Talking Air Filtration National Air Filtration Association

A poolside chat with Bob Burkhead about lessons learned from testing, developing, and using air filters - Moderated by Tom Justice. View the slides from Mr. Burkhead's presentation:
For detailed show notes, read below and use the timestamps to navigate the episode:
[5:38] Bob Burkhead and Tom Justice explore the trends for testing products for filtration. Indoor air quality is
more than just filters. The issues are efficiency degradation, chamber testing, and  ISO 17025 Lab certification.
[10:30] Mr. Burkhead discusses efficiency
degradation in detail, using an efficiency over time graph to illustrate a scenario involving filtration in a surgery room.  
[14:37] Mr. Burkhead describes chamber testing and variations in techniques assembled for the ideal filtration
application. He compares a single-pass testing method to a multi-pass testing method. A new room air testing standard involving a recirculating loop is currently being worked on.  
[17:42] Mr. Burkhead concludes with the value of ISO 17025 Lab Certification, which provides validation and credentials for overall operation and focuses on continuous improvement. The structured decision rules and methodology should include the rest of the world.
[22:29] Q & A session with Mr. Burkhead.

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This episode is from NAFA’s Tech Seminar, recorded in April 2022. Our speaker was Dr. Jordan Clark from The Ohio State University.  

As in many engineering problems, the control of our indoor environments is rapidly moving from a prescriptive,

rule-of-thumb paradigm to an entirely data-driven paradigm enabled by the Internet of things. The first step in such a shift is generating data reliably and cheaply with low-cost sensing.  To this end, we will look at several studies of the performance of low-cost airborne pollutant sensors and discuss their strengths and weaknesses and

application domain. Finally, we will look at some things we can do with these sensors once they are robust and reliable.

View the slides from

⁠Dr. Jordan Clark's presentation⁠.

For detailed show notes, read below and use the timestamps to navigate the episode:

[2:08] Dr. Clark describes the engineering controls for air filtration in buildings. Prescribed ventilation rates and filter rates mean releasing quantities of air and waiting for feedback. We don’t have performance-based metrics or real-time feedback to avoid high costs of money and energy. An aging electrical infrastructure can’t keep up with grid peak times in buildings across all sectors and homes. 

[5:07] Dr. Clark examines the evolution of prescribed air rates within Standard 62 over time from an ASHVE article. In the late 19th century, the germ theory was developed, starting the hygiene revolution that influenced the implementation of natural air ventilation. In the middle of the 20th century, central air conditioning and heating were adopted and costly.

The energy crisis at the beginning of the 1980s caused the ventilation rate to decrease. Now, the ventilation rate is prescribed per person per floor area. What we should expect in the future post-pandemic is still ambiguous. One idea is to treat buildings like hospitals to reduce the

transmission of viruses. We require a reevaluation of ventilation rates and consumption of energy.

[9:39] Dr. Clark reviews the US Department of Energy's depiction of a grid-interactive, efficient building of the future. However, there is no mention of air quality, and that is what Dr. Clark is working on.

[10:38] The first step to getting that data is using the hardware to measure quality in real-time.

Air quality sensors constantly evolve, but the current focus is on low-cost particle sensors, which cost about $1,000 USD. Dr. Clark reviews the anatomy of this device.

[15:15] Dr. Clark describes his performance testing as field testing with naturally occurring particle sources like gravel roads and highways. Other sources were created in the form of essential home functions like cooking. A comparison of devices and measured the sensor detection of events and if the sensor can return to baseline after

an event. Other tasks included quantitating exposure to events, averaging times of performance, determining the functional range for sensors, and determining correlation and linearity among models.

[23:25] Sensor performance based on sources is evaluated and found to be insensitive to building temperature. Further analysis showed that this temperature defect was a light and optical defect. Sensors are, however, significantly sensitive to humidity. Dr. Clark expands on performance as a function of size, which was evaluated to show calibration for a specific particle size. His takeaways from his research and literature help make predictions on the drift or long-term changes in performance.

 

[31:11] Dr. Clark concludes with gas sensors and total volatile organic compound (TVOC) detection. A total VOC sensor in low-cost particle sensor devices has limitations compared to a colorimetric Formaldehyde Sensor. The predictive abilities examined using machine learning and low-cost sensors didn't lead to any concrete conclusions.

 [36:08 ] Q & A session with Dr. Clark.


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In this recorded conference session (Tech Seminar 2022), David Space (former Boeing engineer) spoke about the airplane operating environment, how an airplane Environmental Control System (ECS) works, air filtration advancements over time, and how the air distribution system and airplane design features control for air quality and spread of disease.

