1982
Act 
Information 
Official 
the 
under 
Released 

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1982
Act 
Information 
Official 
the 
under 
Released 

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Regards
 
Robyn
 
 
From: Ian Longley <[email address]>
Date: Friday, 17 December 2021 at 10:06 AM
To: Mark Jermy <[email address]>, Ackley Aniebietabasi <[email address]>,
Robyn Phipps <[email address]>, Scott MacKenzie <[email address]>
Subject: RE: some thoughts on CO2 guidelines for schools
1982
A more philosophical issue is what are we trying to achieve? Zero transmission in schools is one objective, in which case
I’d go for 800 (or even lower). By going for 1000 I’d say we’re signalling that that is not our objective. Our national switch
from elimination to suppression of COVID-19 would imply zero transmission is not our goal. However, I’d argue that’s
specific to COVID-19 delta variant.
Act 
 
More generally, these are public health and political issues. 9(2)(g)(i)
 
 
Ian
 
From: Mark Jermy <[email address]> 
Sent: Thursday, 16 December 2021 3:45 PM
To: Ackley Aniebietabasi <[email address]>; Ian Longley <[email address]>; Robyn Phipps
Information 
<[email address]>; Scott MacKenzie <[email address]>
Subject: RE: some thoughts on CO2 guidelines for schools
 
Hello all,
Excellent points from Ackley and Ian.
 
My 2 cents worth:
Official 
1.  Calculating the percentage risk a student has, over a school day, is very difficult. It requires data on the viral load of
the infectious person and the susceptibility of others in the class. These are not well known for Delta for adults, and
are even more uncertain for children, or for Omicron, and are of course unknown for the next variant of concern.
the 
Instead, I prefer a ratio approach: what is the risk to student A (who is sitting far from the infectious case)
compared to student B (who is sitting right next to the infectious case, thus their risk is not strongly affected by
ventilation).
2.  If we want this ratio to be 1/10 (student A has 1/10th the risk of student B) then for a typical 190 m3 classroom
with 31 people, we need 5.3 ACH and 1000 ppm CO2 (assuming no air filtration)
If we want this ratio to be 1/15, we need 8.3 ACH and 800 ppm CO2
under 
Personally I am happy with 1/10 instead of 1/15, as student A has other opportunities for close contact with the
infectious case outside this classroom, and children don’t catch COVID-19 easily, etc... however that decision is for
others to take, it’s outside my lane!
3.  ASHRAE recommend, for hospitals, 4-6 ACH for patient rooms, and 6 ACH for examination and treatment rooms,
with at least 2 ACH being fresh air (the rest can be recirculated). That’s a high standard. By achieving 5 ACH, in a
school where we expect fewer highly vulnerable people compared to a hospital, we’re already choosing a high
safety level
4.  CIBSE note that ventilation rates of 10 litres per second per person or less are recommended by a number of
official bodies for health and comfort in normal times. 1000 ppm is about 9.5 litres/second/person and 800 ppm is
Released 
about 15 litres/second/person.
Therefore 1000 ppm meets the ASHRAE recommendation for hospitals and the 10 L/s/person target, and meets my
arbitrary 1/10th risk ratio.
 
Another consideration is that setting a threshold at 800 ppm will result in more rooms being identified as needing
investigation and remediation. 1000 ppm will keep this list shorter, leaving off the less urgent spaces.
 

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Against that, 800 ppm is commonly used elsewhere and is the default green/orange threshold for many CO2 monitors.
There is value in using the same number consistently in all communications.
Cheers,
Mark
 
 
From: Ackley Aniebietabasi <[email address]> 
Sent: Thursday, 16 December 2021 12:12 pm
To: Ian Longley <[email address]>; Robyn Phipps <[email address]>; Mark Jermy
<[email address]>; Scott MacKenzie <[email address]>
Subject: RE: some thoughts on CO2 guidelines for schools
 
Thanks Ian and Mark,
1982
 
I agree with the practical cases you’ve listed below, which is consistent with our previous CO2 measurements in schools,
but I’m inclined to suggest that we consider an average of 800 ppm to ensure the extra ventilation needed to prevent
Act 
transmission, and for consistency with some of the international recommendations.
 
Thinking about ACH, my understanding from Mark’s explanation at the meeting yesterday was that 1000 ppm is about
5.2 ACH, and ideally, our target is for 6 ACH. So, the question that comes on my mind is: What is the ACH and
background ventilation rate (l/s/person) for 800 ppm, and what does it equate to in a % risk of infection?
 
In a typical Avalon classroom in Wellington, we provided a traffic light CO2 monitor, where I set the CO2 thresholds
shown in the bar chart below. In the first phase of the experiment, we provided a pre-designed template and asked the
students/teachers to record the CO2 levels based on the green, orange and red peeps.
 
After two weeks, we went to the school and discussed the results with the students and their class teacher. As reported
by Newsroom, “the students identified that often carbon dioxide levels on the electronic monitoring device we provided
increased quickly when the windows were closed, but as they opened the windows the levels decreased significantly. The
students found it difficult to persuade a relief teacher to keep the windows open on a cold winter day”.
 
Information 
This suggested an awareness of what to do when CO2 levels are above the recommended threshold helped to promote
environmental competency (reflecting on our discussion with Chris on Tues). 
 
Official 
the 
My thoughts are that we should consider a target that will provide the good ACH, background ventilation rate, which will
potentially reduce the risk of infection, and consider consistency with international recommendations and our
forthcoming on-demand DQLS CO
under 2 target.
 
Happy to discuss further.
 
 
Nāku noa, nā
Ackley
Aniebietabasi Ackley (Jnr), PhD | Senior Technical Advisor | TPHM School Design Team
TPHM-Te Puna Hanganga, Matihiko | Infrastructure & Digital
https://nz.linkedin.com/in/ackley-aniebietabasi-2b361a85
DDI +6444637590 
Released 
National Office Mātauranga House
education.govt.nz
We shape an education system that delivers equitable and excellent outcomes 
He mea tārai e mātou te mātauranga kia rangatira ai, kia mana taurite ai ōna huanga 
 

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From: Ian Longley <[email address]> 
Sent: Wednesday, 15 December 2021 7:46 PM
To: Robyn Phipps <[email address]>; Mark Jermy <[email address]>; Ackley Aniebietabasi
<[email address]>; Scott MacKenzie <[email address]>
Subject: some thoughts on CO2 guidelines for schools
In principle I’m happy with a 1000 ppm guideline, which I make to roughly equate to a 1% risk of infection over 1 hour
(based on numerous assumptions).
I’m mainly concerned about the practical application/implications.
Firstly, I would clarify that this is a instantaneous guideline, which in practice should be interpreted as CO2 should not
stay over 1000 ppm for at least 5 minutes (or instruments providing running 5-minute averages are fine), followed by
1982
immediate behavioural action if it does and training/infrastructural intervention if it happens persistently over
days/weeks.
Act 
In practical cases, and looking at our study data, most of our classrooms fall into three categories:
1.  Under-occupied or well-ventilated – never get close to 1000
2.  Under-ventilated but vacated after within the hour – these tend to get to around 1200 ppm (if normally occupied)
by the end of the period
3.  Under-ventilated and occupied for > 1 hour (or insufficiently flushed between classes) – these get well over 1200
and over 2000 in many cases
Let’s imagine for now we have a visual traffic light indicator which is only either green or red either side of 1000 ppm.
Type 1 are obviously fine.
Information 
Type 2 tend to go over 1000 ppm only towards the last half, and maybe even the last 10 minutes of the period. Generally
small modifications (1 or 2 extra window openings) are likely to bring CO2 down below 1000. We’d like to hope that after
this happening multiple times the teacher will get the gist and open that extra window earlier to pre-empt the monitor
going red in which case – job done (depending on how many teachers use the room).
Type 3 are the really problematic ones, but note that there are three interventions:
Significantly increase ACH (not an option in winter)
Official 
Schedule a “flush” after an hour
Don’t timetable rooms to be used continuously for more than an hour
Note that emptying the classroom for 5 minutes has very limited effect without the flush and the flush is still effective if
everyone stays put. The question is – is a 5 minute flush practical?
the 
It may also be worth bearing in mind (and maybe communicating) the non-linear relationship between CO2 and infection
risk:
The longer a room is occupied the more likely CO2 is to level off and stop rising (except in really poorly ventilated
cases)
Infection risk does THE OPPOSITE – growing exponentially with time. Another reason why double-periods without
under 
mid-period mitigation might be the biggest risk in schools.
Hope that helps!
Ian
Dr Ian Longley 
Principal Scientist - Air Quality
Programme Leader - Atmospheric Environment, Health and Society
Released 
9(2)(a)
National Institute of Water & Atmospheric Research Ltd (NIWA)
41 Market Place Viaduct Harbour Auckland New Zealand
Connect with NIWA: niwa.co.nz Facebook LinkedIn Twitter Instagram
To ensure compliance with legal requirements and to maintain cyber security standards, NIWA's IT systems are subject to ongoing monitoring, activity logging and
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NIWA's IT systems

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Document 2: Discussion between VTAG members and programme team re CO2 testing
F om
Ma k Je my
To
Ian  ongley  Sco t MacKenz e  Scott MacKenz e  Robyn  h pps
Cc
Jeff W lson  V cky Evans  Jason Chen  Ackley Aniebie abasi  Renelle G one t
Subject
RE   nal Results  Home Test Set #11 - whe e it takes us next
Date
day  7 Janua y 2022 8 18 09 pm
A tachments
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Hi a l,
A couple of points  n case they a e of use
1)     Scott, if you need a  efe ence fo  10 l/s/pe son and 6 ACH, he e s a passage w th  efe ences
“Vent lat on  ates of 10 l t es pe  second pe  pe son a e  ecommended fo  health and comfo t  n no mal t mes by a numbe  of sou ces [3]  The h ghe  the vent lat on  ate  the lowe  the  nfect on  sk
Fo  hosp tals  ASHRAE  ecommends 4-6 a  changes pe  hou  (ACH) fo  pat ent  ooms  6 ACH fo  exam nat on and t eatment  ooms  and 12 fo  a bo ne  nfect on  solat on  ooms  w th at least 2 ACH be ng f esh outdoo  a   n each case  and the  est may be  ec culated  f clean  [4]
A l t es-pe -second ta get depends on the numbe  of people  n the  oom  and a -changes-pe -hou  ta get does not  We  ecommend both types of ta get a e ach eved  f poss ble
[3] C BSE Gu de B Heat ng  Vent lat ng  A  Cond t on ng and Ref ge at on (2016)
[4] ASHRAE Standa d 170-2021 -- Vent lat on of Health Ca e Fac l t es (Ame can Soc ety of Heat ng  Ref ge at on and A -Cond t on ng Eng nee s)”
We also have a  ationale fo  5.3 ACH. At this ai  change  ate, afte  1 hou , a suscept ble pe son  n the same  oom, but fa  enough f om the  nfectious case that the ai  they b eathe is well mixed,  eceives a dose of vi us which  s less than 1/10th the dose fo  a pe son s tting bes de the infect ous case.
(We assume the pe son sitting next to the infect ous case is 1 met e away and facing the same way).
2)     If we a e to compa e pu ging with constant vent lat on, I th nk the  isk of t ansm ssion of COVID is best assessed by the total dose of vi us  eceived while spend ng a given pe iod in the  oom. The efo e we could compa e the effectiveness of pu ging vs. the effect veness of constant vent lat on by the level of PM (o  CO2) integ ated ove  a
given pe iod of time (say a 1h  lesson). It should be easy to calculate this fo  set ai  change  ates, I ll have a go.
3)     I think the p io ty fo  Jason and I is to complete the calculat on algo ithm fo  the self assessment tool (we ll include w nd d iven flow) and then  un it fo  a  ep esentative set of class ooms fo  diffe ent times of yea  in diffe ent cl mates.
Chee s,
1982
Ma k
From  Ian Longley  Ian.Longley@niwa co.nz> 
Sent  F iday, 7 Janua y 2022 3 46 pm
To  Scott MacKenz e  Scott@sapius nz>  Scott MacKenzie  [email address]>  Robyn Phipps  obyn ph [email address]>  Ma k Je my  ma k je my@cante bu y ac.nz>
Cc  Jeff Wilson  [email address]>  V cky Evans  V cky Evans@education govt.nz>  Jason Chen  jason.chen@cante bu y.ac.nz>  Ackley Aniebietabasi  ackley.aniebietabas @education.govt.nz>  Renelle G one t  Rene le G one [email address] nz>
Sub ect  RE  Final Results  Home Test Set #11 - whe e it takes us next
Hi Scott
Act 
Ag ee with all of that, I think. I like the idea of ai  cleane s be ng used tempo a ily wh le mo e pe manent building modifications a e made (if you have enough), but also awa e a cleane  allocation/p io it sation p ocess w ll be  equi ed.
Rega d ng ongoing studies and evidence to pin  ecommendat ons upon, I see it like th s .
1.  Solid and easily  nte p eted evidence that
a.  c ossflow MUCH mo e effective fo  CO2 and PM
b.  egula  pu ge 2nd best method
c.  single o  mino  openings not sufficient and should not be  elied upon
d.  ai  cleane s (filt ation) effective supplement so long as x, y, z
e.  (could do ANVS again)
f.  I think these can be add essed  elatively quickly (one week) at Epuni (o  s mila ) w th some methodological imp ovements wh ch I can elabo ate on anothe  time
2.  good p actice fo
a.  c ossflow (what methods a e  eliable/va able, influence of weathe )
b.  ai  cleane s (speed sett ng, noise acceptabil ty, placement)
c.  these  nvolve a longe  set of  epeated obse vations ove  a longe  timef ame, p obably best done if the p ocess can be at least pa tly automated ( emote cont o led) so that school  s v s ted only an hou /day (fo  example).
3.  Implementation – can teache s/schools follow inst uctions?
a.  G ven Leeds expe ience that the answe  will be NO unless this is ca efu ly conside ed
And f nally, my  egula   equest that any CO2 data  s captu ed and sto ed, along with metadata, acco d ng to standa d p otocols whe eve  poss ble to max mise lea n ng. Mikael, myself and othe s have long been keen on an “Indoo  Ai  Quality Obse vato y” that would p ovide th s cent alisation/standa disation to multiple secto s and now seems an
exce lent time to explo e that idea fu the .
Ian
From  Scott MacKenzie  Scott@sap us.nz> 
Sent  F iday, 7 Janua y 2022 10 58 AM
To  Ian Longley  Ian.Longley@n wa.co.nz>  Scott MacKenz e  [email address] nz>  Robyn Ph pps  obyn [email address]>  Ma k Je my  ma k je my@cante bu y.ac.nz>
Cc  Jeff Wilson  [email address]>  V cky Evans  V cky Evans@education govt.nz>  Jason Chen  jason.chen@cante bu y.ac.nz>  Ackley Aniebietabasi  ackley.aniebietabas @education.govt.nz>  Rene le G one t  Renelle.G one [email address]>
Sub ect  RE  Final Results  Home Test Set #11 - whe e it takes us next
Love it!  G abb ng back the talk ng stick noting Robyn s emails as I m typing this type of content fo  the pape .  Really app ec ate the spit balling, I find it the best way to a ve at sma t and quick gold nuggets.
Information 
10 lps good  efe ence point gives  ts  elevance and p ominence in bu ld ng pe fo mance (Jeff and Ma k – nudges) and maybe something ou  TAG should fo m a solid view/statement on?  6ACH al eady common  ef point fo  the sta t of  good ventilation  vs 2.5-3.5 being  adequate  in schools (but maybe less so in this  n a chang ng wo ld).
P og amme pos tioned as COVID  esponse to seg egate its aims away f om cu ent DQLS, so we can leave that be fo  now noting we a e a cu ent “ ” guidel ne due to COVID but what we lea n/do eventua ly folds into DQLS – so think we ve cove ed that angle.
Risk-based ta gets needs to app eciate if we a e at g een/o ange/ ed, then down to if we have infect on at this pa ticula  school, what cont ols a e in fo ce (distanc ng, coho t ng, masks etc) and also the  isk inhe ent  n the occupant (age, medical cond tions, vac status, he d immunity etc).  We can neve  know if the e a e no infected people. 
Good topic fo  the wide   esponse wo k within the M nist y to be tasked with and consult us on – I can seek th s inte na ly as an INPUT to ou  th nking. V cky something we could pick up with Helen s team.
Ag ee that 800PPM is an a bit a y numbe  –  eads as such on CDC – you could say with Omic on it now should be lowe , o  you could say it now matte s less because it s so t ansmiss ble you w ll need 12 ACH to sta t making a diffe ence – which wi l neve  be an option fo  schools unless we make them [new] hospitals.
Really like this type of simpl c ty f om Ian below (though Ackley wi l have thoughts – think I am  eflecting discuss on late last yea  on 800-1000PPM, we can cement  t in at the  ght time
If you can meet 800-1000 ppm consistently – you e fine in te ms of needing to focus on ventilation-specific st ateg es to minim se COVID-19 ai bo ne t ansmission.
If you can stay unde  800-1000 ppm by us ng hou ly o   nte -pe iod pu ges – please do.  And let s conside   ecommending th s as a  do anyway  st ategy  ega dless of ventilation pe fo mance – especially fo  high schools who al eady have inte -pe od b eaks (noting coho t management needed alongside)?
If you go consistently ove  800-1000 ppm eve y pe iod – imp ove natu al ventilation until you don t.  Conside  changing  go cons stently ove  to  on ave age go ove  so it s measu able?  Th s is why we need the class oom study  esults a e c it cal – th s is l kely a REALLY BIG piece of wo k to get schools, and my bed oom to this level.
If you can t – now go to f lt at on (which may be temp while othe  imp ovements a e sought o  pe manent, and noting that the effect of filt ation will NOT be  eflected  n CO2 data). Yes on that bas s that we have ev dence that lowe ing CO2 also lowe s PM – which NIWA study does not have good data on, but my  bed oom  test
nd cates it does.
AND the e will be specific s tuations whe e due to  sk p ofile you go to filt at on anyway  [Fictitious] a school of 1000  ncludes 50 yea  6-7 k ds deemed high  sk due to vac status and p e-existing health condit ons, who have class oom with max of 15, 3m desk spacing, assisted ventilation AND in  oom filt ation.  Seen something like
this in the US.  That would be an ope at onal management decision suppo ted by ventilation advice.
So should in ou  action plan clea ly include
Studies (part of GUIDE workstream)
A follow-up cont ol  oom study at Epuni whe e we apply the  incense  PM to  epeats of CO2 build-up testing (and which with what I ve now got, we could also  nclude steady CO2/PM p oduct on vs vent lat on  educt on testing).  We need accepted evidence that methods of lowe ing CO2 also moves and lowe s PM (beyond my
bed oom test ng), if this type of data is not al eady p oved in othe  studies.
We push  1 on Epuni and move  ts status f om a  epeated study to becom ng ou  ongoing test lab  oom we have continued access to, whe e we keep com ng back to it to test new methods/techniques/technolog es ove  the next six months (UVC comes to m nd).
Official 
We conside  if the occupied class oom studies need to continue/by expanded/ epeated to get mo e building type, occupant, changing cont ols etc cove age.
Keep a watching b ief on the wo ld a ound us (Ian s ones below, Leeds, SA, etc, etc)
Fund ng needs to be discussed ac oss a l of th s as benefit much wide  than education domain.
Calls to action (part of ASSESS workstream)
Set a  ta get  800-1000PPM numbe (s) and associated actions as pe  bullets above – and  efe ence this f om the vent lat on calculato .  We do a cha t/g aphic of this type of bas c advice, but needs to align to existing IEM mate ial/advice (Ackley).
We push fo wa d w th the self-assessment toolkit  ollout, wh ch will also be backed by an enginee ing  ev ew p ocess = we need to know who has what potential p oblem, and what options have al eady been exhausted befo e we h t the bigge  buttons.
School- mplemented intervention advice (part of SUPPORT workstream)
Joining ou  GUIDE   ASSESS =  he e s what YOU can and should do  advice – th s is mainly about wo kflow and managing volume of que es, then lea n ng f om them.
BE READY fo  the  esult of this being high numbe  of schools NOT meeting this ta get and what they m ght need to do to fix it- we signa led to Min ste s a high % could via management tact cs, that may no longe  be as t ue with Omic on, if we a e not limiting class numbe s etc.
L nks to panels below, which  s whe e the SCHOOL elects to take action but it doesn t meet the MINISTRY s c ite a to take the same action (e.g. ai  filte   n eve y class oom).
the 
M nistry-implemented interventions (part of ENHANCE workstream)
Supplie  panels
Eng nee s/fi ms who can do ASSESS p ocess to ou  standa d/c ite ia/ equi ed outputs etc.
Technology p ovide s of CO2, ai  cleane s, ANVS, HVAC, and othe  magic devices we suppo t schools p ocu ing di ectly if they choose to do so (may be mult ple panels)
Minist y  nte ventions (cent alised p ocu ements and deployments, p epa ed at va ious scale scena ios depending on ASSESS)
ANVS pilot
Po table ai  cleane s
Hyb id systems and components (ext act fans, standalone mixed mode systems fo  bath ooms, heat  ecove y, sola  etc etc) – whe e not p ocu ed at least on a list somewhe e of  not a bad thing but not what we e  oll ng out at this stage
CO2 monito s
Maybe othe s (e.g. UVC)
Assoc ated  we OK w th th s technology types, b ands and p oducts  listing unde  GUIDANCE (dec s on on if we st ck to tech types in the above o   assu ance of pe fo mance of p oducts  wh ch is a slippe y slope.
Robyn bet me to the talk ng stick but I now hand  t on to……..[next!]
Scott
under 
From  Ian Longley  Ian.Longley@niwa co.nz> 
Sent  F iday, 7 Janua y 2022 9 36 am
To  Scott MacKenz e  [email address] nz>  Robyn Ph pps  obyn ph [email address]>  Ma k Je my  ma k je my@cante bu y ac.nz>
Cc  Jeff Wilson  j ff @ h-
>  V cky Evans  V y E
@
g
>  Jason Chen  j
h @
y
>  Ackley Aniebietabasi 
l y
@
g
>  Scott MacKenzie  S
@
>  Rene le G one t  R
ll G
@
g
>
Sub ect  RE  Final Results  Home Test Set #11 - whe e it takes us next
Hi Scott
N ce look ng document eme ging the e.
My thoughts on you   ed question . have we got evidence that suppo ts a decision point at which ACH becomes insuff c ent to meet ou  PM goals, yet  emains  OK  fo  ou  CO2 goals, and we move adopting the eACH/f lt ation st ategy fo  a space?
I wonde  if some misunde standing has c ept in (as it usually does). This is how I see it.
In my head we have two ventilation goals (mo e co ectly stale-ai   emoval/clean-ai  del ve y goals) –
1.  ou  p e-ex st ng “comfo t/lea n ng pe fo mance” goal (as exp essed in DQLS). Th s is chosen to be p otective aga nst adve se effects f om bu ld-up of a  ange of contam nants including wate  vapou  (which p omotes mould), solvents and othe  unpleasant chemicals, and the effects of exhaled CO2 on lea ning pe fo mance.
2.  ou  new COVID-management goals. This  s expl c tly to  educe the  sk of vi us t ansmission. It is cons de ably mo e demanding as the  isk is h ghe .
The gene ally ag eed goals a e a ound 5 l t es/pe son/second averaged over a day fo  #1 and 10 l/p/s at all times fo  #2. In typical class ooms that equates to a ound 2.5 - 3 ACH fo  #1 and 5 – 6 ACH fo  #2. The t me element is impo tant because COV D infection can happen much mo e  ap dly than the effects that goal #1 is p otecting against.
If you can t achieve that th ough ventilation then you can b ing in filt at on to achieve the same effective ACH.
It s the implementation/monito ing whe e it gets t cky.
Released 
We cannot measu e ou  goals di ectly so we use  ndi ect p oxies. Using CO2 (o  any concent at on) to  ep esent ai  exchange is like t ying to use the depth of wate  to  ep esent the leakage  ate of a wate  bath in the  a n. It s not as simple as it looks!
If we e NOT using filt ation then we can tu n the two ventilation goals into CO2 ta gets, i.e. 1500 and 800 ppm  espect vely. So, theo etica ly if you knew the e we e no  nfected people  n you  class oom 1500 ppm would be sufficient, but you don t, so you aim to achieve 800 ppm f om ventilation as a p ecautiona y measu e. We need to be ve y
ca eful w th language, though. The 800 ppm goal is just a way of judging whethe  ventilation alone can manage COV D  isk –  t s nothing to do with the effect of CO2 itself.
If you can meet 800 ppm consistently – you e f ne.
If you can stay unde  800 ppm by using hou ly o  inte -pe iod pu ges – please do.
If you go consistently ove  800 ppm eve y pe iod – imp ove natu al ventilation unt l you don t.
If you can t – now go to f lt at on (noting that the effect of filt ation wi l NOT be  eflected  n CO2 data).
BTW it is my unde standing that 800 ppm  ep esents an effect vely a b t a y  isk th eshold ( isk cannot be  educed to ze o). I have seen one a gument that it  ep esents a  isk of 1% of  nfection of one pe son w th delta ove  one hou . In p nciple, om c on, o  some othe  mo e infect ous va ant, would  equi e a lowe  CO2 value fo  the same  isk (o
you stick with 800 and accept a highe   nfection  sk). Simila ly you could adopt 1000 o  1200 ppm, acknowledging the highe   isk, on the basis of g eate  achievab lity, especially if the  educed  nvestment was mo e effect vely di ected somewhe e else. These a e quest ons fo  health people.
I would avoid any ment on of PM goals. PM in class ooms is highly va iable/ andom and the vast majo ity of PM  n any class oom has nothing to do with  espi ato y ae osols ( t s ca pet dust, soap powde , k tchen em ss ons, t affic/heating emissions, etc). We have only stale-ai - emoval o  clean-ai -del ve y goals.
The final point is how do you know if you  filt ation s achieving anything? Only  eally two options at the moment – calculate it and t ust the calculat ons, o  do an incense-style expe ment.
In the med um te m I d just like to highlight two st ands of  esea ch we e involved  n that should come onst eam at some point
1.  we e cu ently wo king on code to conve t live CO2 data into live estimate of ACH (so you can judge pe fo mance di ectly to the actual goal, not a p oxy) – hoping to make good p og ess in next few months
2.  devices to  apidly assess filt ation effectiveness (waiting on fund ng decis on – timef ame next few yea s)
W ll stop the e fo  now awaiting ag eement o  cha lenge f om the othe s!
Ian

