What Engineers Want in a Ventilation Standard

A SHRAE JOURNAL

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CHICAGOAsk engineers what theywant in a ventilation standard and youllget surprisingly similar answers: simplic-ity, flexibility and technical accuracy. Butcan a ventilation standard fulfill these ob-jectives and still meet the needs of de-signers, building operators and code of-ficials?

This is one of the topics covered dur-ing a recent roundtable in Chicago thatinvolved key members of the committeerevising ANSI/ASHRAE Standard 62-1989, Ventilation for Acceptable IndoorAir Quality, experienced engineers, andbuilding operations professionals.

What follows are excerpts from the dis-cussion.

What are the elements of an idealventilation standard?

Dennis Stanke: Ill start. I think anideal ventilation standard is characterizedby the three-legged stool. It includes de-sign requirements; it includes installationand start-up requirements; and it includesoperation and maintenance requirements.If you take any of the legs away, youllhave difficulty achieving proper ventila-

tion. Therefore, all three of those ele-ments need to be addressed.

Steve Taylor: I think you first haveto ask yourself, Whats the purpose of aventilation standard? If its supposed to

not an appropriate position for ASHRAE.Were primarily HVAC engineers andthats what we know how to do. I thinkits really important that we dont sug-gest that this standard is going to deliverwhat it cant possibly deliver.

Frank Gallo: I agree with Steve thatthe standard should clearly defineventilations role in IAQ. This includesits benefits as well as its limitations. Andthere should be clear, concise methodsto determine ventilation rates. The ratesshould be based on sound technical dataand assumptions and good correlationwith field experience. So, to me, the stan-dard has to correlate with whats happen-ing in the real world, and ideally have uni-versal acceptance.

Tom Tamblyn: I think the indoor airquality subject is more of a guideline is-sue than a standards issue because thereare many, many different things involvedin indoor air quality. Ventilation is one ofthose. My opinion is that those relatedto indoor air quality should be dealt within the guideline and those involving ven-tilation go to the standard.

Steve Taylor: So we can call the stan-

Bill Coad Steve Taylor Frank Gallo

What Engineers WantIn a Ventilation Standard

. . .the world expects us tocome up with a standardthats going to deliverhealthy indoorenvironments, and wevepainted ourselves into acorner by limiting ourselvesprimarily to ventilation.

Steve Taylor

Roundtable

deliver acceptable indoor quality, youhave to decide, What is acceptable in-door quality? Thats a very complex sub-ject and, unfortunately, it isnt limited toventilation. So one of the challenges thatASHRAE has is that the world expectsus to come up with a standard thats go-ing to deliver healthy indoor environ-ments, and weve painted ourselves intoa corner by limiting ourselves primarilyto ventilation. Im not saying that thats

The following article was published in ASHRAE Journal, June 1998. Copyright 1998 American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.It is presented for educational purposes only. This article may not be copied and/or distributed electronically or in paper form without permission of ASHRAE.

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V E N T I L A T I O N S T A N D A R D

dard ventilation for no particular pur-pose?

Tom Tamblyn: No. I think that youcan state what its ventilation for, andcarry on from there. But were on shakyground when you state in the standardthat its for acceptable indoor air quality.

Doug Simpson: I believe that theventilation standard should be simple andflexible.

Frank Vaculik: To me, the standardshould be a document that speaks topeople beyond the designer. This in-cludes the commissioning agent, the con-tractor and the people operating systemson a day-to-day basis. It should besupplemented by a lot of educational ma-terial, especially for those who may notbe as up to snuff with the topic as thedesigners are.

Dick Pearson: We know that thisstandard is becoming a code throughoutthe country. In fact, were encouragingthat. So the ideal standard, in my opin-ion, has to be something that a code offi-cial can understand, that a plan reviewercan understand, and that a building in-spector in a typical city can enforce. Iftechnology in the code is too difficult forthose people, weve developed some-

thing that cant be applied.Bill Coad: I agree with Tom. A friend

of mine used to say that if youre goingto eat an elephant, you have to do it onebite at a time. Air conditioning is provid-ing good indoor air quality, but ventila-tion is only one component. Since weretalking about a ventilation standard, Ithink we should stick with the ventilationcomponent. I think this will allow us toachieve consensus.

ASHRAE has been researching venti-lation for over 100 years. And our litera-ture is full of research on ventilation. Someof it is not too scientific, but its beenvery effective. Until 1973 we didnt havea ventilation standard. We had policiesand practices that were published in ourhandbooks and our guides. We designedperfectly acceptable buildings for thetechnology of the times. And these build-

Frantisek (Frank) Vaculik, P. Eng., Member ASHRAE,worked for many years in the operation of buildings andheating plants at Public Works in Ottawa. He is a past chair-man and current corresponding member of ASHRAE Tech-nical Committee (TC) 1.7, Operation and Maintenance Man-agement.

Steven T. Taylor, P.E., Member ASHRAE, is a consultingengineer from Alameda, Calif. He is chairman of ASHRAEStanding Standard Project Committee (SSPC) 62, Ventila-tion and Acceptable IAQ. He is a member of TC 4.3, Ven-tilation Requirements and Infiltration, and a member ofthe Multidisciplinary Standards Committee. In addition, heis vice chairman of the IAQ 98 Steering Committee.

