Zones in the actual building that are served by an extract only system will be served by the same in the notional building.
For extract only air-side systems you are able to input the design flow rate in l/s, l/s/m2, or ACH. If this value is zero then the minimum fresh air rate specified by the NCM will be used. The same design flow rate will be used by the actual and notional buildings.
As per paragraph 65 of the NCM modelling guide (2013) for zones with local mechanical exhaust the specific fan power in the notional building will be 0.4 W per l/s. If the extract fan is remote from the zone then the specific fan power will be 0.6 W per l/s in the notional building.
Monitoring for out-of-range values set to True will reduce the heating, cooling, auxiliary, and HWS consumption by 5%.
Exercise and Notes
In this example there is local mechanical exhaust and the SFP has been entered as 0.5 W per l/s.
The design flow rate will be 2 l/s/m2, giving a fan power density of 0.5 x 2 = 1 W/m2.
Monitoring for out-of-range values = True.