In light of this past year’s events, the AHS Building Committee directed the Project Design Team to take steps to increase indoor air quality and airborne virus mitigation strategies within the new high school HVAC system design. In December 2020, the Building Committee approved a revised HVAC system design that will be included in the project. The new school’s HVAC system design includes increased filtration (MERV-13) and central air handling systems (MERV-14), a space level bi-polar air purification system and an increased Indoor Air Quality (IAQ) setting in the HVAC Control System.
HVAC System Design
Filter efficiency varies greatly depending on the type and size of the desired particles to be captured. The COVID-19 virus is most commonly embedded in larger particles in the 1 µm to 5 µm size range. At this size, a very high percentage of particles will be captured by MERV-13/14 filters.
In addition, the new high school’s Air Purification System will aid in capturing airborne viruses by releasing ions into spaces within the building. Positively charged ions will attach to and deactivate particles in the air, dropping them from the breathing zone or increasing their size to be large enough to be captured by the MERV-rated filters.
HVAC Control System
Part and parcel to filtration and air purification, the HVAC Control System will be provided with an Increased IAQ setting (Pandemic Mode as referred to by governing bodies). When activated, this setting will:
- extend air handling system operating hours to flush the building’s air during unoccupied times
- increase the quantity of outdoor air in the building
- modify building/space pressure relationships to mitigate air transmission between regularly occupied group spaces.
The school district realizes that air quality is important in the current high school as well and has taken steps to ensure that all of the HVAC systems have been restored to full function. Existing filtration has been upgraded to MERV13, and fresh-air intake has been increased. Classroom spaces will also be outfitted with portable HEPA air cleaning machines.
While there is no way to completely eliminate the spread of airborne viruses within buildings, the AHS Building Committee believes that the measures that will be implemented into the new school offer a suitable approach.
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