Online educational resource on achieving indoor environmental quality with radiant based HVAC systems
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educational programs on indoor environmental quality

Simplified and Idealized Illustration of a Portable Fan/Filter (CR) Box in a Classroom
Copyright (C) 2021, Robert Bean, ASHRAE Fellow & Distinguished Lecturer, Free use is granted when credited.

See also: How to set up an emergency isolation room inside a home or apartment for a suspected infected occupant.

This Version 7 is the most current. Free use is granted when credited. Edits included addition of UVGI see note 10.


The Corsi Rosenthal box...for less than $200 CDN you can build a portable fan/filter assembly that outperforms  the most expensive retail products available. I've lost count on how many I have made for family and takes less than 20 minutes to need 1 box fan, 4 @ MERV13 Filters (equal to Filtrete 1900 or 2300), packing tape, scissors/knife...and your favourite beverage. Search online for videos and visit


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