20 NOVEMBER 2020

Lessons Learned: The Pandemic and Space Metrics

Kirksey's Director of Building Physics addresses Indoor Air Quality and the lessons we can learn from the pandemic.

The 2020 Performance Huddle went virtual this year in response to the current pandemic but was not short on content or networking. The two-day symposium kicked off on November 12th and showcased three sessions, eight speakers, and two workshops. The speakers included a range of professionals, from medical doctors and engineers to architects and scientists, focused on performance in the built environment. 

Kirksey's Director of Building Physics, Kapil Upadhyaya, presented on day two and discussed Indoor Air Quality Simulation Models. His presentation included the following four metrics that are significant when measuring performance in building design, and the lessons learned.
 

Metric One: Virus Decay (% & time, eg. 90% decay in 2 hours)

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Lesson
Increasing daylight, temperature, and humidity to 60% RH increases virus decay. Together, these three parameters can reduce the kill-time of 90% of aerosolized viruses from two hours to 26 minutes. 

Tool:  SARS-CoV-2 Airborne Decay Calculator, by US Department of Homeland Security
 

Metric Two: Socially Distanced Occupancy (Number of people / square-feet)

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Lesson:
Architectural design, especially interior layouts, can account for two cases:
- Typical occupancy.
- Socially Distanced Occupancy that reduces the risk of infection during a pandemic.

ToolManual calculation or Cove Tool (generates an Occupancy Assessment Score)
 

Metric Three: Outside Air Rate (cfm/person)

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Lesson:
Increasing Outside Air Rate dilutes ambient air but also increases energy consumption. New air handlers can be oversized for pandemics and can be run in standard mode or 'pandemic mode.' Alternatively, Dedicated Outside Air Units or operable windows can provide increased Outside Air Rates. 

Existing buildings can increase 'effective' Outside Air Rate with social distancing/remote working. For example, an admin space with 23 people and 14 cfm/person of outside air increases 'effective' Outside Air Rate to 20 cfm/person (42% more) with 17 people if six people work from home.
  
Tool: ASHRAE 62.1 Ventilation Rate Procedure Calculator
 

Metric Four: Probability of Infection (%)

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Lesson
Ventilation rate combined with behavior can affect the probability of infection. An infected person speaking loudly increases particle emission, which increases the probability of infection. For example, in a classroom, an infected teacher/professor represents a 1.8% probability of passing on the infection. Compare this to an infected student who represents only a 0.3% probability of passing on the infection. If everyone wears a mask, it reduces particle emission rates, which reduces the probability of infection.

Tool: Calculator (under continuous development)
 
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