hello everyone uh very good morning good afternoon good evening to all the attendees from world over i hope and pray you all are fine and keeping yourself safe welcome to this as we say a very thought-provoking final discussion on forward 19th and indoor spaces we have a panel comprising of the best minds from the industry and domestic and international my name is dividita i'm a member of the australia standards committee and vice president at ashrae mumbai chapter uh before we begin the session today let's briefly take a look at what ishrey is all about because there are quite a few international participants and i would like all of them to know about it so ishrey ishre is the indian society of heating refrigerating and air conditioning engineers this was formed in 1981 uh at delhi eastward today has a presence of in over 44 chapters and sub chapters across the country with the student fraternity we have around 150 student college student branches uh their engineering as well as architecture 27 000 members across the country with around 114 international members next on the technical front what issue has to offer is 40 plus publications which have around already 10 000 circulation technical groups which is started around the few years ago they are already 13 number and there are 1500 volunteers as of now that's in a very short span quite a number uh the history journal started in 1998 it's a bi-monthly publication so sent by mail to all as well as now it's in the soft version so we have 15 000 downloads of the journal along with 1200 plus articles that have been published a weather data book which is for 250 cities across india including our neighboring countries sri lanka bangladesh and nepal we have not been been behind in the standards our uh environmental quality standards started it's already rather in the second version uh which was launched last year we have a vrf standard and the chiller standard besides that the recently launched error handling units standard and the commissioning process standard on the research front we have already invested 12.3 million rupees uh on the research projects that are that have been going on for the past couple of years on the student uh projects which our student chapters have for the past 10 years we've had around 500 plus projects that have been funded we have the issues certification courses these are five in numbers and one four-month diploma course so besides this of course we have around 1600 or so programs done every year by chapters and sub-chapters so with this i hope to we can get many more members uh from the audience that year and feel attracted towards history now let me get on to the session by inviting our national president mr amitabh can we have amitabh take on the platform please yeah thank you hello and uh namaskar friends i heartily welcome you to this panel discussion on kovit 19 and indoor spaces uh you know the annual theme of ishrey this year is laksha raksha is actually a hindi or a sanskrit word uh english meaning of it is goals or targets so uh laksha is also used as an acronym in the ishrey theme so it's spelled as l-a-k-s-h-y-a where l stands for lifelong learning a for adapt best practices k for knowledge enhancement s for share and serve h for harmonious growth y is yearn for excellence and finally a for accomplish so in line with the team you know the learning adapting best practices knowledge enhancement which we want to do also sharing the members with the members and serving the society at large is that that is the reason we have arranged this panel discussion today and it's on a very current and relevant issue not only for air conditioning engineers only but also for users you know there was a lot of dilemma in our mind whether to use air conditioners during kovaid if to use then what are the precautions to be taken you know what is the best ways to kind of mitigate the weak risks in the indoor spaces we have heard of more uh you know taking more outdoor air improving filtration levels but how to do it in existing installations blah blah blah so today's panelists friends are domain experts on these and they will certainly help us understand better the best practices that needs to be adopted while designing an air conditioning and ventilation system today so i'm excited to listen to them and to learn from them and particularly more because i'm aware our moderator vishal kapoor has come with his guns loaded but i'm sure our learned panelists will happily chest those technical bullets from vishal's technical gun so i'm not going to keep you waiting further i hand over the platform back to nivedita to press the start bell and uh please feel free to ask your questions on the question and question box vishal will appropriately take them and most importantly friends please take care of care of yourself stay safe and stay healthy thank you namaskar thank you amitabha now just this just before i draw all the away the curtains from this session i just want to inform you all that we will be sending all the handouts of this presentation by email to all the attendees so you all can concentrate on this session so now to welcome our moderator of the day vishal kapoor vishal kapoor is a btec mechanical engineering from iit rookie he's done his mba from fms delhi he is the managing director of mayho xp air systems private limited he is also a partner in environmental protection services company a firm offering hvac remediation and ieq services for history he has been the national president in the society of 2017-18 uh national chair commit uh technical committee for the past three years and he covet uh task force chair and also a board member of the indoor environmental quality global alliance so what are you vishal thank you so much thank you thank you thank you very much and a warm welcome to our audience from across the globe good morning good afternoon good evening to everyone it's a wonderful day and uh we've been talking about covert now for the last 15 months we hope we never had to talk about this but then the reality in our faces uh this pandemic has disrupted the lives of all of us in many ways but it has also presented us opportunities to learn and change the ways we live it has taught us not to take humanity and science for granted we've hopefully learned the value of research and knowledge and the implementation of it covert 19 has compelled us to confront our limitations as a species and yet we have risen to the challenge to bring our tests vaccines treatment protocols in such a short time the number of active cases have surely gone through waves but the total cured numbers globally do give us some hope of the future specifically to our own country india we are facing a very very strong wave the second wave which is very severe but at the same time we have conducted 370 million tests the numbers are straggling for people listening in the globe 370 million deaths the death percentage is surely going to go down in the days ahead because the world's biggest ever vaccine program is underway 240 million doses have already been given which is possibly larger than most country populations and adding up to 12 percent of the world's vaccine still date travel and face-to-face meetings have surely reduced but the world has become closer working together supporting each other with resources of knowledge technology there are going to be some permanent changes in our lives post-covet and one of the biggest impact areas would be in the design and usage of indoor spaces most infections of the virus have occurred indoors and this has forced the world to ask questions of how safe are our indoor spaces how can we reduce the spread if at all we can the amount of time people spend in a closed environment matters and the greater the number