EE80 series set new standards in CO2 measurements for HVAC. The transmitters resp. switches combine CO2, relative humidity (RH) and temperature (T) measurement in one modern and userfriendly housing. The basic EE80 version for CO2 and T can be easily extended with a RH plug-in module. The CO2 measerument is based on the infrared principle. A patented auto-calibration procedure compensates for the aging of the infrared source and ensures outstanding long term stability. EE80 provides analogue outputs (in V or mA). The optional display indicates sequentially the actual measuring data. As one more option a switching output with adjustable switching point and hysteresis is available. A wide variety of models ensures an optimal adjustment for customised requirements.