I am working on a multi-story office fitout for a single tenant, and we received a review comment on our submission regarding EAc1.3 asking us to "provide documentation that all conference rooms have been provided with demand control ventilation PLUS thermostat setback." The reviewer then refers to LI#10242 and LI#10263 for further guidance.
Looking at LI#10242, the Ruling states "...active controls typically regulate the required outdoor air flow for ventilation, such as using demand controlled ventilation with CO2 sensors in each private office and specialty occupancy space, OR (emphasis added) regulate temperature set point based on occupancy..."
In the subsequent LI#10263, the Ruling gives specific guidance for densely occupied spaces, requiring "a separate thermal control for each space paired with a CO2 or occupant sensing device, which is used for demand control ventilation AND (emphasis added) to set back the temperature setpoint to the space when the space is unoccupied."
My question is, does the later LI override the former? That difference between OR and AND is a big one, as the newer LI is adding a third requirement for densely occupied spaces (separate thermal zones, CO2-based DCV, AND occupancy sensors to force temperature setback). We have successfully submitted other tenant fitouts under this same rating system using just individual zone temperature sensors and CO2 sensors driving DCV, so to get this comment on our review was a shock. (Just when you think you understand the requirements...)
I'm also not certain how to use a CO2 sensor as an occupancy sensing device, as alluded to in the LI#10263 text. I suppose we could set some limit on CO2, perhaps a little below our limit for returning the damper to thermal control from DCV control, that would initiate temperature setback. That seems a little cumbersome though. We do have occ. sensors for our lights, but unfortunately they do not have the spare contacts required for connection to the HVAC control system.
I'm also not sure I'm on board with temperature setback during "occupied" hours in conference rooms. If we allow the temperature to rise to 80 deg F because the conference room is unoccupied, the next group to come into the room is going to be uncomfortable and the system may not be able to bring the temperature down to occupied setpoint quickly enough. I see this control causing a lot of headaches for building maintenance.
Thanks in advance for your time and advice.