ASHRAE Journal:
ASHRAE Journal presents
Bill Bahnfleth:
We did a research project back in those days and tried to apply them to some different buildings and found that some things didn't work and some things actually made the situation worse. We can't just follow this like a checklist and assume it's going to work in every building.
ASHRAE Journal:
Episode one: William Bahnfleth and Jason DeGraw discuss ASHRAE Epidemic Task Force's Core Recommendations.
Bill Bahnfleth:
Hello everyone, my name is Bill Bahnfleth. I'm a professor of architectural engineering at Penn State and past president of ASHRAE and perhaps more to the point of today's discussion, the chair of the ASHRAE Epidemic Task Force. I'm here to have a conversation with Jason DeGraw, who's also involved in the task force. I'll let him introduce himself.
Jason DeGraw:
My name is Jason DeGraw. I am the program manager for weatherization and intergovernmental programs at Oak Ridge National Laboratory, and I am the transportation team lead for the ASHRAE ETF.
Bill Bahnfleth:
So for the last 15 months or so, Jason, we've been involved in this effort of developing guidance through the ASHRAE Epidemic Task Force, which has been kind of all-consuming for some of us, but not everyone is paying quite as much attention to it as we are.
I think it would be good if we tried to clarify a few issues about what the ETF is, and what it's been doing and that may help the listeners have a better idea of how to interpret what comes out of the taskforce. Very briefly, the Epidemic Task Force was formed by direction of the ASHRAE executive committee back in March of last year, and we were really put together as kind of a rapid response team to provide guidance on what to do with HVAC systems during the COVID-19 pandemic.
I emphasize that what we're producing is guidance and recommendations—not standards. I think that's one thing we want to make very clear is that what we're doing is trying to deal with the present situation and the future is something that will require a lot more discussions although we intend to weigh in on that as well.
Maybe one more thing I'd like to say is that from the beginning, what the ETF has done is to make recommendations on the assumption that airborne or aerosol transmission is possible, which initially was kind of in contradiction of what WHO and CDC were saying, but that's what we've been doing.
I think the thing we want to talk about today is the ASHRAE Epidemic Task Force’s Core Recommendations, which were published in January of this year for a couple of reasons. There was an inward facing reason for doing it, which was because we were trying to produce a lot of guidance rapidly. We've got almost 400 pages of guidance now that's been developed, and we had over 130 people working on it. There became at some point an issue of coordination, so that while everyone was working so rapidly, they could stay on the same page as far as what commercial buildings group was recommending and the schools team and all of the others.
But there was also an outward facing purpose to make sure that the public knew what ASHRAE was actually recommending at a given point in time, and you've had a lot of involvement in that aspect of it. Maybe you want to expand on that point?
Jason DeGraw:
Sure, thanks, Bill. So what we were hearing from our partners—both within the Department of Energy and some of our partners from outside the Department of Energy—was there was a need for sort of simplified guidance was mainly what they were asking for. But I think that most of the members of the ETF would agree that simplified guidance for something like this is going to be very difficult to provide.
So while we couldn't provide simplified guidance, we could provide an entry point that would provide a higher level sort of overview of the guidance that we were providing and in enough detail to engage somebody—but not so much detail that it gets into the weeds and requires the sort of expertise that so many ASHRAE members already have and looking outward both professionally in my career and also as part of my volunteer work with ASHRAE.
The Core Recommendations for me were more an almost ammunition to use when speaking with people outside of ASHRAE, people outside of, for me, research and buildings, but for others that are in more practical aspects of buildings a way to communicate with those people that need to know some of these things, at least at a high level, but maybe don't need to know all of the details around why we would want to choose MERV-13 filters, for example, which we'll talk more about later.
And then definitely also to help with what you mentioned earlier, which was what is ASHRAE's position? I mean, even today, it hasn't happened within the last couple of weeks, but I do hear people say, “Oh ASHRAE said you should run your systems 24/7.” And maybe that was in an ASHRAE Journal article maybe, but I don't think ASHRAE ever said that.
Having these Core Recommendations as an entryway into the very extensive guidance that we have up on the webpage provides an easier way to communicate what ASHRAE current position is and not maybe things that were either not our position or were very early on sort of positions.
Bill Bahnfleth:
Yeah, I think you raise a very important point there about the guidance being dynamic.
Actually, we may not even remember on the task force where we started out, but there was a recommendation to run your systems 24/7 and another one to increase outdoor air as much as possible. But that came out of the Infectious Aerosols Position Document that was expedited. That's a publication in April of last year, and so that immediately created some, I think in retrospect, quite justifiable pushback about, ‘Well, what's the impact of these recommendations on energy and do we really have to do this and do we really have to do all of it?”
