Damper-optimised DCV consists in controlling the airflow rate in the main duct according to the position of the dampers, such that at least one of the dampers is in a maximum open position (Figure 4). The purpose is to ensure minimum fan energy consumption by looking for a minimum pressure rise over the fan. This is achieved if one duct path (critical path) is always open. With damper-optimised DCV, the required airflow rate, the supplied airflow rate as well as the damper angle are recorded for all the DCV dampers. This information is sent to a controller which regulates the fan speed.
Balancing of DCV units in damper-optimized systems is very simple, and consists in specifying minimum and maximum design airflow rate for each DCV unit. This can be done either through the bus-system or by connecting a programming device directly on the DCV units. Various programming devices are used by the different suppliers.
Source from article on “Commissioning for energy-optimal Demand-Controlled Ventilation” by Mads Mysen, Peter G Schild, Axel Cablé and John Woollett