Except for HVAC systems serving dwelling units hotel / motel rooms each system incorporating mechanical cooling with a capacity of more than 1500 l/s or has cooling capacity of more than 20 kW shall be designed to use outdoor air to reduce mechanical cooling energy as 5.2.2.8 (air economizer) and 5.2.2.9 (water economizer).
NECB-2017 Article 8.4.3.6.(1)
The outdoor air ventilation for the proposed building must be set the minimum rates required by the standard (ASHRAE 62.1: 2007). IF DCV is included the basic rates can be adjusted; however as DCV effectiveness can vary only DCV strategies that reliably generate energy savings should be modelled.
NECB-2017 Article 8.4.4.15
The outdoor air ventilation rates for the reference building shall be modelled as being identical to those determined for the proposed building. Outdoor air ventilation rates can be set via the System Parameters>Room Ventilation & Exhaust tab.
For the reference model demand control ventilation (DCV) is required as NECB-2017 section 5.2.3.4 i.e. enclosed semi-heated or conditioned spaces where fuel power vehicles, equipment or appliances are intermittently used or commercial kitchens whose exhaust airflow rate exceeds table 5.2.3.4, otherwise it is not modelled in the reference building.
For NECB Reference Systems in ApacheHVAC that need DCV, modellers may use Prototype System 5b as an example for adding the damper and controllers to the reference system.
Figure 5: Prototype System 5b with network and controllers relevant to DCV selected
Figure 6: Zone Ventilation & Exhaust tab of the System Parameters dialog with DCV option highlighted
It should also be noted that as per Table 8.4.4.7.B that except for HVAC systems serving dwelling units, outside air requirements for the thermal blocks served by the reference systems should be met by a single ventilation system able to meet all the required outside and exhaust air rates. For HVAC systems serving dwelling units, outside air requirements shall be met by a ventilation system identical to that of the proposed building.