So it was very important to pin down where we actually are. And then like you, I occasionally see organizations adhering to ASHRAE guidance that hasn't really been enforced for six months or more. So that's an important thing.
And so let's maybe skim through what's in the Core Recommendations and expand on that a little bit as we also did in the ASHRAE Journal IEQ column that we wrote a couple of months ago.
The first aspect of this is follow public health guidance. We don't want to give the impression that if you do things to improve your HVAC systems management of infection risks that you don't have to do other things. In particular, distancing and use of masks, during the height of the pandemic, are very important because HVAC systems can't do much about close range transmission by droplets, and masks provide some level of reduction of both source emissions from people who were infected ,and also the amount of infectious aerosol that may be inhaled by someone who isn't infected. So that's all good and should be done.
But after that, then we get into things that really have to do with HVAC, like ventilation, filtration and air cleaning, which has been probably the most important section of all. Then there are four sub points in there.
The first one is to at least have minimum code ventilation in your building. It's surprising. well, maybe it shouldn't be surprising, but a lot of people are surprised to find that a lot of buildings really have no mechanical ventilation. And if there is ventilation, it depends on them opening windows. We're not saying that minimum ventilation is necessarily enough, but we should be at least there as a baseline.
With respect to filters, you already mentioned MERV-13s, and those were recommended from the outset because they looked like a pretty cost-effective near optimal level of filtration but even that has generated a lot of pushback because some say that they can't afford to put them in. Some say that they can't put them into their central systems because of the impact on fan power or other considerations.
One of the things that changed over the course of six months or so is we're no longer saying you must have MERV-13 filters, but [we] say combine your filters with other filters or air cleaners to get that level of performance. So perhaps two MERV-11s in series or a MERV-8 plus UV or something like that actually satisfies that requirement.
And the other thing that I think has been pretty contentious there is whether central filters are really effective and that's kind of situational, but I think we are finding that in-room air cleaners are quite effective.
The next thing is that we've recommended to be careful about what air cleaners you pick if you're going to supplement ventilation and filtration. There's a wide range of evidence basis and independent research for different kinds of air cleaners and also a wide range in terms of standards that are available for properly rating air cleaners. We're really consistent with the CDC and others and with other ASHRAE position documents in saying that.
And the final thing that is in that section has to do with selecting control options to achieve exposure reduction targets while minimizing associated energy penalties. And what that really is saying in maybe-kind-of-an-obscure way is that you can combine all of these different things: ventilation, filtration and air cleaning to reach targets in a way that doesn't add a lot of energy use to the building or that doesn't compromise comfort in the building.
There's a lot packed into those four little statements ,and obviously they can't capture all of the nuances, but that's the point of entry is we were saying to ventilation, filtration. The next section is on air distribution. That's really your expertise so maybe you could say a few words about that one.
Jason DeGraw:
Sure. So I guess maybe before we even talk too much about air distribution. One of the reasons that there's less in there is that I think that the ETF agreed that there maybe [there] was less that could be done sort of in the short-term on how distribution works.
And in many situations, I mean, and speaking from in both the office that I work in when they let me go back to it and in the space I am in now, changing how air distribution works is a non-trivial matter. It is not a coincidence I think that ventilation, filtration and air cleaning are number two, rather than other way around.
One of the things about air distribution, you do want to try to do things that are going to minimize the amount of trapped infectious aerosols that may be present in a space. And you don't want to have air currents that are moving from person to person. There's a famous Korean restaurant case where you can sort of draw a line between the infected persons. And while we can definitely talk about how you want to keep that sort of thing from happening, it's very difficult to determine beforehand that may be what's there and certainly changing that is going to be potentially quite difficult.
We embedded in that statement on air distribution about promoting mixing, which I think is just as important as the rest, that by mixing you reduce the concentration of any pathogen at any particular location. So there's just less risk. We don't know what the infectious dose of the COVID-19 virus is, and we may never know. So doing things like just promoting mixing can reduce the risk of having sort of a cloud of a pathogen come across a person and infect them.
Bill Bahnfleth:
There's something I wanted to add on here, and it kind of goes back to the previous recommendation is that there are some important interactions between ventilation, filtration, air cleaning and air distribution that we are really still working on within the task force.
One of the important ones is how does air distribution in a room affect the performance of standalone air cleaners, or how do standalone air cleaners actually function in a given space? And that's an area where we don't really know enough yet and are trying to find a way to recommend something to the public that will help them to do that effectively.
