GG IAQ Study 2.0

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Summary of Winter Mode IAQ Related Study

PLANTS - study on CO2 processing


  • How do winter ventilation conditions in the Lg. Conf. Room compare to summer?
  • Repeated CO2 and particle count data logging in February 2016 to compare to summer 2015 readings.
  • Observed CO2 levels exceed 1000 ppm target during most of the scheduled meetings in the Lg. Conf. Room during trend period.
  • Observed CO2 levels at Helen's desk over 1000 ppm Friday after community lunch; otherwise peaked around 800-900 ppm during other days.
  • Focused mostly on CO2 for analysis; no real particle count issues in Lg. Conf. Room but was higher in winter. Helen's desk small particles high, but may be location of meter?
  • Winter results generally similar to summer with no marked differences found.


  • What is the current airflow to Lg. Conf. Room and what would be required with newer ventilation standards?
  • Lg Conf Room existing exhaust (measured 9/9/16)
    • With door closed 46 CFM
    • With door open 49 CFM
    • Current exhaust airflow approximately 50 CFM
    • APPEARS TO BE APPROX. 30%-40% lower than original design/TAB report currently (may be some leakage in reading taken, but deficiency more likely due to Red Panda exh added).
  • Check 2012 Ventilation Standard for State of Michigan (ASHRAE 62.1-2010)
    • Ventilation for 265 SF large conf room with standard people density = (13 people x 2.5 CFM) + (265 SF x 0.06 CFM/SF) = 81 CFM
    • For Demand Control Ventilation (DCV using measured CO2 to control ventilation amount), minimum setting would be 16 CFM with maximum 81 CFM just for the large conf. room.
    • NOTE: GG DCV design is for whole bldg CO2 measurement as a single zone with multiple spaces.
    • Also supply air is transferred from main building area, not introduced directly into conf. space.
  • ERV System during measurement activity, on a Friday afternoon
    • ERV on high, booster fan on high (RH call; DCV call).
    • Verified calibration of TH-1 controlling sensor for dehumidification control (Results: temp -0.2F; rh -3%; calibration acceptable).



  • What could be done to improve the ventilation for the Lg. Conf. Room?
  • With existing system
    • Rebalance exhaust airflow to achieve original design values or higher in enclosed spaces
      • Make sure enclosed spaces balanced over target exhaust airflows, not under (design value 0 to +10% instead of +/- 5%)
      • Need to increase the total airflow through the conf rm/toilet rm exhaust air branch which is the low speed setting on the ERV to accomodate Red Panda Exhaust (approx. 100 CFM additional)
      • Need to approximately match the supply inflow to the exhaust outflow for bldg pressurization considerations (can supply/exhaust fan speeds be adjusted independently?)
      • Need to check/adjust ERV high speed setting/airflow also to confirm proper airflow in all branches once main system exhaust branch damper is open
      • Need to check/adjust ERV high speed with booster fan running also to confirm proper airflow maintained
    • Observed that ERV controls appear to have two manual speed adjustment cabinets for setting speed, but it appears that only one cabinet is wired into the fan motors?? This seems to suggest that both fans (supply and exhaust) for the ERV are being controlled to the same speed signal. Recommend speed control adjustment be further investigated and possibly re-wired so that speed of supply and exhaust fans can be adjusted individually.
    • Open windows in occupied conf. room when outside air conditions are favorable
    • Increase exhaust from space if more than 13 people expected frequently for improved ventilation and to help prevent build-up of heat from people; not significant cooling since air transfered from main space, but movement and reduction of buildup may still help (check limitations of current duct/exhaust diffuser sizing; watch air noise)
  • With additions or revisions to existing system
    • Inject some supply air directly into conf. space
    • Provide dilution air by recirculating main building air through conference room when occupied (fan, transfer ducts, AireShare, etc.?)
    • New ERV just for conf. room(s)
    • CO2 scrubber
    • Add plants that are best at cleaning indoor air of excess CO2


  • How can we improve airflow to the supplemental register that provides air to main historical open area when booster supply fan is on high?
  • Cut back 12" round duct to make transition to register elbow/boot behind supply register
  • Transition from 12" round duct to rectangular elbow/boot either with a round diverging conical fitting or a round to rectangular transition (Air Works preferred method)
  • Transition should be limited to maximum of 15 degree angle on both side and should be symmetrical
  • Inside rectangular elbow/boot, use either turning vanes or sweep sheets to ease the airflow around the turn
  • Only use turning vanes if able to make the leading edge and leaving edge of the turning vanes exactly parallel to airflow direction; otherwise, use series of sweept sheets
  • If turning vanes are not parallel to flow, they may actually increase air pressure drop rather than reducing it
  • Looked at using radius elbow instead of square with turning vanes or sweep sheets, but it appears that this would pull the 12" round duct too far away from the wall to make an adequate radius turn into the register