Number of CO2 sensors for various room configurations - KBA234947
Community Translation: 様々な部屋の構成に対応するCO2センサーの数 – KBA234947
Infineon’s XENSIV™ PAS CO2 sensor is based on Photo Acoustic Spectroscopy (PAS) technology and measures the true concentration of CO2 in ppm. Simulations for three scenarios based on the size of the room and number of people in the room, and considering realistic assumptions on the breathing rate of people present in a room with no ventilation or circulation of fresh air.
Assume a classroom of 60m2 with 20 students (aged 12-20 years) and 1 teacher (above 30 years). Air volume exhaled per human is about 8 L/min. The CO2 emission per student is assumed to be about 680 grams/day and the emission per adult is about 900 grams/day. Heat emission per human is about 60 W. In this case, there are three CO2 sensors placed as shown in the following figure. Probe 1, Probe 2, and Probe 3 indicates the placement of sensor on the floor, ceiling, and behind the black board.
Based on particle matter dispensation simulation using advance physics simulation tools, you can observe the distribution of CO2 over a period of time as shown below:
Based on the position of the sensors, you can see that the difference in the measurement value of CO2 concentration after 480 seconds with probes 2 and 3 is almost similar. For such a room size, a single CO2 sensor is sufficient to take decisions on increasing ventilation.
Consider a meeting room of 30 m2 with 6 adults. Using the same assumption as before (8 l/min air volume exhale rate per human, CO2 emission of 900 grams/day and heat emission of 60 W per human), you can see that a single CO2 sensor is sufficient for the entire room.
An open office of 4x25 m2 divided into 4 blocks with distribution as follows:
Block 1 – 2 adults
Block 2 – 0 adults
Block 3 – 3 adults
Block 4 – 1 adult
Using the same assumption as before (8 l/min air volume exhale rate per human, CO2 emission of 900 grams/day and heat emission of 60 W per human), even in this case, you can see that a single CO2 sensor is sufficient for the entire office space.
The graph shows that among different locations, no significant difference in CO2 concentration is observed. In the beginning there is a difference in the CO2 concentration but after 200 seconds there is no much difference in the CO2 concentration. Therefore, in most situations, you can use a single sensor to measure the concentration of CO2.