.Buildings.Controls.OBC.ASHRAE.G36.TerminalUnits.CoolingOnly.Controller

Information

Controller for cooling only terminal box according to Section 5.5 of ASHRAE Guideline 36, May 2020. It outputs discharge airflow setpoint VSet_flow, damper position setpoint yDam, AHU cooling supply temperature setpoint reset request yZonTemResReq, and static pressure setpoint reset request yZonPreResReq. It also outputs the alarms about the low airflow yLowFloAla, leaking damper yLeaDamAla, and airflow sensor calibration alarm yFloSenAla.

The sequence consists of six subsequences.

a. Heating and cooling control loop

The subsequence is implementd according to Section 5.3.4. The measured zone temperature TZon, zone setpoints temperatures TZonHeaSet and TZonCooSet are inputs to the instance of class Buildings.Controls.OBC.ASHRAE.G36.ThermalZones.ZoneStates to generate the heating and cooling control loop signal.

b. Active airflow setpoint calculation

This sequence sets the active maximum and minimum airflow according to Section 5.5.4. Depending on operation modes uOpeMod, it sets the airflow rate limits for cooling supply. See Buildings.Controls.OBC.ASHRAE.G36.TerminalUnits.CoolingOnly.Subsequences.ActiveAirFlow.

c. Damper control

This sequence sets the damper position setpoints for the terminal unit. The implementation is according to Section 5.5.5. According to heating and cooling control loop signal, along with the active maximum and minimum airflow setpoint, measured zone temperature, the sequence outputs damper position setpoint, and active airflow rate setpoint. See Buildings.Controls.OBC.ASHRAE.G36.TerminalUnits.CoolingOnly.Subsequences.Dampers.

d. System reset requests generation

According to Section 5.5.8, this sequence outputs the system reset requests, i.e. cooling supply air temperature reset requests yZonTemResReq, static pressure reset requests yZonPreResReq. See Buildings.Controls.OBC.ASHRAE.G36.TerminalUnits.CoolingOnly.Subsequences.SystemRequests.

e. Alarms

According to Section 5.5.6, this sequence outputs the alarms of low discharge flow, leaking damper and airflow sensor calibration alarm. See Buildings.Controls.OBC.ASHRAE.G36.TerminalUnits.CoolingOnly.Subsequences.Alarms.

f. Testing and commissioning overrides

According to Section 5.5.7, this sequence allows the override the aiflow setpoints, damper position setpoints. See Buildings.Controls.OBC.ASHRAE.G36.TerminalUnits.CoolingOnly.Subsequences.Dampers.

Revisions

• January 12, 2023, by Jianjun Hu:
  Removed the parameter have_preIndDam to exclude the option of using pressure independant damper.
  This is for issue 3139.
• August 1, 2020, by Jianjun Hu:
  First implementation.