Reset: A Focus on Air Quality
As we move toward spring and an eventual option for students to attend school in-person, we continue as a Hamilton staff to focus on the bucket of work that we call “Reset”. This Reset work includes readying the physical spaces at our school, and the identification of protocols that seek to maximize staff member and student safety to the greatest extent possible. All Hamilton staff members have been going through a process that we are calling “space liberation” in which classrooms, offices, and other workspaces are having items removed in an effort to create seating that can maintain six feet of social distancing. In addition, we have a working list of 75 safety related protocols with those most pertinent to students just about ready to be shared in an upcoming Hamilton Headlines.
Part of our work to Reset is related to our heating, ventilating, and air conditioning systems (HVAC). As we all know, the vast majority of COVID infections are contracted through breathing in air that contains the virus. So, what do we know about district and Hamilton specific efforts to maintain clean air to the greatest extent possible in our buildings?
At the district level there has been a concerted effort to address factors related to the air in our buildings. These factors include the updating of existing mechanical systems in efforts to meet national standards related to indoor air quality. The district is confident that HVAC systems in all buildings can and will be operated per CDC and ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) recommendations to reduce airborne exposures. These recommendations include ensuring that HVAC systems are operating as designed. In addition, the district is disabling user controls in individual classrooms and offices to make sure that all systems are running as intended at each school and to avoid the inadvertent shutting down of HVAC systems. Historically, the district has prided itself on energy efficiencies that serve to reduce our carbon footprint, including the operation of ventilating systems only during the student school day. Moving forward through this pandemic, ventilation systems in all schools will be operating two hours before students arrive in the morning until two hours after students have left for the day.
Classrooms and offices at Hamilton are served by forced air central systems and hydronic terminal devices (classroom units that bring in outside air). Central air handling units and terminal equipment in these systems are equipped with air filters that are designed to clean the air as it circulates through the filters. Prior to the pandemic, these filters across the district for the most part had a MERV rating of 8 (see the next news item if interested in the finer details of MERV ratings) At a cost of $300,000, the district has installed new filters that range in MERV rating from 10 to 13, depending on what each mechanical feature can accommodate. These higher MERV rated filters are much more efficient at capturing airborne viruses. For Hamilton specifically, our classroom systems have MERV 11 filters installed, while all rooftop equipment has been refitted with MERV 13 filters.
Building codes also require our classrooms to exchange air a minimum of six times every hour. So, every 10 minutes the entire volume of a classroom's air is exchanged and filtered with outdoor air. One of our specific Hamilton strategies will also be to keep windows open in classrooms, restrooms, and other occupied spaces to the greatest extent possible. Research on air circulation indicates that opening a window just a small amount has a significant impact on the rate at which air is replaced in a classroom or other interior space. See this link to a short article from The Washington Post on the benefits of opening windows in classrooms and on buses.
Keep in mind that essential components of staying safe in a pandemic world extend beyond air filtration systems and include proper mask wearing, maintaining social distance, symptom screening, and handwashing, all of which will be the focus of several Hamilton specific protocols once an in-person schooling option has been added.