And the other thing is I mentioned combining controls to reach risk reduction targets. Well, that actually suggests that we know how much uncontaminated air needs to be delivered to a space to control risk, and that's been probably the other really thorny problem that we're trying to address and that's still in progress. Our science applications team is working on both these air distribution and ventilation rate issues, and we hope to publish something useful about it soon, but they're among the hardest things we've tried to deal with.
Jason DeGraw:
Yeah, I think that since we still know so little [that] some of these things are very hard to get at, and it's sort of... I think that a lot of the guidance that we've given, all those 400 pages, a lot of it, you need to do more than just one thing. It's not enough to think about just one aspect of this problem. You need to think about your systems, your people, everything all at once, which makes it harder.
Bill Bahnfleth:
Yeah. And you have to, even though we've got 400 pages of guidance, you still have to use it as a starting point and apply it to your actual situation. I hear all the time from people say, “Well, this is too simplified, and that's too simplified.” And I agree with them.
There are complexities in real buildings that need to be assessed when deciding how to use these things. And it reminds me of all the guidance that was written for protecting buildings from biological weapons 15 or 20 years ago. FEMA and others put out a lot of really nice checklist about things you should do, and we did a research project back in those days and tried to apply them to some different buildings and found that some things didn't work and some things actually made the situation worse.
I don't think that's happening with anything we're recommending now, but we can't just follow this like a checklist and assume it's going to work in every building.
Jason DeGraw:
Yeah exactly. I totally agree. I think it's a pretty good segue into the next point, which was the HVAC system operation, where there's a four sub bullets again.
I think what runs through all of these is that there's a building-specific aspect here that none of these are going to work for everybody, and it may not be perfect, but again, this is an entry point into what's in the overall ETF guidance on particular buildings. These four items here sort of cover all of them, but you do have to think about what your building is and what your building is intended to do before you really think about how you would apply these.
The first item here is maintain temperature and humidity design set points. I recall very early on in the pandemic, maybe they were apocryphal stories about people wanting to shut off their HVAC systems. Well, if you shut off your HVAC system in the wrong climate area, you could have a real problem for your occupants. You may be reducing their risk of contracting COVID-19. You may be risking their health through the thermal stresses.
I think that's part of where that item is coming from. You want to keep your building operating as it should be so that their systems are doing what they should be. You obviously don't want it to increase people's risks, but the design set points are there for a reason.
Humidity has sort of waxed and waned. There's a popular topic on this: what's the humidity range that you need to be in to reduce infection risk? I think that at least part of the ETF would agree that while there may be some impact of humidity on infection risk, it's perhaps less than doing things up in your ventilation and filtration and air cleaning that you can get more bang for your buck there if you're making sure your systems are operating as they should be.
The second item is maintaining equivalent clean air supply for design occupancy. Whenever anyone is present, I think there's some risk there for thinking. You really do need to think of everyone that's potentially a source for the virus that even if they're the “just the cleaning staff” there for an hour or two after everybody's gone, they're just as much at risk as anyone else. You really need to be operating the systems in a way to protect them as well.
Bill Bahnfleth:
Yeah I think this point also gets into the operation of the demand controlled ventilation controls. So it's implicit in this one that you maintain the design outdoor air for the design occupancy all the time and don't allow your DCV system to turn it down to a really low level because that's not good for infection risk management.
Jason DeGraw:
Exactly. The third item is the controversial flush. I think with our original guidance, we were talking about flushes before and after. Certainly flushing a space before or after occupying periods is perhaps superfluous if you're able to do everything else perfectly, but in my experience, most buildings are not operating perfectly. There's always going to be challenges in doing things and there are cases where maybe it would make sense to do it a pre- or post-occupancy flush just to make sure things are at a lower risk.
I think that we picked three air changes, which the old first order differential equation gets us down to something like, what, a 95% reduction. Is that what it is? If you just run your systems for another couple of air changes, you get a great deal of reduction there.
Bill Bahnfleth:
And of course, someone will say that, well, if the ventilation effectiveness isn't good, then that may not be enough. And that's another one of those points that we've been saying that people should look at.
And then the other thing here is that this flush between occupancy periods, if you need to, like between classes is really also overriding that original recommendation to run systems all the time. So this really creates an opportunity to cut way back on the energy impact of enhancing risk management.
Jason DeGraw:
Yeah, certainly running your system for a couple extra hours or a couple extra hours, it's certainly going to be a lot cheaper than running it overnight.
The last item under HVAC system operations is limiting re-entry of contaminated air. I think this one I've already done, maybe, Bill, you can correct me if I'm wrong here, but I always felt that this one was more of just for this particular virus in this particular situation that re-entry is less of a risk but more looking forward or even looking backward to the SARS epidemic back in, what, 2002, that timeframe, that virus was much longer lived, and there was much more possibility that exhausted air could either re-enter or re-enter into another space and cause more of a risk. So this one is maybe less applicable for this particular pandemic, but in terms of overall sort of preparedness, this one is a good one just for more general purposes.