of people in an inflow space the higher the odds that one of them is going to be contagious as it is we spend 80 90 percent of our time indoors and during lockdowns even much more whether in the residence office school shop restaurant air conditioned or not the avon nature the confirmation of the virus being airborne has further caused a panic leading to doubts regarding the design and operation of hvac systems whether this helps in the spread or reduces the same there have been incidents of people not wanting to open their halls windows feeling that the virus might come in thinking it's airborne there are others who are advising do not turn off any air conditioning keep it off if you want to be safe all kinds of things are going around us at the same time we cannot ignore the importance of htac as humans need thermal comfort and a good air quality for all aspects of life work leisure rest or play in fact it is hvac that can also mitigate the spread of this and other infections in the future as long as we know what to do and how since february march last year most of the leading technical organizations globally have been working hard to bring out guidelines on operation and maintenance of hvc systems and technologies good practices to mitigate the spread we at israel also brought out several documents for the same covering all kinds of applications including healthcare this found phenomenal acceptance with the statutory authorities facility managers designers service providers property owners users etc the guidelines centered around five principles indoor conditions ventilation filtration airflow management and maintenance our guideline also addresses specific applications like residences offices and industry factories including operations protocol to reopen post lockdown good practices for technology such as evaporative cooling was also presented as also non-ac applications using fans the document covered safety protocol for the service engineers and technicians in the field subsequently we also launched guidelines for operation of air conditioning systems installed in healthcare facilities this was done jointly with the indian medical association ima and we covered surgical operation room quarantine intensive care units patient ward chambers diagnosis centers clinics general areas in a hospital in spite of all these efforts globally within india and all over the globe unfortunately india air quality has not received the new important it deserves and we all wonder why standards and codes have not been mandated and taken as seriously as say water safe water for all what about safe air not just outdoors and the indoors is 10 to 15 times more polluted but possibly the last year has made people sit up and ask questions in the process multiple solutions products technologies have been suggested all of which might not be right technically or economically or from a health perspective we should not implementing a solution which might solve one problem but create to others covet hopefully is temporary but good iaq will always be needed please remember a building is all about people and of utmost important is their health safety and comfort also in the process of changing design using new technologies products etc we should not forget that the most important aspect of controlling suspense and improving iq is source control and that has to be the first step always to cover these topics and more we are pleased to have a panel of experts with in-depth knowledge rich experience and detailed research over the last year years maybe in this subject the presentations and discussions will reflect on their experience from a spectrum of perspectives and knowledge updates the presentations will focus on the most critical recommendations of solutions which are airborne infection ventilation air cleaning air flow management humidity control iaq monitoring and finally hvac design for fast track health care facilities each speaker shall start with a short presentation on a specific subject and subsequently we will have one hour or more of relevant questions being shown at them if you have any questions any questions which are not addressed in the presentations please feel free to enter them in the questions box please do not repeat a question which has already been asked by somebody or if it has already been addressed in the presentation also please note that we are not going to get into detailed workings of any technology please keep it a little bit more generic in nature because we would not have the time to get into a deep down dive into any subject we can always have that at a later date please do remember the final solution is a mix of various practices and protocol and no one size fits all so the first speaker i would like to invite does not need any introduction but for formality sake we would do that is dr william banfflet our friend bill one of the most active persons in this field over the last 15 months bill could we have you on the zoom hall uh my videos on do you see me uh yes absolutely absolutely you are all right there you are so bill is a professor of architectural engineering at the penn state university pennsylvania state university to be committed like a clear family uh has held previous positions as senior consultants for zba incorporated principal investigator at the u.s army construction engineering research laboratory he holds a bs ms and a phd degree in mechanical engineering from the university of illinois and a registered professional engineer his research interests cover a wide variety of indoor environmental control topics including chilled water pumping system stratified thermal energy storage protection of building occupants from bio aerosol releases and uvgi author co-author of more than 170 technical papers articles and 14 books and book chapters he's a fellow of israel fellow of ask me and the international society for indoor air quality and climate served as president of israel in 1314 currently chase his epidemic task force his ashrae honors include the lewin bill holiday distinguished fellow award iki campbell award and the f paul anderson award recipient of the penn state engineering alumni society's world-class engineering award and a penn state exemplary designation for faculty outreach well over to you for taking on on the subject of airborne ventilation airborne infection and ventilation thank you there you go yeah thank you very much for the uh the kind introduction and i'm glad to uh to be here with everyone i appreciate the the large audience um my uh talk today is uh going to cover just the bare basics of transmission of covet 19 and then the most fundamental of engineering controls uh ventilation with uh with outdoor air that hopefully will set the stage for the others uh one of the the things that's been a prominent feature of the last 15 months has been the the debate over whether covid is is airborne or droplet transmission using the the terminology from infectious disease epidemiology predating the the pandemic and it's been a very costly debate between a number of parties including public health organizations and aerosol scientists and public health experts and then engineers if we go back to to last march or april uh who and cdc and the u.s were were very strong in their statements that uh by their definition covered wasn't an airborne disease but at the same time we were already seeing uh papers like the the one shown here written by lydia moroska and juji ciao that we're pointing out reasons why we should uh believe that that kovid could be airborne and and so that went back and forth uh really through all of 2020 and it wasn't until may of this year that uh who and cdc both made statements that were clear about the potential for uh airborne transmission why is