The room CO2/RH/T Transmitter incorporates three sensors and the room CO2/T Transmitter incorporates two sensors in one attractive wall mount enclosure for the most efficient environmental monitoring and control system. It uses dual channel optics and LTA (long term adjustment) signal processing technology to monitor CO2 levels within a range of 0 to 10,000 ppm, a field-proven RH sensor to monitor relative humidity from 0-100 %RH (If included in model ordered) and a thermistor to measure temperature over common field-selectable ranges. All measurements are continuously available on separate outputs as linear 4-20 mA or 0-5/0-10 Vdc signals. The device includes an LCD for configuration and operating parameters are programmed using a keypad for specific applications. Options include a control relay, override switch and slide pot set-point control.