A HVAC CO2 sensor is a device used to measure the amount of carbon dioxide in the air. It is typically used in commercial and industrial buildings to monitor the air quality and to adjust the ventilation system accordingly. The sensor works by measuring the concentration of CO2 in the air and sending a signal to the ventilation system to adjust the air flow accordingly. This helps to maintain a healthy and comfortable environment for the occupants of the building. The CO2 sensor is also used to monitor the air quality in greenhouses, where it is important to maintain the right levels of CO2 for the plants to grow. The sensor is also used in some industrial processes, such as in the production of beer, where it is important to maintain the right levels of CO2 for the fermentation process. HVAC CO2 sensors are an important part of any ventilation system, and they are becoming increasingly popular as a way to maintain a healthy and comfortable environment.