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 | Jul 26, 2017
New ISO standard on video fire detectors will help identify fires more quickly
The standard marks the first comprehensive international specification for this equipment.
Codes and Standards | Jul 25, 2017
Geotechnical solutions prevent building distress due to expansive clay soils
The condition is the most common geologic hazard in the U.S.
Codes and Standards | Jul 24, 2017
Non-union labor gaining ground in New York City
President of contractors’ group says competitive pricing is spurring more open shops.
Codes and Standards | Jul 20, 2017
New tallest tower west of the Mississippi built to stringent seismic standards
L.A.’s new 1,100-foot skyscraper dominates city’s skyline.
Codes and Standards | Jul 20, 2017
Chicago rises to the top of U.S. cities in percentage of LEED or Energy Star office buildings
Certified office buildings reach 66% in windy city.
Codes and Standards | Jul 19, 2017
Economic impacts of climate change will jump over next two decades
Average annual cost to buildings and infrastructure from eastern storms to rise by $7.3 billion.
Codes and Standards | Jul 18, 2017
Energy modeling yields accuracy within 4%, says new study
Results of the study support the usefulness of the practice.
Codes and Standards | Jul 13, 2017
Net Zero Energy rebranded as ‘Zero Energy’
ILF aims to make new certification the sole standard for highest performing buildings.
Codes and Standards | Jul 13, 2017
New York City creates $10 million fund to help women- and minority-owned firms win construction contracts
The money is earmarked for up to $500,000 surety bonds per contract.
Codes and Standards | Jul 12, 2017
New International Building Code allows weather-resistive barriers above 40 feet
Danger of propagating flames now deemed negligible.