this important um if you believe that the transmission is due to large droplets at close distance that are striking your eyes nose and mouth and that's how transmission occurs then one set of protections is warranted and if you believe that there is significant risk from inhalation of small particles then another is warranted so the the two roads diverged in a yellow wood analogy so for a long time public health authorities were promoting droplet transmission protections that limited the use of high efficiency masks and that focused on cleaning and distancing and there was not very much emphasis on measures to reduce inhalational exposure at a distance that there is now a very large body of information that uh supports the idea that inhalational transmission is is perhaps the most important basic aerosol dynamics are one argument uh historically five microns has been used the distinction between a droplet and an aerosol something that could travel a long distance and something that would fall quickly that's simply not true and then we have uh studies that have found uh cyrus cody2 rna and in aerosols and actual active virus in aerosols and other research has shown that the virus can be active in the air and on surfaces for periods of hours today so all of the fundamentals are there and then we have a large number of case studies at which i've only listed a few here the guangzhou restaurant that's been investigated extensively and the skagit valley choir rehearsal in the u.s and and more recently the sydney church service case that have all when investigated essentially ruled out the the likelihood of close contact or fomite transmission intermediate surface transmission by touching being the the cause and the guangzhou restaurant which now has two very good papers published about it we saw a transmission in a poorly ventilated restaurant where nine diners were infected and they were at distances up to nearly five meters away from the infected person and video evidence rules out the likelihood that there was transmission by fomite in this case uh much more recently there was a an article published about a case in in australia in a church service where one infected singer on two different occasions infected 12 persons on the right you can see the the plan of the church and the red dot is where the infected person was standing and in two different cases had a large number of infections caused that certainly can't be due to any other cause than an airborne transmission so we have that evidence and and this uh very vigorous dialogue has actually uh seems changed the terminology that we use to describe uh infection transmission the the old list was droplet airborne or or fomite and the the assumption was that if it was close contact transmission that it was these large droplets and and that aerosols were only relevant far away a lot of good research that's been done in the last year has showed uh conclusively that a lot of the exposure even at close range is by inhalation of aerosols and so when the cdc in the us came out with its updated statement on transmission and in may they put at the top of the list inhalation of fine droplets and and particles and now they're calling what used to be droplet transmission deposition from splashing or spray onto eyes nose or mouth and fomite is at the bottom of the list and described as touching as time has gone on the likelihood that there has been significant transmission due to touching or fomite transmission has decreased steadily there are really no good studies that show that there have been serious uh outbreaks as a result of that the figure on the right comes from some of yugoli's work and shows how these definitions relate to one another we can have uh aerosol transmission at short distance as well as as spray but we can also have distant inhalation where droplets are not a factor and that touching can occur either directly from an infected person touching another or it can be through an intermediate surface and importantly this new definition of large droplets is more like 100 microns or larger smaller droplets and strong air currents can move surprisingly long distances so what are the means for reducing risk of transmission some of them relate to buildings and building systems others don't distancing face coverings hand hygiene reduced occupancy reduced occupant density are all things that can help and have helped during the pandemic today we're talking mainly about the engineering controls ventilation mechanical filtration and air disinfection so ventilation is our most fundamental indoor air quality control simply involves bringing in outdoor air that we believe to be less contaminated in some sense than the indoor air and using it to dilute contaminants and then contaminated air is exhausted in equal volume this can be mechanical ventilation so brought in by an hvac system using fans or it could be natural ventilation from openings in the enclosure of the building but the effect is the same although the effectiveness may be different from one method to another and air distribution here is very important that'll be talked about later but we have a range of ventilation delivery techniques that ranges from personal ventilation where we supply clean air to the place where someone is breathing uh more commonly most ventilation is mixing ventilation where we generally mix cleaner air with the air in a space and and get more uniform concentrations of contaminants and there are more efficient methods like displacement that put the cleaner air into the occupied zone and push contaminants up and out so there's a big impact here of how air is distributed that you'll hear about later uh but what about the rates how much outdoor air do we need to to bring in uh the current rates in non-healthcare facility design are based on controlling some known indoor health risk contaminants like vocs and also controlling odors and there's a moderate particulate filtration requirement that goes along with that so ashwagandha standard 62.1
for example puts us at uh about 15 cfm or seven and a half liters per second per person maybe one to three air changes per hour if we view it that way and mervate filtration and this certainly isn't very effective for infection control it's just been well discussed if we look at health care facilities they have higher outdoor air supply requirements typically and higher recirculation requirements through high efficiency filters which is very important ashford standard 170 deals with health care facilities and typically the outdoor air is two to four air changes per hour with a total supply of six to twelve air changes per hour with pretty high efficiency merv 14 filters or even up to hepa for some types of facilities the recommendations based on risk assessment for covet typically recommended total clean air delivery rates of 46 air changes per hour you can see in the figure on the right that historically we've had a hard time deciding what we want to do with ventilation if we went back 100 years we see typical ventilation rates of 30 cfm per person which actually could have some significant impact on health um and for energy conservation reasons we've been as low as 5 cfm within the last 50 years or so but most of the time floating around this 15 cfm or so odor and and basic health protection limit so if we want to have ventilation rates that will protect us against infection risk we have to do some kind of a risk assessment during the pandemic the wells riley model has been used extensively it's been extensively criticized too but it's the one that we have and and it's been uh helpful to do at least some level of risk assessment so it predicts the predict the percentage of new infections in a space on the basis of the source strength