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Clean Air Buildings Info Sheet
In 2022 this research focused on how to educate people on ventilation and the development of tools to help capture, document, and understand a facilities ventilation performance levels.
Once people are educated and the tools are provided, the key challenge is how to get facilities to disclose their ventilation performance levels. The following template is provided that can be submitted to facility managers to request disclosure of ventilation performance levels in their buildings. It was developed from white papers that were requested by a very large organization to help them address this critical need. (do not click the link yet, keep reading)
There is a presentation that attempts to address the education challenge. The goal is to provide a general presentation that can be distributed everywhere to stimulate building ventilation discussions that are based on performance numbers and the full disclosure of the ventilation performance numbers within buildings. (do not click the link yet, keep reading)
There is an earlier generic presentation. There were different versions of this presentation.
The ACH Calculations Tool (ACT) allows users to capture the Air Changes Per Hour (ACH) of rooms in a building. This seems like a trivial exercise until one attempts to capture this data. It is about the human factors interface to allow for fast and easy entry of data. This is a third generation attempt to create a user friendly mechanism to capture ACH performance levels. It is integrated with the Clean Air Buildings (CAB) database that allows users to print room and building level certificates. (do not click the link yet, keep reading)
Clean Air Buildings (CAB) was developed to allow anyone to capture the ACH of rooms in a building and post it in a public database. The public database also allows users to search for buildings and examine the ACH performance levels. Unlike the BCMC, it does not subject the ACH to a risk scale. The goal is to just assess buildings for their current conditions but not make any judgments of risk. (do not click the link yet, keep reading)
Building Ventilation Logos: Copy and paste to your emails.
CAB Info Sheet
Building Ventilation (video1)
Building Ventilation (video2)
Request Entry of Multiple Buildings
Building Ventilation In The Age Of Contagions
Why is Ventilation Suddenly a Problem
COVID-19 is endemic, it is like tuberculosis, measles, and other airborne contagions from the previous century
It has been a leading cause of death for 2 years
To eventually eliminate tuberculosis and other airborne contagions, it took vaccines and modern forced air heat and cooling systems
Our building ventilation systems have been ignored during the time of great health when our parents and grandparents understood building ventilation
Professor Edward A. Nardell Harvard Medical School
From Time Magazine: If We're Going to Live With COVID-19, It's Time to Clean Our Indoor Air Properly, Edward A. Nardell is Professor of Global Health and Social Medicine, Harvard Medical School.
COVID-variants may be with us for years to come, and this will certainly not be the last respiratory virus pandemic. We have long suffered from annual contagious respiratory infections, but exceptionally low rates of influenza and common colds during COVID-precautions have demonstrated that not all of this suffering need happen. So, we need to think clearly and scientifically about how better we can reduce the spread of viruses indoors especially when and where masks will no longer be in common use.
Are there effective engineering controls that can help make indoor environments truly safer?
A Paradigm Shift to Combat Indoor Respiratory Infection
In May of 2021, 39 scientists published "A Paradigm Shift to Combat Indoor Respiratory Infection"
There is great disparity in the way we think about and address different sources of environmental infection. Governments have for decades promulgated a large amount of legislation and invested heavily in food safety, sanitation, and drinking water for public health purposes. By contrast, airborne pathogens and respiratory infections, whether seasonal influenza or COVID-19, are addressed weakly, if at all, in terms of regulations, standards, and building design and operation, pertaining to the air we breathe.
Ventilation what is it?
We hear that we need ventilation in small indoor spaces, But why?
We hear we need to increase ventilation but what does that mean?
Ventilation what is it?
It is about Ventilation performance levels
Ventilation performance is measured as Air Changes Per Hour (ACH)
ACH is a measure of how often air changes in a room
1 ACH changes the room air 1 time per hour
20 ACH changes the room air 20 times per hour
or every 3 minutes (60 min / 3 min = 20 ACH)
Disease specialists address ventilation only in ACH
ACH = Fan Cubic-feet per Hour / Room Cubic-feet
Ventilation what is it?
