Siemens has introduced the Series 2200 range of CO₂ room units. Designed to work with Siemens’ APOGEE Building Automation System and BACnet programmable terminal equipment controllers (PTEC), the units include sensing-only and fully interactive models. The units offer numerous options for zone level CO₂, and temperature- and humidity-sensing. On display models, a 96 × 64 pixel graphical organic light-emitting-diode display alternately indicates zone CO₂, temperature, humidity, and/or day-and-night operation status. A convenient plug-in human machine interface (HMI) port is standard. The maintenance-free, compact, low-profile units connect to the BACnet PTEC controller via the controller’s RJ-11 port.  Ventilation slots in the room unit housing optimize airflow through the cover for fast measurement response and superior control. —Siemens