How does a fan control the volume flow based on the current CO₂ measurements?

The CO₂-controlled automatic mode of a ventilation unit differs fundamentally from humidity control and odor detection, as it operates without averaging or background reference. This means that the control system reacts directly to the currently measured CO₂ concentrations in the room air without referring to average values or comparative values from the past. An increase in the CO₂ content in the room air is a clear indication of an increased need for ventilation, as this indicates an increased presence of people or an insufficient supply of fresh air.

The fan adjusts its volume flow in eight stages to the measured CO₂ values, which in practice corresponds to almost infinitely variable control. In normal operation, the control system starts with the preset basic ventilation level, which ensures continuous minimum ventilation.

As soon as the measured CO₂ value exceeds the defined lower switching threshold, the system leaves the basic ventilation level and increases the ventilation output according to current requirements. If the upper limit for CO₂ content is exceeded, the device automatically switches to the demand ventilation level to ensure a rapid and effective reduction in CO₂ concentration.

If, despite maximum ventilation performance, it is not possible to reduce the CO₂ content in the room to an acceptable level, it is recommended that windows be opened in addition to ensure sufficient air exchange. This procedure ensures optimum indoor air quality and helps to maintain the well-being and concentration of the people present. CO₂-controlled ventilation control is therefore an important component of modern ventilation concepts and ensures a demand-oriented, energy-efficient supply of fresh air.

The Silvento ec series exhaust air units, in combination with the 5/VOC control board, enable infinitely variable automatic operation that regulates the volume flow depending on CO₂ content, humidity, and VOC values. The CO₂ control range is typically between 1200–2500 ppm or 1500–3000 ppm. The fan automatically adjusts its speed as soon as the CO₂ value rises, thus ensuring a supply of fresh air in line with requirements.

The TAC (Touch Air Comfort) as the central comfort control for various LUNOS devices, such as the e² and e^go series and the Nexxt, can be equipped with an optional external CO₂ sensor (SCO2-TAC). This adds CO₂ control to the automatic mode, which controls the air quality based on the CO₂ content.