can we install a CO2 sensor in return air duct before any supply,return air duct bypasses the return air duct from space where CO2 needs to be monitored, if it is a mechanical ventilated system as recirculated air is returning from single space instead of 3-6 ft above floor levels as mentioned in guide?
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Vamshi Gooje
AssociateThornton Tomasetti | Fore Solutions
30 thumbs up
September 30, 2010 - 3:30 pm
Even if there is no dilution of the return air from other return ducts before the CO2 sensor's location in the duct, LEED does not allow installing CO2 sensors in the return duct. (There is a CIR under LEED NC 2.2 (6/27/2008) that confirms the same.) We cannot find any exceptions to this.
If a space does not have well mixed air (which is possible for various reasons) then the CO2 concentration may not be uniformly distributed. In such situations, locating a CO2 sensor in a return duct may not depict real conditions in the breathing zone.
Ankit Jain
8 thumbs up
October 1, 2010 - 7:47 am
Thanks for you reply, is there any criteria or standard which mention how much CO2 sensor should be placed in a breathing zone. what i feel that placing one CO2 sensor for a breathing zone of say 200 person will also not give accurate measurement of CO2 due to non uniform distribution of occupancy?
Vamshi Gooje
AssociateThornton Tomasetti | Fore Solutions
30 thumbs up
October 1, 2010 - 10:46 am
It is at the designer's discretion to determine the quantity and location of multiple Co2 sensors. It depends on configuration of the space , distribution of population etc. There is some guidance in Appendix A of ASHRAE 62.1 but it does not address the quantity of Co2 sensors required in such spaces.