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From  Scott MacKenzie  [email address]> 
Sent  Thu sday, 6 Janua y 2022 6 03 PM
To  Robyn Ph pps  [email address]>  Ma k Je my  ma k. e my@cante bu y.ac.nz>  Ian Longley  Ian.Longley@niwa co nz>
Cc  Jeff Wilson  j ff @ h-
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Sub ect  RE  Final Results  Home Test Set #11 - whe e it takes us next
 
Hi – sha ing that attached with a subset of the most-engaged aud ence so you (if the mood g abs you) cab pe use whe e th s conve sation  s head ng.  I ve committed to p oducing an implementation plan by…geez…Monday…which will be made up of two pa ts – one be ng the d scussion on the actual p oblem and ou  inte vent on st ategies  the
second being the mo e mundane time/cost/ esou ce/scope etc plan on how we get it all done.  Most of the latte  exists in va ious docs/updates al eady, hence why I ve been focuss ng on the fo me .
 
When pulling togethe  these foundation docs I tend to sta t w iting an exec summa y, that gets ove ly ve bose, then then content gets p og essively moved  nto the main document as the key points su vive.  You w ll see the below has led to cu ent section 1.7, which by its natu e needed p o  sections to explain why PM, CO2 and ACH whe e a l
the  elevant points.  I bel eve  t maintains the same logical flow but a bit smoothe  in the logical jou ney.  Defin tely needs a pictu e o  two to suppo t (you will spot some late  in the doc which should also assist).
 
At the tend of today s long d afting sess on, my nagging question  s – have we got evidence that suppo ts a decision point at which ACH becomes insuff c ent to meet ou  PM goals, yet  emains  OK  fo  ou  CO2 goals, and we move adopting the eACH/f lt at on st ategy fo  a space? This  s a key facto  that will play out  “OK, we ve got p etty good
ventilation.  But  t s va iable due to ambient condit ons.  O  the CO2 peaks, but not so h gh that it s  eally wo ying.  So we want to ensu e PM  s in check and put in a po table ai  filte .”  How would we app oach the yes/no on th s advice?  I know we can say  well it won t hu t so put one in anyway , but that sets a p ecedent fo  all  ooms meeting the
same c te ia to then  eceive the same solution (wh ch we, o  schools may be funding).  Is it something l ke  PM monito ing to decide?  O  if CO2 c eeps between  nte vals consistently up into (?) 1500  ange?  Mag c 8 ball?
 
Thoughts always welcome, will d scuss with Vicky about getting some wo kshops into the calenda  ove  the com ng weeks.  It s going to be a busy yea  – day job o  not!
 
 
Scott MacKenzie
Programme Direc or, Ven ilat on 
Mob l 9(2)(a)
 
 
From  Robyn Phipps  obyn.ph [email address] nz> 
Sent  Wednesday, 5 Janua y 2022 11 24 pm
To  Ma k Je my  ma k je my@cante bu y ac.nz>  Scott MacKenzie  Scott.MacKenz e@educat on govt.nz>  Ian Longley  [email address]>  Rene le G one t  Renelle.G one [email address]>  Manf ed Plagmann  Manf ed.Plagmann@b anz.co nz>  Guy Coulson  guy.coulson@n wa.co.nz>  Je emy Tuohy
Je [email address] nz>  B ooke Hollingshead  b [email address]>  Mikael Boul c  m [email address]>  dav d  [email address]>  Pe y Davy  p davy@gns c i nz>  Ackley Anieb etabasi  Ackley.An ebietabas @education.govt nz>  Vicky Evans  [email address]>  Jason Chen
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Cc  Jeff Wilson  [email address]>
Sub ect  Re  Final Results  Home Test Set #11
 
Good summa y Scott.  In point 3 we should  nclude Sola  Ai  heate s. We found (but d dn t expected) a signif cant  eduction in PM in ou  p evious study,  t s ANV w thout the tempe atu e penalty.  
 
1982
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From  Ma k Je my 
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Sent  Wednesday, Janua y 5, 2022 7 37 45 PM
To  Scott MacKenz e  scott mackenz e@educat on govt.nz>  Ian Longley  Ian [email address]>  Robyn Phipps  obyn.phipps@vuw ac.nz>  Rene le G one t  Renelle.G one [email address]>  Manf ed Plagmann  Manf ed.Plagmann@b anz.co.nz>  Guy Coulson  guy [email address]>  Je emy Tuohy  Je [email address]>
B ooke Holl ngshead  b ooke.ho lingshead@health govt.nz>  M kael Boulic  m.boulic@massey ac.nz>  dav d  [email address]>  Pe y Davy  p.davy@gns.c i.nz>  Ackley Aniebietabasi  ackley.aniebietabasi@educat on.govt.nz>  V cky Evans  Vicky.Evans@educat on govt.nz>  Jason Chen  ason.chen@cante bu y.ac.nz>
Cc  Jeff Wilson  j ff @ h-
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Sub ect  RE  Final Results  Home Test Set #11
 
You nailed it he e (but d dn t nail  t shut J)
 
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From  Scott MacKenzie  [email address]> 
Sent  Wednesday, 5 Janua y 2022 6 03 pm
To  Ian Longley  I
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Cc  Jeff Wilson  [email address]>
Sub ect  RE  Final Results  Home Test Set #11
 
Hi Ian, yes that  s the knub of the concept we a e t y ng to nail down that has been bugg ng me ove  the b eak.  The e s a set of IF/THENs h ding  n he e, my comments a e not a  ebuttal but hoping to st mulate this conve sation fu the .  And because I m in the middle of d aft ng the implementat on plan that d aws in these lines of th nk ng.
 
You  po nt is well made, if I have abso bed  t co ectly
a)      Any  oom,  ega dless of how ventilated, will have a continual p esence of PM that needs to be  emoved/mit gated in some way  and the slowe  th s occu s, the highe  the  isk of t ansm ssion.
b)     Whe e it  s possible fo  a  oom s f esh ACH  ate to be cons stently h gh, in- oom PM filt ation may se ve little pu pose (f om cost/benefit pe spective) as the h gh f esh ACH al eady being achieved cont nually keeps CO2 and PM levels low.
c)      Whe e it is only poss ble fo  the  oom s f esh ACH  ate to be inte m ttently high  ( pu ge ), in- oom PM filt ation MAY se ve a pu pose by keeping PM levels low.  The e would be a balance point calc in the e somewhe e that when f esh ACH d ops below a ce ta n point vs the effective ACH c eated by an ai  cleane , justifies the latte
investment [MATH NEEDED].
d)     Whe e it  s 
 possible fo  a  oom s f esh ACH  ate to be h gh, th s would equate to an ongo ng CO2 PM issue only add essed by change o  use, building and/o  ventilation system imp ovements – and afte  being applied, you e back to (b) o  (c).
 
The p oblem we have with (c)  s that it also  nd cates the p esence of a CO2 issue which I ag ee is an  ssue  n  ts own  ight, that is t eated as an  nd cato  of COV D-19 t ansmiss on  isk  but this COVID  isk can be m t gated by add essing PM  n  solat on.  We call th s a dilemma.  So if you e going to spend $2000 (o  whateve  $) on a class oom, you
look fo  a solution that add esses the most  isks  t can.  This leads to an o de  of p ecedence fo  investment
 
1)     Invest in ensu ng that the existing ventilation solution (be it natu al, mechan cal o  hyb id) is cu ently ope at ng as  t was designed to do – we e d scove ng cases whe e subsequent changes have been made that counte act the o iginal ventilation des gned pe fo mance.
2)     Once done, if you have ach eved (b) above, good job.
3)     If not and you e up to (c) o  (d), use the class oom calculato  to see what you  options might be (change usage etc).
4)     If an investment is needed, invest  n solutions that consistently inc ease f esh ACH  ates – fo  example upg ades to HVAC, ANVS, ext act/make up fans etc– but only if they get you to (b) –  .e. imp oved CO2   PM levels.
5)     Fo  spaces whe e th s cannot be achieved cost effect vely, conside   nvesting in in- oom PM filt ation noting you ve most likely got an ongoing CO2  ssue  n that space that isn t being  esolved.
 
Look fo wa d to  ound #3!
 
Scott MacKenzie
Programme Direc or, Ven ilat on 
Mob l 9(2)(a)
Information 
 
 
From  Ian Longley  I
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Sent  Wednesday, 5 Janua y 2022 3 31 pm
To  Scott MacKenz e  [email address] nz>  Robyn Ph pps  obyn ph [email address]>  Renelle G one t  Renelle.G one t@educat on govt.nz>  Manf ed Plagmann  Manf ed.Plagmann@b anz.co.nz>  Guy Coulson  Guy Coulson@niwa co.nz>  Je emy Tuohy  Je [email address]>  B ooke Holl ngshead
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Cc  Jeff Wilson  [email address]>
Sub ect  RE  Final Results  Home Test Set #11
 
Hi Scott (and colleagues)
 
Looks like you ve been busie  than I have!
 
A potentially useful dataset. Howeve  just want to take ca e that we e compa ing apples with apples (o  a e awa e when we e compa ng apples w th o anges).
 
These data do  ndeed show a 5 – 20 minute “pu ge” is much mo e effective using natu al c oss-flow than filt ation.
 
Ag eed. But  n most cases I don t think that s the choice.
 
The case fo  filt ation is p event ng the bu ld-up that p esents the need fo  the pu ge. The pu ge alone doesn t p event inte -pu ge build-up and that p esents a  isk (espec ally w th omic on??) On you  cha t if filt ation had been  unn ng fo  an hou  the PM would be of the o de  of 1% of what  t sta ted at an hou  ago ( .e. it has been fall ng  athe
Official 
than  ising as would be the case in an unde -vent lated occupied class oom). You the efo e wouldn t  eally need to do a pu ge fo   emoving PM. You might need to do a pu ge fo  CO2 but that s fo  CO2 in it s own  ight, not SARS-CoV-2, which the filt ation has (99%) taken ca e of.
 
I see a natu al ai flow pu ge and constant f lt ation as being l ke mask ng and vaccination – both useful laye s that a e mo e effective in comb nat on, g ving  esidual p otect on if one fails. Both have costs (heat  eplacement o   unning cost) and  isks of unde -use.
 
Not that I m p omot ng filt ation he e – just felt that this evidence wasn t the  ight evidence to  eject it.
 
Chee s
Ian
 
 
the 
 
 
From  Scott MacKenzie  S
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Sent  Wednesday, 5 Janua y 2022 11 40 AM
To  Robyn Ph pps  [email address]>  Renelle G one t  Renelle.G one t@educat on govt.nz>  Manf ed Plagmann  Manf ed.Plagmann@b anz co.nz>  Guy Coulson  Guy [email address] nz>  Je emy Tuohy  Je emy.Tuohy@health govt.nz>  B ooke Holl ngshead  b ooke.ho lingshead@health govt.nz>  Boul c, Mikael
[email address]>  Ma k Je my  ma k.je my@cante bu y.ac.nz>  david  dav [email address] nz>  Ian Longley  [email address]>  Pe y Davy  p.davy@gns.c .nz>  Ackley An eb etabasi  ackley.an eb [email address]>  Vicky Evans  [email address] nz>  Jason Chen  jason.chen@cante bu y.ac nz>
Cc  Jeff Wilson  j ff @ h-
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Sub ect  F nal Results  Home Test Set #11
 
Happy New Yea !
 
Time to d aw this l ttle s de p oject to a close, but on a nagging theo y yeste day I  e- an some tests including the additional NIWA ai  cleane s I m  n possess on of.
 
1.      Cha t 1 aga n shows how d amatica ly natu al ventilation  educes PM2 5 levels compa ed to any filt ation unit tested, but also inte esting is how afte  about 20 m ns the  eduction in PM2.5 begins to match the natu al  ate of decay/settling ( ed line).
2.      This led me to Cha t 2, looking at what is the deg ee of change each unit  s having compa ed to the  ed l ne.
3.      And then zoom ng in on Cha t 3 showing that afte  20 mins p etty much a l inte vent ons a e not having much of an effect on  educ ng PM2.5 – they a e matching the natu al  ate of decay/settling.
under 
4.      But it  s inte esting to  emembe  than at the 20 min ma k, each inte vention  s at a ve y diffe ent PM level ( efe  cha t 1) – so it s not l ke a l a e  eaching a simila  PM no malisat on level when th s begins to occu .
5.      A f nal w ap up would see us th ough this  oom th ough ou  calculato  with opening sizes etc measu ed, and also  eco ding the specs etc of each of the ai  cleane s to see how the data co elates w th thei   epo ted CADR etc.
 
Reta ning my  not a scientist  caveat, pending challenge it still leaves me with the opin on that it would be bette  fo  class ooms to be doing hou ly pu ges of 5-10 mins to  ef esh CO2 (ea l e  emails below) AND to  educe PM levels  and focus on what is the heating/cooling solution you would  nt oduce to deal w th the  apid change in indoo
tempe atu e th s could cause, befo e I d invest in ai  f lt at on?  And save ai  filt ation whe e the  oom cannot be pu ged (e.g. natu al vent lat on  neffective), o  h gh  isk (staff  ooms?)
 
“Discuss” 
 
Scott MacKenzie
Programme Direc or, Ven ilat on 
Mob l 9(2)(a)
Released 

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Act 
Information 
 
 
From  Ma k Je my 
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Sent  Sunday, 2 Janua y 2022 8 20 pm
To  Scott MacKenz e  Scott@sapius nz>  Jason Chen  jason.chen@cante bu y.ac nz>  Ackley Aniebietabasi  Ackley.An eb [email address] nz>  Ian Longley  ian.longley@n wa.co.nz>  Jeff Wilson  [email address] nz>
Cc  Scott MacKenzie  S
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Sub ect  RE  Home Test Set #10
 
Happy New Yea  eve yone!
 
This  s b i liant Scott!
 
Looks like the ai  cleane  helps you  each the steady-state PM level qu cke , but does not affect that steady state much, if the e  s good ventilation.
Ai  cleane s w ll  educe total quantity of vi us  nhaled by  educing the levels ci culating a ound an infect ous pe son.
Official 
 
I don t think the absolute level of PM at the sta t matte s much, if the PM sou ce is constant (like an  ncense stick) as, ultimately, the most useful data f om these tests is  elat ve  ate of  eduction.
 
Hope you a e getting some downtime in between the sc ence mahi!
Chee s,
Ma k
 
From  Scott MacKenzie  Scott@sap us.nz> 
Sent  Thu sday, 30 Decembe  2021 10 49 am
To  Ma k Je my  ma k je my@cante bu y ac.nz>  Jason Chen  jason chen@cante bu y ac.nz>  Ackley An eb etabasi  [email address]>  Ian Longley  [email address] nz>  Jeff W lson  [email address]>
the 
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Sub ect  RE  Home Test Set #10
 
Yeste day I moved into combo testing of openings   ai  cleane s – stick ng with the Samsung M un t  unning on High speed.  In all cases I moved the ai  cleane  out of the di ect ai  path when the e was c oss vent lat on.
 
1.      Tests 29&30 (45 deg ee opening c oss vent lat on) a e the only ones that saw the ai  cleane  speed up the  eduction of CO2 by ~5 m ns – maybe due to wind change, o  the ai  cleane  flow supplementing w nd path – dese ves  etest.
2.      Tests 31&32 (45 deg ee opening single side ventilation) showed no impact f om  unning the ai  cleane .
3.      Tests 33&34 (3x doo  c oss ventilation, 1x exte nal, 2x inte nal) had the ai  cleane  slow the  educt on of CO2 by ~7 mins.
4.      Test 35&36 (opening exte io  doo  and 3x windows by 10cm each) was ove all poo  pe fo mance and had the ai  cleane   l   h  
 of CO2 by ~17 mins.
 
