Too many densely occupied spaces

Hello everyone, I am working on a three-level commercial office project. The project includes, in total, 223 densely occupied spaces consisting of meeting rooms of different sizes (4, 8,10 and 14 people) as well as phone booths and some training rooms and cafeterias. As you can tell, this many densely occupied spaces make the credit very expensive for the client, as the number of CO2 sensors needed is very high. Do you know any Alternative Compliance Path that we can use to comply with this credit without installing CO2 sensors on each space? As additional information, we can't install CO2 sensors on the return air ducts, per HVAC design. Thanks in advance,