Our project have 1 PAU supply fresh air to many plenum of FCU (return air + fresh air), beside that we also have some meeting room which fresh air is supply through VAV box, control by CO2 sensor (CO2 put at breath level). The issue here is in some case, some space will turn of FCU and damper of fresh air will close, similar to VAV box will alway change openable rate. So the total air of PAU will change. We wonder which device monitor will be suitable in this case?
The design minimum outdoor airflow rate always change, so we can not define the value to compare to varies by 15%.
Dang Thi
ESD EngineerGreenViet Consultancy Company
3 thumbs up
June 15, 2020 - 2:27 am
Who can help me? Because we get this issue for many projects!
Saif Alsaeed
June 27, 2020 - 5:58 pm
For the outsid air that is being supplied throug a VAV system I think you can consider the VAV as a measuring station for the outsid air based on the damper positon. The VAV will genergate an alarm incase the ouside air does not match the required amount by the CO2 sensor. For the fan coil units you can provide one of the measuring options required in the LEED Reference Guide:
"For constant-volume systems, balance outdoor airfow to the design minimum outdoor airfow rate defned by ASHRAE Standard 62.1–2010 (with errata), or higher. Install a current transducer on the supply fan, an airfow switch, or similar monitoring device."
Doing that I think you can avoid installing a measuring station for the PAU