Bill Bahnfleth:
Yeah, and of course, there's a backstory to this one too. This is another thing that was put in here specifically because the original recommendation had been to shut off energy recovery wheels, which obviously is not going to help with energy use of building. Something that we worked on quite a bit (There's a lot of guidance on it now at the ashrae.org/covid19 pages) in building readiness is under what conditions is it safe to use an energy recovery wheel? Which is most of the time. Most configurations actually are safe to use. So once again, this is updating the guidance from where we started to where we are now.
Jason DeGraw:
At least we commented a couple of times that perhaps some buildings don't work exactly as intended all the time, and that's sort of the last item in the Core Recommendations is a system commissioning one: verify that HVAC systems are functioning as designed.
There's evidence that everyone sort of thinks their building is above average—that like woebegone situation as it were. In my life as a building researcher, we've encountered all sorts of strange things in buildings from fans installed backwards to the dead pigeon between a coil and a filter. And I didn't get to encounter that one directly. I think that was one of Bill's students that got to see that one close up.
The fan installed backwards had been there at least five years, and it was taking the air through the system backwards. The air was going out the returns and in through the diffusers, and nobody noticed. Nobody noticed. It was only when we were doing sort of a commissioning operation to determine whether or not we should use the building as part of this demonstration project did someone notice that, “Oh, well, this fan is installed backwards, maybe we should fix that.”
And that one is maybe an easy one to talk about maybe kind of funny, but when you start looking at school buildings and things like that, the story can get pretty bad actually.
There's a GAO report, the way it's expressed is a little funny, but it's 41% of school districts—at least half of the schools—need updates or replacements or repair of their HVAC systems. And that one, when you start talking about schools, that's a lot harder to laugh about if 40% of the schools out there need work on their air-conditioning systems.
That doesn't speak all of us perhaps keeping our systems working well. And then I think probably everybody has their own personal story about how the system that served their office or room or something was somehow not perfect, but the guidance that we've put out there, all those 400 pages are much less impactful if the systems aren't working like we think they are.
Bill Bahnfleth:
Yeah, this is something that many have been talking about for a long time. Gordon Holness, when he was president, his theme was maintain to sustain. But the importance of keeping systems operating properly is something that I've seen in some of the reports that I've read during the pandemic [which] has been that if they would do commissioning to make sure the systems are operating properly; you normally can expect perhaps 10/15% improvement in energy use of an out of whack system. And some of them were reporting that that was basically paying for the cost of any upgrades they might be making.
Completely aside from the pandemic, I think it's a good opportunity to reiterate the importance of maintaining systems well.
That's the Core Recommendations. and it's scratching the surface of a lot of issues that are explored in more detail in the guidance that can be found in the COVID-19 resources page.
I think looking forward, one of the things that we've discovered is that there are a lot of things that we thought maybe we knew that we don't know nearly as well as we ought to, and there are many projects for the future that will keep us busy years into the future. Some of the things that we've talked about here: what should ventilation rates be? How should air distribution be designed to be more effective in spaces that we haven't really paid much attention to in the past? How do you deploy air cleaners? Standards for some of the emerging technologies that aren't available now. So many, many projects there.
I think it will be interesting to see how much of what we've learned during the pandemic, and how much of the pain that we've experienced during all of the different things that have happened to people, working from home for over a year and not being able to go to restaurants and then some people losing their jobs, losses to families who have had loved ones die.
All of that is really something we don't want to experience again. But I have to say I have a lot of concern that we'll be able to maintain our resolve after all of this is over and really follow through on these things. And I say that, unfortunately, because I've seen it before. I have a presentation, or I go through example after example about how we've been told how important indoor air quality is and how we've had lesser epidemics and other things happen and we always managed to forget how bad things were and go back to the way things were afterwards. And I hope that won't be the case this time. I know that your employer, Jason, is talking about this and maybe they'll have some positive impact here in changing standards and best practices in the future.
Jason DeGraw:
Yeah. I certainly hope so. I don't think we want a repeat. I know you did a lot of that research back after the 911 anthrax attacks. As that sort of receded into people's memory and people coming into the workforce [and] into the research field that don't even remember those sorts of things now. I have seen some people redoing some of the work that was done back during that timeframe. It's just we don't have a good record in terms of remembering some of these things.
I do have a sort of a broader question for you: how do you think this should change what we do? Should HVAC designers be thinking about pandemic modes when they design HVAC systems, or do we need the manufacturers to be part of that? Does it need to be everybody?
