Using DCV to reduce energy use and meet IEQp1

Ralph, feel free to use this forum to share "Project CIRs"! (And encourage others.) If it starts to become popular we might be able to set something up.I am looking for USGBC to soon announce a key change to its CIR process, FYI.

It isn't completely clear what you're trying to achieve. All designs need to be ASHRAE 62.1-2007 compliant. The breathing zone airflow rates have been carefully developed through research and application and should be used to set your design airflow rates. Demand controlled ventilation can be used to reduce the amount of ventilation air brought in, for energy savings, but I'm not sure how that would help you meet the prerequisite. Also, CO2 monitoring should occur in the breathing zone, not in the return air ductwork, to be effective.

If I understand the question correctly, it sounds like you're having trouble demonstrating through testing that the ASHRAE 62 minimum OA is being delivered by the demand-control ventilation (DCV) system. I had a similar question come up with a client and haven't resolved the matter. To illustrate, the DCV approach introduces OA to maintain CO2 at a prescribed level. Therefore, the OA is not based on zone-based occupancy numbers but, rather, on CO2 feedback (in the breathing zone). Thus, any testing done to demonstrate OA deliver will yeild a lower number since the space likely is not fully occupied (and less OA is being delivered). While troublesome, would it be possible to correlate actual occupancy at the time of testing (showing adequate OA is being delivered) and demonstrate that the AHU has the capacity to deliver the required OA at full occupancy (through calculations)? A possible augmentation to this would be tracking of CO2 levels in the breathing zone.

Has anyone documented this prerequisite with demand control ventilation? I'm going through this with a project right now, and it's a concern because the minimum OA setpoint is below the ASHRAE 62.1 requirement. If we take our measurements at the current minimum, it will surely not meet the prerequisite. However, if we increase the minimum to the amount of OA required to meet 62.1, then the DCV is not saving us any energy. Does anyone have any insight on this? Thanks.