C403.2.5.1 is a mandatory requirement and requires that demand control ventilation (DCV) must be provided for each zone with spaces > 500 ft² and the average occupant load > 25 people/1000 ft² of floor area where the HVAC system has:
· An air-side economizer,
· Automatic modulating control of the outdoor air damper, or
· A design outdoor airflow > 3,000 cfm
In ApacheHVAC, applicable IECC systems include pre-defined options for DCV. Users can enable DCV on these systems by checking the “Demand-controlled ventilation using zone CO2 sensors” box on the Zone Ventilation & Exhaust tab of the System Parameters dialog.
Figure 2: Zone Ventilation & Exhaust tab of the System Parameters dialog with DCV option highlighted.
For IECC standard reference systems in ApacheHVAC that do not include the option for DCV, modellers may use Prototype System 5b as an example for adding the damper and controllers to the standard reference system.
