We intend to incorporate demand control ventilation in our project. AHSRAE 62.1 limit on CO2 concentration is 700 ppm. If we have to meet the 30% increase in ventilation air for subject credit, what should be the maximum CO2 concentration in the conditioned space? Our outdoor CO2 concentration is 400 ppm.
You rely on LEEDuser. Can we rely on you?
LEEDuser is supported by our premium members, not by advertisers.
Go premium for
Roger Chang
Principal, Energy and Engineering LeaderDLR Group | Westlake Reed Leskosky
LEEDuser Expert
398 thumbs up
March 25, 2010 - 4:38 pm
700 ppm is still an appropriate target for demand controlled ventilation, regardless of the design ventilation rate. With a properly functioning system, the amount of ventilation air supplied to spaces with CO2 sensors will end up matching occupant loading and will be decoupled from the peak design value (e.g. 20 cfm/person). Increased ventilation will have more of an impact on spaces that don’t have CO2 sensors and likely result in CO2 levels less than 700 ppm.
Shillpa Singh
Senior Sustainability ManagerYR&G
131 thumbs up
March 31, 2010 - 8:37 am
Hi Conrado
This is a question for ASHRAE 62.1 2007, and more specifically, we find the ASHRAE 62.1 2007 User’s Manual to be super helpful in navigating this credit. The credit addresses the system capacity to supply that 30% extra outside air. It doesn't stipulate CO2 levels that trigger the call for more outdoor air -- that will depend on the ambient conditions and activity levels of your project. Roger is correct that CO2 sensors support demand control ventilation for some spaces while this credit intent is to include all spaces.
Check out the User's Manual (Appendix A) for CO2 set point and see if it's helpful.
Good luck