Review the slides: ⁠https://amped.egnyte.com/dl/LEPxPrUWAK⁠

For detailed show notes, read below and use the timestamps
to navigate the episode: 

[2:01] David describes the airplane operating environment and how an environmental control system has multiple functions, such as maintaining cabin pressure anti-icing systems, cargo heat, and ventilation. 

[3:00] David describes how an ECS system continuously circulates outside air when it enters the engine and into a mixing chamber, where it is mixed with recirculated air. This 50/50 mix is distributed to the cabin and exits the airplane through valves.  

[4:33] David begins his review of the history of air filtration and advancements in aircraft with the Boeing Stratoliner, the first aircraft to implement air recirculation in 1945. After that, NASA research led to the application of HEPA filters for recirculated air, allowing for less fuel waste without compromising the quality of the cabin air. David Space participated in this research in 2002 and expanded on carbon air purification and filter capture methods for HEPA research in 2015 at the Lawrence Berkeley National Labs.  

[7:28] David Space analyzes a graph comparing airplane filtration to filtration in other modes of transportation and in environments such as hospitals and office buildings.  

[8:18] What do the latest statistics show on the spread of disease? The industry was hit hard by the COVID-19 pandemic; international flights dropped by 75% in 2019, and few reports on the spread of COVID during flights were available. 

[9:50] The Department of Defense used United Airlines for an eight-day study with four days on the ground and four days in flight. Mannequins released particles in the air with simulated coughing and breathing mechanisms. Decay, also known as how soon the particles leave the cabin, occurred much quicker due to a higher air exchange rate. 

[15:21] David compares the ASHRAE 1262 in-flight research to another study he was a part of with American Airlines on the factors that affect comfort for passengers while in flight. They took this data to the Technical University of Denmark for more human subject research on air quality. They found that air purification could raise humidity and lower gaseous contaminants. David’s research continues at Rutgers to find that bio effluents are the primary contaminant due to the high density of people. 

[21:17]
David presented actual measurements collected during flights across the Boeing fleet, indicating that the 787 has lower volatile organic compounds. The FAA adopted prescriptive regulations for ventilation systems, but David believes performance-based regulations would be better. He
suggested implementing filtration systems to handle particulate matter and gaseous contaminants, which would improve passenger comfort and reduce engine emissions.


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NAFA recently published the Best Practices and Guidelines document, Filtration for Continuing Care Retirement Communities.

Patrick Rosenthal, CAFS (lead author of this NAFA Guideline) will educate HVAC and air filtration professionals on what facility managers need to know about clean air in continuing care retirement communities.

Download 2023 Best Practices and Guidelines Webinar Filtration for Continuing Care Retirement Communities Slide Deck

Download Filtration for Continuing Care Retirement Communities Best Practices and Guideline

About NAFA Air Filtration Best Practice Guidelines:
What’s the difference between ASHRAE has Standard 52.2 and NAFA’s Best Practices and Guidelines?

The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) has minimum standards for air filtration.

Organizations like the National Air Filtration Association (NAFA) go beyond these minimum standards. NAFA publishes best practices and guidelines for several facility applications based on the experience and expertise of their membership, as well as current mandates and research provided by governmental and scientific communities.

HVAC and air filtration professionals should use NAFA’s Best Practices and Guidelines as a tool to educate their clients on how to protect their facilities’ occupants.


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This week’s episode is a May 2021 presentation from Dr. Joseph G. Allen.

Dr. Joseph G. Allen is an associate professor at the Harvard T.H. Chan School of Public Health and co-author of Healthy Buildings: How Indoor Spaces Drive Performance and Productivity.

Dr. Allen directs the Healthy Buildings program at Harvard, where he created ‘the 9 Foundations of a Healthy Building’. He is also a Certified Industrial Hygienist and Deputy Director of the Harvard Center for Education and Research on Occupational Health and Safety.

He has also been translating science to the business community and the general public, publishing more than 10 op-eds in leading newspapers and translating science into actionable tips for the public.

Enjoy his presentation and a lively Q&A!


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Hi, It’s Tony Veroeven, Associate Director of NAFA, and host of Talking Air Filtration.

We’ve got a bunch of episodes on the docket to release over the next several weeks, most of which will be some of our conference content since we’ve gotten back in person.

This episode is Dr. Shelly Miller, a professor and environmental engineer from the University of Colorado.

As the COVID-19 pandemic moved across the world, scientists like Dr. Miller work around the clock to better understand how the SARS-CoV-2 virus and its variants are transmitted, the details of the symptoms and illness, and how to stop the spread of the virus

She presented “Helping to Save the World from COVID-19: why an urban air pollution engineer got involved, and what she did to makes things better” at our Technical Seminar in April of 2022.

Listen and you will hear to her outline her research into how air filtration can be used in the battle against COVID.

Do your customers and colleagues a favor and share this episode with them!

Enjoy!


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