Episode 660: Andrew K. Persily, PhD - Understanding Indoor CO2, Building Ventilation and Their Affects on IEQ

Where the IAQ Radio Discussion Continues
Post Reply
User avatar
admin
Site Admin
Posts: 37
Joined: Wed Aug 18, 2021 3:06 pm

Episode 660: Andrew K. Persily, PhD - Understanding Indoor CO2, Building Ventilation and Their Affects on IEQ

Post by admin »

Show Resources: Show Discussion:

12:03:55 From LaNguye : IAQ Radio is financing Don's lifestyle with his correct answers to trivia!
12:04:14 From cliff zlotnik : TRivia: At what time does counting solar mean time begin?
12:05:45 From Donald Weekes : Midnight at Greenwich, UK
12:06:17 From cliff zlotnik : correct Don, send your address
12:07:17 From LaNguye : Congratulations Andy for your fellowship.
12:08:12 From Donald Weekes : Cliff: That was one I knew w/o looking it up. :)
12:08:35 From cliff zlotnik : WOW!!!!
12:08:45 From Donald Weekes : Congrats, Andy on the NIST Fellowship!
12:12:20 From AAH : 1994 - Womble, Develop Baseline Info on Bldg and IAQ BASE'94, Part I-Study Design, Bldg Selection, and Bldg Descriptions, Healthy Buildings, 95, 1305-1310, 1995.
12:16:42 From Kishor Khankari : What it would take those in the building design and operation to realize that "Buildings are for People" so that our buildings human-centric?
12:19:44 From LaNguye : Andy did a fabulous job as Chair.
12:24:23 From Kishor Khankari : Breathing zone of occupants is the most critical zone in occupied space. Don't you think current building design guidelines are "beating around the bush".
12:25:25 From AAH : Question: Andy - does your dissatisfaction curve vs CO2 still stand? [Persily, The Relationship Between Indoor Air Quality and CO2, Proc 7th Int. Conf IAQ Climate, 2, 1996]
12:33:11 From Donald Weekes : Andy: What are your thoughts about the CO2 measurements in schools and used for determining that the IAQ in the school is 'acceptable', or 'not acceptable.\
12:34:24 From Kishor Khankari : Traditionally emphasize is placed on quantity of air rather than how well the air distributed to breathing zone. How can we change this thinking?
12:36:11 From Lukas Jenkins (Edifice Rx) : For smaller buildings without ducted OA, due to operable windows and code allowing this, how about CO2 demand control to circulate air throughout the occupied space for local CO2 dilution. Say one room has higher CO2 due to occupancy but other rooms in the building have low CO2. Thoughts?
12:36:32 From Lukas Jenkins (Edifice Rx) : Room by room CO2 sensors, 1 AHU.
12:38:44 From AAH : Question: Andy - over the years I have found both the outdoor air and indoor air to be normally distributed (including longitudinally). Have you also seen this?
12:44:56 From David Miller : https://nap.nationalacademies.org/read/11170/chapter/5
12:53:18 From Kishor Khankari : Please share the link for this tool
12:53:36 From Ya Gotta Have Faith : https://pages.nist.gov/CONTAM-apps/webapps/CO2Tool/#/
12:59:21 From AAH : Persily, Analysis of ventilation data from the US Environmental Protection Agency building assessment survey and evaluation (BASE) study, NISTIR 7145, 2004
13:00:08 From LaNguye : when is this coming out Andy ?
13:00:59 From Lukas Jenkins (Edifice Rx) : Follow up question for Andy in the after thoughts based on Cliff’s paraphrasing of my question and Andy’s response. So in a 1 AHU scenario if one were to monitor CO2 in every office would fan recirculation be a plausible “demand control strategy” to keep spaces close to the bldg. average vs. CO2 building up in one space but then low in common area. CO2 demand recirculation I’ll call it as we are under the premise the codes don’t have OA ducted into the building and windows would be the “ventilation” but we still want to keep CO2 low or balanced space by space rather than building up.
13:01:06 From Lukas Jenkins (Edifice Rx) : Thanks Andy!
13:02:02 From Andrew Persily : https://link.springer.com/referencework ... -10-5155-5
13:10:35 From Victor Cafaro : Great show
13:11:14 From Lukas Jenkins (Edifice Rx) : Great show! A lot of food for thought as we reinvent IAQ HVAC and infection control with energy consumption in mind and sensors for demand control ventilation!
User avatar
CliffZ
Posts: 26
Joined: Thu Sep 09, 2021 3:36 pm

Re: Episode 660: Andrew K. Persily, PhD - Understanding Indoor CO2, Building Ventilation and Their Affects on IEQ

Post by CliffZ »

Z-Man's Takeaways from Today's Interview:

Dr. Andrew Persily, PhD has a calm demeanor and a knack for explaining complex concepts in an understandable way.

The roots of NIST can be traced back to founding of our country. The power to coin money, to regulate the alloy and value of coin, and to fix the standard of weights and measures throughout the US, was granted to Congress in the Articles of Confederation in 1776 and in the US Constitution. A story about a great fire in Baltimore responded to by multiple fire departments whose fire hoses couldn’t be connected, an example of the need for consistency.

