YAY for “tools to improve ventilation and air filtration” in WH plan
I often hear: too difficult, too $$$, wasn’t designed for it, everything’s fine.
As an engineer, I think it’s very doable. Doesn’t have to be $$$. Buildings are adaptable. We don’t know til we measure. 1/x
I often hear: too difficult, too $$$, wasn’t designed for it, everything’s fine.
As an engineer, I think it’s very doable. Doesn’t have to be $$$. Buildings are adaptable. We don’t know til we measure. 1/x
Where are ventilation and filtration now? What does improvement look like?
We wrote a paper on our 2020-now work:
From Guidance to Implementation: Applying ASHRAE Epidemic Task Force Building Readiness Strategies in 95 Commercial Office Buildings ashraem.confex.com/ashraem/w22/me…
2/x
We wrote a paper on our 2020-now work:
From Guidance to Implementation: Applying ASHRAE Epidemic Task Force Building Readiness Strategies in 95 Commercial Office Buildings ashraem.confex.com/ashraem/w22/me…
2/x
We followed the ASHRAE Epidemic Task Force Guidance. There are 100s of pages of detailed guidance for engineers, facility operators, etc. High-level core recommendations here: ashrae.org/file%20library…
3/x
3/x
VENTILATION.
Goal: Provide and maintain *at least* the required minimum outdoor airflow rates.
What buildings should be doing, pandemic or not. We calculated required OA per ASHRAE 62.1-2019. Then measured OA, verified over time.
Re "minimums":
4/x
Goal: Provide and maintain *at least* the required minimum outdoor airflow rates.
What buildings should be doing, pandemic or not. We calculated required OA per ASHRAE 62.1-2019. Then measured OA, verified over time.
Re "minimums":
https://twitter.com/DavidElfstrom/status/1503410432807251974
4/x
Result: Out of 95 buildings, about half (44%) already met current minimum ventilation rates.
About half were *under-ventilated*:
33% need minor adjustments to operations & maintenance (O&M) practices
23% need more significant work (retrofit, replacement)
5/x
About half were *under-ventilated*:
33% need minor adjustments to operations & maintenance (O&M) practices
23% need more significant work (retrofit, replacement)
5/x
Note that a new building didn't guarantee minimum ventilation rates were provided. Nor did an old bldg guarantee need for retrofits. Kind of even distribution of “in compliance” and “action needed: O&M” across years. More on the interesting pattern in 1980s buildings below.
6/x
6/x
33% need minor adjustments to O&M practices to meet or exceed min OA rate. Issues with actuators, sensors, control schemes, basic “stuff breaks”
Fix these, and we get to 77% of buildings that met minimum ventilation requirements at low effort / low cost! Such opportunity! 7/x
Fix these, and we get to 77% of buildings that met minimum ventilation requirements at low effort / low cost! Such opportunity! 7/x
23% needed retrofits. Their original ventilation rates fall far short of current 62.1 rqmts. The 1980s were not great for IAQ standards! But HVAC equipment has ~25 yrs of expected service life so upgrades should be expected. These bldgs need investment - find them & plan now
8/x
8/x
For those already in compliance. Great!
What’s the plan to ensure it continues? Stuff breaks, weather changes.
For the hottest/coldest/smokiest day? People need (clean) OA at all times.
Opportunities to exceed the minimum ventilation rate?
9/x
What’s the plan to ensure it continues? Stuff breaks, weather changes.
For the hottest/coldest/smokiest day? People need (clean) OA at all times.
Opportunities to exceed the minimum ventilation rate?
https://twitter.com/WBahnfleth/status/1503514108406206468
9/x
That’s it for today. Filtration & conclusions for tomorrow.
For more technical deep dives in the HVAC trenches (on the rooftop?) @davidelfstrom and @joeyfox85 are putting out great twitter work. E.g.
10/x
For more technical deep dives in the HVAC trenches (on the rooftop?) @davidelfstrom and @joeyfox85 are putting out great twitter work. E.g.
https://twitter.com/joeyfox85/status/1503812309445189633
10/x
Wow! So much enthusiasm for ventilation and filtration! The White House’s National COVID-19 Preparedness Plan (Mar 2022) has details on pages 81-83
whitehouse.gov/wp-content/upl…
11/x
whitehouse.gov/wp-content/upl…
11/x
Continued: Following ASHRAE ETF guidance (pic). Layered strategies for reduced exposure risk and better IAQ. Ventilation above.
