Corsi-Rosenthal Boxes
Using funding and resources from his recent MPowering the State award, Dr. Donald Milton bought fans, furnace filters and duct tape in bulk for the production of Corsi-Rosenthal boxes at the University of Maryland, College Park. The devices have been shown to effectively improve indoor air quality and ventilation, and are a cost-effective alternative to traditional air purifiers.
Images: Dr. Milton’s PHABlab set up a booth where students, alumni, and community members built their own Corsi-Rosenthal boxes at UMD’s Maryland Day
FAQs
What is a Corsi-Rosenthal Box and how did it get its name?
Corsi-Rosenthal (CR) Boxes were conceived by Dr. Richard Corsi (UC Davis) and constructed by Jim Rosenthal (Tex-Air Filters). They are a kind of DIY air filter comprised of air filters and a box fan.
What do CR Boxes do and how do they work?
CR Boxes work to clean indoor air by removing particles from the air that are too big to pass through the filters. The fan sucks air in through the filters on the sides, trapping particles, and blowing the filtered air out through the top of the box.
It is recommended that filters on CR Boxes be changed every six (6) months.
How effective are CR Boxes at cleaning the air? What do they target?
CR Boxes are quite good at cleaning the air and are even comparable to High Efficiency Particulate Air (HEPA) filters. CR Boxes can be used for a wide range of particles such as allergens and smoke. Most importantly, however, CR Boxes can be used to reduce your risk of infection by respiratory pathogens including, but not limited to, COVID and the flu.
How much do the supplies cost and how long does it take to build a Box?
CR Box supplies are readily available at most home improvement stores and typically have a maximum cost of around 100 USD. Compare that to a HEPA filter which can cost hundreds of dollars!
It typically takes between 20-30 minutes to build a large CR Box.
Why do I need a CR Box? Is my home HVAC system not good enough?
A typical HEPA filter can be pretty costly whereas CR Boxes can provide the same level of protection against airborne pathogens without breaking a budget. The main difference between a HEPA filter and a CR Box is the price point.
You may not know the level at which your current HVAC system is working but most HVAC systems in the United States don't provide a sufficient amount of clean air to rooms. In fact, the group that sets standards for HVAC systems, along with the CDC, updated their standards to specifically address ventilation as a form of infection control. CR Boxes are a good, temporary solution to bridge the gap between current HVAC systems and the new guidelines until the HVAC systems are updated.
Will having a CR Box in my space mess with my current HVAC system?
No. CR Boxes do not interact with or impact existing HVAC systems. They are separate and apart from each other. CR Boxes supplement the air filtration in any given indoor space.
Those boxes seem a little big. Are there other size options?
Yes. The standard CR Box is constructed using a standard box fan (roughly 20 in. x 20 in. x 5 in.) and 20 in. x 20 in. x 2 in. MERV-13 filters. If that size is too big for your space(s), you can scale down the box using a smaller fan and smaller filters.
What can I do to get a Box for my spaces?
We typically schedule builds with classes and other campus and community groups in the College Park area. If you are interested in having a build, please email us at phablab@umd.edu and we would be happy to help you build some boxes.