I found a weird behaviour of autosizing. For DOAS, when a zone, some zones or all zones have 0 m3/s of outdoor air flow rate (which is often define by DesignSpecification:OutdoorAir), the air flow of the correspond DOAS Air Terminals should be 0, but actually EnergyPlus assigns non-zero air flow to the DOAS Air Terminals.

Example: 5ZoneFanCoilDOASCool_rev.idf (V24-1-0). I changed the outdoor air flow rate 0 m3/s in DesignSpecification:OutdoorAir.

The air flow rate of the DOAS Air Terminals and the DOAS Fan is not 0m3/s. The DOAS Fan constantly runs with this non-zero air flow, which increaes fan end use.

We can avoid the bug by not connecting DOAS to zones with no outdoor air flow requirement. This is just a reminder.