Richard J. (Dick) Pearson, P.E., Fellow ASHRAE, is a con-sulting engineer in Madison, Wis. He has been the chair-man of the Environmental Health Committee and is cur-rently a member of TC 9.6, Systems Energy Utilization.

William J. (Bill) Coad, P.E., Fellow/Life Member ASHRAE,is a consulting engineer from St. Louis, Mo. Currently, he isan ASHRAE vice president and serves on the Board of Di-rectors and the Societys Executive Committee. He chairsthe Publishing Council and the Research Journal Policy com-mittee. In 199899, he will be a voting member of theASHRAE Planning Committee and a member of the FinanceCommittee. He is a member of TC 8.10, Pumps and Hy-dronic Piping, and TC 1.10, Energy Resources.

So I think the idealventilation standardwould be just thatastandard that addressesthe ventilation aspects ofwhat we design.

Bill Coad

ings were well ventilated, as a matter offact.

So, I think the ideal ventilation stan-dard would be just thata standard thataddresses the ventilation aspects of whatwe design. I think we can achieve a con-sensus on that. Its my personal opinionthat well never achieve consensus on thewhole thing. Theres too much we dontknow. I think were trying to eat the wholeelephant in one great big swallow...

Steve Taylor: Its interesting listen-ing to this conversation because this isso similar to many of the debates at thecommittee level. Weve heard people saythey want it to be simple, but then wealso want it to be sound technically andcorrelate with field experience. We wantit technically correct, but it has to beuseable by multiple audiencesdesign-ers, building officials, property managers,non-technical people. We want it to belimited to ventilation without regard tohow it might affect health. But this iswhere you start to lose focus. How doyou determine a ventilation rate, if youdont have some basis for determining it.You eventually deal with concentrationsof contaminants. Thats what dilutiondoes.

Gil Avery, P.E., Fellow/Life Member ASHRAE, is a con-sultant from Memphis, Tenn. He is a member of SSPC62 and is 1998 chairman of ASHRAE Guideline ProjectCommittee 16P, Specifying Outside, Return and ReliefDampers for Variable Air Volume Systems. He is alsoa member of TC 9.1, Large Building Air-ConditioningSystems.

Dennis A. Stanke, Member ASHRAE, works in appli-cations engineering at the Trane Company in LaCrosse,Wis. He is a member of SSPC 62; TC 5.2, Duct De-sign; and IAQ 98 Steering Committee.

Thomas Tamblyn, P.Eng., Member ASHRAE, is a con-sulting engineer from Toronto. He is research subcom-mittee chairman of TC 1.7, Operation and Mainte-nance Management.

C. Douglas Simpson is CEO of an engineering firmin Charlotte, N.C., where he has worked since 1962.He has been active in ASHRAE at the chapter level.

Francis Michael (Frank)Gallo, P.E., MemberASHRAE, is a consultant in Trumbull, Conn. He is amember of SSPC 62 and chair of TC 1.7, Operationsand Maintenance Management.


incredible strength. Its very possible thatwe may not veer all that far from 62-89.

Frank Vaculik: I think the light atthe end of the tunnel is fueled by educa-tion. By a good transfer of knowledge thatis coming out of the ASHRAE researchand going all the way down to the veryend of the tunnel. Thats why I mentionedthat we may have to have a standard thatwill say, This is a good practice to do

this and this, for the designers and con-tractors. But the property manager is deal-ing with the needs of the tenants for thenext 25 years. We need something thatestablishes good practice, both for thedesigner and the building manager.

Bill Coad: There are a lot of peoplehere who are in operations. I will abso-lutely assure you that after the engineeris gone, somebody will take all the com-plexity we put into the building and re-duce it to their level of understanding.We have to make the ventilation systemalmost foolproof.

So if we are talking about our stan-dards, our design guidelines, our hand-books, everything we do, the first thingwe have to do is look for simplicity. Wenow have people with massive degreesthat are absolute experts at making thingscomplicated. And were putting systemsout there that no one knows how to oper-

So how do you combine all those ele-ments together? Thats what the consen-sus process is all about, of course. A partof the challenge is educating people towhat the issues are.

Everybody wants a silver bullet, ev-erybody wants it to be a certain cfm perperson. You put that in the building andeverything is peachy keen and its allgoing to work. Its simple. But indoor airquality isnt simple. Itll always be a com-promise between simplicity and techni-cal correctness. Everybody has a per-sonal opinion where the right answer is.But there is no right answer.

Bill Coad: Id just like to say that itsounds like almost an impossible task thatyouve been dealing with, Steve, over theyears that youve been involved. Is therea light at the end of the tunnel? Do yousee a way to get consensus on an IAQstandard?

Steve Taylor: I dont know the an-swer because the political forces are nowstronger than the technical forces. Itscausing us basically to return to the sta-tus quo. Thats the current standard. Ithas the strength of being there, of alreadybeing published.

Trying to change it right now, accord-ing to our new rules, is very difficult. Ev-ery vote has to be a majority vote of themembers, whether theyre at the meetingor not. Thats a challenge in itself. Thenyoure trying to get members to voteyes on a change when we dont have alot of the technical data wed like. Theresearch isnt there. Therefore, trying toget 19 people with varied backgroundsto vote yes on change is very difficult.So what happens is the status quo has

ate, including the guy who designed it.The ideal standard, in my opinion, has tobe simple.