While NIST's research interests have changed fortunately, physics don’t change.

Building design is not a high-tech industry that is slow to change.

CO² is an ideal tracer gas because it is easy to measure and building occupants are a built-in injector.

I was surprised that studies on affect of CO² on cognitive performance have shown inconsistent results. I was unaware of studies to the contrary and have always taken it for granted that high CO² levels lowered cognitive performance.

The discussion of CO² levels indoors and in schools is over 100 years old.

Low indoor levels of CO² doesn’t mean good IAQ as there are many indoor emission sources (e.g. furnishings)

Indoor CO² measurements should be compared with outdoor CO² measurements because the outdoor levels of CO² are not constant.

It is important to point out the mistakes and quirks in test methods.

While a famous green building had sophisticated sensors which provided valuable information feedback; the building lacked the capability to modulate the amount of fresh air. The sophistication, efforts and cost provided no benefit!

When you look close enough at any building, you will find problems.

CO² and infectious airborne aerosols are very different. Filtration will reduce infectious airborne aerosols, filtration has no effect on CO².

To solve a problem, you must search for answers where the problem is.

The 7 fundamental units of measure:
Mass, Time, Electric Current, Amount of Substance, Illumination, Distance & Temperature.

Z-Man signing off
User avatar
RadioJoe
Posts: 24
Joined: Thu Aug 19, 2021 3:58 pm

Re: Episode 660: Andrew K. Persily, PhD - Understanding Indoor CO2, Building Ventilation and Their Affects on IEQ

Post by RadioJoe »

Wow, great interview and questions from our audience. I think we can let the Cliff's blog and the comments speak for themselves. I am working with Dr. Persily on follow ups to questions we could not get to today!
User avatar
admin
Site Admin
Posts: 37
Joined: Wed Aug 18, 2021 3:06 pm

Re: Episode 660: Andrew K. Persily, PhD - Understanding Indoor CO2, Building Ventilation and Their Affects on IEQ

Post by admin »

Audience Questions Answered:

From Kishor Khankari : What it would take those in the building design and operation to realize that "Buildings are for People" so that our buildings human-centric?

I don’t have an answer to this important question, but this is not a new idea at all. It goes back millennia in many respects, but I note that I have an actual book on my shelve from 1980 called Building for People published by the National Bureau of Standards that stresses the people and behavioral side of building design and operation.

From Kishor Khankari : Breathing zone of occupants is the most critical zone in occupied space. Don't you think current building design guidelines are "beating around the bush”.

I’m not sure what you mean by beating around the bush but getting ventilation air to where occupants are doing their breathing is essential. I often start with a focus on getting it into the building, as that’s where the process starts, but it is not over until it gets to the people!

From Kishor Khankari Traditionally emphasis is placed on quantity of air rather than how well the air distributed to breathing zone. How can we change this thinking?

I don’t have an answer to this one either but getting air to the occupants is absolutely essential. I will note that some folks have emphasized air distribution for longer than any of us have been working on this topic.

From AAH : Question: Andy - does your dissatisfaction curve vs CO2 still stand? [Persily, The Relationship Between Indoor Air Quality and CO2, Proc 7th Int. Conf IAQ Climate, 2, 1996]

This is not my curve. The research supporting the relationship between CO2 concentrations and perceptions of odors from human bioeffluents is well established based on research done by others from several decades ago.

Lukas Jenkins (Edifice Rx) : For smaller buildings without ducted OA, due to operable windows and code allowing this, how about CO2 demand control to circulate air throughout the occupied space for local CO2 dilution. Say one room has higher CO2 due to occupancy but other rooms in the building have low CO2. Thoughts?

I’m not sure I understand the question, but I am not familiar with using demand control ventilation in buildings without ducted outdoor air. If your asking about using CO2 control to facilitate mixing within buildings, I’m am not familiar with that concept but I’d be interested in learning more.

From AAH : Question: Andy - over the years I have found both the outdoor air and indoor air to be normally distributed (including longitudinally). Have you also seen this?

Sorry, but I don’t quite know about you mean by air being normally distributed so I can't comment on whether I’ve seen it or not.

From Lukas Jenkins (Edifice Rx) : Follow up question for Andy in the after thoughts based on Cliff’s paraphrasing of my question and Andy’s response. So in a 1 AHU scenario if one were to monitor CO2 in every office would fan recirculation be a plausible “demand control strategy” to keep spaces close to the bldg. average vs. CO2 building up in one space but then low in common area. CO2 demand recirculation I’ll call it as we are under the premise the codes don’t have OA ducted into the building and windows would be the “ventilation” but we still want to keep CO2 low or balanced space by space rather than building up.

This sounds like using demand control to manage within building air mixing as noted above. Again, this is a new idea to me, but I’d like to learn more.

From Lukas Jenkins (Edifice Rx) : Great show! A lot of food for thought as we reinvent IAQ HVAC and infection control with energy consumption in mind and sensors for demand control ventilation!

I’m glad you enjoyed it. I did as well.
Post Reply