Tuesday, August 17, 2021


UW buildings vary enormously by age and usage. Denny Hall was completed in 1895; its neighbor, PACCAR Hall, opened in 2010. Some buildings hold classrooms, some are used primarily for offices or labs and some buildings combine all three. To accommodate these differences, UW buildings use a variety of ventilation systems to keep air circulating.

UW Facilities (UWF) proactively monitors the performance of ventilation systems and responds to problems or concerns reported by building occupants. Since the onset of the COVID-19 pandemic, UWF staff has worked closely with UW Environmental Health & Safety as public health guidelines evolved. Modifications included extra checks of air fan filters and extending system hours, as well as other varied changes based on space usage and type of ventilation systems.

Ventilation 101

It’s common for UW buildings to contain a hybrid of mechanical and natural ventilation systems. Mechanical ventilation systems (also known as HVAC systems) use fans to pull outside air into buildings or to draw inside air out or a combination of both. Some HVAC systems have computer controls, others have pneumatic ones.

In natural ventilation systems, operable windows can be opened to let air flow through. This is a common and effective strategy in the Seattle area, owing to generally mild outdoor temperatures. At the UW, both historic and recent buildings contain spaces with natural ventilation.

Most mechanically ventilated systems have MERV-13 filters. UWF staff inspect and change the main fan air filters on a regular basis according to recommended maintenance schedules.

The UW follows maintenance guidelines from ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers), Washington Labor & Industries, and the CDC as well as local and state codes. 

Changes made in response to COVID

UW Facilities has operated and maintained ventilation systems throughout the pandemic and conducted extra checks of ventilation systems and equipment. This included special out-of-cycle checks on central supply air fan MERV-13 filters as well as checking mechanical components such as fans, dampers and cooling/heating coils.


UW Facilities technician inspects a filter

UW Facilities Lighting and Filter Maintenance Technician Virgilio Hernandez conducts a filter inspection.

Operating hours for mechanical ventilation systems were extended and now operate from 6 a.m. to 10 p.m., or longer where appropriate. Outside air ventilation rates were also increased where possible. In spaces with natural ventilation, building coordinators and occupants are encouraged to open windows wherever possible. These steps aim to increase the circulation of fresh air without compromising temperature comfort.

Air purifiers are being purchased to install in small and medium-sized classrooms. Airflow tests and analysis are also being conducted in a selection of classrooms identified by Academic and Student Affairs.

Several dozen buildings that were curtailed due to low occupancy during the 2020-21 academic year have received additional inspections. All curtailed buildings have been returned to normal status as of August 6, 2021. No building ventilation systems were ever shut off.

Building coordinators are conducting thorough walk-throughs of their spaces using the EH&S building checklist to proactively identify any issues before the return to campus. These will be completed by September 10.

A joint team of UW Facilities and EH&S staff regularly meets to track and resolve specific ventilation issues as they are raised. Recommended solutions may include modifications to building systems, installing air purifiers or changing how the space is occupied.

How to report concerns

If you notice evidence of inadequate air supply (for example, the air seems stuffy or stagnant) in a space on the Seattle campus, you can request an evaluation of the space by submitting an Online Work Order Request. Please let your building coordinator know you have submitted a work order or ask them to place one for you to avoid duplicated requests. Concerns about classroom spaces should be directed to Academic and Student Affairs.

For concerns about ventilation on the Tacoma and Bothell campuses, please contact them directly: