The use of CO₂ as an indicator for indoor air quality and control of ventilation according to EN16798-1 and TR16798-2

In many building regulations, the indoor air quality criteria is specified as an absolute level of CO₂ concentration, being also the most common parameter used by demand controlled ventilation systems. The use is however challenged by new research showing that the CO₂ as a source itself may influence cognitive performance of people. In the indoor environmental quality European standard, EN16798-1, different methods are listed for calculating the design ventilation rate. Nevertheless, they do not result in the same level of indoor air quality. One of the methods uses CO₂ concentration as criteria and specifies different concentrations for different categories of indoor air quality (I-IV). The related technical report, TR16798-2, provides recommended CO₂ concentrations for different types of spaces and shows how the use of gas phase air cleaning may reduce the required amount of ventilation for the same level of indoor air quality. The use of this technology will however result in an increase of the CO₂ concentration. This paper discusses these issues and gives recommendations for future revision of the standard and guideline in relation to the use of CO₂ as an indoor air quality indicator.