so the number of infectors and the rate at which they're producing infectious doses or quanta this can be affected by their activity level by whether they're wearing a mask or not and then also the the uptake of contaminated air by the susceptible depends on their breathing rate which also means their activity level and the time that is spent breathing that air and those both increase risk uncontaminated air flow into the space can reduce concentration and reduce risk so we can use this to develop requirements relative to certain risk targets and it's important to point out that uncontaminated air doesn't have to come from outdoors it can come from filters or air cleaners as well as will be discussed uh we have infectious quantum numbers that are being used for sars two but they're pretty um uh smudgy in terms of their accuracy two uh two orders of magnitude between the fifth percentile the 95th percentile and we can see in this figure on the right that the quanta number that you choose has a big impact on on risk so we're doing the best we can but could do better and just in general if we look at reviews that have been done on ventilation we we certainly know that there is a relationship between ventilation rate and infection risk but the conclusion of some uh pretty careful uh literature reviews that have been done in recent years like this one by leodoll have concluded that there's insufficient data to specify and quantify the minimum ventilation requirements in relation to spread of infectious diseases by the airborne route so we we still have some work to do so to summarize here we've been debating for a year and now agree that cyrus cope ii is is airborne therefore we should be taking airborne precautions to reduce this inhalational component of exposure which is very important ventilation is just one way to lower exposure um and its effectiveness is uh strongly impacted by air distribution and another concern about it is that increased outdoor air will cause higher energy demands on buildings and also can affect energy use and comfort so it's not necessarily the the first recourse to increase ventilation a lot uh ventilation plus uncontaminated air supply from other sources is probably a better approach and then finally to re-emphasize that we have a lot of work to do to define what appropriate ventilation rates are for infection control and ran over a little bit but uh i hope not too badly and that's all i have to say thank you thanks a lot bill i think uh in your time slot i know it was not doing justice to cover two big items of airborne infection as well as ventilation in a short span of 10 to 12 minutes i think you pretty much summarize it very well and saying that the importance of ventilation uh to control the infection is only one of the solutions it's not the only solution which a lot of people you know have this concept that if i went that's good enough and that is why we organized a presentation like today where we are talking of all the possible options to ensure the spread is reduced or mitigated to a large extent so thank you for starting it off and there are a lot of questions which i already have and some are being asked i think we pick up the questions uh common towards after all the speakers have finished their presentations so thank you and absolutely you would now like to invite uh next speaker uh dr marva zatari uh marwa is a phd in architectural environmental engineering from the university of texas at austin a master's degree in engineering management from the american university of beirut lebanon with a focus on energy management a partner in design and partner design partners and a co-chair of inverted systems advisory board ieq 2020 conference organizer a lead committee member also serves on the usgbc board for ashrae she's a distinguished lecturer a member of the epidemic task force voting member of the standard 62.1 chair for trg for indoor air quality procedure sorry you had to cut short your profile otherwise i would have taken up half of your presentation time only reading audio profile so welcome barbara and i know you're going to talk about a very interesting topic uh it's air cleaning uh 10 minutes is nowhere near sufficient to cover uh all kinds of air cleaning options but nevertheless we'll see what best we can do and then we can obviously address more of those questions so over to you marvel to take it one from there thank you very much uh thank you so much and thank you for all the attendees i'm very excited to present this topic um so i'm going to talk about air cleaning and this is the agenda i know i have short time so i have 10 minutes and five questions i'm going to start with the ashley recommendations i'm going to talk about merv hepa what are some consideration for in-room air cleaning requirement for uvgi and then what is the state of science regarding electronic or additive air cleaners starting with ashley recommendations when it comes to filtration air cleaning air cleaning ash recommends the use of one or combination of filters and air cleaners to achieve a murph 13 equivalent or better level of performance of air cleaning so you can use one or multiple to achieve mars 13 or equivalent the only thing here is that you need to to use proven technologies and actually definition of proven technology is that technologies where we have sufficient evidence of effectiveness and no harm and i have a quick checklist when i evaluate these technologies first is there a standard or guideline that i can use to understand what are the test conditions and more importantly how they translate to real realistic or real life conditions the second one in case of an emerging technology is there sufficient peer-reviewed data that found the same finding what the manufacturer published and the last one which i think the most important do we have enough do we know enough about safety so there are some things that we look for and we know for example do the device generate ozone or some vocs or ultra fine particles we know how to look for this but also there are things we don't know how to look for and we don't have yet studies for example what is the no no harmful level of ions or specific chemicals i'm going to talk about this a little bit a little bit later but first i'm going to start with mechanical filters when we talk about mechanical filters i refer to media with porous structure or struct or basically stretched membrane to remove particles from the air the fraction of particles removed when air goes through a filter is called filter efficiency and we have an ashley standard 52.2 and also have international standard like iso but actually standard 52.2 has a specific rating it's called mirv minimum efficiency reported value and it gives you among other things efficiency by particulate size so merv goes from 1 to 16. i still see
