As scientists learn more about the COVID-19 virus, opinions are changing on how it is spread from person to person, and that has implications for how to reopen buildings safely.
Emphasis to date on protocols for reopening buildings has focused on surface cleaning and occupant density. But, if as some scientists suspect, the virus can live for at least three hours in aerosols—tiny particles that can be carried through the air for long distances—HVAC systems could play a key role in spreading the virus. There are opposing views on whether aerosols actually can transmit the virus, but if they do, then ventilation systems could spread the virus through unfiltered re-circulation of indoor air.
In April, ASHRAE addressed the issue of possible aerosol transmission with recommendations that include:
· Maintain a relative humidity of 40% to 60% inside buildings instead of the usual 20% to 40%.
· Install air filters rated at least at MERV-13.
· Minimize re-circulation of indoor air, and bring in outside air either by mechanical means or by opening windows.
The humidity recommendation was made because higher humidity makes aerosols heavier, causing them to drop to the floor faster. ASHRAE has also recommended that the intake of outside air be set to the highest level permitted by the mechanical equipment. Some specialists recommend a full re-commissioning process for reopening buildings.
Related Stories
Codes and Standards | Mar 20, 2020
Feds prod use of eminent domain to force people out of flood-prone homes
Local officials that don’t comply could lose federal money to combat climate change.
Codes and Standards | Mar 19, 2020
ASHRAE provides COVID-19 resources for operating, maintaining HVAC systems
Includes recently approved position document on Airborne Infectious Diseases.
Codes and Standards | Mar 19, 2020
CaGBC launches new version of its Zero Carbon Building Standard
Version 2 draws on lessons from more than 20 zero carbon projects.
Codes and Standards | Mar 16, 2020
Concrete industry reduces carbon footprint by 13% over five years
Result mostly due to more efficient use of Portland cement.
Resiliency | Mar 13, 2020
Feds push use of eminent domain to force people out of flood-prone homes
Local officials that don’t comply could lose federal money to combat climate change.
Codes and Standards | Mar 12, 2020
Design guide for sloped glazing and skylights updated for first time in 30 years
Helps with choosing proper glass for non-residential applications.
Codes and Standards | Mar 11, 2020
Two tree species native to the Northeast found suitable for CLT
Eastern white pine and eastern hemlock pass strength testing.
Codes and Standards | Mar 10, 2020
Prescient receives ICC certification for seismic resilience system
Technology suitable for buildings up to 12 stories in earthquake-prone areas.
Codes and Standards | Mar 6, 2020
Design firms creating plans to re-imagine D.C.’s tidal basin
Area including National Mall is facing increased flood risk.
Codes and Standards | Mar 5, 2020
France to mandate all new public buildings be 50% timber or other natural materials
Measure would go into effect by 2022.