How to model unit ventilator (with cooling) equipped with ON/OFF economizer?

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Hello,

I need to model a packaged cooling system that allows a constant outdoor airflow whenever outdoor temperature is lower than indoor setpoint (24°C). When temperature raises over 24°C a cooling coil is activated and air is fully recirculated with no outdoor air. I looked for something similar among Zone HVAC equipment but nothing seems to work with it. Is there some equipment or control feature that allow modeling such a system without using EMS? Am I missing something?

Thank you very much for your help