The Series CDX Carbon Dioxide Transmitter is a low cost and high performing CO2 sensor. This product will provide immediate energy savings by functioning in conjunction with building automation systems and allowing the user to effortlessly and effectively control fresh air into preferred areas. On-Demand ventilation using CO2 sensors prevents energy losses from over ventilation while maintaining indoor air quality. The potential for the greatest energy saving occurs in areas where occupancy alters over the duration of the day. The Series CDX Transmitters utilize the patented Automatic Background Calibration (ABC) Logic self-calibration system. ABC Logic virtually eliminates the need for manual calibration in applications where the indoor CO2 level drops to outside levels during unoccupied periods. If the transmitter is being used in an application where a building is continuously occupied 24 hours per day, then the user will permit that the ABC Logic feature be turned off.