Simple and Cheap Air Change Rate Measurement Using CO2 Concentration Decays

Buildings are aired to evacuate indoor pollutants, in particular those produced by the occupants. CO2 is a good indicator of occupancy, as long as there is no other significant source. This is the case in most buildings. Cheap, portable analysers and loggers that allow easy recording of the CO2 concentration in a room or in the exhaust duct of a ventilation system are available on the market. The peak value of CO2 concentration during occupancy is an indicator of the minimum air flow rate per person.

Methods for predicting air change efficiency.


ECSC promoting domestic energy efficiency.


Measurement techniques for air change and air penetration of residential buildings Messmethoden zur Erfassung des Luftwechsels und der Luftdurchlassigkeit von Wohnbauten.

Defines air change and air penetration. Describes the differential pressure method, the infrasound method, qualitative judgement methods, and acoustic measurement devices for determining air penetration. Explains procedures todetermine air change - the rate of decay method, the constant concentration method, and the constant emission method.