CDC's 15 Considerations for School Ventilation

  • When the school year started, the initial CDC’s guidance regarding ventilation systems were twofold and rather simple: buildings needed to intake fresh air from outside two hours before the school day started and air filters needed to be frequently changed. All but a few schools met this requirement and necessary repairs were applied for compliance, a complete list of schools where repairs were needed are listed below. In February, the CDC provided additional guidance on ventilation systems, including 15 points of consideration. Those considerations are listed below as well as how the district has already met the standard or how we are working toward that goal.

    The dashboard below will be updated as repairs are made.

    1. Increase outdoor air ventilation, using caution in highly polluted areas.

    Assessments conducted prior to the opening of schools in September 2020 and again during mid-winter break showed one hundred percent of district schools increase outdoor air ventilation by use of air handler units, roof top units, unit ventilators, or open windows. List of schools may be found in the appendix.

    2. When weather conditions allow, increase fresh outdoor air by opening windows and doors. Do not open windows and doors if doing so poses a safety or health risk (e.g., risk of falling, triggering asthma symptoms) to occupants in the building.

    While eighty-four percent (83.5%) of our buildings open doors and windows when weather conditions allow, fresh air intake is supplied at all District facilities. Five of the district’s facilities, found in the Appendix, were constructed with curtain wall windows that do not open. All of these buildings now have functioning air conditioning as well as operable ventilation systems. A number of schools were built with windows in need of repair however, these buildings were designed with central mechanical systems to circulate outside air without use of windows. If staff members at these schools, listed in the Appendix, would like a fan for additional circulation, they may contact the COVID-19 reporting line anonymously at (313)578-7018 or by email: info.reopen@detroit12.org.   

    3. Use fans to increase the effectiveness of open windows. To safely achieve this, fan placement is important and will vary based on room configuration. Avoid placing fans in a way that could potentially cause contaminated air to flow directly from one person over another. One helpful strategy is to use a window fan, placed safely and securely in a window, to exhaust room air to the outdoors. This will help draw fresh air into room via other open windows and doors without generating strong room air currents.

    Most of the older constructed buildings were designed to use a combination of windows and corridors to supplement the natural fresh air intake of ventilation systems. Fans will be provided for staff upon request made with the building engineer. 

    4. Decrease occupancy in areas where outdoor ventilation cannot be increased.

    Facility team members continuously work with principals to assign spaces based on daily operations. The district completed baseline ventilation assessments prior to opening schools at the beginning of the year to identify problem areas. Areas will poor ventilation were taken offline and building engineers collaborated with principals to determine alternative placement. Ventilation assessments are a continuous process; should problems arise in the future, building engineers will continue to work with principals to identify use of other classrooms.   

    Any rooms without outside ventilation will not be used until after repairs are made. Our current indoor air quality assessment and analysis report will report problem spaces on a dashboard that will be placed on the District’s website. 

    5. Ensure ventilation systems operate properly and provide acceptable indoor air quality for the current occupancy level for each space.

    All district buildings were assessed in the summer of 2020 by facilities vendors.  Results showed 34 schools needed immediate repairs for optimal functioning, see Appendix for list of schools.  Repairs were completed and the units were reassessed during mid-winter break in 2021. As an additional measure, an independent environmental health company is completing carbon dioxide testing in all district schools. CO2 assessments can ensure acceptable levels of ventilation are provided.  If assessment results demonstrate the need for additional ventilation repairs, the identified space will be removed from use until repairs are made. A dashboard listing assessments results will be placed on the district’s website upon project completion.   

    6. Increase airflow to occupied spaces when possible.

    Assessments conducted prior to the opening of schools in September 2020 and again during mid-winter break showed one hundred percent of district schools increase outdoor air ventilation by use of air handler units, roof top units, unit ventilators, or open windows when outside weather conditions permit.

