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air thru filter

Staff from the Division of Maintenance and Operations is continuing the process of upgrading the air filters in the mechanical systems of all MCPS schools. This ongoing project also includes installing air cleaners in the facilities that have HVAC systems that require supplemental measures for air ventilation.


The summary below is updated in real-time as work is performed in the field and recorded by office personnel. The REOPENING column indicates the date that in-school learning programs are anticipated to resume. Our facilities represent four primary scenarios with regard to our HVAC systems, and schools have been categorized (HVAC SCENARIO) as follows:

⧫⧫⧫⧫ = Schools with enhanced ventilation systems that require minimal modifications (filter upgrades and control adjustments are all that is needed)

These schools predominately have sophisticated ventilation equipment called dedicated outdoor air systems (DOAS). These rooftop units have the sole job of providing outside air to individual classrooms and support staff workspaces. Coupled with individual classroom units that focus on temperature control, the work associated with these schools is not visible and these classrooms will look much like they did prior to this HVAC work. 

⧫⧫⧫ = Schools with recently replaced systems that have enhanced ventilation (limited spaces require air cleaners)

These schools have varying HVAC systems but generally have systems that can achieve ventilation and filter modifications to meet indoor air quality recommendations. Most of these systems have DOAS equipment and/or classroom units that achieve higher levels of ventilation air, and at rates that meet current recommendations. The schools in this category without DOAS equipment have classroom units that can modulate higher levels of ventilation airflow directly within the classroom HVAC unit and then ultimately mixed and distributed with filtered classroom air. Much of this work will not be visible, but we have have limited spaces with individual air cleaners.

⧫⧫ = Schools with older systems that can be modified (air cleaners are required to meet new COVID-19 IAQ requirements)

These schools also have varying HVAC systems but generally have systems that provide ventilation and temperature controls within an individual packaged unit. These schools typically have unit ventilators and fan coils that are 10 years and older that provide adequate ventilation rates for pre-COVID-19 standards. Achieving higher ventilation flow rates in these units will make a significant impact on temperature control. While we will be increasing filter efficiencies in these units, we will also require air cleaners to be placed in classrooms to provide supplemental support.

 = Schools with systems that require more extensive mechanical attention as well as air cleaners

Similar to the older HVAC systems with limitations, the schools in this category required additional attention, including but not limited to temporary HVAC systems to assist with temperature control challenges. Additional follow-up communication about the work performed will be provided to individual school communities prior to the return of in-person learning. 

It is important to note that many schools have varying systems and the information outlined below is consistent with large portions of buildings. However, some schools with additions may have varying degrees of modifications in different areas of the building. Schools designated as requiring air cleaners may also have newer additions that have more sophisticated equipment that will not require the use of supplemental equipment in those areas. 

In addition, the timelines listed below are focused on whole building implementation. Work on individual spaces will be accelerated to meet any future phase-in approaches to in-person learning that are approved by the Board of Education. This includes special education discrete programs.  

For more information about the air ventilation work being done in our facilities, visit our FAQ page.