1/ Really enjoyed the National Conversation on Indoor Air and Schools during the Pandemic this morning and honored to have participated. Thanks to @polsiewski.
2/ One important outcome was general agreement that schools will continue to struggle to do the right thing to re-open until @CDC does a better job of guiding, particularly on making improved ventilation a prominent risk reduction step.
3/ Additional guidance on portable HEPA air cleaners and avoidance of ineffective technologies is also needed. A lot of great discussion and agreement by experts on a number of important issues that are missing from @CDC guidance.
4/ A lot of good "dos and don'ts" for layered risk reduction. Webinar was recorded & I encourage school officials to watch it when available. I will post a link at corsiaq.com in the same pull-down as my previous webinar on layered risk reduction in K-12 schools.

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More from @CorsIAQ

25 Feb
1/ Investment in engineering and computer science education has a significant return on investment (ROI) to states.

Proud of the great ROI that the Maseeh College of Engineering and Computer Science provides the State of Oregon.
2/ Every dollar that the State spends on helping to educate one of our students yields a 320% ROI over 10 years, or 12% compounded annually.
3/ Based on a detailed analysis of graduates who stay and work in Oregon, their starting salaries, incremental annual salary increases, and use of a State income tax calculator ….
Read 4 tweets
24 Feb
1/ Thanks to Oregon Department of Education for inviting @Wymelenberg and me to speak with a very large number of school officials in the State today about effective layered risk reduction, proven technologies, & variations across different types of school buildings/classrooms.
2/ 55 minute presentation w/ 35 minute GREAT Q&A period. Major kudos to the Department for their proactive approach to making schools as safe as possible prior to re-opening.
3/ Schools across US are suffering from confusing & inadequate guidance on ventilation & portable air filtration systems, & their importance for signif' reducing inhalation dose of virus-laden aerosol particles. Info available, but often not where schools are looking.
Read 5 tweets
22 Feb
1/ One of my slides. Cost of good portable HEPA filter system in a 600 to 800 square ft classroom with 25 students (equivalent ACH increase of 2.7 to 3.5/h). Cost is broken down by classroom and student.
2/ Cost = year 1 capital cost + annual recurring costs for filters + electricity at $0.11 per kW-hr.

Total 3-year cost per classroom < $790 (< $11/student for 75 students over 3 years).
3/ If school has 50 classrooms (larger than my K-8 school) the total cost over 3 years < $40K for entire school. Less for less classrooms.

If noise is an issue can go with 2 HEPA air filters per classroom at lower setting for around $20/student.

How much do books cost?
Read 9 tweets
20 Feb
1/ Tragedy in Texas. When I was Chair of @ut_caee at UT Austin we implemented a new strategic vision that revolved around water, energy, growth of the built environment, and innovations in infrastructure that tie these elements together as a COMPLEX system.
2/ I was so proud of our early-career faculty who led an effort, for example, to develop a new graduate area in Sustainable Urban Systems (SuS) that rapidly grew into one of the most in-demand graduate areas in our department. Great effort. Great success.
3/ The ongoing tragedy in Texas reflects the importance of systems-oriented thinking to make cities, states, regions, and countries more resilient, and to understand the connection between built & natural environments as climate continues to change.
Read 9 tweets
19 Feb
Portable HEPA Filter Systems.
1/ The cost of retrofitting EVERY public school classroom in the entire US w/ a portable HEPA air filter w/ CADR = 300 cfm is approximately $1 billion w/ recurring cost of about $300M/yr for replacement filters. To be clear, EVERY single classroom.
2/ For a classroom that holds 20-25 students, say 600 to 700 ft2 w/ ceiling height of 9 ft, this portable HEPA unit will yield approx equivalent increase in ventilation (equivalent ACH increase) of 3/hr. For a classroom under-ventilated to 2 ACH the bump up is to 5 ACH!
3/ That leads to a 60% reduction in inhalation dose of aerosol particles. Capacity exists. It can be done now.
Read 10 tweets
13 Feb
1/ Ventilation of Schools. My experience working with public school districts for more than two decades is that classrooms are, in general, woefully underventilated (and that's before COVID-19 times!). Others have found the same.
2/ Some results from a 4-yr study involving 7 high schools of different ages & construction, & 46 classrooms (focus on occupied day - plot at right). Approx 80% of classrooms = permanent. Red bar shows approx ASHRAE 62.1-2019 ventilation rate (small variations around bar).
2/ For permanent classrooms, median ventilation rates are less than 50% of ASHRAE 62.1-2019, w/ mean values approx 40% lower. Schools all had mechanical systems and capability of much greater ventilation. When asked why, our team was told (firmly) - energy savings ($$).
Read 20 tweets

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