    7. Turn off any demand-controlled ventilation (DCV) controls that reduce air supply based on occupancy or temperature during occupied hours. In homes and buildings where the HVAC fan operation can be controlled at the thermostat, set the fan to the “on” position instead of “auto,” which will operate the fan continuously, even when heating or air-conditioning is not required.

    Numerous facilities have unit control systems in need of repair and upgrade. Building engineers manually control mechanical units in these buildings to prevent overheating during summer months and pipe and system freezing during the winter season.  While manual controls reduce efficiency and effective use of each building engineer’s time, this work maintains adequate ventilation levels. The district’s broader plan involves use of CARES Act funding to upgrade broken controls and implement automatic controls that can be monitored onsite and remotely.

     8. Open outdoor air dampers beyond minimum settings to reduce or eliminate HVAC air recirculation. In mild weather, this will not affect thermal comfort or humidity. However, this may be difficult to do in cold, hot, or humid weather.

    Automated air damper controls are in need of repair limiting the maximum opening of the units in 37% of schools. In such cases, the ventilation system is manually controlled and operated by engineers using a combination of mechanical air passage systems, windows, and fans for fresh air intake. 

    A more detailed assessment is scheduled for spring 2021 after which recommendations for improvement will be produced by independent HVAC consultants. Upon receipt of external air quality assessments, identified units will be repairs and upgraded for digital operations. 

     9. Improve central air filtration: 

    A. Increase air filtration to as high as possible without significantly reducing design airflow. 

    Approximately 88% of schools can increase air filtration through use of higher rated MERV filters without affecting design.  The remaining 12% of schools use filter ratings designed for existing units.  

    B. Inspect filter housing and racks to ensure appropriate filter fit and check for ways to minimize filter bypass. 

    All filter housing and racks have been inspected at all schools and 93 units were repaired.  

    C. Check filters to ensure they are within their service life and appropriately installed. 

    Filter replacement frequency increased at all of District facilities.  At the time of the assessment, 10% of filter replacements were in progress as scheduled.  

     10. Ensure restroom exhaust fans are functional and operating at full capacity when the building is occupied. 

    The district conducted building assessments based on CDC guidance during mid-winter break of 2021. The results showed approximately 68% of restroom exhaust fans work per design, see list of schools in Appendix. The capacity of district buildings far exceeds current use and therefore allows for other restrooms to be used while repairs are made to exhaust fans. A ventilation dashboard clearly showing repair areas and opportunities for improvement will be placed on the district’s website and updated as repairs are completed. CARES Act funding will be used to repair/replace units in need of upgrades. 

    11. Inspect and maintain local exhaust ventilation in areas such as kitchens, cooking areas, etc. Operate these systems any time these spaces are occupied. Consider operating these systems, even when the specific space is not occupied, to increase overall ventilation within the occupied building. 

    OSN contracted an outside company, Hoodz, to inspect and clean kitchen exhaust systems once annually. The units are run everyday and will now be inspected twice per year. All kitchen ventilation systems were inspected and cleaned over the last year.  

    12. Consider portable high-efficiency particulate air (HEPA) fan/filtration systems to help enhance air cleaning (especially in higher risk areas such as a nurse’s office or areas frequently inhabited by persons with higher likelihood of COVID-19 and/or increased risk of getting COVID-19). 

    Designers can integrate features into the ventilation system that will provide benefits for the school occupants as well as the efficiency and longevity of the HVAC system. In addition, these features can reduce the need for expensive cleaning of the duct work and air handling units. 

    Architects and engineers can integrate high-efficiency purification systems into school ventilation systems that will improve reduce the need for air handling repairs.  New technologies have recently surfaced to provide a supplemental layer of filtration. The district contracted an independent environmental team to assess indoor air quality. Environmental Health and Safety team members are working with an independent environmental company to research, test, validate, and recommend filtration units suitable for the district’s wide portfolio of schools. The results of the indoor air quality assessment will be placed on the district’s website.  