until today some like big box retail stores are online you still see merv 20 murph 20 does not exist in the ashrae building readiness guide we have a detailed explanation of how to calculate efficiency and what is the assumed particle size distribution as a summary merv 13 is eight on average is 89 efficient and it's not one or zero if you still use merv 11 or merv 8 they have some efficiency for the virus i'll explain a little bit later but imagine this merv 13 is the most cost effective solution so it's cheap we probably can install it in our building and it's very efficient since most of the air is recirculating our building pass it through and a very efficient filter will give us like a large portion of the air exchange rate we're looking for as everything else it need to be properly designed specked and installed we talk about pressure drop does my system is my system able to handle the pressure drop from the nerf 13 can i seal it very well and the seal and the fit is really important for the filter when you put it the gap between the filter and the air handling unit need to be minimized to basically practically zero um and and and lastly is that we need uh an airflow to go through the filter so if we talk about residential system or other system the cycle on and off you need to make sure that if you if possible to keep the system on during the occupied hours so you have constant removal of the of the particles and by proven technologies this is a proven technology because we have azure standard among others that basically give you efficiency by particle size and also pressure drop so able to take take the data from each manufacturer distributor and apply it to your specific system uh specifically in the graph that shows the efficiency on the y-axis on the x-axis particle size you see the shape of the graph is an inverse bell curve make note of that because i'm going to talk about it when i talk about hepa filters one of the things i encounter personally is the notion when people say oh we cannot upgrade our filter because we're going to choke our system we're going to reduce the airflow i'm going to damage my system and we're going to increase energy consumption that might be true but not necessarily true if you do your homework i show you this work on the y y-axis is a pressure drop on the x-axis is three different move category eight eleven thirteen and the different blue diamonds refer to different manufacturers i show you here that you can have a merv 13 filter that have equal or l or lower pressure drop than a merv 8. so if you do your homework and you ask for the specific data and apply it not necessarily you're going to choke your system but not necessarily you're going to increase energy consumption moving on to hepa which stands for high efficiency particulate air filters but hapa i'm at high path by definition hepa filter are at least 99.97 efficient at 0.3 micron and also they
have to be individually tested for efficiency and also for leaks and i've seen some manufacturers start to put a label on each filter to say you know what is actual efficiency another form of a proven technology but one thing i wanted to highlight about the inverse bell curve you see it as well with the hepa and the merv graph i showed earlier there's a notion that i'm hearing a lot about it since the beginning of this pandemic is that oh since hepa filter is specified at 0.3 micron it's not able to remove below 0.3 micron and the virus is so small so hepa do not work this is a false statement we know for a long time since the manhattan project since the creation of atomic bomb is that the smallest size uh is at a particular size between 0.1 micron to 0.3 micron are the most difficult to remove so if you see the inverse bell curve you see like below 0.1 micron and above 0.3 micron
is very efficient the dip happened between 0.1 micro and 0.3 micron so hepa are specified at 0.3 micron or the most penetrating size it might be a little bit less than 0.3 micron because they are the most difficult particle to remove same thing for motion for mirth the other thing is that uh and the reason why nerf 13 is very efficient is although the virus size is so small but when we cough we sneeze we talk we generate particle size much bigger than 0.1 micron can be most particle size distribution is above 1 micron and this why merge 13 is very efficient now moving in the same line for hepa it can be installed in hvac system but if your system is not designed for hepa probably is going to damage your system because of the high pressure drop what we've seen is that hepa filters are specifically used in portable air cleaning when we talk about commercial building actually in rumor cleaning because it can be portable as you see on the top picture or fixed can be fixed on the uh basically the wall or on the on the ceiling and i did this homework when i was trying to look uh for my house and my son's school for hepa and room air cleaners the very important thing here to note is that you only need a hepa filter and a fan you can have a sensor you can have display of particulate matter concentration that's fine but make sure that you don't have any of other things that we don't understand like for example ionizers or a uv light that shining light on a catalyst or some hydrogen peroxide for example so it's very important to know what you're paying for so if i'm paying for a hepa filter i want to get a hepa filter so i summarize here some of the things that i found that you know manufacturer will say that it's a hepa but it's not actually hepa filter like they use terminology like hepatite pepa like near hapa helper some of them they don't have a hepa filter to start with like for example hepa silent is actually an ionizer with a small pleated filter the other thing just to pass it through very quickly i saw also plants being marketed as as air purifier and from dr richard corsi research they do very very little they look nice but they do very little so definitely not for covet there are some consideration when using the in-room air cleaners we start with the space size layout airflow distribution i know dr kishore is going to talk about airflow distribution but basically what is room size height what is the layout of the room can you put it in a way that you have access to power and also no safety issues and you ensure a good airflow distribution like the clean air is not gonna go for example to be exhausted or deflected second one is noise and this is extremely important depending on the space type but we know from history is most people do not use for example the range hood because it's noisy so it's very important to look at the noise at the highest efficiency what we call it is a clean air delivery rate so clean air delivery rate is a terminology approximately equal to air flow times efficiency and it's from aham the association of home appliance manufacturers and then you can calculate an air exchange rate and this is a very nice metric because you can compare different models and you can know what you're paying for again it's important what is the cost of the air cleaner replacement cost and what is giving you in return a method that i like to use all the time is called dollar per risk reduction or dollar per exchange rate or dollar per clean air delivery rate and i show you here at the end of the slide an example of how much each clean air delivery rate will give you an air exchange rate and i have in the extra slide a review of many different manufacturers in terms of efficiency and in terms of cost but basically you have a lot of options a quick word about uvgi uvgi is another proven technology uh i know dr banflet that has a lot of work about this the the recommendation from actually about induct so you the one you put after the cooling coil is a 1500 micro joule per centimeter square and this is a conservative estimate that takes into account many factors like temperature humidity aging of the of the of the bulb uh the soiling of the surface and the airflow and the air exchange rate now um remember like the actual recommendation is one or combination of filters so i'll show you how to do the math one client was saying that they have nerve 16 because they have merv eight and nerve eight so double stage filtration this is not the way to do the math fortunately ashley published an open source tool to help you to do an addition of several technologies and here's just an example so if you cannot use my 13 it you know you're not doomed there is a lot of things you can do like addition of uv or for example having in-room air cleaners and you can mix and match between the different technologies to obtain murph 30. my last topic of today is electronic air