Steve Taylor: Id like to comment onthat. Its like Einstein said, Everythingshould be as simple as possible but nosimpler. I think you quoted that in oneof your articles, Bill. Its right to the point.When we first started doing load calcula-tions, people took the square footage ofthe building and divided it by a rule ofthumb number, x square foot per ton, andthen they realized that that wasnt quiteaccurate enough. Over time, we got moreand more complex to the point now wherewe do load calculations by computer. Idoubt if any engineer would argue thatwe should do load calculations simply,that we should do them by square footper ton because its simple.

Well, heat transfer isnt simple. Andweve developed techniques to addressthat over time. Indoor air quality isntsimple. Just because the building engi-neer is going to try to make it simple,doesnt make the science simple. So, likeEinstein, we have to try to make our viewof that world and our concepts behind itas simple as possible. But it cant be sim-pler than the fundamentals. And as withload calculations, we have to realize asengineers that the issue is complex andwe have to deal with them in the appro-priately complex manner.

Bill Coad: We may have started outwith square feet per ton for load calcula-tions, but that was long before my time.When I started, we were doing the steadystate heat transfer calculations, and thenwe got into transient heat transfer calcu-lations. As we learned more, we spent

We need to provide asimple ventilationstandard and leave it tothe engineer to decidewhat else he needs.

Gil Avery

Gil Avery Frank VaculikDennis Stanke



more time at it and we got better answers.Now weve become so sophisticated, aperson cant possibly do the arithmeticto do a load calculation anymore. ThankGod we have computers.

Weve only been talking about indoorair quality in those terms for about 15years. Weve just gotten in the business.We dont know what good indoor air qual-ity is as we sit here. Were still working onthat. The last thing in the world we wantto do is take the technology in its infancyand write a standard on it. It fixes it in placeand research stops. I dont think wereready for a standard on indoor air quality.I think we may be ready for a standard onventilation. We may be. Im not sure weeven need a standard on ventilation. Weveventilated for years without a standard. Idont think we know enough about indoorair quality to write a standard on it.

What should drive the stan-dard, i.e., economics, occupantsatisfaction, technology, culturalissues?

Gil Avery: I think weve tried to in-clude all the components in the ventila-tion requirements, including off-gassing,odors, everything else we could think of,and its pyramided the rates. We need toprovide a simple ventilation standard andleave it to the engineer to decide whatelse he needs. If we didnt try to includeeverything, we could write a four or five-page standard.

It would be a simple ventilation stan-dard and the engineer would add the re-quired amount of air depending on thebuilding, because theyre all different. Forexample, there may not be any off-gas-

sing in a building. One expert says dontworry about off-gassing because itsgone anyway in six months.

Steve Taylor: Id like to share thisbecause I started out thinking the wayyou guys do. I suggested six years agothat we change the name of the standardto ventilation and that we not mentionthe phrases indoor air quality or ac-ceptable indoor air quality. It got voted

down for a very simple thing: If you donthave any basis or purpose for ventila-tion, you dont have a rationale for whatthe right numbers should be. So, youhave to say its ventilation for somethingto determine the appropriate ventilationrate. And once you say that, once youstart getting into acceptable indoor airquality, which is the ultimate purpose, itexpands into these other things.

If you dont expand into those things,youre doing a disservice to the engineersand the designers and the building own-ers and everybody whos going to be us-ing this document. Theyre going to bemisled as to what really affects air qual-ity. So we progressed if its progressfrom the concept that the standard should

just address ventilation into realizing thatit really cant.

Gil Avery: Cant you leave it up tothe engineer, though, to decide how com-plicated it gets?

Steve Taylor: Unfortunately, that de-cision was made before us. The standardsthere. Its being referenced. So we cantdecide now that it shouldnt be there,because it is. If ASHRAE decides 62-89sgone, people are still going to use thosenumbers. Somebody needs to write a ven-tilation standard because theres a de-mand for it. If we dont write it, some-body else is going to and were probablynot going to like their answers. Were themost qualified, so we might as well bitethe bullet and do it.

Gil Avery: Its fair to say that whatshould drive the standard are technicalissues, but what is now driving the stan-dard are political issues, going back toyour point you made previously.

Steve Taylor: Certainly theres poli-tics involved. If you put 62-89 out in thestreet for public review as if it were a newstandard now, youd get 8,000 commentsjust like we did on 62R because its muchmore visible now than it was in 1988 whenit went out for public review. The politicsare there because people know that itsgoing to become code, or at least a stan-dard of care. Therefore, its going to drivemarkets and business, and so youve gotlobbyists, youve got...

Gil Avery: It has a profound eco-nomic impact. Standard 62-1989 is almost10 years old and its effect on the country,especially school districts in the South,is being felt. In the humid South, the costof school air conditioning has increased

Weve only been talkingabout indoor airquality in those termsfor about 15 years.Weve just gotten in thebusiness. We dont knowwhat good indoor airquality is as we sit here.

Bill Coad

Doug Simpson Dick PearsonTom Tamblyn


about 40% because of the requirement for 15 cfm (7 L/s) ofoutdoor air per student. Re-heat or expensive heat recoveryequipment is now needed.

Many of the committee members agree that the 15 cfm perstudent is too high because it includes an allowance for smok-ing and other contaminants that may or may not be present. Thequantity may be reduced by addendum to at least that whichwas required by 62R (about 9 cfm [4 L/s]). This is the rightdirection but it does not help the many educators who havewasted millions on unnecessary, oversized, costly equipmentand maintenance trying to comply with the existing standard.