Bill Bahnfleth:
I think it's a comprehensive project. We need an approach to making buildings safe when they need to be safe that won't make them either too expensive to build or energy hogs. We've got to do all of this in the context of sustainability, and I think we need to bring together the idea of healthy buildings or wellness. What really is the appropriate baseline all the time in buildings? So we know from work that was done 20 years or more ago by Bill Fisk and others that there's a huge benefit being lost because of the level of air quality in buildings if we look at the healthcare costs and the productivity benefits that could be achieved.
We merged that with the idea of resilience. That's the other thing is thinking about how we can design systems to be adaptable. Resilience in the past has meant earthquakes and floods and that sort of thing. We want to extend that concept to indoor air quality, both with respect to infectious diseases and also with respect to outdoor events like wildfires.
At one point during the last year, you'll remember we were trying to figure out what we should say to people from the West Coast who were asking, “Do I open my outdoor air intake to protect myself from COVID knowing that I'm going to be bringing in smoke from the wildfire nearby?” I think those are important questions to address.
We need to bring energy focused people and environment focused people into this as well. So it's a big, big challenge, really a grand challenge and the words that some like to use and if we can make some progress towards that goal. I think we'll really be changing life for many people for the better.
Jason DeGraw:
If I can just add on the topic of resilience [is] that there's always been sort of a focus on resilience of infrastructure in terms of what we should care about. Nobody really cares about the resilience of an office building or the resilience of somebody's house until it matters like it mattered this time because when we talked about regain of functionality sort of resilience. How quickly can you return to standard operations that had always been?
The conversation had always been sort of about the metal boxes. Is the HVAC system able to work? Do we have electricity to power it? Does it work in a condition that the spaces if you can't have anybody in there because of like this pandemic? It doesn't really matter if the systems work properly.
It doesn't really matter if the building itself is ready to go if you can't have people in the space. That's just as important as making sure that all of the metal boxes work after Superstorm Sandy where you had all of those mechanical rooms flooded, and the systems are out. They have to be replaced.
There's just not enough systems available, so you have the sort of lead times. And that's a sort of way I know I thought about this problem, is more in the sheet metal boxes [is] that we have and making sure those actually work when there's an equally important component to this: that if you can't have the people there, it doesn't matter if the building works as you intended it.
So I hope that the resilience conversation will change a little bit after this where we won't be so focused on command and control-type resilience as much as resilience of the building stock as a whole.
Bill Bahnfleth:
Yeah, and I think it's good to point out that I hope everyone has read the ASHRAE Strategic Plan. It's not a long document, but the two technical emphasis in the 2019 Strategic Plan that came out less than a year before the pandemic started were indoor environmental quality and resilience. So we were almost there. We knew it was an important issue, but we didn't get the solution out in time. But that just shows that this is something that we've identified as a priority for the future, so that makes me a little more optimistic than I may have sounded in my earlier comment.
Jason DeGraw:
Yeah, I think that having been involved in the resilience cognizant technical committee for a few years, a lot of those conversations over the past 10 years have been sometimes fairly frustrating when people wanted to only talk about the grid and whether the grid was okay. “Let's talk about the resilience of the grid.”
Well, if anything, I hope that one outcome is that people will recognize that it is important to talk about the resilience of residential buildings in a serious way because having been working from home now for so long, it seems like I don't even know what it's like to be in an office anymore. It's just a completely different thing, and I feel like at least personally now, when having conversations with people about resilience of maybe nontraditionally resilient buildings.
It's a bit easier to convince people now because before that nobody really wanted to talk about anything but the grid. While the grid is important, if everybody's working from home, you got to have good enough conditions at home to be able to work.
Bill Bahnfleth:
Yeah, I think the terminology is changing or the understanding of what resilience means. I know that's a good sign too, but who knows? We'll see. I've been watching this happen for more than 30 years of my career, and we've gotten close to really making a paradigm shift in the past. Maybe now is the time.
I was just looking for quotes to use in another one of my talks, and I usually try to quote literary or historical figures, but I found a great quote from Captain Jack Sparrow in Pirates of the Caribbean. He says to the guy who was wanting to express his feelings for a pretty young lady. He says, “If you were looking for the opportune moment, that was it.”
I hope that a few years from now, we don't feel like we've missed another opportunity and have to wait for something bad to happen again to take another run at it.
ASHRAE Journal:
ASHRAE Journal Podcast team is editor Sarah Foster; managing editor Mary Kate McGowan; and associate editor Chadd Jones. Original music by Chadd Jones. Copyright ASHRAE.
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