cleaners or additive air cleaners unfortunately like even we don't have a name for these like a terminology but there are four broad categories and many different names because we don't have any type of regulations we talk about photocatalytic oxidation like it's a uv light shining on a catalyst trihydrogen peroxide ionization oxidant like for example generation of ozone and fumigation but the mechanism although the there are very broad category the mechanism is the same they add something to the air to subtract so they add like reactive oxygen species um ozone radicals to subtract so to have a chemical reaction to remove something the fact is that indiscriminate indiscriminate and unpredictable reaction will happen and these technologies are unproven in the same definition i i basically explained before they're unproven to be safe or effective and the reason why i say that is that we don't have a standard and a guideline so as engineers or users we don't know what what to do in order to specify for specific room size height temperature humidity airflow what is the specific ion count correlation with efficiency how far is the instrument is is put is it in room is it induct is it in the air handling unit what is the effect of the length of the duct on basically the output and we have emerging research i didn't inside them here they are cited later in my extra slide that show basically that some ionizers um that basically the efficiency is negligible some of them they do something but some of them negligible and some of them even though the manufacturers say they don't produce by-products produce actually vocs ultrafine particles and ozone even though the manufacturer will have a zero ozone claim the last thing i want to say is that i worked with the researchers in three different universities to produce an open source tool to help you decipher what the manufacturers say versus what is the realistic efficiency i'm not going to go through it but basically this specific manufacturer will say that they have 98 percent efficiency and removal of covid in a if you put it in this calculator the exchange rate is 0.3 at exchange
rate per hour you know dr bonfless mentioned er exchange rate recommendation between four to six air exchange rate per hour so you see this device although costly will do very little to achieve five air exchange rate per hour as specified by this device you need actually 64 devices 64. my summary is that stick with the proven technologies we know they work they work before covid we know they're working during covid and more importantly they will work after covid we talk about mechanical filters hepa and uvgi in addition to what dr bunfla said before about ventilation thank you so much thank you very much dr marva i think uh subject no egg cleaning has been one of the most if i may use the word controversial specifically over the last year year and a half uh because of the scare the panic and so a lot of technologies and solutions coming in the market with uits that have not been really tested or proven till now but yet they keep on coming out and people are buying at risk or not effective or not is something which i think time only will tell but it is it it is a most important subject of air cleaning because till now we were all just bothered about uh media filters and uvgi and now it's a different line of world all together and also this uh this open-end tool of putting filters together to get the effective filter rating is also something that is very important for retrofit projects because where people want to improve the filtration levels this is one way of actually looking at what they are putting in so thank you very much for addressing this very very important topic and we will be coming back to you later with a lot of questions which are directed your way and we'll see how best whatever time we have we can look at that thank you very much uh i would now like to welcome dr kishore kankari so we have diluted the air sir we have cleaned it we know to ensure it flows in the right manner so it's a good job that you have in hand dr kishore is a phd in computational following dynamics from the university of minnesota uh president and site llc a specialist in cfd a member industry advisory board for architectural engineering design the discipline of lawrence technology university a proud history member with aishwarya he is a dl a fellow award a distinguished and exceptional service aboard leads a multi-task group on air change rates also very recently nominated as a director at large on the ash report uh welcome sir and a very important and i would openly say it a very neglected subject on air distribution and air flow because most people believe just throw in air if it's cooling they're happy and not bothered about anyone else so over to you to take this subject from here on thank you vishal uh thanks for your invitation uh for me to participate in this esteem uh panel uh in fact you introduced the subject so well i don't think i need to uh speak anymore of this one my message is very simple airflow patterns in indoor spaces matter everything matters how you bring the clean air how you clean it whether you have uvgi in the room or in the dark air cleaner in the room at the end of the day how air flows into our spaces is is important so why does it matter air is the primary carrier of heat moisture and airborne contaminants we who work in hvac industry we are fortunate that we are to work with only air as a fluid and not worry about most of the other time the other fluids that's why understanding the air flow pattern in indoor space this is very important because the what path airborne pathogens take or airborne contaminants state it depends on how air moves within the spaces so the high level ventilation strategies as we know it's the containment pressurization which is often used in the healthcare facilities positively or negatively pressurized rooms so that the zonal transport of contaminants from one room to another or room to the corridor or corridor to the room is minimized the one which is very popular very well studied is the dilution philosophy where you bring the clean air you have it contaminants in the space and you can dilute it to the acceptable level so that you can reduce the risk and and more air you bring it more dilute the uh atmosphere would be the indoor air would be the last one as vishal said not too many people pay attention to is once you bring the clean air and once it becomes dirty uh we need to remove that so that we can effectively uh create the good environment in indoor so that is often neglected part and i'm going to talk more about that part about the dilution philosophy this is very well known equation that if you know the generation rate of contaminants and if you know what is the acceptable level of concentration that you need you just divide g by c and you will know how much air you need well there are several things in this equation first of all do you know what is the generation as bill pointed out what are those quantum we don't know there are all those and then what is the acceptable concentration not much is known leave alone covered situation but for other contaminants there are different values for that so what engineers do they use that safety factor and that safety factor really overrides all the basic equations g o c uh those factors are so loud that uh sometime i question why do we need this equation and most importantly all these theories of dilutions over the years or the decades have been developed thinking that the space is well mixed as if this is your cup of tea and you add sugar to that and stir it and momentarily it becomes a sweet tea the room is not like your cup of coffee or tea uh it's a large space there's several things