Clean Air Buildings

COVID-19 Research From A Systems Perspective

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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

• 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

Scenarios Analyzed

• 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

https://www.cassbeth.com/cleanairbuildings/index.html

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

Ventilation Approaches

• Natural

• HVAC - Heating Ventilation & Cooling

• Exhaust Fans

• 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?

• ASHRAE

• CDC

• Department of Defense via DOD standards

• ISO

• Others

Most of the ACH levels are based on comfort except for when airborne contagion mitigation is required in hospitals

ACH Standards & Guidelines

Area	AUC min	AUC max	Source	Area	AUC min	AUC max	Source
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
Restaurants	8	12	EPA	Kitchen	12	60	Greenheck
Restaurants	8	20	NCI	Kitchen	7	8	NCI
Restaurants	15	20	wiki	Kitchen	14	18	NCI
Bar	15	30	Greenheck	Kitchens (commercial)	15	30	EPA
Bar	15	20	NCI	Retail	6	10	NCI, wiki, EPA
Bar	15	20	wiki	Laboratory	12	30	Greenheck
School Classroom	4	12	EPA	Laboratory	6	12	wiki
Auditorium	8	15	EPA	Club Houses	20	30	EPA
Assembly Hall	6	8	EPA	Theatres	8	15	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:

• Square feet:

• Cubic feet:

• CFM:

• ACH Level:

• Vents Unblocked: yes/no

• Dampers Open: yes/no

• Timers Working: yes/no Inspection Authority and Date:

• Comments:

Building Certificate Key Elements

• Building Name & Address:

• Square feet:

• Cubic feet:

• CFM:

• Min ACH Level:

• Max ACH Level:

• Average ACH Level:

• Inspection Authority and Date:

• Comments:

Final Comments

• 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

Final Comments

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

Some Screen Shots

ACH Calculation Tool

Example ACH Calculations Entry

CAB Entries

Example CAB Entries

CAB Certificate

Example Certificate

Links & Contact

COVID-19 Research From A Systems Perspective

• https://www.cassbeth.com/covid-19/faq.html

• https://www.cassbeth.com/cleanairbuildings/index.html

• https://www.cassbeth.com/covid-19/index.html (this is a huge area, use the TOC links for parts 1, 2, and 3)

Walt's Bio

• 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

Healthy Infrastructure

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:

• Clean water systems
• Proper sewer systems
• Proper waste removal sanitation systems
• Proper housing and removal of high density tenement housing with no ventilation
• Forced air HVAC systems
• Effective use of ceiling level UV-C ventilation systems
• Use of contagion resistant materials (furniture, table surfaces, building materials, etc.)
• Use of contagion resistant high touch surfaces (railings, door fixtures, toilet fixtures, etc.)

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:

https://www.youtube.com/watch?v=HlneLDi9r54 (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.

How to Calculate Room ACH

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.

1. Measure room Length, Width, and Height in feet

2. Measure each Vent Length and Width in inches

3. Measure each vent Linear Feet Per Minute (LFM) using anemometer (buy the lowest cost ~ $19)

4. Example anemometer: https://www.amazon.com/Anemometer-Handheld-Detector-Temperature-Windsurfing/dp/B07ZJ38ZMX

5. Use the following steps to calculate the ACH

6. Vent Cubic Feet Per Minute (CFM) = Vent 1 Length * Vent Width * LFM  1 / 144

7. Room Ventilation CFM = Vent 1 + Vent 2 + ...

8. Room cu-ft = Room Length * Width * Height

9. 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.