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Strengthening Ventilation in Schools

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The health and safety of the students and staff of Edmonton Catholic Schools is our top priority. ECSD’s ventilation systems are checked regularly and maintained so that they are functioning as intended. Further, our centralized monitoring system alerts our staff in real-time indicating if a piece of equipment is not functioning properly. If a mechanical fault is detected, repair or evaluation of the fault occurs rapidly.  

On December 1, 2021, the Northern and Southern Alberta Chapters of American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) issued recommendations to support mitigation of airborne viral particles. 

In response to the recent ASHRAE recommendations, ECSD will be installing MERV 13 rated filters at all Division sites. This process is currently underway and will be completed in the coming weeks. MERV 13 filtration will be the Division standard moving forward. 

Minimum Efficiency Reporting Value (MERV) represents the rating of the filter (ratings range from 1-20). The higher the number, the smaller the particulate that the filter is capable of capturing. A typical home furnace filter (Filtrete 1000) is the equivalent of a MERV 11 filter.  

The ASHRAE recommendations are as follows: 

We are writing to share COVID-19 mitigation strategies that are outlined in ASHRAE’s official COVID-19 guidance documents which apply to a variety of building types, including schools. 

The guidance documents are available on the ASHRAE website at: https://www.ashrae.org/technical-resources/resources  

 Potential mitigation strategies and the accompanying sources (in brackets) are as follows: 

  • Upgrade air system filters to filters with higher minimum efficiency reporting value (MERV) ratings. MERV 13 or better is suggested as a minimum target to remove airborne viral particles in recirculating systems, MERV 14 is preferred.
  • Install in room air cleaners with high-efficiency particulate air (HEPA) filters. HEPA filtration units within the space are recommended if MERV 13 filters cannot be installed due to HVAC system constraints.
  • Provide and maintain at least the required minimum outdoor airflow rates for ventilation as specified by applicable codes and standards. HVAC system operation should be verified by commissioning. 

 *Use of supplemental, in room HEPA air cleaners to remove airborne viral particles are supported by ASHRAE guidance if the primary ventilation system does not provide the suggested MERV 13 level of filtration or if the ventilation system’s ability to mitigate viral particles has not been verified and measured through engineering analysis (such as commissioning). 


Why are you not installing HEPA Filters in your classrooms?

We are strengthening our already robust HVAC systems so their performance is enhanced meeting ASHRAE recommendations. The MERV 13 filters allow the HVAC system to operate as intended and designed. This is a long-term solution that strengthens HVAC functioning in an enduring way.

Health Canada advises that “portable HEPA air filters should not be used as a replacement for proper indoor ventilation; rather, they should only be used during periods of inadequate ventilation measures.” This guidance can be found here.

The Alberta Government has neither recommended nor endorsed the use of HEPA filters in conjunction with HVAC systems. We continue to review HVAC industry air quality recommendations and studies as they become available.


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