    13. Generate clean-to-less-clean air movement by re-evaluating the positioning of supply and exhaust air diffusers and/or dampers (especially in higher risk areas). 

    Supply and exhaust units are located on the roofs of commercial buildings and schools. Architect and design firms determined the placement of the units prior to construction commencement and roofing systems were built in consideration of this HVAC equipment. While the location of outdoor supply and exhaust air diffusers and dampers can be examined, it is not structurally or financially feasible to reconstruct the roofing systems because district facilities were designed with the current placement of these units. Moving forward, new construction will prioritize the of the units with the same contemplation and planning used with existing facilities.  

    14. Consider using ultraviolet germicidal irradiation (UVGI) as a supplement to help inactivate SARS-CoV-2, especially if options for increasing room ventilation are limited. Upper-room UVGI systems can be used to provide air cleaning within occupied spaces, and in-duct UVGI systems can help enhance air cleaning inside central ventilation systems 

    While trendy, classroom air purification systems are not sustainable due to required filter changes and electrical requirements. Some models also generate heat and create a humming noise that may distract students during instruction and independent work. UVGI systems use a form of ultraviolet light to neutralize airborne microorganisms and can be placed in classrooms or centralized air handler systems. 

    Irradiation technology is under consideration at all district schools.  As technologies evolve, more methodical research and sampling is needed to make an appropriate decision for the wide range of building ages in the district’s portfolio. The district’s environmental health team and HVAC specialists are evaluating systems including charcoal filtration, bipolar ionization, and UV purification systems.  CARES Act monies will be used to install units as assessment results dictate.  

    15. In non-residential settings, consider running the HVAC system at maximum outside airflow for 2 hours before and after the building is occupied. 

    Building engineers and HVAC controls have the ability to maximize airflow two hours before and after school.  This process began at the beginning of the school year yet fresh air flow was tempered during winter months to maintain the proper functioning of heating systems. Outside air supply was increased in all district facilities this year. 

     

Appendix

  • 2. Schools with Curtain Wall Windows, Designed not to open  

     
    Ben Carson   
    Carstens   
    Cass Tech   
    Martin Luther King Jr. High School   
    Mason   
       

    2. Schools in Need of Window Hardware Repairs

    Status 

    Academy of Americas In Progress
    Barton In Progress
    Bates In Progress
    Bethune In Progress
    Central/Durfee In Progress
    Clippert In Progress
    Cody In Progress
    DCP In Progress
    Douglass In Progress
    Ludington/CMA In Progress
    Mann In Progress
    Mark Twain In Progress
    Moses Field In Progress
    Pasteur In Progress
    Osborn In Progress
    Sampson-Webber In Progress
    Vernor In Progress
       

    5. Ventilation Systems in Need of Repair Per 2020 Assessment

    Status 

    Ann Arbor Trail  Completed 
    Bagley Elementary  Completed 
    Bow Elementary/Middle  Completed 
    Brewer Elementary  Completed 
    Bunche Elementary Completed 
    Carleton Elementary  Completed 
    Carver Elementary  Completed 
    Catherine Ferguson  Completed 
    Clark Prep Academy  Completed 
    Cody High School  Completed 
    Cooke Elementary  Completed 
    Davison Elementary  Completed 
    Old DIA (Northern)  Completed 
    Edison Elementary  Completed 
    Gardner Elementary  Completed 
    Hamilton Elementary Completed 
    Greenfield Union  Completed 
    Henry Ford High School   Completed 
    A. L Holmes Elementary  Completed 
    Logan Elementary  Completed 
    Mann Elementary  Completed 
    Marquette Elementary  Completed 
    Thurgood Marshall  Completed 
    Noble Elementary  Completed 
    Osborn High School  Completed 
    Palmer Park  Completed 
    Pasteur Elementary  Completed 
    Priest Elementary  Completed 
    Pulaski Completed 
    Paul Robeson  Completed 
    Spain  Completed 
    Thirkell Elementary  Completed 
    Vernor Elementary  Completed 
    Wayne Elementary  Completed 
       

    8. Ventilation systems are manually controlled in the buildings listed below. Air damper control repairs are in progress.

