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 | Jan 29, 2020
Half of Manhattan’s new residential skyscrapers are empty
Excess comes as middle class housing shortage worsens.
Codes and Standards | Jan 28, 2020
Updated Engineered Wood Construction Guide now available
Provides guidance on building engineered wood floors, walls, and roofs.
Codes and Standards | Jan 24, 2020
Fenestration Rating Council earns ANSI certification
FenStar Certification Program ensures windows, doors, and skylights meet Energy Star specifications.
Codes and Standards | Jan 23, 2020
Rent control policies backfire on goal of boosting affordable housing
Natl. Apartment Assn. study says rent control decreases housing supply, harms condition of housing stock.
Codes and Standards | Jan 22, 2020
Potential energy savings from smart meters is largely unrealized
Most utilities underuse the technology that can help customers save money.
Codes and Standards | Jan 21, 2020
Contractors pay practices reviewed in new database
Fastest and slowest paying GCs revealed.
Codes and Standards | Jan 17, 2020
Several states with ambitious climate goals will have to restrict natural gas as a fuel
Buildings would have to heat and cook with electricity.
Codes and Standards | Jan 16, 2020
New solar-ready mandate affects commercial and residential buildings in St. Louis
All new buildings must have reserved rooftop sections for PVs.
Codes and Standards | Jan 15, 2020
Trump Administration blocks new light bulb efficiency standards
Move defies bipartisan 2007 law.
Codes and Standards | Jan 14, 2020
L.A.’s expedited permitting process credited with faster approvals on $1 billion project
Parallel Design-Permitting Process includes flagging elements for correction during conceptual design.