Talking Air Filtration National Air Filtration Association

Growing crops indoors allows farmers to control many production variables, including water, nutrients, lighting, and climate. Keeping the air free and clear of contaminants also improves crop quality and yield and helps to ensure consumer and food safety. Many indoor farmers use a combination of air filters, air purification systems, and good sanitation practices to avoid and eliminate mold spores, bacteria, VOCs, chemicals, and other potential sources of contamination in their facilities. In this presentation, Dr. Sabeh will review the efficacy and necessity of using various technologies that are commonly used and sometimes misused in indoor plant environments, including cannabis.

Download Dr. Nadia's slide deck: https://amped.egnyte.com/dl/EPQJLlrXJ7

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

[6:03] Dr Nadia begins with an introduction to the indoor farm and what defines it; she describes the many types that exist to date and the many names it goes by. She showcases the array of crops possible with indoor farms, including but not limited to leafy greens, herbs, microgreens, and even certain fruits and vegetables.

[9:43] Indoor farming has numerous benefits. It allows for a high crop density, conserves water, reduces waste, and enables eco-friendly pest management. Evolving technology maintains an ideal indoor space, maximizing profitability while minimizing risk and ensuring consumer safety. This has sparked a new era of sustainable and efficient farming.

[11:41] Dr. Nadia defines a controlled environment as variables such as pests, climate, and irrigation that can be controlled.

[12:09] Dr. Nadia explores the critical role of HVAC (Heating, Ventilation, and Air Conditioning) systems in indoor farming. Firstly, these systems maintain optimal temperature, humidity, and air movement, which is crucial for plant growth. Secondly, HVAC systems play a vital role in controlling air quality. Plants require specific levels of carbon dioxide and other gases to grow, and some gases like ethylene and formaldehyde can be harmful to plants in particular doses and at different times of the year. Additionally, plant-emitted gases such as Cannabis odor can be challenging to measure, but they can be filtered out at low concentrations to improve air quality. Particulates such as dust and smoke can also harm crops, mainly if neighboring facilities do not filter their air. Finally, Dr. Nadia describes how insect pests and plant pathogens can threaten crops and how they can be transmitted.

[25:26] Dr. Nadia breaks down the technologies and techniques for providing clean air to crops based on the plants' needs. The top priorities are managing CO2 levels to provide for crops and sustain worker health exposure to CO2. Dilute infected air is essential. Particle filtration is possible due to variances in screen sizes and MERV filters. HEPA is only useful for people because plant viruses are transmitted by contact, not air. Dr. Nadia discusses irradiation, ozonation, odor control, and room pressurization. She highlights the importance of sanitation and maintaining a clean environment for good air quality.

[39:02] Q & A session with Dr. Nadia.


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Zach Konway explores air pollutants and the sensor technologies available to measure pollutants. Gain insight into the advantages and disadvantages of various sensor technologies. Tackle industry myths and facts as they pertain to air quality monitoring. Learn the advantages of continuous air quality monitoring and how air quality data may be leveraged with purification and ventilation for a healthier building environment.

View the slides from Mr. Konway's presentation:

https://amped.egnyte.com/dl/mqqbmdCH4E

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

[3:42] Mr. Konway introduces indoor air quality and the benefits of measuring it. One of the first techniques was the use of canaries in coal mines. Continuous air quality ensures that concerns are addressed before they become widespread. Other benefits include saving energy without compromising the environment of an infrastructure or the occupants' health. Clean air is due to removing pollutants at the source and infrastructure material that doesn’t compromise health and efficient clean air devices.

[8:18] Mr. Konway focuses on the following pollutants and their sensor technologies, starting with particulate matter, the most harmful and common air pollutant. Studies have shown a correlation between high concentrations of this pollutant and a drop in productivity. Carbon dioxide can affect cognitive function. Volatile organic compounds (VOC) commonly enter a building through materials such as paint and carpet. Radon is the second cause of lung cancer after smoking. The last pollutant he covers is ozone, formed from high voltage and reactions with Nox or VOCs, UV light, and oxygen.

[24:56] Mr. Konway describes relative humidity's role in transmitting a pathogen or virus in occupied spaces.

[25:52]Mr. Konway reviews how IAQ data gives insight into the filtration system and slows down viral spread. It can assist building management in ensuring that radon is not present, showing that the equipment is working properly and when efficiency decreases.

[28:35] Mr. Konway reviews the key benchmarks to strive for when monitoring occupied spaces, including the concentration of particulate matter, carbon dioxide, radon, relative humidity, and volatile organic compounds.

[29:51] Mr. Konway concludes with key takeaways from his presentation, including device utilization, calibration, and what gases it will measure. Other considerations should focus on evaluating air quality monitoring companies and the project's goals.


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Recent Updates and Upgrades to ASHRAE SSPC 52.2 - SSPC 52.2 has made many updates and upgrades over the last few years to improve the standard. Many of those updates are meant to increase the repeatability and reproducibility of intra and inter-lab test results. Recent upgrades include an optional method to determine filter efficiency in removing or inactivating airborne viruses and bacteria. The addition of a Particulate Matter (PM) calculated filter efficiency by using currently available data points from the 52.2 test. This session will summarize in detail all the updates and upgrades and touch on what is next for 52.2.


View the slides from Mr. McGrath's presentation:

https://amped.egnyte.com/dl/ACqyqKb6fQ

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

[1:50]
Mr. McGrath begins the overview of recent 52.2 upgrades in the last five years with the MERV Table for better progressions and shedding data for testing filters. He then moves on to updates for relative humidity and narrowing down the range of percentages. For the optical particle counter, updates were more terminology-related.

 

[5:11]
Mr. McGrath explains the goal of repeatability and reproducibility with graphs outlining how filters are tested for efficiency across different labs. Improvement should revolve around the grouping of data points for the particle diameter.

 

[5:43]
Mr. McGrath introduces the most recent project, Research Project 1784, in which samples were filtered across multiple labs to determine whether lab testing standards vary. These results will assess changes in ASHRAE standard 52.2.

 

[7:37] Mr. McGrath examines the removal of MERV 17 and what led to that reference removal, as well as MERV 18, 19 and 20 references.

 

[10:04] Recent Upgrades to 52.2 in the last year or two, including the addition of PM 52.2 filter efficiency based on a flat distribution curve and using E-values.

 

[13:31] The recent COVID-19 pandemic led to
changes in ASHRAE 52.2 Addendum C, which helps collect filter efficiency data for viruses and bacteria. Calculations were created to determine the presence
of the organism and its ability to grow. Variety in organisms detected is still needed due to organism resistance.

 

[17:00] Mr. McGrath concludes with current
52.2 pursuits that revolve around unifying terminology for testing and parameters for checking devices. Research project 1784 is ongoing, and its results will lead to new upgrading projects.


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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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