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 | Dec 28, 2020
Dept. of Energy offers Better Buildings Field Validation Results Hub
One-stop-shop for information associated with technology validations in buildings.
Codes and Standards | Dec 28, 2020
2021 Defense Authorization Act includes mass timber provision
Directs defense, agriculture secretaries to review potential for wood frame construction on defense building projects.
Codes and Standards | Dec 28, 2020
New York City proposal would require rainwater detention tanks for new development
Rule would apply to projects on lots sized 20,000 sf or larger.
Codes and Standards | Dec 17, 2020
Energy efficiency as a service gaining ground as financing approach for adopting innovations
Building owners can invest in new technology with no upfront cost.
Codes and Standards | Dec 16, 2020
Resources available to address Legionella threat
Buildings reopened after extended pandemic closure are at risk.
Codes and Standards | Dec 16, 2020
New Specifications for Concrete Construction reference manual released
Scope expanded to include shotcrete, internal curing, mineral fillers, and recycled concrete aggregates.
Codes and Standards | Dec 15, 2020
Despite COVID-19 population flight, don’t write off big cities yet
Lure of urban life and jobs may draw people back after pandemic subsides.
Codes and Standards | Dec 10, 2020
Test method for vertical fenestration installation procedures updated
FGIA issues first update for document created in 2005.
Codes and Standards | Dec 10, 2020
Updated EPDs for Polyiso Roof and Wall Insulation; EPD for Polyiso High-Density Cover Boards published
Cover Boards EPD is an industry first.
Codes and Standards | Dec 9, 2020
Newly formed Rainscreen Association aims to be recognized authority on rainscreen assemblies
Will address innovations in material performance and building designs.