Dick Pearson: The energy standard is primarily applied tonew buildings and politics are at play there, but Standard 62affects existing buildings as well, so the economic impact ismuch more profound.

Steve Taylor: We just hadan addendum to limit the applica-tion to new buildings.

Dennis Stanke: The ques-tion is What should drive thestandard? Were certainly notwriting the standard to save de-sign time for designers, or to makethe manufacturers more money. Ithink it comes down to the occu-pant, odor-related satisfactionand occupant well-being. So, oc-cupant satisfaction and well-be-ing should be the foundation pur-pose for writing a ventilation stan-dard.

Bill Coad: I think the first thing that should drive the stan-dard is technical integrity. If its technically correct, we can de-fend it. If it isnt, we cant. So it must be technically correct. So itstechnical integrity and then occupant satisfaction. The objectiveof everything we do is to provide environmental comfort. I dis-agree that we should have a standard that should have anythingto do with protecting the health of people. I think that thats myjob as a professional engineer, to make sure that Im designing ahealthy environment. And I dont think the standard can do that,because its a variable. It changes every day.

Look at food, for example. One day somethings good foryou, the next day its killing you. We cant give the designengineer hard numbers that he uses blindly to cover his back-side. We have to give him the best information we have basedon the best data available. Then we can defend it.

Dick Pearson: I agree in principle with Bill, but Id like Billto respond to Steves dilemma in basing the rate on an underly-ing principle or purpose behind the ventilation.

Bill Coad: Environmental comfort.Steve Taylor: So thats odor acceptability?Bill Coad: I would consider the environment uncomfort-

able if it smells, but thats not the way its been interpreted.Acceptable indoor air quality has been interpreted as meaningthat we have to guarantee the health of all of the people. Ivebeen told that means that if theres a known carcinogen, wecant have any of it in the space. The fact is we live in a sea of

carcinogens and have for years, natural and man-made. Now Imtold that acceptable indoor air quality contains no carcinogens.Well, we cant design for that. Try as we might, we simply cantachieve it. Maybe we ought to change the title and be on with it.

Steve Taylor: Thats been tried.Bill Coad: But why not for environmental comfort? Its

amazing how healthy we are when were comfortable.Tom Tamblyn: Well, in fact, theyre related. Thats one of

the difficulties. If Im in an environment thats odorous, it willeventually give me a headache and thats a health problem. Soyou cant separate the two very easily. Weve designed comfort-able buildings for years and years with nice environments thatdo not smell. Weve done that. So we know how to do it.

Steve Taylor: The ventilation rates that are in the stan-dard and in the revision to the standard are, in fact, based

entirely on odor. Theres nohealth component to them. Thepresumption is that once yousatisfy the odor criterion, youtend to satisfy the health crite-rion. So were doing just that.The draft standard did not guar-antee acceptable indoor airquality. In fact, it says that bycomplying with the standardyou are not demonstrating thatyou have acceptable indoor airquality, but that you meet all therequirements of the standard.Unfortunately, the standard

thats now in play, which is the old standard, does have animplied guarantee of health.

Bill Coad: Perhaps we can change that.Frank Gallo: What should drive the standard is its title,

purpose and scope. That begs the question, What should bethe title, purpose, and scope? Thats where you start to con-sider economics, occupant comfort, technology, cultural inter-est, all the things that weve been discussing. At the end of theday, the big factor is the purpose for ventilation. In one way oranother, we are going to payeither as a society or as an indi-vidual building ownerfor comfort or discomfort, or for healthor lack of it. If theres too much ventilation, then someone, andeventually society, pays the increased costs for equipment andenergy. If theres too little, society eventually pays throughincreased medical costs or loss of productivity. So one way oranother, economics has a big impact.

The rates in Standard 62-1989 are based on re-moving odor. Is this the primary concern of build-ing owners and occupants?

Steve Taylor: Of course not. When you have indoor airquality lawsuits, it isnt because somebody says, My buildingsmells. Its because they feel they have some health impacts.That goes back to the dilemma. Even if you say that these rateshave nothing to do with health, that they just have to do with

See Roundtable, Page 36

Buildingowners andmanagers haverecognized thatthis is asignificant issuethats not goingaway.

Tom Tamblyn

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odor, people are going to interpret them differently. Theresnothing we can do about that. So it all comes back to healthimpacts, even if we say all over the place that it has nothing todo with health. The fact is, people want healthy buildings andodor is a secondary concern.

Dick Pearson: I think that Im in Bills camp on this basicissue. The primary concern of people in buildings is comfort. Iftheyre comfortable, theyre not going to have headaches andtheyre not going to perceive the various things that lead tolawsuits.

Frank Gallo: Odor has been the subjective benchmark ofperceived IAQ from an occupants standpoint. Thats whatpeople notice when they enter into a space.On the other hand, the highest priorities forbuilding professionals are the health, safetyand comfort of the occupant. I dont believethey even think about odor. In fact, I sus-pect that most people dont realize that theventilation rates are linked to the perceptionof odor.

Tom Tamblyn: Weve been involved ina lot of surveys, and indoor air quality showsup number one or two from the tenantsstandpoint. It ranks right up there with build-ing security. So the building owners andmanagers have recognized that this is a sig-nificant issue thats not going away. How-ever, you want to define the indoor air qualityissue. In my experience, indoor air quality getsdown to a combination of thermal comfortissues and air distribution issues.

