNetwork:MultiZone:Surface's venting availability schedule act on the AirflowNetwork:MultiZone:SpecifiedFlowRate type of path? If the answer is no, then some clarifications about this point in the IORef documentation might be helpful.

If the answer is yes, then some code changes would be needed to take the AFN surface’s venting availability schedule into account when doing the path flow calculations and filling the solving matrix contents. The matrix element (F &D) calculations for the afn flow path element would then also be affected (may or may not be a good situation to deal with since it will get more or all zeros in the F&D entries there when venting availability is being shut off).

Details

Some additional details for this issue (if relevant):

• Platform (Operating system, version): All
• Version of EnergyPlus (if using an intermediate build, include SHA): v9.6 to v22.1
• Helpdesk ticket number: 16196

Checklist

Add to this list or remove from it as applicable. This is a simple templated set of guidelines.

• Defect file added (list location of defect file here)
• Ticket added to Pivotal for defect (development team task)
• Pull request created (the pull request will have additional tasks related to reviewing changes that fix this defect)

Start by resolving whether the AirflowNetwork:MultiZone:Surface venting availability schedule is intended to affect AirflowNetwork:MultiZone:SpecifiedFlowRate. Then inspect the AirflowNetwork flow-path calculations and solving-matrix F&D handling described in the issue. Done means either clarifying the IORef documentation or implementing and validating the intended schedule behavior.