Demand controlled ventilation

Demand controlled ventilation is a control strategy that modulates ventilation rates based on demand. While typically associated with mechanical extract ventilation, it can be applied in other applications too, notably including passive stack ventilation and mechanical ventilation with heat recovery. As such there is some discussion over whether demand controlled ventilation should be referred to as a ventilation system, or a control approach for various ventilation systems.

Typically DCV systems modulate ventilation rates based on relative humidity levels, though it is also possible to utilise sensors to track other pollutants, such as CO2.

While ventilation systems should be principally thought of in terms of indoor air quality rather than energy performance, it's estimated that a typical demand controlled mechanical extract ventilation system (DCMEV) would reduce ventilation heat loss by approximately 50% compared to an MEV system with no demand control.