Building owners and managers have alsorecognized that IAQ affects the rentabilityof their building and the productivity in thesebuildings. If you start looking at the eco-nomics, the cost of the salaries is about $200per square foot per year. That can be quite aprofound impact as far as tenants are con-cerned, which is why this issue is near the top of the charts.This isnt to say that everybody knows what to do about it.

Should a ventilation standard go beyond ventila-tion rates and include elements such as buildingenvelope?

Bill Coad: A leaky building envelope in a warm, humidclimate is an absolute disaster from the standpoint of indoor airquality and ventilation. I think that beyond addressing the im-portance of the security of the building envelope, we need tosay no more. If were providing an indoor air quality standard,we have to go into the building envelope in detail. Microbes areprobably the most dangerous contaminants, particularly in awarm humid climate. Moisture in the building construction isthe most damaging thing in a cold climate. So if were going totalk about indoor air quality, we cant avoid the building enve-lope. If were going to talk about ventilation, all we have to talk

about is the security of the envelope.Steve Taylor: If a ventilation standard is going to be con-

sidered an indoor air quality standard, whether we say it or not,shouldnt we cover elements in the standard that affect indoorair quality? Designers are held accountable, so shouldnt wesay that ventilation isnt the only consideration?

Bill Coad: I think we should provide in a standard theknown technology. Then the standard should be used by de-signers with full knowledge that if they dont do a good job, itstheir fault.

Steve Taylor: Earlier we talked about limiting the standardto ventilation and not talking about other factors that affect airquality. But is that really doing a service to the core member-ship of ASHRAE, by implying that ventilation is the method of

delivering acceptable indoor air quality whenwe know its not.

Bill Coad: I dont think that implication isthere at all. I think ventilation is one compo-nent. Now, if we say were going to tell themhow to provide good indoor air quality, thenweve opened Pandoras Box. By saying its aventilation standard, were not implying thatyou can provide the ventilation and not worryabout microbes.

Steve Taylor: I think people misconstrueit then. They see ASHRAE as saying heresthe silver bullet. All you have to do to getacceptable indoor air quality is put in the 15cfm (7 L/s) per person.

Dick Pearson: Im back to Frank Gallosstatement: title, purpose and scope. So, Billyou want to say its ventilation for comfort.

Bill Coad: Environmental comfort. Ihadnt thought that one through, but thatsperfectly fine.

Dick Pearson: And, youre making a bigdifference between that and indoor air quality?

Bill Coad: Absolutely.Frank Vaculik: I would like to add to Bills

statement. Yes, ventilation is only one element.The designer is the responsible for making sure that the HVACsystem can deliver an amount of outdoor air, or cool or treat it.How the building is used and abused and misused is beyondthe control of the designer. The standard should say its a goodpractice to provide ventilation at a particular level. But thatdoesnt guarantee indoor air quality, unless some other thingsare also observed. But for them to be observed, youve got toprovide education.

Dick Pearson: I agree with you on the education aspect.But there are many opinions in our industry, and Im not surewere in a position to do a lot of educating now. On certainsubjects, we barely know enough, and were speculating. I thinka concern with the standard now is how much speculation andhow much real knowledge went into various elements of it.

Dennis Stanke: I think the steady state concentration equa-

Roundtable, From Page 34


I think a concern withthe standard now ishow muchspeculation and howmuch real knowledgewent into variouselements of it.

Dick Pearson


tion rate brings this issue into focus. Itsused to maintain a specific concentrationindoors relative to outdoors of any con-taminant, whether its an odor, particulatematter or whatever. If you want to main-tain that concentration level, you dividethe indoor generation rate by the outdoorventilation rate. There are three things inthat equationconcentration, generationrate and ventilation rate. It doesnt workto ignore the first two and just specify thelast. You have to have made some as-sumptions about the first two if youregoing to talk about the last one.

What weve been trying to do, or whatASHRAE 62-89 tries to do, is figure outwhich of those other things have to beaddressed for us to write down the venti-lation rates. You cant ignore the sourcesand you cant ignore the target concen-trations or level of acceptability and justlook at cfm. It just doesnt work that way.

Frank Gallo: Id like to support whatDennis has said. Should the ventilationstandard go beyond ventilation rates? Ab-solutely. The more difficult question is ifthe standard should go beyond the ven-tilation system and parameters that im-pact its design.

What type of guidance do youwant when designing to accom-modate environmental tobaccosmoke?

Bill Coad: If Im given the job to de-sign a space in a building in which peopleare going to smoke, I would like to havesome guidance. Twenty-five years ago Icould go to the ASHRAE Guide and DataBook. They had a column for smokingand a column for no smoking. I dont havethat option today. If somebody asked meto design an air-conditioning system forthis room and were going to have smok-ing, Id go back to the old handbooks.

Steve Taylor: There is guidance inthe standard. The smoking room is 60 cfm(28 L/s) per person. Thats a smokingroom. I think the issue becomes more dif-ficult when dealing with tobacco smokein general, or in a non-designated smok-ing area. And like many things in the stan-dard, its become a political issue as muchor more than a technical issue. And itsgoing to be a tough situation for

ASHRAE as long as our government saysETS is a Class A carcinogen.

Obviously, ASHRAE shouldnt estab-lish whether ETS is a carcinogen, thatssomebody elses job. Well, somebodyelse did their job, and they say it is a car-cinogen. ASHRAE has to respond to that.We cant claim that you have acceptableindoor air quality in the presence of car-cinogens.

