Development and Verification of Control Sequences for Single- Zone Variable Air Volume System Based on ASHRAE Guideline 36

This paper presents work on the development and verification of ASHRAE Guideline 36-2018 control sequences for single-zone variable air volume airhandling unit (AHU) systems. The Control Description Language, a subset of the Modelica Language, is used to implement those advanced control sequences. The sequences address control for components such as the economizer, supply air temperature setpoint reset, fan speed control, and zone heating/cooling states determination. Each component sequence is validated in open-loop tests and then used to compose a single comprehensive controller. This controller is also first validated in open loop and then tested in closed loop with an AHU system and building envelope model constructed using the Modelica Buildings library. The Guideline 36 controller is compared with a conventional control strategy applied to the same AHU and building model. Annual simulations show that the Guideline 36 control sequences yield 17.3 % of annual HVAC energy savings against the conventional control strategy in this case study.