Where do I find information on the small Winix air filter or large portable filters:
You've mentioned Needlepoint Bipolar Ionization. What is it:
- We are taking this technology to the Board on 12/15/20 and will provide more information shortly.
What are the exact guidelines of the Santa Clara County Health Department:
- The guidelines are what we initially targeted and what most Districts are doing that are back to school. That was our direction back in the summer and early fall. In late September, as a result of the information we learned from the first Hays commissioning, as well as ongoing input from consultants, engineers as well as the faculty, staff, and parent community. The Santa Clara County Health guidelines are to open the windows to increase outside air. Absent that, they recommend MERV-13 filters when windows cannot be opened. To be clear, we met those guidelines in a majority of our classrooms prior to the certification standards we established and the upgrades we commenced.
- The Direct language is: Increase ventilation by increasing outdoor air circulation (e.g., by opening any operable windows and/or doors) or using high-efficiency air filters and increasing ventilation rates.
Footnote: Increase circulation of outdoor air as much as possible by opening any operable windows and doors, unless doing so would pose a health or safety risk to individuals using the facility (e.g., allowing in pollen or smoke or exacerbating asthma symptoms). If opening windows poses a safety or health risk, maximize central air filtration for HVAC systems (ideally with a targeted filter rating of at least MERV 13).
- That is an important distinction. The County's guidelines are to open doors and windows for increased ventilation by outdoor air or have increased central air filtration with "ideally" MERV-13 filters. There is a lot of confusion around the terms. I've had conversations with engineers that use the terms loosely. What the county guidelines are calling for is ventilation or filtration. It is a little confusing the terms seems like the same but they are not. We try to explain it on the ventilation website so I encourage you to look at that explanation but basically the County is calling for either increased outside air or improved and increased recirculated, filtered air.
- The District chose to meet and exceed the County's guidelines by doing both. We mechanically set an increased outside air component (that is the 30 cfm/ occupant) and then we improved filtration with the addition of MERV-13 filters.
Our buildings are old. How can we trust the systems that are built in the 1950's:
- Almost all of the 1950's systems have been removed at this point. There are only a few select locations with original systems.
- A majority of the District mechanical units were installed in 2001/2002 or later.
- The original design of many buildings was for radiant heating and window ventilation. The radiant would often leak and was therefore abandoned throughout in the late 90's and early 00's.
- The performance of your mechanical units has not changed much in that time and has only started changing in the last 8 years or so. Even with that, many new rooms are designed for MERV-13 but specified with MERV-8 filters for energy savings measures. Our District standard was MERV-8 prior to COVID-19. This is typical in many office buildings, schools, and other public spaces.
Do I leave my doors and windows open or closed:
- Initially we've said either is fine. Upon further review and consultation, our recommendation is to close the doors and windows with either certification method.
- Mechanical Certification: The certification process is to ensure a measurable amount of outside air that is brought into the room to dilute the air. We are effectively controlling the effect of open doors and windows. Due to that set amount, we are recommending doors and windows closed so the mechanical ventilation can do the work it is certified to do. The built-in systems are providing a lot of outside air. In many cases far more than the minimum baseline we've set. You should be fine with the doors and windows closed if you have mechanical ventilation.
- The portable filters don't have mechanical ventilation but they trap most of the COVID particles in the HEPA filter. With the doors/ windows open, you will dilute the air more but also make the filter less effective and take longer to trap any COVID particles if you have a sick person in the room. Therefore, we are recommending keeping doors and windows closed with the portable filters as well.
- Now that the weather is getting colder, it will be more comfortable in the rooms with the doors and windows closed.
- Per standard security protocols, you should close your windows at night.
Can I just bring in or use my classroom fan:
- No. Do Not Use Fans.
- Fans create turbulence which will kick up any COVID-19 particles that fall to a surface.
- The way the filters pull the air does not create the same kind of turbulence.
My building / room does not have windows. What about my room:
- Based on our certification process and our recommendation to leave doors and windows closed (see doors and windows above) the rooms are certified even with no windows.
My building / room is a sustainable building designed with passive ventilation and not mechanical systems. How will you certify that room:
- Based on our certification process rooms with passive ventilation or radiant heating and no ventilation are certified based on the portable air filters.
Why was my room not safe and needed a portable unit and now is considered safe and the portable filter is removed:
- Your room was never considered "not safe". It was considered not tested.
- As you can see from the process outlined above in the long description section, we put portable filters in the rooms prior to testing them. That was our means of certifying as if there was no mechanical system.
- Some people have missed this in the volumes of information about the reopening measures. Trust us, we've repeatedly said this is our process. The decision to purchase the portable filters was for two main reasons:
- We knew we had some rooms that would not meet our certification and
- A factor of time and the desire to certify before children return to the rooms since the independent consultants had a limited availability and would not be able to test all the sites before we returned to school.