Ac oss all the e we e some m no   mp ovements in PM  eduction by  unning the ai  cleane  f om 750 down to 100 PM2.5, afte  that the ai  cleane  does seem to have imp oved PM  eduction ove  no ai  cleane  p esent.
Need some adv ce on what level of PM you think we should be sta t ng at  n this testing to make  t  ealistic to a class envi onment?
 
Today will do the full natu al pu ge of the  oom w th, and without the ai  cleane   unning.
I also have a CO2  egulato  now so can beg n c eating  steady state  CO2  elease which w ll be bette  than flood ng the  oom.
 
 
under 
Scott
 
 
 
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1982
 
From  Scott MacKenzie 
Sent  Wednesday, 29 Decembe  2021 11 44 am
To  Ma k Je my  ma k je my@cante bu y ac.nz>  Jason Chen  jason chen@cante bu y ac.nz>  Ackley An eb etabasi  [email address]>  Ian Longley  [email address] nz>  Jeff W lson  [email address]>
Act 
Cc  
@
g
Sub ect  RE  Home Test Set #7
 
Now he e s some  nte est ng PM  esults – cha ts below a e both same data, bottom appl es a loga thmic scale.
 
-        Afte  35 mins the  esult of most ai  cleane s  sn t much of an imp ovement ove  the  oom s natu al decay  ate (thick  ed line).
-        Nothing beats the full natu al pu ge, getting us down to 10 PM2.5 with n 25 mins AND has a much faste  init al  educt on  ate (thick g een line).
-        Next is Samsung L un t on full (which has 2 fans/filte s) w thin 40 m ns, but only ~4 min imp ovement between H gh and Med um fan settings.
-        Samsung M un t on High sett ng takes 50 mins but  s othe w se ve y close to L unit n Medium sett ng fo  the most pa t.
-        Low sett ngs on both Samsung M and L un ts not effective.
-        Fo  compa ison I d d my Sheffield un t and H gh, not  eally in the ballpa k of the Samsung units.
 
As we know, and I t acked in the data ( efe  Combo Pivot by Test, and PM Gen P vot), ai  cleane s do not add ess CO2 levels.  I did some  nitial tests of  unning the un ts w th doo s open, PM still being gene ated etc but method p oved to not be b lliant – the Samsung unit could not keep up with the inc easing PM f om 1x  ncense bu ning, while
opening the exte o  doo  did.  So next set  s to t y and balance some open ng of doo s/windows to lowe  CO2 (and by natu e, PM) as well as ai  cleane s  unn ng in the  oom to also lowe  PM2 - eplicat ng the windows model of needing some windows fo  CO2 management but wo ied that PM wi l be too h gh.
 
If you wanted to exit the  oom long enough fo  an ai  cleane  to be effect ve in  educ ng potentially contaminated PM, you would need to exit fo  40-60 minutes.
 
But it s looking to me that a 5 10 minute  oom pu ge eve y hou  with no ai  cleane  p esent will be significantly mo e beneficial  unning a closed  oom w th an ai  cleane   unning  then use the money saved on the ai  cleane  to up the heat ng of the  oom post/pu ge.
 
Scott
 
 
 
Information 
Official 
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From  Scott MacKenzie 
Sent  Monday, 27 Decembe  2021 9 28 am
To  Ma k Je my  ma k je my@cante bu y ac.nz>  Jason Chen  jason chen@cante bu y ac.nz>  Ackley An eb etabasi  [email address]>  Ian Longley  [email address] nz>  Jeff W lson  [email address]>
Cc  scott mackenzie@educat on.govt.nz
Sub ect  RE  Home Test Set #7
 
Moved on to PM testing using incense st cks – wo ked we l, also did some tests with continual PM gene ation (not shown he e) - these we e all built it up then shut it off.
 
This shows the Samsung Med um sized un t  unning at its fou  speeds – low, med, high and auto.  I have PM1 0, 2.5 and 10.0 data, ve y little diffe ence between 2 5 and 10 0 though 1.0 always sits lowe  (thinking  ncense not c eating volume of smalle  pa t cles).  Inte esting obse vations
-        Fu l f esh ai  pu ge of the  oom massively mo e effect ve than an ai  cleane   n  educing PM levels
-        Only mode ate ga n  unning Samsung unit on auto o  high, compa ed to med um.
-        CO  educt on fo  ai  cleane s (which we know is not a th ng) shown fo  completeness, d op  e lects  oom s natu al decay.
 
So opening all doo s and windows fo  ~13 m ns  achieves what a Samsung unit can ach eve afte  ~40 m ns, noting the latte  does not imp ove CO2 levels.
 
Next I m going to  un the same test with the Samsung L unit, and maybe 2-3 othe  smalle  non-Samsung units I have he e.
 
Then onto combo testing, and active gene ation testing.
 
Scott
Released 
 
 
 

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1982
 
 
From  Scott MacKenzie 
Sent  F iday, 24 Decembe  2021 11 36 am
To   Ma k Je my' 
j
y@
y
>  'Jason Chen'  j
h @
y
>  'Ackley Aniebietabasi' 
l y
@
g
>  'Ian Longley' 
l gl y@
>  Je f Wilson  j ff @
h-
>
Cc  '[email address]'  [email address]>
Act 
Sub ect  RE  Home Test Set #2
 
Updated obse vations
1.      The e  emains no substitute fo  the  pu ge  in qu ckly lowe ing CO2 (~5.5mins).
2.      Next most effect ve is c oss vent lat on using 1x exte io  doo  and oppos ng window (~8 m ns), with othe   nte io  doo s x2 shut (p esumably having these open weakens the ai flow between the exte nal open ngs).
3.      C oss ventilation (2) above is ~20% bette  than single sided ventilation.
4.      Using a po table fan to assist natu al ai flow is a gamble, as fac ng in vs out needs to match the natu al ai flow di ection which can change th ough the day depending on w nd di ection. 
5.      I am assum ng an ANVS/m xed mode solution would ove come the va iabil ty in (4) th ough inc eased fan powe  – to be p oven.
6.      Use of a heat pump o  any othe  f xed device that c eates  ts own ai flow, should only be used if  ts p oven to always supplement the natu al ai flow di ection – which as noted in (4) can be p oblematic.  In th s case the heat pump ai  di ection was 90 deg ees f om the natu al ai  path (exte io  to inte io  doo s) – I will  e- un th s test with
test 06 (exte io  doo  to window) which might actually supplement the natu al flow towa ds the window.
 
I ve now included the Pu pleAi  data and cu ently showing no co elat on to CO2 and inte ventions – but now I have the datasets associated we l see what happens when we bump up the PM levels.
 
Ch istmas colou s a e pu ely coincidental.
 
 
 
Information 
Official 
the 
 
under 
 
 
 
From  Scott MacKenzie 
Sent  Thu sday, 23 Decembe  2021 7 56 am
To  Ma k Je my 
j
y@
y
>  Jason Chen  j
h @
y
>  Ackley An eb etabasi 
l y
@
g
>  Ian Longley 
l gl y@
>
Cc  
@
g
Sub ect  Home Test Set #1
 
H , fi st set of  esults below and wo kings attached, I have all the cont ol data  e audit log, spec of windows/ oom/fans etc still to  nclude.
 
Method was to flood  oom with CO2 up to 2000-2500ppm, then do inte vention, and (fo  most) give it 20 mins.  Done back to back last night so simila  outdoo  conditions.  Will  edo single sided ventilation fo  full 20 min alongside pa tial opening tests next  ound.  2x inte io  doo s (that  eally go nowhe e f om a ventilation pe spective), 1x exte io
doo , 3x side windows.  Heat pump faces ac oss the path of the exte io  doo .
 
Observations
-        Fu ly opening all doo s and windows (“pu ge”) wi l  educe CO2 to 800ppm in less than 8 minutes.
-        Hav ng windows on thei  second latch and all doo s open (c oss vent lat on, albeit poo ) wi l  educe CO2 to 800ppm  n less than 15 minutes.
-        Then tu ning a po table fan on  n the exte io  doo way blowing INTO the  oom  educes this to less than 9 minutes – the efo e fac ng this way  s supplement ng the natu al ai  di ect on (which you could not dete m ne in the  oom).
-        Alte natively tu ning the heat pump on, which  n this  oom competes with the natu al ai flow di ect on f om the exte io  doo , g eatly impacts CO2  educt on time.
 
Have Pu ple Ai  data to inco po ate next to see if/how PM levels changed du ing  nte ventions.
 
 
Scott MacKenzie
Di ec o  Sap us  td
9(2)(a)
scot @sap us nz
Released 
 
 
 
DISC AIMER
Th s ema l and any a tachments may  onta n  n o ma ion that  s con den ial and sub ect  o  egal p ivi ege  I  you a e not  he in ended  ecip ent  any use  disseminat on  d st bu ion o  dupl cation o   h s email and a tachments is p ohibi ed  I  you have  ece ved th s email in e o  please no i y the au ho   mmedia e y and e ase a l copies o   he ema l and attachments  The Min st y o  Educa ion accepts no  espons bi ity  o  changes made to  h s message o  at achments a te  t ansm ss on  om the
M nist y
D  Ian Longley 
P inc pal Sc ent st - Ai  Quality
P og amme Leade  - Atmosphe ic Envi onment, Health and Soc ety
9(2)(a)
Nat onal Institute of Wate  & Atmosphe ic Resea ch Ltd (NIWA)
41 Ma ket Place Viaduct Ha bou  Auckland New Zealand
Connect with N WA  niwa.co.nz Facebook L nkedIn Twitte  Instag am
o ensu e compl ance w th  egal  equi emen s and to main a n cybe  secu ty s anda ds  N WA s I  sys ems a e sub ect  o ongo ng monito ing  ac iv ty  ogg ng and aud t ng   his mon to ng and aud t ng se vice may be p ovided by  hi d pa ies  Such thi d pa t es can access in o ma ion t ansmi ted  o  p ocessed by and sto ed on NIWA s I  sys ems
DISC AIMER
Th s ema l and any a tachments may  onta n  n o ma ion that  s con den ial and sub ect  o  egal p ivi ege  I  you a e not  he in ended  ecip ent  any use  disseminat on  d st bu ion o  dupl cation o   h s email and a tachments is p ohibi ed  I  you have  ece ved th s email in e o  please no i y the au ho   mmedia e y and e ase a l copies o   he ema l and attachments  The Min st y o  Educa ion accepts no  espons bi ity  o  changes made to  h s message o  at achments a te  t ansm ss on  om the
M nist y

