DOAS is not autosized correctly

asked 2024-04-12 05:38:18 -0500

Keigo's avatar

updated 2024-04-12 09:24:08 -0500

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.

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

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