Bill Coad: I think you hit the nail onthe head when you said that the govern-ment has decreed that ETS is a Class Acarcinogen and that no amount is accept-able. Theres an awful lot of evidence thatthe government is wrong. Im suggest-ing we dont have to get into that issue.We only get into that issue if were talk-ing about assuring acceptable indoor airquality. Not if were talking about how toventilate buildings.

Steve Taylor: This is where I thinkwere headed, as far as the committeegoes. I dont think the body of the stan-dard will address smoking. But it will beincluded in an appendix. The appendixwill give the guidance to deliver accept-able perceived air quality, which meansdiluting tobacco smoke to a level wherepeople can find it acceptable from an odorstandpoint. That seems like a reasonablecompromise. Dont you agree?

Bill Coad: Yes, as long as its there. Ididnt mean to get off on the tobaccosmoke, because thats a volatile issue. Itjust happens to be one of the carcino-gens that were dealing with. There areothers, of course.

Steve Taylor: Its clear that ourgovernments position on the issue is onethats not technically right. We know thatpeople smoking outside are polluting theoutdoor air so there is clearly a concen-tration of ETS that is acceptable from ahealth perspective. But nobody is willingto put their butt on the line and say whatit is. And, until somebody does, we cantaddress it from a technical standpoint.

How should minimum ventilationbe determined? Is the prescrip-tive or indoor air quality methodmore helpful?

Steve Taylor: Nobody really usesthe indoor quality method. You have tohave three things. You have to know thecontaminants of concern, the sourcestrengths of the contaminants, and theconcentration limits to be maintained. Wedont know any of those three things. Soits an impossible method.

Dennis Stanke: I may not charac-terize it as impossible so much as specu-lative, subjective or judgmental. In myview, designers avoid it because it is toorisky. It isnt a bad idea to have a perfor-mance-based procedure, if we want one.If somebody does, at some point in time,actually know source strengths and con-taminant removal rates at the filter andacceptable concentrations, we could ac-



I think flexibility is whatwere looking for, not just afixed number.

Doug Simpson

Who do we set the floorfor? Adapted persons,visitors, healthy individuals,the infirm, the elderly, theyoung?

Frank Gallo


tually tell them how to calculate the required outdoor airflowrate at a space. The designers can speak for themselves here,but it seems like to me that most prefer a prescribed rate for aspace type. Thats a lot easier than going through a bunch ofcalculations and guessing at a bunch of things.

Doug Simpson: I think that designers do need tables andrates to go by. But I feel we should have more rates than arelisted now. I feel like situations vary. I like the indoor standardwhere you can consider variable occupancy.And to be able to do some balancing as tohow much air goes into the building. I thinkflexibility is what were looking for, not just afixed number. I think we get hung up with 15cfm (7 L/s) per person in a classroom. I look atschools that have an exterior classroom withoperable windows. You have a brand newschool and maybe have an extra door. Andyou look at another school and theyve put inzero windows. Shouldnt there be some con-sideration for the envelope when youre de-ciding how much total outdoor air youre put-ting in that classroom?

Dick Pearson: The other questions are:What is an acceptable level of indoor qualityin the space? What should the standard beshooting for? Just like we have a Class A officebuilding, and a Class B office building, andClass C office buildingwe dont mandate inthe code that everybody should have a ClassA office building. By the same token, weshouldnt mandate in the code that everybodyshould have Class A indoor air quality. Weshould mandate what is a minimum for acceptable health andcomfort. Because thats the basic premise of what codes are.Theyre the floor. And I think that our standards, at least thecode version of the standard, should target the floor. When wehave this guideline document, we can tell people how to make aClass A office building. But the standard, if its the code, shouldbe based on whats the minimum.

Frank Gallo: Who do we set the floor for? Adapted per-sons, visitors, healthy individuals, the infirm, the elderly, theyoung? These are questions that this standard doesnt evenaddress.

Gil Avery: I think we need to leave the flexibility with theengineers. He knows how the building is going to be used.Dont try to dictate exactly how many cfm. Let him decide whatit should be, more or less.

Frank Gallo: Gil, do you think that would open up theengineer to greater liability? Theres really no shield if its to-tally up to the designer to arbitrarily determine ventilation rates.

Gil Avery: Well, of course the engineer always has someliability. I still think he should have the flexibility of increasingor decreasing the amount of air. I think we ought to set theminimum or floor.

Dick Pearson: See, youre arguing basically what I was

arguing, which is basically that we establish a floor thats basedon a Class C-type building, which is the minimum acceptable. Ifsomebody wants to go above that, thats their choice.

Steve Taylor: Its another way of doing range.Gil Avery: You put in a range, attorneys will select the top.Steve Taylor: The complainers will pick the top of the

range, if you dont. So, you have to pick the top. Thats why wehave to only establish a minimum. Its fine if you want to havesome guidance somewhere else that says if you do more, youmay get these benefits. But that shouldnt be in the code be-

cause the lawyers will twist that.Dick Pearson: Complying with a code,

of course, just gets a lawyer to ask the ques-tion a different way. Hell explain that a codeis nothing but a minimum standard and ask ifyou only design for minimum standards. Idont see this changing our liability. I think Iagree with Bill Coad. If we are professionalengineers, we have a liability. I dont see thestandard as a shield or a weapon. Im just notconcerned about that.