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Act 
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From:
Ian Longley
To:
Mark Jermy; Robyn Phipps; Scott MacKenzie; Jason Chen
Subject:
RE: For review - toolkit letter and CO2 info.docx
Date:
Monday, 31 January 2022 11:18:23 am
Attachments:
DRAFT - toolkit letter and CO2 info IL.docx
Here’s mine. Sorry – did these before Robyn’s came through so they don’t incorporate her o
Mark’s changes.
Ian
1982
From: Mark Jermy <[email address]> 
Sent: Monday, 31 January 2022 11:13 AM
To: Robyn Phipps <[email address]>; Scott MacKenzie
Act 
<[email address]>; Jason Chen <[email address]>; Ian Longley
<[email address]>
Subject: RE: For review - toolkit letter and CO2 info.docx
Morning all! A few comments from me in addition to Robyn’s.
From: Robyn Phipps <[email address]> 
Sent: Sunday, 30 January 2022 9:43 am
To: Scott MacKenzie <[email address]>; Mark Jermy
Information 
<[email address]>; Jason Chen <[email address]>; Ian Longley
<[email address]>
Subject: Re: For review - toolkit letter and CO2 info.docx
Some comments from me in track changes.
Official 
Robyn
the 
From: Scott MacKenzie <[email address]>
Date: Friday, 28 January 2022 at 2:54 PM
To: Mark Jermy <[email address]>, Jason Chen
<[email address]>, Ian Longley <[email address]>, Robyn Phipps
under 
<[email address]>
Subject: FW: For review - toolkit letter and CO2 info.docx
Hi first look at letter to go with monitors as discussed, expect some minor tweaks before ready for
VTAG review but any immediate reactions/feedback appreciated – as getting our narrative clear
on this is now impacting CO2 deployment.
There’s a lot of more specific guidance been dropped from this which I hope will find its way onto
Released 
the online page to be built behind it – your thoughts on it being too light etc appreciated, but
special focus is risk/benefit of this initial focus on PPM while the calculator builds up some
pace/credence.
Scott MacKenzie
Programme Director, Ventilation 
Mobile 9(2)(a)

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When: Wednesday, 27 April 2022 1:00 pm-2:00 pm (UTC+12:00) Auckland, Wellington. 
Where: Microsoft Teams Meeting 
 
Good afternoon everyone, 
 
An agenda and draft minutes and supporting papers will be sent out by midday Monday each week. 
 
 
Kind regards 
Anastasia 
 
____________________________________________________________ 
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Microsoft Teams meeting  
Act 
Join on your computer or mobile app  
Click here to join the meeting 
Learn More | Meeting options | Legal 
________________________________________________________________________________ 
 
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Document 5a: Attachment to email for 27/04/22 meeting
Pre-Winter Ventilation Checklist: 
Making sure indoor spaces are well ventilated and have lots of fresh air is recommended for schools.  
This applies at all levels of the COVID-19 Protection Framework in addition to using face coverings, 
physical distancing, good hygiene and other health measures. 
Schools can use this checklist to help you to prepare for the winter session ahead.  The bigger the 
temperature difference between the outside and inside, the more efficiently fresh outside air is 
drawn in through open windows. This allows good ventilation to be achieved on colder days with 
windows partially open, which helps to maintain a comfortable indoor temperature.   
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Act 
Room Name: 
_____________________________ 
Date:  
_____________________________ 
Openable windows and doors: 
Most schools are designed to be naturally ventilated, with opening windows and doors providing 
fresh air.  For your naturally ventilated spaces, please check: Information 
1.  All windows open as originally designed and have not been fixed or painted shut. 

2.  All windows can open freely without having to be forced. 

3.  Any window winders, hinges, catches or closers that are missing or broken, have 

been remediated. 
Official 
4.  Window or security latches are able to hold windows partially open by small 

amounts – for example 2cm, 5cm, and 10cm.  
the 
5.  Exterior doors that are generally sheltered from adverse weather can be held or 

latched partially open, if this is required to boost the flow of fresh air. 
6.  Interior doors that connect to internal corridors or other circulation spaces can be 

held or latched partially open, if this is required to create a cross flow of air. 
under 
Heat pumps and other heating systems 
Naturally ventilated spaces can have differing heating systems including boilers/radiators, heat 
pumps and fitted electric heaters.  Please check:
1.  The room’s heating system(s) are working as originally designed and intended. 

2.  Ensure that regular cleaning or maintenance on heating system(s) are up to date. 

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3.  Run the heating at its highest setting for a period to test that it performs as 

expected and doing so does not create other issues, e.g. tripping circuit breakers. 

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4.   Prior to the coldest time of the winter season, trial setting the heating system(s) 
 
with windows open to determine how you might maximise the flow of fresh air 
while also maintaining a comfortable indoor temperature. 
 
Ducted mechanical ventilation systems (if fitted) 
Ducted mechanical ventilation systems automatically source fresh air from the outside while also 
managing the temperature of the room. One way to identify if your space has a ducted mechanical 
ventilation system is to look for vents in the ceiling that bring in fresh air or extract old air. 
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Configuration and maintenance of ducted ventilation systems should only be done by appropriately 
skilled technicians.  Please check: 
Act 
1.   The system has been recently checked, cleaned and maintained by an 
 
appropriately skilled technician. 
2.   This system has been configured to come on at least two hours before the start of 
 
the school day, and to stay on for two hours after the school day ends. 
3.   Prior to the coldest time in the winter season, ensuing the system is successfully 
 
managing the amount of fresh air brought it (as measured by a CO2 monitor) while 
maintaining a comfortable indoor temperature. 
 
Information 
 
Carbon Dioxide (CO2) monitoring 
Measuring CO2 levels indicates how well-ventilated a room is.  When in use, portable CO2 monitors 
are to be positioned at around student head height, away from doors and windows, out of direct 
Official 
sunlight, and at least 1m away from the closest people.  While the room is occupied, please: 
1.   Use your senses to determine if the room feels stuffy or has lingering smells, and if 
 
the 
so, follow our guidance to try and improve ventilation. 
2.   If the concern is not quickly alleviated, next try performing intermittent spot 
 
checks through the day by placing your portable CO2 monitor in the room for at 
least 5 minutes then reviewing the CO2 levels against our published guidance. 
under 
3.   If the spot check indicates there may be consistent and sustained CO2 levels over 
 
the school day, next leave your portable CO2 monitor in the room for at least a full 
day to gather readings that can be shared with your Ministry Property Advisor 
alongside details of the room’s dimensions, number of students, use of heating 
and window openings.   
* NOTE short peaks in CO2 levels over 1250ppm throughout the day are common, and peaks over 
2000ppm can occur.  If you have followed the published guidance and continue to have consistent 
and sustained CO
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Further assistance 
•  Please contact your Ministry property advisor if you require additional support to address 
any ventilation concerns, or you can contact the Ministry’s ventilation team on 
[email address]. 
 
•  A technical ventilation calculator tool is used by the Ministry’s ventilation team to further 
assess what property improvements may be needed to address ventilation challenges.  If 
requesting additional support, the team will require specific details of the room’s usage, 
dimensions, doors, windows and window openings, supporting floor plans and photos, and  1982
any CO2 readings that are available. 
 
•  Ventilation guidance for all schools is available online: https://temahau.govt.nz/covid-
Act 
19/advice-schools-and-kura/ventilation-schools. 
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Document 5b: Attachment to email for 27/04/22 meeting
Ministry of Education: “Term 2” Ventilation Online Guidance 
Ventilation Technical Advisory Group (VTAG) Content Review  - Final Draft 
Dated 26 April 2022 
IN CONFIDENCE – NOT FOR DISTRIBUTION – SUBJECT TO INTERNAL APPROVALS 
Legend: 
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CYAN 
= 
Headings 
GREEN 
= 
VTAG area of interest / discussion 
YELLOW 
= 
Ministry review still WIP 
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L1 page: Ventilation in schools 
H1: Ventilation in schools  
Good ventilation helps slow the spread of the virus that causes COVID-19. 
Making sure indoor spaces are well ventilated and have lots of fresh air is always recommended 
Information 
for schools.  This applies at all levels of the COVID-19 Protection Framework in addition to using 
face coverings, physical distancing, good hygiene and other health measures. 
The best way to maximise ventilation is to open all windows and doors as much as possible, and 
whenever it is practical to do so. The exception  to this is spaces that are fitted with ducted air 
conditioning systems (excluding heat pumps), which do not rely on opening windows to  bring in 
Official 
fresh air.   
Follow  our  guidance  to  fine-tune  your  school’s  ventilation  strategies  to  maintain  comfortable 
indoor temperatures while achieving good ventilation. 
the 
Subheading: Ventilation help in winter 
Air flow behaves differently at different temperatures – for example, the bigger the temperature 
difference between outside and inside, the more efficiently fresh outside air is drawn in through 
under 
open  windows.  This  means  ventilation  can  work  better  during  cold  weather,  so  you  can  still 
achieve good ventilation with windows just partially open. 
There are several ways to do this depending on your school’s design, how each space is being 
used and the outdoor conditions. Read our tips on how you can do this, with posters and pre-
winter checklists available on our resources page. 
Support  is  available  to  schools  who  are  concerned  about  maintaining  good  ventilation.  This 
includes: 
Released 
• specific ventilation advice from our COVID-19 ventilation team
• an operational funding grant that will become available to all schools in Term 2, to assist
with additional heating costs during winter
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•  funding of urgent property improvements over $5,000 that are required to achieve good 
ventilation 
•  the  free  supply  of  a  limited  number  of  portable  air  cleaners  and  CO2  monitors,  being 
distributed to all schools in Term 2 
•  the supply of additional portable air cleaners where this is found to be the correct interim 
or supplementary solution 
•  the ability to purchase suitable portable air cleaners and CO2 monitors from the Ministry’s 
nominated suppliers at discounted pricing. 
For ventilation advice and to access this support, please contact your Property Advisor or our 
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COVID-19 ventilation team on [email address]. 
 
