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More on Ventilation

September 20, 2020 pm30 11:43 pm

I met a ventilation expert Thursday, and another Saturday

Expert I

I brought a ventilation expert to my school. Thursday. He, and his student, and me, the principal, and a member of my consultation committee walked through a whole bunch of spaces. They brought instruments to measure airflow, not streamers or toilet paper. They measured, observed, took notes. And they made recommendations for needed repairs, for filter inspection cycles. And they made recommendations for occupancy once MERV-13 filters are installed, and them made recommendations for occupancy before MERV-13 are installed. (Differences involved position of occupants, opening windows and doors, spaces to leave empty, where to position purifiers, etc). Based on these recommendations we feel far better.

Also, they explained some of the science. That also helps. I learned about vents and returns, and CFM and humidity and temperature, and air exchanges, and even about crack calculations. They talked about pressure differences, which reminded me of discussions of potential and voltage in high school physics. I was curious about how the air actually moved, and the expert described the shape of the flow, and where actual boundaries formed. His student quietly told me that he wished there was a way to make the air temporarily visible, so we could actually watch the movement.

That reminded me of a project I proposed decades ago. I was in my second year of high school physics, and after studying some simple wave patterns on drumheads with some neat ideas about visualizing them, we talked briefly about fluid flow (It’s complicated). I thought I might visualize some simple kinds of flow, and we discussed taking a small tank and using crystal of a magnesium salt that would dissolve light purple into water. I never got any further than talking about it, but for a moment Thursday I thought about getting some glittery purple dust into the vent, to watch it flow… (not realistic, but inspired me to write this, about, in part, that high school class.)

They also told us that we were fortunate – our ventilation system was well-designed (I was surprised). We are also fortunate, our heating is ventilated, which is not the case in most schools. Most schools have ventilation disasters scheduled for the day the heat comes on. And no one is talking about it. We should come back to this.

Anyway, why go to all that trouble of bringing in experts? Because none of the reports we had gotten said that we were safe, that the ventilation was okay. None of them, not the year-and-change old BCA report, not the DoE’s current report, not the UFT report, none said we were safe. None told us where to avoid putting desks. None told us which windows to open, whether fans should be on, whether doors should be closed. And even the information that they did include, well, no. Trust the UFT report, when we the leadership is hellbent on opening? Trust the DoE report? What, am I and my members stupid?

Expert II

I was at a market. Saturday. Bought some very tasty, very overpriced apples. On my way out I heard a guy telling his companions something about toilet paper. He was talking about school ventilation. He was explaining something. I focused – he actually knew something. “Excuse me” I couldn’t help myself, and then we began to talk. He was in a lot of schools. An inspector. “For the DoE?” Yes, but a contractor. It was one of his colleagues who got caught on video with the toilet paper on the stick.

Toilet paper on a stick is actually useful – it can tell you if air is flowing, or not. Binary like that. I agreed, but mentioned that in my school I’d brought someone in with meters. My new expert got excited. “That’s what you really need! You need to know cfm! You did the right thing!” He became animated. I explained that I didn’t trust the DoE or the UFT on this, and he agreed vigorously.

After the toilet paper on the stick incident, they were ordered not to talk to anyone who was watching them work. But, he felt, it was all for show anyway. “If they wanted to get this right, they would have started in July. They would have measured.”

Then I asked about heating, and yes, most of our schools will have big problems, but his companions had been waiting patiently, but we’d been talking almost ten minutes, so I said goodbye.

But get that – the guy who worked ventilation inspections for the DoE  thought I was right to bring in an outside expert, actually got excited.


The experts spoke the same language. They both value science. And they were not impressed by the politics that are taking place.

To decide what to do with a space, they agreed that we should take air flow measurements. They agreed that the proper filters were important. And they both recognized that getting this right takes time.


Ask yourself this – who told you the ventilation in your building was fine?

Did they tell you which doors to keep open, and which to keep closed? Did they recommend placement of purifiers? Did they recommend places not to set up a work space? Did they tell you which windows to open?

And did they warn you about what would change when the heat gets turned on?

12 Comments leave one →
  1. MIke Trembley permalink
    September 21, 2020 am30 10:26 am 10:26 am

    And you are in that tiny little building on the reservoir and that tin building has good air flow?

    • September 21, 2020 am30 10:35 am 10:35 am

      Yes, it is a tin shack, constructed 1970, And yes, the ventilation system, according to our expert, was properly designed. He seemed a little surprised, too.

      We do have some issues, but pretty easy to address. We looked at some space on campus, as well. It was an education.

      • MIke Trembley permalink
        September 21, 2020 am30 10:39 am 10:39 am

        Well I am glad you all have a safe place to learn because its definitely a special school…when i see the kids leave at the end of the day it is a mirage of some sort, a throw back of the student body that use to occupy the nycdoe and seeing it today makes the mind wander a bit which is use to the mine field of the “regular” schools and their student body.

        • September 21, 2020 pm30 2:52 pm 2:52 pm

          Definitely not the typical DoE experience. You are nearby?

  2. MIke Trembley permalink
    September 22, 2020 am30 8:42 am 8:42 am

    Walton Campus educator across the street in the “regular” school

  3. Quinn Zannoni permalink
    September 23, 2020 pm30 10:23 pm 10:23 pm

    The DOE’s ventilation guidance says there need to be 4% of the sqft of the room of open windows. Have you heard anybody using this rule in practice? I made the calculations for my school, and our rooms would each need a lot of open windows (not just one window).

    See page 2: “The windows must have 4% of the total square footage of the room opened when occupied.”

    Click to access HVAC_Protocols_for_School_Reopening.pdf

    • September 24, 2020 pm30 10:57 pm 10:57 pm

      Thank you – I did not know that.

      In one problematic space, the engineer who came to the school did calculate the square feet of window… but that was a different cicrcumstance.

  4. MIke Trembley permalink
    September 24, 2020 am30 10:42 am 10:42 am

    Yeah and you can purchase those geezer sheets that is sold by my pillow company for a $150…its a corrupt society and the human beings that occupy the planet are evolving into organisms incapable of cohabitating which will no doubt cause the end ala planet of the apes original movie at the end where charleton heston sees the statue of liberty broken in half..

  5. MIke Trembley permalink
    September 25, 2020 am30 9:29 am 9:29 am

    I really do feel that diblasio and carranza are doing their best to help us get through this time with our schools. Its not easy to manage the vast buildings across the boroughs and deal with custodial issues such as sanitizing and cleaning properly as well as air flow and ventilation. Carranza has been cool and calm and diblasion has been a trooper for us but sooner or later we will have to have students come into the buildings.

    • September 26, 2020 am30 8:52 am 8:52 am

      Seriously? I think they’ve made a horrible mess. Deciding that NYC was the one big city in the US that could open schools… Bad mistake. And the models they chose? Bad mistake. Knee-jerk, last-minute changes? You get the picture.


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