Mechanical systems in school facilities became a critical talking point in the conversation to safely reopen schools, particularly ventilation and air filtration. As health officials, the State Education Department, Superintendents, administrators, teachers, and professional services teams strategized to reopen schools, significant research and energy was put into ensuring school’s air filtration and ventilation systems met the necessary safety requirements by engineering teams.
As we are in the midst of winter here in the Northeast, it’s a challenge to adhere to the initial guidance, particularly involving significant amounts of outdoor air. We’ve identified a multitude of ways facilities can improve air quality in all seasons, and in turn safety for students, teachers, and staff in the buildings each day.
- Make sure all existing systems are operating as originally designed and comply with code as to the sequence of operation and fresh air intake damper operation. This seems simple but our engineers were shocked to find many systems were simply not working properly or not turned on.
- Ensure that relief grilles and exhaust registers are not blocked by furniture or covered by new hung ceilings, remove obstructions from unit ventilators to allow for proper air flow.
- Run all equipment, including exhaust fans, for longer periods of time; at least two hours before and two hours after school to flush out the buildings.
- Increase the amount of outdoor air to up to 100%, weather conditions permitting. This will not be possible during the peak heating season, as the original equipment was most likely only designed for 40% – 50% outdoor air at peak design conditions.
- Disable any CO2 based demand control ventilation, which limits the amount of fresh air in the space based upon the amount of carbon dioxide and bypass any energy recovery systems.
- Remember, by reducing the number of occupants in a space, you are automatically over-ventilating the space by providing additional outdoor air per person.
- Install MERV 13 filters, or the highest rated MERV rated filter each piece of equipment can handle. Higher efficiency filters will decrease airflow in certain instances and could cause premature motor failure in some cases, and will require more frequent filter replacement. MERV 13 filters are recommended, but not able to be accommodated by all systems.
- Make sure nurses offices and isolation rooms are under negative pressure and review the exit points of the exhaust systems to ensure they are not too close to adjacent fresh air intakes.
- Consider deploying portable air cleaners, which typically have MERV 13 pre-filters and HEPA final filters, in areas of concern.
- Be careful when using ceiling fans or wall mounted fans. They can spread the travel distance of droplets, prevent settling, and re-suspend surface droplets.
- SED is currently not permitting UV light technology, ion generators, etc. While we may have reason to be hopeful of this emerging technology, very little has been proven to kill COVID-19.
- Utilize natural ventilation (operable windows) where mechanical ventilation does not exist, weather and safety permitting, and leave classrooms doors open for cross ventilation as per SED’s latest memo dated August 26th, as a temporary COVID-19 emergency policy change.
Be advised that the above strategies, while improving ventilation, will result in both increased costs in energy use, as well as increased maintenance and filter replacement costs.
Each building and need is unique to each district. Contact us to continue taking steps to improve air quality in your buildings. We’re here for you during these transitional times to address the essential needs schools are facing.
Fred Seeba PE, LEED AP, NCEES
Director of Engineering