Act 
TILE 1 link to separate page: Ventilation guidance  
TILE 2 link to separate page: Assessing ventilation 
TILE 3 link to separate page: Ventilation resources 
L2 page: Ventilation guidance 
H1: Ventilation guidance 
A space’s ventilation will be influenced by how it was designed, how it is currently being used, 
Information 
and  the  outdoor  conditions.  Good  ventilation  will  provide  fresh,  clean  air  while  maintaining 
comfortable temperature and humidity levels for the people in the space. 
Good  ventilation  helps  reduce  COVID-19  airborne  transmission  by  quickly  and  consistently 
removing the old air and replacing it with fresh, clean air. 
Indicators that a space may not be well-ventilated include a feeling of stuffiness, lingering smells 
Official 
and elevated CO2 levels created by the people in the room.   
You can quickly improve the air quality in any space by: 
the 
•  limiting more vigorous activities, or moving them outdoors or to a better ventilated space 
•  limiting the number of people, especially in smaller, confined spaces 
•  fully opening all windows and doors to flush the air in the room, and where it’s an option 
to do so, briefly vacating the room at the same time. 
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<Quick links/jump links/contents/on this page> 
•  Guidance for all naturally ventilated spaces 
•  Guidance for naturally ventilated spaces on cold, wet or windy days 
•  Guidance for ducted, mechanically ventilated spaces 
•  Guidance for using heat pumps and other heating systems 
Released 
•  Other supplementary solutions  
 
 
 
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H2: Guidance for all naturally ventilated spaces 
Most New Zealand schools and classrooms are naturally ventilated using windows that can be 
opened. Make the most of this by: 
•  Opening all windows and doors as much as possible, and whenever it is practical to do 
so.  Do not wait for a space to get stuffy before opening windows and doors. 
•  Opening all windows before the school day starts and having them open whenever the 
room is vacated during the day. 
•  Opening windows and doors on the opposite sides of a room where possible to enable the 
cross flow of air, including any that connect to internal corridors or other circulation spaces. 
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•  Turning on any fitted ceiling fans to increase air movement, but only when the windows 
are open to avoid recirculation of stale air. 
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•  Taking regular short breaks (5-10 minutes each hour) where everyone exits the space 
with the windows and doors fully opened, to flush the space with fresh air. 
 
Regularly check for any property issues that may need to be resolved, such as: 
•  ensuring any window that was originally designed to open, can still open 
•  unsticking windows which may have been fixed or painted shut 
•  replacing missing or broken window winders, hinges, catches or closers 
Information 
•  correcting any previous alterations which may be impeding good ventilation 
 
Please  contact  your  Ministry  property  advisor  if  you  require  additional  ventilation  support  to 
address any property concerns. 
Official 
 
H2: Guidance for naturally ventilated spaces on cold, wet or windy days 
the 
Bad weather can make it impractical to fully open windows and doors, but on cold days good 
ventilation can still be achieved with windows partially opened.  
This is because air flow behaves differently at different temperatures  – for example, the bigger 
the temperature difference between outside and inside, the more efficiently fresh outside air is 
drawn in through open windows. 
under 
For example: 
•  as  a  rule  of  thumb,  it’s  possible  to  achieve  good  ventilation  when partially  opening  all 
windows by 5cm   
•  having two windows open by 10cm each through the day provides the same benefit as 
running a large portable air cleaner, while also creating fresh air flow  
•  fully opening all windows and doors for three minutes every hour provides the same benefit 
as running a large portable air cleaner for 20 minutes, while also creating fresh air flow 
Released 
 
On colder days, in addition to our general ventilation guidance, try to: 
•  Pre-heat spaces before the start of the school day. Having it warm inside improves the 
draw of fresh air through partially opened windows. 
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•  Increase indoor heating during the day, if you need to, to offset the impact of having the 
windows partially open when it’s cold outside. 
•  Where high level windows are fitted, open these first and wider than low level windows to 
reduce cold draughts in the room. 
•  Open lots of windows a little, rather than a few windows a lot. Close the door before you 
begin  closing  windows,  reduce  or  close  any  windows  directly  facing  the  worst  weather 
conditions (e.g. wind, rain or snow). 
•  On a wet day, try to keep wet clothes out of the classroom as bringing them in will make 
the classroom more difficult to heat. 
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•  Consider adjusting the classroom layout to move students away from open windows, and 
other areas that may have cooler air or draughts. 
•
Act 
  Consider relaxing uniform rules/dress codes and allowing warmer clothes to be worn, for 
people who are more sensitive to colder air and draughts. 
•  Continue  to  use  refresh  breaks,  where  all  windows  and  doors  are  fully  opened  and 
preferably everyone exits the room for a few minutes each hour. 
•  Fine-tune your approach through the day as the weather changes. Fully opening windows 
still achieves the best ventilation, so increase your window openings if it warms up outside 
later  in  the  day  or  whenever  this  can  be  done  while  maintaining  a  comfortable  indoor 
temperature. 
 
Information 
Continue using your portable CO2 monitors to check if your ventilation is working effectively, in 
addition to  the appropriate use of face coverings, physical distancing, good hygiene and other 
health measures. 
An  operational  funding  grant  will  become  available  to  all  schools  in  Term  2,  to  assist  with 
additional heating costs during winter. More information about this will be made available in May.  
Official 
 
H2: Guidance for ducted, mechanically ventilated spaces 
the 
Some  schools  are  fitted  with  ducted  mechanical  ventilation  systems  that  automatically  source 
fresh  air  from  the  outside  while  also  managing  the  temperature  of  the  room.  These  are  often 
referred to as HVAC or air conditioning systems. This doesn’t include heat pumps, because they 
don’t supply fresh air. 
under 
One way to identify if your space has a ducted mechanical ventilation system is to look for vents 
in the ceiling that bring in fresh air or extract old air. 
Where ducted mechanical ventilation systems are fitted, the above advice for naturally ventilated 
spaces doesn’t apply unless the system has specifically been designed to work in conjunction 
with windows and doors being open.  If not, windows and doors should remain closed to allow the 
system to work as designed.  
A  well-configured  ducted  mechanical  ventilation  system  will  provide  good  ventilation  while 
managing indoor temperatures. Make the most of this by:  
Released 
•  Ensuring the system is regularly checked, cleaned and maintained by an appropriately 
skilled technician. 
•  Having the system configured to come on at least two hours before and after the school 
day. 
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•  Increasing the amount of fresh air brought in by the system and minimising the amount of 
old air it filters and recirculates. 
•  Continuing  to  use  your  portable  CO2  monitors  to  check  if  the  system  is  working 
effectively. 
Configuration  and  maintenance  of  ducted  ventilation  systems  should  only  be  done  by 
appropriately skilled technicians. Technical guidance on this topic is available on our  resources 
page. 
 
H2: Guidance for using heat pumps and other heating systems 
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You can continue to use heat pumps to heat or cool spaces, even when windows and doors are 
open.  
Act 
Heat pumps and most other heating systems only heat or cool recirculated air within the space. 
They do not bring in fresh air, so to achieve good ventilation they must be used alongside a means 
of providing fresh air.   
When using heat pumps and other heating systems: 
•  pre-heat the space  to a comfortable temperature before the school day to improve the 
draw of fresh air through partially opened windows 
•  increase indoor heating or cooling during the day, if you need to, to offset the impact of 
having the windows open  
Information 
•  resetting the temperature of the room to a comfortable level after it has been vacated and 
aired out, by briefly closing all windows and doors and running the system on its highest 
setting before re-occupying the room and re-opening windows. 
Ahead of the colder months, your heat pump or heating system should be checked and serviced 
to make sure it is running at its best. 
Official 
Using a heat pump with windows open will be less efficient and may incur some additional power 
costs. An operational funding grant will become available to all schools in Term 2, to assist with 
additional heating costs during winter. More information about this will be made available in May. 
the 
 
H2: Other supplementary solutions  
H3: Portable air cleaners (purifiers) 
Air  cleaners  are  a  supplementary  solution  that,  in  some  cases,  may  be  suitable  to  use  in 
under 
combination with good ventilation practices in spaces that are challenging to ventilate well.  
Air  cleaners  can  reduce  COVID-19  airborne  transmission  by  filtering  and  recirculating  the  air 
within  a  space.  They do not  replace  ventilation  in any  circumstances,  and do not  reduce  CO2 
levels.  
It is more effective and beneficial to use a space’s natural or mechanical ventilation to supply 
fresh air. For example: 
•  Good ventilation is consistent throughout a space, while the benefits from air cleaners can 
Released 
be localised to the immediate area they are placed in, especially for smaller units with a 
Clean Air Delivery Rate (CADR) under 400 m3/hour.  
•  Running  a  large  (700  CADR)  HEPA  air  cleaner  on  its  highest  setting  will  clean  and 
recirculate the air in a space at the same rate as having two windows open by 10cm each 
through the day, but the windows will also create a flow of fresh air and reduce CO2 levels. 
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•  Running  the  same  large  air  cleaner  will  clean  and  recirculate  the air  in  a  space  in  20 
minutes, whereas fully opening all windows and doors will fully refresh the air within three 
minutes. 
 
Due to these factors, in some circumstances air cleaners are  appropriate  but they are not the 
primary or most effective method of reducing COVID-19 airborne transmission. 
All state and state-integrated schools have been offered air cleaners to use at their discretion in 
spaces that may have a higher risk of airborne transmission such as  some staff rooms, music 
rooms, high-use meeting and break-out rooms. Units are being distributed  starting from March 
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2022. 
Additional air cleaners are available for schools where ventilation  cannot be improved through 
other  immediate  measures.  Please  contact  your  Ministry  Property  Advisor  for  assistance  and 
Act 
consultation to determine if air cleaners are the right interim solution for your school. 
As the Ministry will supply air cleaners to schools where they are required, there should be no 
need for schools to purchase their own, however some schools may elect to do so at their own 
cost.  
In  May  2022  we  will  advise  arrangements  for  schools  and  other  education  sector  entities  to 
purchase air cleaners direct from the Ministry’s selected supplier, at a discounted price. 
If purchasing brands outside of these arrangements, our panel of experts recommend air cleaners 
that use H13-14 HEPA filters, have a Clean Air Delivery Rate (CADR) greater than 400 m3/hour, 
Information 
operate at less than 60dB and do not use any emerging technologies the emit particles into the 
air  (for  example  ionisers,  plasma  discharge,  ozone  generators,  photocatalytic  oxidation,  and  
hydrogen peroxide). 
 
H3: Ceiling and other fixed fans 
Official 
You can use ceiling fans and other fixed fans with windows and doors open, provided they do not 
interfere with the natural flow of air. Do not use fans when windows and doors are closed.  
Well-designed and positioned ceiling fans can boost natural ventilation by up to [x]% when used 
the 
in conjunction with opening windows and doors.  If you are considering fitting new fans, please 
discuss  with  your  Ministry  Property  Advisor  first  to  ensure  that  they  will  improve  existing 
ventilation. 
 
under 
H3: Portable fans 
We recommend limiting use of portable fans as it can be difficult to determine whether they are 
assisting  or  interfering  with  air  flow. Portable  fans  are  also  noisy  and  can  be  a  safety  hazard 
depending on how they are positioned in the room.  
Most  non-industrial  portable  fans  do  not  produce  sufficient  air  movement  to  offer  a  notable 
improvement to ventilation.  
Do not use portable fans when the windows and doors are closed, including in spaces with ducted 
Released 
mechanical ventilation systems. 
L2 page: Assessing ventilation  
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There are several ways to quickly assess whether a space is well ventilated.  Your senses can 
give a good immediate indication – for example if a room feels stuffy or has lingering smells, it 
may not be well ventilated. You’l  be able to verify this using your CO2 monitor. 
If you can’t resolve ventilation issues using our guidance, or you are concerned about ventilation 
in your school you can contact your Ministry Property Advisor or the Ministry’s ventilation team 
on [email address]. 
 
