.Buildings.Controls.OBC.ASHRAE.G36.AHUs.SingleZone.VAV.Economizers.Controller

Information

Single zone VAV AHU economizer control sequence that calculates outdoor and return air damper positions based on Section 5.18.5, 5.18.6, 5.18.7, 5.1.17 of ASHRAE Guidline 36, May 2020.

The sequence consists of three subsequences.

• First, the block damLim computes the damper position limits to satisfy outdoor air requirements. See Buildings.Controls.OBC.ASHRAE.G36.AHUs.SingleZone.VAV.Economizers.Subsequences.Limits for a description.
• Second, the block enaDis enables or disables the economizer based on outdoor temperature and optionally enthalpy, and based on the supply fan status, freeze protection stage and zone state. See Buildings.Controls.OBC.ASHRAE.G36.AHUs.SingleZone.VAV.Economizers.Subsequences.Enable for a description. The block ecoHigLim specifies the economizer high limit cutoff values based on the energy standard, device type and climate zones. See Buildings.Controls.OBC.ASHRAE.G36.Generic.AirEconomizerHighLimits for a description.
• Third, the block mod modulates the outdoor and return damper position to track the supply air temperature setpoint for heating, subject to the limits of the damper positions that were computed in the above two blocks. See Buildings.Controls.OBC.ASHRAE.G36.AHUs.SingleZone.VAV.Economizers.Subsequences.Modulation for a description.

Revisions

• July 30, 2019, by Kun Zhang:
  Added fixed plus differential dry bulb temperature high limit cut off.
• October 31, 2018, by David Blum:
  Added heating coil output.
• June 28, 2017, by Milica Grahovac:
  First implementation.