When can we see the data for our rooms:
- We are working with the consultants to get the results in a publishable format.
- We still don't have the data on many of our sites which is why our portable filters are still deployed.
- WE DO NOT CERTIFY A ROOM UNLESS THE REQUIRED OUTSIDE AIR MEETS OUR CRITERIA. IF WE DON'T HAVE THE DATA, WE CERTIFY WITH THE PORTABLE FILTERS.
- We hope to publish reports soon showing the measurements for every room.
What are the air change ratings (ACH):
- Many recommendations looks at air changes per hour (ACH) but that metric only looks at filtered air and we have chosen to certify based on dilution with outside air or filtered air with the portable filters. So the ACH numbers would represent different things.
- The outside air turnover is about 3-4 times per hour depending on the room but that rate is more important depending on the number of people in the space. (ie if you have 2 people in the space, filtering the air is more appropriate since the air exhaled is highly diluted in the large space but if you had 100 people in the space you would really want to turn over that air with a lot of outside air to dilute it.)
- Many have heard of 6 air changes which is actually part of the ASHRAE recommendations for dealing with COVID-19 but we don't feel that is sufficient enough. That is why we are not using that as a certification metric and are instead focusing on the dilution of the air with the amount of outside air per occupant as our determining factor.
- Our consultants recommended and many schools are following the 6 ACH guideline for filtered air. We chose to exceed those requirements and instead are exceeding that by setting the outside air metric.
- You can have MERV-13 filtered air ACH, HEPA filtered air ACH, outside air ACH and all of that changes based on the room volume. Since that metric is more variable, we chose to focus primarily on the amount of outside air for the occupancy to emphasize the dilution.
Which is better, Mechanical Filtration or Portable filtration:
- Based on these factors, in our opinion, they are about equal in efficiency.
Which solution is safer,Mechanical Filtration or Portable filtration:
- For a comparison of the mechanical ventilation to the portable filters they are partially doing different things and it is a little like comparing apples to oranges. The portable HEPA filters do not provide outside air. The mechanical classroom systems do.
- The mechanical ventilation is both diluting and filtering the air
- The portable units are only filtering the air but are doing so at an even higher rate that is closer to Hospital operating room grade. Some studies suggest the HEPA level will catch almost all of the COVID-19 particles while other studies suggest not.
- So there is no clear winner between the two directions. They each have their own tradeoffs. As you can tell by the noise of the portable units, the increased filtration requires significantly higher airflow while the built-in system allows us to mix in fresh air to dilute the air more without the added noise.
- If we go back to the previous point about air changes, the HEPA filters are providing anywhere from 2-4 ACH depending on the space. The mechanical method is providing 6-10 ACH depending on the space. The tradeoff is the HEPA filters block more COVID-19 particles but at a slower rate. If we were to install HEPA filters equal to 6 ACH your rooms would be a wind tunnel and you would not be able to teach.
- We are trying to balance all aspects of the environment and the portable filters at the lowest possible setting that we are comfortable with is still too high for many teachers. Most teachers thus far have been happy to have the portable filters removed from their classrooms as they are noisy due to the added air required to push air through the HEPA filter. So again, this is a balancing act.
- Additionally, we did a series of baseline air quality tests in comparable sample classrooms with both MERV-13 filters and compared them to the HEPA filters. We tested for mold, allergens, VOCs, etc and the results were similar supporting the effectiveness being similar.
Can we bring in our own air filter:
- You are welcome to bring in your own but the District will not maintain them. We are planning on providing sufficient ventilation/ purification with the district equipment.
I thought the systems were off except when we turned on the heat for a limited period of time:
- That is how our systems used to be set up to conserve energy.
- Part of the commissioning process we spoke of was to change those settings so they provide outside air all day long. We start at 5:30am and turn it off at 7pm.
- The heat works independent of this setting
What are other Districts doing:
- Every District is currently asking the same questions we have been.
- Many are choosing to meet the first step criteria outlined above and stopping there.
- A few Districts have upgraded to the MERV-13 filters including East Side USD, Las Lomitas ESD, and others.
- Many Districts bought smaller HEPA filters similar to our additional filters that we are adding.
- We were the first to commit to the portable commercial grade filters as a backup and were therefore first in line. Two other Bay Area Districts have also just ordered these units.
- We've talked about the bipolar ionization (step 3 outlined above) that we commissioned air quality tests before deciding. Other Districts bought them outright and are now testing them. Those Districts include Acalanes, Berkeley, and Bakersfield. Others are considering adding bipolar ionization. Many are waiting for our test results from the vendor.
- Some Districts are considering installing complicated fan systems with UV light. We researched those and they are less effective and considerably more expensive than the other options we are pursuing.
