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 | Sep 2, 2020
California releases guide for state water policy
Water Resilience Portfolio is roadmap for meeting water needs as climate changes.
Codes and Standards | Aug 31, 2020
Fenestration alliance updates fenestration sealants guide
First update to 2009 document.
Codes and Standards | Aug 25, 2020
Platform will allow researchers to test energy system integration at scale
The U.S. Department of Energy’s (DOE’s) National Renewable Energy Laboratory (NREL) recently launched the Advanced Research on Integrated Energy Systems (ARIES) platform.
Codes and Standards | Aug 20, 2020
Wariness of elevators may stymie office reopening
Workers could balk at returning to high-rises.
Codes and Standards | Aug 19, 2020
Existing laws may be restricting efforts to cut carbon emissions
Outdated policies favor fossil fuels.
Codes and Standards | Aug 18, 2020
Florida becomes the third state to adopt concrete repair code
Sets minimum requirements for design, construction, repair of concrete structural elements in buildings.
Codes and Standards | Aug 17, 2020
ASCE seeks comments on seismic standard
Pertains to design criteria for nuclear facilities.
Codes and Standards | Aug 13, 2020
COVID-19 reboot guide offers strategies for reopening K-12 schools
Looks at space considerations for reopening at different scales.
Codes and Standards | Aug 12, 2020
Document provides guidance for mass timber construction
Overview of Intl. Building Code requirements included.
Codes and Standards | Aug 11, 2020
Inefficient air conditioning is a key contributor to global warming
More efficient equipment and buildings could make a big difference.