Modeling VAV Terminal Unit Controls: Lessons with EnergyPlus

Why Modeling Modern HVAC Systems Is Harder Than It Looks 
In this presentation, we walk through a subtle but critical issue in EnergyPlus: how ventilation minimums can be incorrectly modeled in VAV systems, especially during heating mode. We show how to correctly account for outdoor air minimums and highlight a gap in how newer control strategies—like those from ASHRAE Guideline 36—are represented. 

We also touch on how CBECC Title 24 modeling similarly overlooks the concept of a heating minimum flow, which exists in real VAV box logic but not in the simulation. These mismatches can lead to underestimated fan energy and poor design decisions if you're not careful. 

Perfect for modelers working with advanced HVAC controls or anyone wondering why simulation results sometimes don’t match field performance.