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 | May 7, 2018
Plan advances in Los Angeles for Climate Emergency Mobilization Department
Would oversee efforts to reduce greenhouse gas emissions across the city.
Codes and Standards | May 3, 2018
Data collection, machine learning boost building efficiency
Sensors, software algorithms squeeze out waste.
Codes and Standards | May 2, 2018
Energy Department releases Updated EnergyPlus and OpenStudio building energy modeling tools
The tools can now accept input in epJSON format.
Codes and Standards | May 1, 2018
ASHRAE publishes new energy simulation-aided design standard
Requires building energy modeling during schematic design.
Codes and Standards | Apr 30, 2018
CALGreen projects pre-approved for streamlined LEED v4 requirements
Reduces need to run additional energy models.
Codes and Standards | Apr 26, 2018
New standard supports community resilience
ASTM International guidance supports cost-effective ways to withstand and recover from disasters.
Codes and Standards | Apr 25, 2018
Lessons learned from decades of Superfund cleanups guide contaminated land reuse
Sites repurposed for residential, commercial use, and solar energy generation.
Codes and Standards | Apr 24, 2018
Vibrant downtown core the key for urban multifamily development
Nighttime activity makes the difference.
Codes and Standards | Apr 19, 2018
ILFI launches new Zero Carbon Certification
Offers greater flexibility around project fuel types and offsetting renewables.
Codes and Standards | Apr 18, 2018
New Green Globe pilot program launched
Precursor to revised Green Globes Assessment Protocol for Commercial Buildings.