Demand-controlled ventilation
The fan and the air handling processes – heating, cooling, humidification and dehumidification – are the major energy users in ventilation and air conditioning plants. For this reason, the fan should be switched off when ever possible and operated only when there is demand for ventilation resulting from inadequate indoor comfort conditions, using the lowest possible fan speed.
Switching on and increase of the amount of outside air delivered to the space take place via demand-dependent control (by means of indoor air quality (IAQ) sensors for acquiring CO2/VOC), presence-dependent control (with the help of presence detectors) or resulting from the sustained mode function for controlled variables such as temperature, humidity, etc. The process runs until the required operating state is reached. Then, the plant is shut down again.