Gas Sensors must be tested properly using calibration gases and be calibrated / adjusted so that they can function as they were intended to.
Manufacturers state that sensors must be tested according to their specifications and the type of environment the sensors are exposed to i.e. residential or industrial installations, between every 6 > 12 months to maximise the life of the sensors and to ensure correct operation.
Consequences of not calibrating your gas sensors.
Your Automatic Ventilation System does not function properly. This means either your fans run too much or continuously and thereby wasting energy or the fans do not run enough or at all; creating a health hazard for the building occupants and car park users due to potentially dangerous levels of CO or NO2 (Carbon Monoxide for Petrol & Nitrogen Dioxide for Diesel vehicles)