Key Takeaways:
When wildfire smoke blankets a community, facility managers must keep fresh air flowing without bringing harmful smoke indoors.
Though wildfire smoke tops the headlines, air quality events come in other forms. High ozone, heavy traffic, extreme heat, infectious disease outbreaks and other events can all force facility managers to reconsider how they operate their buildings.
The answer to these events begins with understanding where the threat is coming from and which levers to pull as conditions change.
Nathan Stodola, chief engineer at the International WELL Building Institute (IWBI), says outdoor pollutants generally enter a building through:
These entry points, he says, give facility managers three important places to start.
A leaky building envelope makes airflow harder to control. For this reason, Stodola recommends airtightness testing to pinpoint leaks and prioritize sealing.
“Understanding the building envelope under normal conditions gives the facilities team a better idea of how the building is likely to perform when outdoor conditions deteriorate,” he says.
Airtightness testing assesses the building envelope, and can reveal trouble spots, like window openings, where outside air can infiltrate.
In addition to the static building envelope, doors pose a unique challenge, Stodola says, because they have to open. Installing revolving doors, vestibules and air curtains can reduce the polluted outdoor air entering as people move through the building.
Higher-efficiency MERV filters can play a key role in keeping poor quality air out of occupied spaces, he adds.
Minimum Efficiency Reporting Value (MERV) rates a filter’s ability to capture airborne particles, with higher ratings capturing smaller particles more effectively.
“A MERV 13 filter will remove about two-thirds of a PM 2.5 mass, which is generally one of the key indicators for wildfire smoke,” Stodola says. “A MERV 16 filter will remove about 95%, and any filter rated as MERV 8 or below, won’t do much to remove particles of that size.”
But higher filtration also can come with a trade-off, according to Stodola.
He explains that a higher MERV rating can increase resistance to airflow. An HVAC system that is not designed to handle the added pressure drop may struggle to support normal airflow.
Facility managers must know the MERV rating their HVAC system can handle before an air quality event so they can improve filtration without compromising performance. Stodola explains some systems can compensate, while others may deliver less conditioned air or require fans to work harder, increasing energy use.
“Have an engineer, either the building’s engineer or an external engineer, look at the system and assess that before an air quality event,” he says.
That assessment should measure airflow and static pressure, check fan capacity and compare pressure drop across the existing and proposed filters. Once higher MERV rated filters are installed, technicians should re-measure airflow and pressure to ensure the system continues to operate correctly.
Ronnie Wendt is the owner of In Good Company Communications and a freelance writer specializing in articles for the facilities management, aviation, RV and automotive, meetings and events, security, logistics and business technology industries.