It is not about measuring and maintaining CO2 levels
Maintaining CO2 levels leads to a system with ACH levels that are too low such as 1 ACH or less
It is not about Liters/min or cubic-feet/min per person, this will never provide visibility into the actual ACH level in a room and when scenarios are run the ACH levels are too low such as 1 ACH or less
Ventilation performance when dealing with airborne contagions is always in terms of ACH in a real room setting, not a lab or test fixture
Example: 60 min / air changed every 3 min = 20 ACH
Small indoor space - problem is massive
Large indoor space - problematic
Outside - extremely rare
Mask on / off
Exposure time of 1, 4 , 8 hours
Various ventilation rates - key to reduce risk
Scenarios show probability of infection 99% to .0003%
What should be the ACH Level?
0 leads to infection
1 leads to infection we know from data
CDC recommends 12 ACH for a hospital room with airborne contagion
The number must be greater than 1
As ACH increases the risk of infection drops
What have facility managers done?
Hawaiian airlines ventilation performance level is 20 ACH and they posted it for all passengers to see on their entertainment screens
Philadelphia restaurant program is 15 ACH and 106 restaurants participated
There is a public database with hundreds of facilities showing what they have done
What Must Happen
Facility managers should post their ventilation rates in terms of ACH in all spaces and as a summary for the whole building.
What is the future
Building codes will change because there will be no choice
Certificates of occupancy will include ventilation performance levels as ACH
HVAC - Heating Ventilation & Cooling
Ceiling Level UV Lights
Far UV 222 Lights
Room sanitizers are too small for most public rooms, may be okay for small 1 person office
What About The Home
Turn on the HVAC fan when guests arrive and turn it off when they leave
What about costs?
Typical home fan motor takes the equivalent power of 1 to 3, 100-watt lightbulbs
Commercial Facility Costs
Must turn on ventilation system 1 hour before and after the public arrives and leaves
Most commercial facilities are not on demand systems and the fans run all the time, no cost impacts
However, there are serious maintenance issues
That is why the ACH levels must be determined and posted
o Facilities using on demand systems, some cost impacts
They are negligible because the fans take little power once compared to heating and cooling
Instead of using the HVAC or exhaust fans they can install ceiling level UV or far UV 222 systems, which will run at about 10% of the mechanical motors
Where do ACH standards and guidelines come from?
Department of Defense via DOD standards
Most of the ACH levels are based on comfort except for when airborne contagion mitigation is required in hospitals
ACH Standards & Guidelines
|Hospital Trauma room||15||-||CDC||Classroom (Art)||16||20||EPA|
|Hospital room airborne precautions||12||-||CDC||Malls||6||10||EPA|
|Hospital operating room||25||-||Office||8||30||Greenheck|
|Hospital rooms||6||10||EPA||Engine Room||20||60||Greenheck|
|Bar||15||20||NCI||Retail||6||10||NCI, wiki, EPA|
Commercial Building Challenges
It is more about proper maintenance and operation because this will lead to ACH = 0 or ACH = 1
Are vents blocked
Are dampers partially closed by someone
Are timers working properly
Are sensors, fans, and dampers working properly
Do vents have streamers so people can see system is working
Periodic inspections with documented evidence using certificates that are posted will ensure effective maintenance
Room / Zone Certificate Key Elements
Room / Zone Name:
Vents Unblocked: yes/no
Dampers Open: yes/no
Timers Working: yes/no Inspection Authority and Date:
Building Certificate Key Elements
Building Name & Address:
Min ACH Level:
Max ACH Level:
Average ACH Level:
Inspection Authority and Date:
In the last century, our parents and grandparents had to deal with tuberculosis and other deadly infections
Vaccines did a great deal to eliminate those contagions, but they would not have worked without the introduction of forced air HVAC systems and ceiling level UV systems
Unlike in the last century no new technology is needed, we just need to use what our parents and grandparents developed
There always will be unvaccinated people
The system solution must use vaccines + ventilation
The analysis clearly shows why; large numbers of people will continue to get sick and die - see this research findings
It will take years for the building codes to change to include contagion mitigation, so what can we do?
