Measuring Carbon Dioxide for Ventilation -Why is it necessary? To provide a healthy and comfortable environment, good ventilation system is becoming more and more important. But managing the fresh air brought into the house and polluted air removed outside through its ventilation system is the key point. Thanks to the technology development, high accuracy and high stability NDIR carbon dioxide sensor supports it much easier to realize. What is Carbon Dioxide? When it comes to breathing, the first thing comes into our mind is oxygen. But carbon dioxide is actually important. Carbon dioxide (CO2) is one of the most common gases in atmosphere, which is a key indicator of indoor air quality. It serves as a measure of ventilation efficiency in areas where air-conditioning and mechanical ventilation is provided. The CO2 concentration affection on human body Staying in high level of carbon dioxide will result in increased respiration, headache, dizziness, buzzing in the ears, blood pressure increase, high pulse rate, nausea and eventually. Unconscious, further exposure death Maximum allowed concentration within an 8 hour working period (USA) 5000ppm Adverse health effects may be expected 2500ppm 1000ppm American ASHRAE recommends that the CO2 levels not exceed 1,000 ppm inside buildings Acceptable levels drowsiness

Ventilation system can use CO2 sensor to monitor the carbon dioxide concentration of indoor air and start when the carbon dioxide concentration exceeds a certain standard, thus to keep the carbon dioxide concentration of indoor air below 1000ppm. How do CO2 sensor s help to balance the CO2 concentration between indoor and outside through its ventilation system performance? CO2 levels above 1000ppm in a room with numbers of people are quite normal and maximum concentration may occasionally happen from time to time. A good performance ventilation system should maintain the recommended CO2 concentration...

About NDIR measurement principle Molecule like CO2 and CO is composed of different types of atoms, it has absorption spectrum in infrared range. Absorption intensity abides by Lamber-Beer’s Law. When light wave corresponded to certain gas with absorption spectrum passes through measured gas, the intensity of light wave will be significantly weakened. The intensity attenuation is related to concentration of measured gas. This relation follows Lamber-Beer’s Law. Basic working principle of NDIR sensor is as below: Inlet outlet Basic mathematical model: A majority of both organic and inorganic...