Disease Mitigation in Buildings: Comparing Increased Ventilation to Air Filtration

We’re often asked by architects and owners how to manage ventilation to reduce the spread of disease in their buildings.  Here are some slides from one of our lunch and learn presentations describing a very interesting case study by Azimi and Stephens comparing the costs for two strategies: (1) Increasing fresh air intake vs. (2) Increasing air filtration.  The two main conclusions were that: (1) It is less expensive to filter the air than to increase air intake to achieve the same disease mitigation results; and (2) Increasing air filtration is not that expensive.  In a small 5300 sq. ft. office with 25 people, increasing air filtration from MERV 7 to MERV 13 might cost $17, but would reduce the number of flu cases by one person, saving about $375.

 

 

Note on the graph the cost vs. effectiveness “sweet spot” at MERV 13.  Increasing filtration from MERV 7 to MERV 13 reduces the spread of disease while having minimal impact on cost.  However, above MERV 13, there are diminishing returns; the energy cost of filtration starts to increase more significantly while the effectiveness at reducing the spread of disease is minimal.

 

 

References:

[1] Azimi, P., & Stephens, B. (2013). HVAC filtration for controlling infectious airborne disease transmission in indoor environments: Predicting risk reductions and operational costs. Building and Environment, 70, 150–160. https://doi.org/10.1016/j.buildenv.2013.08.025