in the room and so achieving a well-mixed concentration in the spaces to my opinion is a myth you try very hard and you can't get well mixed concentrations into the space so this is slightly a side topic here is the air changes per hour in india we call it scph air changes per hour here in us we call ach very well taught terminology people use this left and right without understanding why are we talking in terms of air changes for our uh why not we just say how many cfm how many meter cube per second how many liters we are putting into space we divide it by the uh room volume so this is a double edged saw what it does is definitely tells you is how much you are going to dilute because the air you are bringing in at just in the numerator higher the numerator more the dilution will be one other thing that is often not understood is when you say in terms of air change rates what you imply by that is how fast you want to clean the room and more often when you push the room the sources of contaminants are not there for example people leave the office space and then they say you purge the room it means assuming i believe there is no source of contamination people who are breathing out germs are gone and we want to clean the space the first space so this is the another important aspect of air change it's when you talk in terms of air changing because the volume of the space it acts like an inertia larger the space more air you will need to clean it faster what this does not help you and that is the topic is how well you are cleaning the skulls it is not how much air you are bringing in it is how well you are cleaning the space and what amitabha said is the lux the luxury of ventilation is to bring the clean air to maintain the desirable indoor indoor quality so these are some of the components you can see the clean air comes often from a four-way uh diffuser cleaner i mean uncontaminated there's a debate about what you call it clean and then there are off occupants of course it's an occupied space and they breathe in and breathe out and in the cobie situation they may breathe out some pathogens covered pathogens into the space and then this clean air touches the sources and occupants and kind of gets delty now this dirty air has to be removed from the place you cannot just circulate the diet here for long then your effectiveness of cleaning is going to go down what is important in all this discussion is the breathing zone of occupant you may keep the your ceiling near the roof it is very clean or your floor is clean doesn't matter we all breathe what i call is the breathing zone which is generally four to six feet height from the floor so we have to pay attention what is the indoor air quality the breathing zone of the occupant it doesn't mean that other spaces like above and below the breathing zone they don't matter they do because they will bring the contaminants into the breathing zone but our criteria should be in the breathing zone various factors can affect how well you ventilate your space location and number and type of diffusers supply air flow rate especially the discharge velocity from the diffusers type of diffusers location and number of exhaust or written reels in your space location extent of heat sources because we generate heat there are other heat generating equipment probably in the space and the buoyancy can play an important role and as bill pointed out the displacement ventilation works on that principle rate of contaminant generation of course how many people are there how many are contaminated where they are sitting so location of contaminant generation and finally the layout of the facility these are the obstructions to airflow the furniture the the cubicle walls uh and whatnot so when we design the space we design a space with a blind sheet on our drawing board uh we rarely think uh what is the height of the cubicles here how people are sitting in the space can matter how air distributes now i'm going to tell you a few tales and my first tell is the tale of two office spaces this will be published in next month the national journal so in one space two identical cubicles here there are six people and there is one infected person here and there is only one single four-way diffuser one single written if at all it in my observation when i go and look for returns i have to look for them where are those are there any reasons sometimes those resets are in the corridor somewhere far from the occupied space so there's one return one supply here in the other space i have two supplies and two returns i did not change the air changing this is three air changes in this way same amount of air is coming in both spaces so if you look at the air distribution what it says when you are single diffuser this air moves along the ceiling strikes the wall and creates a strong recirculation pattern in this cubicle when you put these two identical supply diffusers two returns it creates its own loop of circulation not that it is free of circulation but it is kind of creating a contained zone in each of these air supply and air written uh location here now it has a significant effect on the uh on how you clean the space now uh we'll talk about wells rayleigh correlation and i use this in this competition of dynamics analysis and you can see without increasing the air flow rate how you place how you bring the air where you place your return plays an important role and you can see this makes a significant difference on the probability of infection this picture shows the probability of infection closer to the infected person your probability is close to 100 once you go away from the person your probability reduces if you have a poor air distribution in the space and you're bringing all the murph 13 west clean air into the space poor distribution can defeat all your strategies in fact the social distancing you can see you defeat the principle of social distancing by putting the poor air distribution into the space and this this very well shows that this is the animation showing a probable flow path of airborne pathogens when you have one supply there and one written if at all there it kind of pulls all those jumps everywhere into the space when you have a path of least resistance for the germs to leave the space contaminants to leave the space they have no intention to cross over and get into another cubicle uh if you draw a cloud of infection probability this is like 10 or higher infection probability when you have a single supply single written it almost covers 50 percent of the room and kind of swallows all the occupants in that bubble if you don't increase the air flow rate just distribute it properly and take the dirty air out properly you can reduce it to 36 of course when you have active source of a contaminant you can't bring it to zero or any reasonable low value unless you control the source such as mass wearing the mass and taking people before they come into office and avoiding infected people to come this another tale of two patient rooms and and in in this patient room we have one return generally in the entry of the patient and these are some linear diffusers here what i did is i i moved this return to oh above the patient's head and made it two by four instead of just two by two or one by one uh food uh exhaust there and it makes tremendous difference you can see these are the air flow patterns computed by computational fluid dynamics you can see all this air is moving over the patient towards that wreath and versus creating this colorful spaghetti in the other space and what happens to the germs breathed out from the patient you can see they sprayed all over the space entire patient room when you keep that small tiny uh written there and if you create a path of this resistance for the