Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page
Ask Your Question

Revision history [back]

DOAS is not autosized correctly

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.

image description

image description

image description

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

DOAS is not autosized correctly

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.

image description

image description

image description

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