Steve Taylor: There is a difference if youviolate a code because guilt is clear. If youviolate a standard of care, there is at least somegray area. So, it does matter if we feel the ratesare too high and we want to do somethingless. You cant go less than a code. So, weneed to make the level in the code appropriate,so that you wouldnt want to go below it.

Bill Coad: This gets back to the oldASHRAE Guide and Data Book that has mini-mum and recommended rates.

Dick Pearson: Except now, because ofthe legal things, well have minimum in one

book and the recommended rate in another one.Bill Coad: Which really is kind of circumventing the prob-

lem.Steve Taylor: If we could digress on that one point, Id

like to get your opinion on something. In 62-89, there is a mul-tiple space equation that tells you how to take ventilation ratesin various spaces served by a common system and figure outwhat you need to bring in the system. Its not very commonlydone. And when I talk to ASHRAE Chapters about whats go-ing on, few know what it is.

Weve had lots of debates in the committee because it addsa level of complexity that most people are ignoring, but theyseem to be getting away with it. But philosophically you haveto address it. Because, if you say youre supposed to deliver Xcfm to this room, you should do it. If thats the right number,you should figure out whats required to actually deliver thatventilation rate to that space, even though it introduces com-plexity to the standard. Before Dennis got on the committee, Ihad swayed the committee into throwing that stuff out. Wewere going to use the California Standard approach which saysbring whats required into each building and dont worry how



You cant go less thana code. So we need tomake the level in thecode appropriate, sothat you wouldntwant to go below it.

Steve Taylor


its distributed. You just add up the outside air for each space,and thats it. But Dennis and a couple of others on the commit-tee said that cant be right. If youre going to be true to yourself,and what little we know about technology in ventilation, thenwe really cant do that. So the committee has gone back to themultiple space equation. Id like some feedback on this.

Bill Coad: If the engineer doesnt worry about getting theventilation air into the space, theres a good chance the systemisnt going to work. Thats what engineering is all about. If amultiple space equation is the way you do it, then thats oneway to do it. Another way is to just deliver the ventilation air tothe room. People have done that for a long time, and it workslike a charm.

Dennis Stanke: I agree with that 100%. Thats a differentkind of ventilation system. It has better efficiency then a mul-tiple space recirculating type of ventilating system. Differentsystems have different efficiency levels. You described a veryefficient one.

Steve Taylor: But, the fact exists that most engineers arentdoing it. So that means that maybe we need to mandate it.

Bill Coad: I have a problem with that. I think that we canonly do so much in a standard.

Dennis Stanke: Manufacturers often talkto a designer about a VAV system right afterthe designer realizes that the conference roomin an office space is going to need a richermixture of outdoor air than any other place inthe building. The next question is, How do Iknow how much to bring in at the air handlerthen? The answer is, You solve the multiplespace equation if its a multiple space recirculating system.Thats been in the standard for a long time. I dont think weshould just blow it off. I think we should help them answer it.

Dick Pearson: In response to Steves comments aboutthe multiple space equation, I think the message is very clear.Its 1998 and we have a standard dated 1989. It contains a mul-tiple space equation that virtually nobody is using or evenunderstands. Why is that so? I think its for two reasons. One isthat building code officials cant tell whether youre using it ornot when theyre reviewing your design. More importantly, Idont know that we have that many problems in real buildingsbecause were not using it. I believe were getting away with itbecause the required rates are too high. They are so high thatwhen you dont comply, the space is still okay.

Tom Tamblyn: And so we havent developed a floor stan-dard like we thought we would.

Dick Pearson: Unfortunately, I dont think 62-89 was in-tended to be a minimum standard. If we lower ventilation rates,then maybe the equation would come into play. The entire con-cept of this standard in providing minimum levels of ventilationshould be re-examined.

How should compliance with a standard be deter-mined?

Bill Coad: Its very difficult. Because nobody really knows

how much outside air is really coming into the building. So howcan we comply? Even if you try and measure the outside airintake, its difficult to do in most cases.

Steve Taylor: I think one issue needs to be really clear inthe language. Compliance is not whether you have acceptableindoor quality or not. Its not an operative term. You complywith the standard when you meet the requirements of the stan-dard. Compliance does not mean that everybody in the build-ing is happy.

Frank Vaculik: So, you would use design intent?Steve Taylor: I think that compliance can be shown, just

like compliance with any other code. You see if the require-ments are in fact there. But because of the title of the standard,we tend to expand compliance into meaning that youve actu-ally delivered health. It should be made very clear that that isntthe case.

Frank Vaculik: No, but we can show that we have deliv-ered the ventilation rates as designed. And that is difficult.

Bill Coad: Thats precisely where my opening commentswere going. We can verify and measure that we are providingthe ventilation, although it can be difficult. Thats part of thebuilding commissioning process, and I think it should be donein every building. We could measure CO2, humidity, air motion.

If were going to write an indoor air qualitystandard, we should have a way to comply. Ifwere going to write a ventilation standard,its much simpler.

Dennis Stanke: Compliance could beconsidered at three different times: design,installation and operation.

Doug Simpson: I would like to add afourth to Denniss compliance issues. I think

that manufacturers would have a place in the compliance bymaking sure that the system is built to do the good things that weneed to do.