great deal to live you can see the gym just get lifted and they find here is my exit why should i go somewhere else i can exit the room from there this is the tail of two laboratories exactly same lab exactly same air changes in one lab i have two exhaust wheels and three supply diffusers here in other lab i have three exhaust and same number of supply diffuses it makes ton of a difference in the contaminant distribution same air changes now we can talk in terms of equivalent air changing much higher air change that you will need to get this kind of concentration this is the concentration at the breathing zone breathing plane at four feet height from the uh from the floor and and this animation also shows you the other aspects of air changing in fact keeping the same air changing and if you create the path of least resistance for contaminants to leave for same air did you can deplete this room clean this room much faster than the same room with two exhaust grips and this is obvious how the red the blue color is penetrating into the space uh this is that same blob it's a 25 ppm concentration you can see this guy's face is completely immersed in that dirty cloud which is occupied about 27 percent of the land same air change it throw one more exhaust you can bring it down to 16 and you will see how this red blob is zone of high contaminant moving into the space and you will see that volume of that red blob on the right side is much smaller than the volume of that red blob on the right side exposure is the most important not the absolute concentration but the duration on exposure if you multiply that that's the dose we are exposed to and what i it is showing the difference between two and three exhaust bl it is like your exposure rate also comes down your dose also reduces and and for third person it's a significant improvement to summarize i want to say air flow patterns determine the flow path of airborne contaminants and that's why air distribution is crucial along with other mitigation strategies we need to understand this is the common sense air takes the path of least resistance however that path of least resistance is not very intuitive you can do some of the cfd analysis to understand that location and number of supply diffusers and exhaust will matter just increasing the ventilation rate is not enough i'm not saying don't increase the ventilation rate but it is only part of the equation the other thing is how you distribute that valuable resource form aerodynamic maintenance outcome of hvac layout as i said try to increase the number of diffusers increase the number of exhaust we'll arrange them in a symmetric fashion covering different zones so that you can create the aerodynamic airflow patterns which will not promote the cross contamination between the zone and they understand the air flow patterns right so that's the my message these are my publications you can google them in your handouts you will have those uh i would like to thank my company for giving me the support and funding this message and i think that concludes my my talk thank you very much dr kishor it's always very very interesting uh listening and watching your presentation because the way you make it so easy to understand though it's not so easy to implement for sure uh because it doesn't need uh doesn't need proper science to design a distribution which is unfortunately ignored but you make it so easy to understand the importance of the correct air distribution and this myth of i want to admit we're talking about pumping in outdoor air also to positively pressurize a room or an occupied zone and we believe pressurization in a layman's language or even a naturally ingenious language means you open the door and you have a blast of cold air hitting you and we really do not understand the big negatives of handling that kind of situation so it's very interesting and we will come back to you for a few questions uh later on after the next two presentations thank you very much thank you i would now like to invite dr stephanie uh to come on the platform dr stephanie taylor needs no introduction she's been one of the most visible faces last two years especially the last year and a half and this aspect and md from howard medical school and uh emmark from norwich university a very very unlikely combination i have never heard this combination a practicing physician and a cellular biologist for several decades a member of the mass general brigham hospital's infection prevention steering committee and harvard medical school inside health fellowship with ashrae or distinguished lecturer a member of the epidemic task force and a member of the environmental health committee uh welcome dr stephanie and i know you will be talking about two subjects on humidity control as well as continuous iaq monitoring for occupant health so over to you peace thank you very much and i am honored to to be a part of this panel um and i also want to thank my colleagues uh from building for health for her for helping me get to this place um in my knowledge and in our knowledge so i always feel a little bit like a fish out of water as a primarily a physician talking to engineers however we really are all on the same team so the focus of my presentation is going to be on how we manage indoor air from the perspective and through the lens of human health so in the next 10 minutes i'd like to just touch on these three topics one the importance of indoor air quality not just now during covet 19 but moving forward coven 19 has clearly created tremendous challenges in keeping us healthy and keeping lots of aspects of our lives moving forward but i am grateful and i will use that word for coven 19 in clearly illuminating the value and the importance of the indoor environment to protect human health so instead of limping forward for 50 years trying to decide whether this is important we all now very clearly know that the indoor environment is key to protecting our health then i'd like to talk about how we actually bridge our gap our knowledge gap and our our functional gap between hvac settings building management and human health and thirdly how do we manage the indoor environment how do we scale this approach for building occupants all over the world so right now we're we have come together around this uh very agile rapidly mutating coronavirus as sars cov2 it's agile in that it mutates rapidly it adapts to new environments it finds new hosts and it travels through the air like most virulent viruses however once we are passed thinking about this as much as we do now the cdc reminds us that you know we still have to consider other viruses and bacteria that are mutating to create disease having talked about infection infection control and infectious diseases it's also key to to realize that the indoor air that indoor air quality is not just around preventing infections so while we might have scared ourselves into being aware of how important indoor air management is for disease we also have to remember that we spend most of our time indoors i live in a beautiful state i love to do things outside but i'm still indoors about 90 percent of the time and if you think about how much air we exchange with our body fluids and our body tissues you know this this number we inhale about 11 000 liters of air every day we also know that things that we really were less aware of that are key to preventing disease transmission things like relative humidity and a mid-range relative humidity which inactivates many viruses very quickly study in 2007 showed that 80 of influenza a virus is inactivated in 15 minutes when the indoor ambient relative humidity reaches 40 that's a very key uh statement we also know a lot through dr joe allen's work that when carbon dioxide levels ris
2021-06-17