As responsible managers of our children's future
Stop using my original phrase of increase ventilation
We must talk in terms of ventilation performance levels using the decades old ACH levels
We must post ACH levels throughout our buildings
We are not here to determine the future minimum ACH levels that will become part of future building certificates of occupancy
We are here to measure and document the building ventilation levels and post the resulting ACH performance levels throughout the building
ACH Calculation Tool
Example ACH Calculations Entry
Example CAB Entries
Links & Contact
COVID-19 Research From A Systems Perspective
https://www.cassbeth.com/covid-19/index.html (this is a huge area, use the TOC links for parts 1, 2, and 3)
Walt changed the dialogue to admit that the COVID-19 virus is airborne, and that ventilation is critical
Walt collaborated and shared his research with others at Drexel University and the MITRE healthcare coalition starting in 2020
His research was about determining probability of infection using common operational living scenarios
He wrote a book: COVID-19 A Systems Perspective
The Philadelphia Water Works was the first water treatment facility in the United States. It was a model for all future water works to follow in the New World. People would flock from around the planet to see this facility which combined engineering and art to solve a massive problem of safe water for the inhabitants of Philadelphia. It was born of necessity as the people decided they would not tolerate yet another yellow fever outbreak. The Museum sits on top of the original water reservoir that provided the city with water. As Philadelphia grew the reservoir and Water Works could no longer meet the needs of the city and new projects eventually replaced this once great technological and artistic achievement. It stopped operations in 1909.
A post vaccine world implies that everyone has received a vaccine against the COVID-19 virus. However, we know that will not happen. In the USA some will refuse the vaccine. In many countries the poor will not have access to the vaccine. The idea of a post vaccine world also suggests that we can return to the pre-COVID world. However, we know that is not the case. The contagion and its variants will be in the environment for decades. This is not unlike the situation that existed in the early part of the last century where there were deadly contagions that were part of normal life. It was not until multiple technologies were introduced in multiple systems that there was a decline in many deadly contagions in the USA and other parts of the world. These technologies and systems were embedded in:
In the wake of the COVID-19 disaster the city of Philadelphia has once again taken lead actions like the Enhanced Ventilation Standards for Indoor Dining and Application Form for Increased Dining Capacity dated February 14, 2021. The Enhanced Ventilation Standard calls for 15 air changes per hour (ACH) for establishments wanting to double their seating capacity. The approach is brilliant and uses the incentive to increase income to offset any possible costs that may be needed to increase ventilation. The ventilation level increase is large and will significantly mitigate contagion levels in the restaurant. It is obvious that it is traceable to existing engineering requirements associated with contagions rather than subjective minimum comfort levels. As part of the initiative they posted howto videos:
(video on how to calculate air changes per hour)
https://www.youtube.com/watch?v=58uRfAxh6Cw (video on how to complete the application)
These people are brilliant. The city of Philadelphia is leading the world on how to deal with the COVID-19 disaster for indoor settings. Unfortunately this program stopped in May 2021 leaving a void in this very important area of ensuring public buildings have ventilation levels that mitigate contagions rather than just provide minimum comfort levels. However, the model exists along with the recommended ACH level.
The city of Philadelphia has also taken the time and effort to understand their school facilities and they have performed an extensive site survey (air balance reports) of all their school. The school district has 240+ schools and 12,000+ rooms. They made this critical information public via their website. Once again Philadelphia has taken a lead in trying to deal with another aspect of the COVID-19 disaster and that is to understand the current state of the schools and share the data with the Philadelphia taxpayers and people everywhere.
There are 2 approaches to calculate Room ACH.
The first approach is to use the: ACH Calculations Tool - ACT. When you arrive at the page just press the ACH Calculations button and start entering data. This is probably the easiest approach. You also have the option of adding the building into the open source database of buildings around the world.
The second approach is to use the following steps to calculate the ACH for each room. Some rooms have multiple vents. Make sure to measure all the vents in a room.
Measure room Length, Width, and Height in feet
Measure each Vent Length and Width in inches
Measure each vent Linear Feet Per Minute (LFM) using anemometer (buy the lowest cost ~ $19)
Example anemometer: https://www.amazon.com/Anemometer-Handheld-Detector-Temperature-Windsurfing/dp/B07ZJ38ZMX
Use the following steps to calculate the ACH
Vent Cubic Feet Per Minute (CFM) = Vent 1 Length * Vent Width * LFM 1 / 144
Room Ventilation CFM = Vent 1 + Vent 2 + ...
Room cu-ft = Room Length * Width * Height
ACH = Room Ventilation CFM / Room cu-ft
Write it all down so that you don't get lost. Use a separate sheet of paper for each room. Don't try to make perfect measurements. Room shapes are odd and ventilation readings vary. Set the meter to read the Max rate and move it across the entire vent. These approximate readings are all that are needed to make reasonable assessments of the ACH levels.