Steve Taylor: One of the offshoots of showing compli-ance is that it has to be observable or measurable. It has to bereal things. This inevitably gets into system efficiency issuesbecause the only element you can really measure is how muchoutside air is coming in that outside air intake. And you have tofigure out how much is required to deliver the outside air to thatcritical space. This gets into the complexity of the multiple spacesissues. Thats the big dilemma. If we get into it, we have com-plexity and we dont have the simplicity that everybody wants.Well, its not a simple problem. So what do we do?

Bill Coad: Well, engineers designed the system. If the sys-tem is unmeasureable, then hes designed it wrong.

Frank Gallo: Lets flip the questions around and ask howis non-compliance with the standard determined. Unfortunately,this often is a legal issue. But thats what happens when youdesign a system thats not easily verifiable.

What do you think could be concluded from thecomments expressed here?

Frank Gallo: I still think that we have a diversity of opin-ion when it comes to even the title, purpose and scope of thestandard. Standard 62 is a subjective standard that affects people

Compliance could beconsidered at threedifferent times: design,installation andoperation.

Dennis Stanke




in many ways. The challenge for the So-ciety is to develop a standard that canmeet the needs of diverse populations.

Doug Simpson: I hope that we canget a standard thats practical and under-standable, and can be complied with. Weneed to be realistic. Were not going tobe living in an ideal world. The standardcant make engineers do good engineer-ing. We just need to give them some toolsand guides.

Tom Tamblyn: I think in the finalanalysis, the standard should have itemsthat are measurable and quantifiable, notjust in terms of compliance and design,but also in terms of the implementationfrom an operation and maintenance pointof view. Im still hopeful we can do that.

Dennis Stanke: Standard 62-89 isvery important to our industry. Its gotsome strengths, which we didnt talk muchabout, nobody ever does. Its got someweaknesses, which we talked a lot about.We need to fix weaknesses and build onstrengths. Since it already is such an im-portant document for our industry, letsimprove it and do it as quickly as we can.

Gil Avery: A ventilation standard thatis written for code adoption must be con-cise and simple, and all requirements mustbe verifiable in the field with test instru-ments readily available to HVAC techni-cians. The standard must not be complexsince all verification will be done by me-chanics and journeymen, not by design-ers, engineers or architects.

Bill Coad: Four of the people aroundthe table have been living with the stan-dard for a long, long time now. Its easierfor non-members to expound on these is-sues. But I think that we respect the mem-bers of the committee who have beenworking so hard on this. Its a very, verydifficult endeavor.

This is a very complex issue. I think thatour job is to make it as simple as we possi-bly can. And I would suggest that we havetwo standards. I think we should start bytrying to streamline, update and fix up ourstandard on ventilation. We should findsome way to appropriately address thereasons for ventilation. But if we stick tothe ventilation, the designers will have atool that they can use to design. Then theSociety can have a dialogue on indoor airquality. If that leads to a standard on in-door air quality, so be it. But at this time, I (Circle No. 32 on Reader Service Card)

dont think were quite ready for it.Dick Pearson: I agree it should be

as simple as possible. We should face upto the fact that nine years have gone by,and the multiple space equation is sel-dom used, or even understood. We can-not forget that a standard which becomesa building code must be understandable

and usable by plan examiners, buildinginspectors, and, as Gil has said, some-thing which can be implemented and veri-fied by HVAC technicians. The presentstandard, and the proposed revisions donot provide the required simplicity. Itseems clear that there is much additionalresearch needed, especially in health-re-



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lated issues. I agree with Bill that weshould specify ventilation for comfort,until we are more sure of the health-re-lated issues.

Steve Taylor: We need to make surethat we dont simplify if it isnt inherentlysimple. The challenge is to make it simple,flexible and technically correct. You cantalways have simplicity and flexibility atthe same time. You cant always have sim-plicity and technical correctness at thesame time unless the issue is inherentlysimple. Which, unfortunately, this is not.So we have to find a compromise. Fortu-nately, we have two documents now. Wedo have a standard and a guideline wherewe can put the complexity into the guide-line and the simplicity into the code.

The dilemma, of course, is that youcant go below the code. The code shouldbe somewhat conservative when youhave to make many simplifying assump-tions because you want to make sure youare not under-ventilating. But if you have

that flexibility of reducing the ventilationrates when you dont make those simpli-fying assumptions in the guideline docu-ment, you cant take advantage of thembecause the code says you cant go be-low this. To a certain extent we have tobuild that flexibility and complexity intothe code document just so designers cantake advantage of them without violat-ing the code. Its a tough challenge.

One other thing that I would like to sayis that ASHRAE is the right place to bewriting the standard. If we dont, some-one will and theyre not going to do asgood a job. I know that ASHRAE has beentrying to avoid the controversy that sur-rounds this standard. I think weve justgot to say that comes with the territory.These are controversial things. And if itbrings controversy, so be it. Were willingto do it, because its the right thing to do.

Frank Vaculik: We have to acceptthat we still have a lot to learn, but wecannot wait until all the knowledge is ac-

cumulated. We have to act on the knowl-edge we have at this time. The standard,which is needed now, has to reflect that.We have to have the courage to say thatwe dont know everything but this is thebest we can do based on our knowledge.We need to realize that indoor air qualityis not only a design issue. Its an issue forthe commissioning people and the build-ing operator. We need to think about howto transfer the knowledge to where theindoor air quality is being manufacturedand produced on a day-to-day basis.


What Engineers Want in a Ventilation Standard

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