Sensor for CO2 or volatile organic compounds. Meets ASHRAE 62.1 standards and is optimize HVAC use for demand control ventilation. Some models include sensors for temperature and humidity. Some models include a relay which can be controlled by CO2 level, VOC level, or by LonWorks®. The password-protected color touch screen interface is configurable to show as much or as little information as desired in English or French. Models are available for duct or wall mounting. The wall mount version can be surface mounted or to a junction box. Operates on 24 Vac or 24 Vdc.