FILTRATION.
Goal: Use filters & air cleaners to achieve MERV-13 (or better) performance on recirculated air.
“Typical” office bldg filter: MERV-8.
12/x
FILTRATION.
Goal: Use filters & air cleaners to achieve MERV-13 (or better) performance on recirculated air.
“Typical” office bldg filter: MERV-8.
12/x
Result: In central systems, 90% upgraded to/already had MERV-13. 99% were technically capable of doing so.
Some “green” bldgs designed for MERV-13, didn’t have to scramble to upgrade.
1 bldg had no filter rack (!?) and will install a rack sized for MERV-13. MERV-8 for now.
14/x
Some “green” bldgs designed for MERV-13, didn’t have to scramble to upgrade.
1 bldg had no filter rack (!?) and will install a rack sized for MERV-13. MERV-8 for now.
14/x
Some operators concerned about equipment limits
But can be calculated: filter rated pressure drop (PD) vs fan capacity. Get spec sheets, compare!
Higher MERV does not necessarily mean higher PD
Can find better filters w similar PD to existing filter
13/
But can be calculated: filter rated pressure drop (PD) vs fan capacity. Get spec sheets, compare!
Higher MERV does not necessarily mean higher PD
Can find better filters w similar PD to existing filter
https://twitter.com/marwa_zaatari/status/1373776064313495556
13/
What if your system can’t go to MERV-13?
Can it go to MERV-12, 11, 10…? Check the specs, do the math. No need to guess. ashrae.org/technical-reso…
Some bldgs. got MERV-11 as a compromise bc of lingering equip concerns. Still an upgrade.
15/x
Can it go to MERV-12, 11, 10…? Check the specs, do the math. No need to guess. ashrae.org/technical-reso…
Some bldgs. got MERV-11 as a compromise bc of lingering equip concerns. Still an upgrade.
15/x
What if your system can’t go to MERV-13 or you don’t control central HVAC?
In-room options: right-sized HEPA, engineered upper-room UVGI, and
*my favorite* option, the #Corsirosenthalbox!
engineering.ucdavis.edu/news/uc-davis-…
16/x
In-room options: right-sized HEPA, engineered upper-room UVGI, and
*my favorite* option, the #Corsirosenthalbox!
engineering.ucdavis.edu/news/uc-davis-…
16/x
Sum:
Many buildings are under-ventilated, but many not too hard or $$ to fix now. Check HVAC often.
Find what needs upgrading (1980s?) & plan now
MERV-13 possible, do math now
Make #corsirosenthalbox
Many combos to better IAQ. We can figure out what’s possible / a priority
17/
Many buildings are under-ventilated, but many not too hard or $$ to fix now. Check HVAC often.
Find what needs upgrading (1980s?) & plan now
MERV-13 possible, do math now
Make #corsirosenthalbox
Many combos to better IAQ. We can figure out what’s possible / a priority
17/
Better vent & filt are doable, even with existing systems.
We know how. We need can-do attitudes! A la @CorsIAQ: Just do it!
Get worst-performers to min standards. Turn acceptable bldgs into healthy bldgs.
Design decisions last for generation+. What we do now matters.
18/end
We know how. We need can-do attitudes! A la @CorsIAQ: Just do it!
Get worst-performers to min standards. Turn acceptable bldgs into healthy bldgs.
Design decisions last for generation+. What we do now matters.
18/end
@CorsIAQ BONUS, great papers on these issues in schools:
Vent. rates in CA classrooms: Why many recent HVAC retrofits are not delivering sufficient vent.
sciencedirect.com/science/articl…
Understanding teachers' experiences of vent. in CA K-12 classrooms and implication...
onlinelibrary.wiley.com/doi/epdf/10.11…
Vent. rates in CA classrooms: Why many recent HVAC retrofits are not delivering sufficient vent.
sciencedirect.com/science/articl…
Understanding teachers' experiences of vent. in CA K-12 classrooms and implication...
onlinelibrary.wiley.com/doi/epdf/10.11…
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