100% VENTILATION IMPACT ON CLIMATE CHANGE VIA INCREASED GREEN HOUSE GAS (GHG) EMISSIONS AS IS EXAMPLE HVAC SUGGESTED 100% FRESH AIR SUGGESTED MERV13+ FILTERS FRESH AIR EXHAUST AIR FRESH AIR EXHAUST AIR FRESH AIR EXHAUST AIR (NO VIRUS?) (N0 VIRUS?) (NO VIRUS?) MIXING MIXING MIXING A DAMPERS B A DAMPERS B A DAMPERS B MIXED AIR C MIXED AIR C MIXED AIR C PLENUM PLENUM PLENUM EXISTING EXISTING EXISTING FILTERS FILTERS FILTERS HP “Z” HP ”Z” HP ”Z+” SUPPLY RETURN SUPPLY RETURN SUPPLY RETURN FAN “X” HP FAN FAN “X” HP FAN FAN “X ” HP FAN TOTAL 65˚F TOTAL 30˚F TOTAL 65˚F HEATING AVERAGE HEATING AVERAGE HEATING AVERAGE MERV13+ FUNCTION SUPPLY TEMP. FUNCTION DAY TIME FUNCTION SUPPLY TEMP. FILTERS SUPPLY TEMP. D E D E D E “W” “X” “Y” ROOM ROOM ROOM TEMP. F G H I TEMP. F G H I TEMP. F G H I 70˚F 70˚F 70˚F NOTE: red arrows are virus travel range. All other arrows are HVAC airflow paths. 1) If the virus can be recirculated back to the occupied space as per example “W”, positive correction is required; however, the impact on Climate Change, via increased Green House Gas (GHG), should also be considered. In example “W”, the ∆T from the supply air temperature to the occupied space temperature is 5F˚ based on conservation logic’s average mixed air demand temperature of 65˚F and an occupied space temperature of 70˚F. 2) The supply air “D” may become virus free by altering the HVAC system to 100% fresh air as per example “X”; however, this action will cause a significant increase in GHG emissions. In example “X”, the ∆T from the supply air temperature to the occupied space temperature is 40F˚ based on an average day time winter fresh air temperature of 30˚F and occupied space at 70˚F. 3) Altering from “W” to “X” illustrate a 700% increase in heating energy required at the HVAC system to maintain the occupied space at 70˚F. This will devastate operational budgets and increase the rate of Climate Change via increased GHG emissions. The design of most mixed air systems will not allow this operational change. 4) If the MERV13+ filters can completely capture the airborne viruses, example “Y” might be considered. The benefits are: a) The current energy conservation logic of “W” may be maintained; therefore, the 700% increase in energy use can be avoided, with no extra GHG emissions. b) If the virus is airborne over large distances, the exhaust in “Y” will be filtered to be virus free, removing the possibility of virus returning into the building via exhaust air short circuiting, via wind, into the supply air intakes. The down sides are: a) The return fan will consume more energy to overcome the pressure drop of the MERV13+ filters. b) If the supply air “D” is currently virus free, because the virus cannot travel from the occupied space to the mixing plenum; therefore, the supply air at “D” has absolutely no change in virus content from before to after the changes, the public may develop a false sense of safety and back off on other safety measures. c) This may actually cause COVID-19 infections to increase. 11.202
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