.Buildings.Controls.OBC.ASHRAE.G36.AHUs.SingleZone.VAV.SetPoints.SupplyTemperature

Information

Block that outputs the set points for the supply air temperature for cooling, heating and economizer control for a single zone VAV system. The implementation is according to the Section 5.18.4 of ASHRAE Guideline 36, May 2020.

Supply temperature setpoints

The output TSupCooSet is to be used to control the cooling coil, and the output TSupHeaEcoSet is to be used to control the heating coil and the economizer dampers.

When it is in deadband state, the output TSupCooSet and TSupHeaEcoSet shall be average of the zone heating setpoint THeaSet and the zone cooling setpoint TCooSet but shall be no lower than TSupDea_min, 21 °C (70 °F), and no higher than TSupDea_max, 24 °C (75 °F),

Control mapping

1. For a heating-loop signal uHea of 100% to temPoiOne (default 50%), TSupHeaEcoSet should be TSup_max.
2. For a heating-loop signal uHea of temPoiOne to 0%, TSupHeaEcoSet is reset from TSup_max to the deadband value.
3. In deadband (uHea=0, uCoo=0), TSupHeaEcoSet is the deadband value.
4. For a cooling-loop signal uCoo of 0% to temPoiTwo (default 25%), TSupHeaEcoSet is reset from deadband value to TSup_min minus 1 °C (2 °F), while TSupCooSet is the deadband value.
5. For a cooling-loop signal uCoo of temPoiTwo to temPoiThr (default 50%), TSupHeaEcoSet and TSupCooSet are unchanged.
6. For a cooling-loop signal uCoo of temPoiThr to temPoiFou (default 75%), TSupHeaEcoSet remains at TSup_min minus 1 °C (2 °F), while TSupCooSet is reset from the deadband value to TSup_min.
7. For a cooling-loop signal uCoo of temPoiFou to 100%, TSupHeaEcoSet and TSupCooSet are unchanged.

The figure below shows the sequence.

Note that the inputs uHea and uCoo must be computed based on the same temperature sensors and control loops.

Revisions

• June 30, 2025, by Jianjun Hu:
  First implementation.