    Status 

    Academy of Americas In Progress
    Academy of Americas @ Logan In Progress
    Barton In Progress
    Bates Academy In Progress
    Ben Carson High School In Progress
    Bennett In Progress
    Bethune In Progress
    Blackwell In Progress
    Breithaupt In Progress
    Bunche In Progress
    Burton In Progress
    Clark In Progress
    Cody High School In Progress
    Davison In Progress
    Denby High School In Progress
    Dixon In Progress
    Dossin In Progress
    Drew In Progress
    Early Intervention In Progress
    Edison In Progress
    Edmonson In Progress
    Fisher Upper In Progress
    Golightly CTC In Progress
    Golightly Education Center In Progress
    Gompers In Progress
    Hamilton In Progress
    Harms In Progress
    Mark Twain In Progress
    MLK High School In Progress
    Mumford In Progress
    Munger In Progress
    Neinas In Progress
    Nolan In Progress
    Northwestern High School In Progress
    Pasteur In Progress
    Renaissance High School In Progress
    Roberto Clemente In Progress
    Schultz In Progress
    Spain In Progress
    Thurgood Marshall In Progress
    Western High School In Progress
    Westside Academy In Progress
       

    9. b. Filter Racks in Need of Repair Per 2020 Assessment

    Status 

    Ann Arbor Trail  Completed 
    Bagley Elementary  Completed 
    Bow Elementary/Middle  Completed 
    Brewer Elementary  Completed 
    Bunche Elementary Completed 
    Carleton Elementary  Completed 
    Carver Elementary  Completed 
    Catherine Ferguson  Completed 
    Clark Prep Academy  Completed 
    Cody High School  Completed 
    Cooke Elementary  Completed 
    Davison Elementary  Completed 
    Old DIA (Northern)  Completed 
    Edison Elementary  Completed 
    Gardner Elementary  Completed 
    Hamilton Elementary Completed 
    Greenfield Union  Completed 
    Henry Ford High School   Completed 
    A. L Holmes Elementary  Completed 
    Logan Elementary  Completed 
    Mann Elementary  Completed 
    Marquette Elementary  Completed 
    Thurgood Marshall  Completed 
    Noble Elementary  Completed 
    Osborn High School  Completed 
    Palmer Park  Completed 
    Pasteur Elementary  Completed 
    Priest Elementary  Completed 
    Pulaski Completed 
    Paul Robeson  Completed 
    Spain  Completed 
    Thirkell Elementary  Completed 
    Vernor Elementary  Completed 
    Wayne Elementary  Completed 
       

    10. Restroom Exhaust Fans Repairs Needed in the Following Buildings

    Status

    A.L. Holmes In Progress
    Academy of Americas In Progress
    Ben Carson High School In Progress
    Bethune In Progress
    Breithaupt In Progress
    Carver In Progress
    Central High School In Progress
    Charles Wright In Progress
    Chrysler In Progress
    CMA In Progress
    Davison In Progress
    Detroit Lions Academy In Progress
    Dixon In Progress
    Douglass High School In Progress
    Drew In Progress
    Earhart In Progress
    Early Intervention In Progress
    Edison In Progress
    Edmonson In Progress
    Gardner In Progress
    Harms In Progress
    Keiden In Progress
    MacKenzie In Progress
    Maybury In Progress
    Mumford High School In Progress
    Noble In Progress
    Nolan In Progress
    Former DIA (Northern) In Progress
    Northwestern High School In Progress
    Pershing High School In Progress
    Schulze In Progress
    Thirkell In Progress
    Thurgood Marshall In Progress
    Wayne In Progress
    Westside Academy In Progress