H1: Carbon dioxide (CO2) monitoring 
Measuring CO2 levels indicates how well-ventilated a space is when it is occupied. Elevated CO2 
1982
levels means fresh air isn’t flowing into a space quickly enough to meet the needs of the space’s 
occupants. If sustained at elevated levels this can cause drowsiness and concentration issues for 
the people in the space. 
Act 
Also, if the air in a space is not replaced quickly enough, pollutants and airborne particles including 
viruses stay in the air for longer. That means if anyone in the room is infectious with COVID-19, 
the risk of airborne transmission of the virus is increased.  
To help schools assess CO2 levels, we have distributed portable CO2 monitors to all state and 
state-integrated schools, with more being distributed in May 2022. Some spaces already have 
fitted CO2 monitoring devices (via Internal Environment Monitors). 
With winter approaching it is important to have a regular routine in place of checking CO2 levels 
to gauge how well the supply of fresh air is being balanced with maintaining comfortable indoor 
temperatures.  This is in addition to the appropriate use of face coverings, physical distancing, 
Information 
good hygiene and other health measures. 
 
H2: How to set up your CO2 monitor 
1.  Follow  the  manufacturer’s  instructions  in  the  box.    To  activate  the  device,  fit  the  two 
supplied AA batteries. There is no on/off switch or other controls on the device that need 
Official 
to be set. 
2.  Prior to first use, sit the device outside for 15-30 minutes to let it calibrate to the outdoor 
the 
fresh air CO2 levels (approx. 420ppm). 
3.  Download the Aranet smartphone app from Google Play or the Apple App Store.  The app 
allows you to connect to the device via Bluetooth to track readings over time and download 
the  readings  for  up  to  seven  days,  in  CSV  format.   Doing  this  will avoid  you having  to 
manually record the readings. 
under 
4.  With the app there is the option to change the measurement interval to our recommended 
setting of every 2 minutes, and to adjust the warning levels to match our advice presented 
below. 
 
H2: Using your CO2 monitor to perform spot checks 
Spot checks provide an immediate indication of current CO2 levels.  If the levels are high, follow 
our guidance to try to lower it and also consider if you should monitor the space’s CO2 levels over 
Released 
a longer duration. 
1.  Take  the device  to  each  space and place  it at  around  student  head  height, away  from 
doors and windows, out of direct sunlight, and at least 1m away from the closest people.  
Note breathing directly into or over the device will cause it to report high CO2 levels. 
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Act 
Information 
Official 
the 
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Information 
Official 
the 
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L3 page: Ventilation resources 
H1: Downloadable resources – winter advice  
•  A4 Poster: Promoting air flow in schools  
•  A4 Poster: Maintaining good ventilation in winter (new) 
•  Checklist: Pre-winter ventilation checks (new) 
 
H1: Downloadable resources – other 
•
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  Diagram: The Ministry’s Ventilation Strategy (layered approach) 
•  A4 Poster: How different ventilation methods compare (new) 
•  A4 Poster: How to use a Samsung portable air cleaner  
•
Act 
  A4 Poster: Where to position your portable air cleaner 
•  Technical Advice: Ducted mechanical ventilation systems 
 
H1: Research and studies 
H2: Classroom ventilation study (January 2022) 
The  results  from our  study  with  NIWA  to  understand  more  about  classroom  ventilation  further 
verified our COVID-19 classroom ventilation strategy. 
The study involved looking at ventilation levels in typical classrooms being used as they normally 
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are during the day. This was done by monitoring the amount of CO2, which indicates how much 
fresh air flow there is, in 18 different classrooms across three schools. 
The study verified that good ventilation can be achieved in most naturally ventilated classrooms 
by opening windows and doors. The study highlighted the added benefits of opening windows 
and  doors  on  different  sides of  the room,  of  introducing  short breaks  to periodically purge  the 
room of stale air, and of supplementary assisted natural ventilation systems (e.g. extract/exhaust 
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fans). 
It also identified other areas for further research, including classroom ventilation in cold weather, 
the 
and  the  effective  use  of  portable  air  cleaners  and  other  supplementary  measures. 
 
•  Paper: NIWA rapid study 
[Placeholder here for subsequent study, 2x literature reviews, Nanogirl – add as/when available] 
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H1: Other online resources 
Ministry of Education property advisors — education.govt.nz 
Te Mahau – Advice for schools and kura 
Unite against COVID-19 — covid19.govt.nz 
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Action Log 
 
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Action # 
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VTAG 0016  Renelle to discuss ventilation commentary in schools by 
30/04/22 
Renelle 
Prof Baker with Robyn Phipps to understand his concerns. 
 
 
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Minutes 
Ventilation Technical Advisory Group (VTAG), Wednesday 27 April 2022 1.00pm – 2.00pm 

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that point to other more specific mitigations (i.e. This room has an air cleaner in it for a reason – turn it on FULL all 
day!). 
All ideas and feedback welcomed! 
Thanks again, 
Scott MacKenzie 
Programme Director  – Ventilation (COVID-19) 
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heat.  We will still cover the full set of advice through other mediums.  We want this poster to be assertive i.e. ‘just 
tell us what to do’ advice that anyone can get – including young students. 
My starter for ten (sticking with the sneak, heat and reboot theme yesterday with some tweaks), and these are the 
CONCEPTS not the final wording: 
1. Windows: Open it by a little when you can’t open it a lot, and close it when you have to.  Sneak them open
whenever you can.  Don’t default to full closed just because.  If you can, fully open.
2. Heating: Keep warm, and don’t make it cold just to make it fresh.  If it’s cold, get it to 18 degrees before you
start sneaking windows open.  Preheating, warm clothing, ongoing heating al  fit within this. Nothing we do
should result in cold classrooms or students.
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3. Refresh breaks: Reboot the room at least 4 times a day.  A few minutes with everything wide open will blast
out the bugs but won’t blast out the heat.  Airing out the room during breaks also fits into this. ‘4 times’ is
invented to keep it simple (i.e. our data suggests a 930am break would do the most good – but easier just to
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have this happen regularly; once an hour to impactful on learning).
Trying to be very direct and nuanced in this – i.e. ‘three ventilation tips for classrooms that will help reduce COVID-
19 transmission this winter season’.  Hence aiming for an easy catch-phrase that can be graphically represented like 
sneak, heat and reboot; or keep it fresh, keep it warm and REBOOT. 
But the key questions – do VTAG members agree these are the three themes we should be emphasising with the 
occupants in direct control of the classroom through the school day?  Are we overlooking other parts of our 
ventilation guidance that are MORE beneficial to highlight than these? 
Information 
Note I’ve left CO2 and air cleaners out as these are not a tool in all spaces.  We might following this have a response-
style poster – i.e. one you stick on the door of a room we believe has higher risk due to activities or property factors 
that point to other more specific mitigations (i.e. This room has an air cleaner in it for a reason – turn it on FULL all 
day!). 
All ideas and feedback welcomed! 
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Thanks again, 
the 
Scott MacKenzie 
Programme Director  – Ventilation (COVID-19) 
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To: Robyn Phipps <[email address]>; Ian Longley <[email address]>; Jeremy Tuohy 
<[email address]>; Manfred Plagmann <[email address]>; Mark Jermy 
<[email address]>; Boulic, Mikael <[email address]>; Perry Davy <[email address]> 
Cc: [email address]; Jason Chen <[email address]>; Euan Russell 
<[email address]>; Renelle Gronert <[email address]>; Guy Coulson 
<[email address]>; Ackley Aniebietabasi <[email address]>; Michelle Patience 
<[email address]> 
Subject: RE: VTAG Advice: Most pertinent advice for teachers in a classroom (urgent) 
Importance: High 
Thanks all for the discussion today. 
Late today we had it confirmed that we will be providing some direct information into classrooms to help remind 
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teachers on the pertinent use of masking and ventilation, for the start of Term 3.  Form TBC but think graphical, not 
many words, maybe an A4 poster that can go on the door as you head in.  Half masking, half ventilation but up to 
wider team if other measures go on it too.  I was hoping to defer this into next week’s VTAG but round-robin 
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feedback ASAP appreciated (sorry). 
Our challenge is to pull our advice down to what we believe are the three more pertinent ventilation points for a 
TEACHER (and other occupants of the room) to be mindful of.  Attached are some current material, and we need to 
focus on what the room occupants can control or moderate – for example, often teachers cannot control pre-
heat.  We will still cover the full set of advice through other mediums.  We want this poster to be assertive i.e. ‘just 
tell us what to do’ advice that anyone can get – including young students. 
My starter for ten (sticking with the sneak, heat and reboot theme yesterday with some tweaks), and these are the 
CONCEPTS not the final wording: 
Information 
1. Windows: Open it by a little when you can’t open it a lot, and close it when you have to.  Sneak them open
whenever you can.  Don’t default to full closed just because.  If you can, fully open.
2. Heating: Keep warm, and don’t make it cold just to make it fresh.  If it’s cold, get it to 18 degrees before you
start sneaking windows open.  Preheating, warm clothing, ongoing heating al  fit within this. Nothing we do
Official 
should result in cold classrooms or students.
3. Refresh breaks: Reboot the room at least 4 times a day.  A few minutes with everything wide open will blast
the 
out the bugs but won’t blast out the heat.  Airing out the room during breaks also fits into this. ‘4 times’ is
invented to keep it simple (i.e. our data suggests a 930am break would do the most good – but easier just to
have this happen regularly; once an hour to impactful on learning).
Trying to be very direct and nuanced in this – i.e. ‘three ventilation tips for classrooms that will help reduce COVID-
under 
19 transmission this winter season’.  Hence aiming for an easy catch-phrase that can be graphically represented like 
sneak, heat and reboot; or keep it fresh, keep it warm and REBOOT. 
But the key questions – do VTAG members agree these are the three themes we should be emphasising with the 
occupants in direct control of the classroom through the school day?  Are we overlooking other parts of our 
ventilation guidance that are MORE beneficial to highlight than these? 
Note I’ve left CO2 and air cleaners out as these are not a tool in all spaces.  We might following this have a response-
style poster – i.e. one you stick on the door of a room we believe has higher risk due to activities or property factors 
Released 
that point to other more specific mitigations (i.e. This room has an air cleaner in it for a reason – turn it on FULL all 
day!). 
All ideas and feedback welcomed! 
Thanks again, 
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Scott MacKenzie 
Programme Director  – Ventilation (COVID-19) 
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from the Ministry. 
Dr Ian Longley 
Principal Scientist - Air Quality 
Programme Leader - Atmospheric Environment, Health and Society 
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