Here you find the text version of the webinar, Building America: Score with Indoor Air Quality, presented in October 2016. Watch the presentation.
Linh Truong:
Hello everyone. I'm Linh Truong with the National Renewable Energy Laboratory. We'd like to welcome you to today's webinar hosted by the Building America Program. We are excited to have Brett Singer here today to discuss Indoor Air Quality. Before we begin, I'll quickly go over some of the webinar features.
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Before our speaker begins, I'll provide a short overview of the Building America Program. Following the presentation, we'll have a Q&A session and closing remarks. For more than 20 years, the U.S. Department of Energy Building America Program has been partnered with industry to bring cutting-edge innovations and resources to market. This webinar will discuss the development of an indoor air quality scoring system and the planned elements of a national new home study.
Now for today's presentation. Our webinar today is Building America; Score with Indoor Air Quality. Our speaker today is Brett Singer, staff scientist and group leader of Indoor Environment in the Energy Analysis and Environmental Impacts Division at Lawrence Berkeley National Laboratory. He is a principal investigator in the Whole Building Systems Group in the Building Technologies and Urban Systems Division. The recent focus of his work has been indoor environmental quality and risk reduction in high-performance home with the goal of accelerating adoption of IAQ, comfort, durability and sustainability measures into new homes and retrofits of existing homes. I'd like to welcome Brett to start today's presentation. Brett?
Brett Singer:
Thank-you very much. It's very good to be here. Thank-you for inviting me and thanks to all the people who are taking some time out of the middle of their day. I'm going to dive right in and I do encourage you to send in your questions. I designed the presentation to allow lots of time for questions and look forward to engaging with you in that way. So as noted, the title of the talk is Building America Research: Score with Indoor Air Quality. You've heard who I am, so I'm going to dive right in.
So the outline. I'm going to first talk about the connection of this work to the Building America Roadmap. I'm going to talk about the IAQ score development, the baseline field study and then we'll do some questions. Pretty straightforward. So the roadmap, hopefully most of you know that there is such a thing as a Building America Roadmap. If not, I highly encourage you go check it out. This enables us all as a community of researchers and implementers to accomplish a lot more than we would if we were all just working independently without a roadmap, which is what a roadmap does, of course.
So it's broken into three main areas, and these are areas that the Building America Program has determined are very important and an opportunity really for government-sponsored research to advance the industry and that's really the ultimate goal. So the three areas are high-performance moisture managed envelope systems, optimal comfort systems for low-load homes, and the one I'm going to be talking about today is optimal ventilation systems and IAQ solutions for low-load homes. There's a little key down there. Kudos to Eric Whirling and Sam Rashkin and some others for developing a really nice visual cues about what is in the roadmap.
Overall, the roadmap objectives is to take what is now considered best practice, demonstrate that and then ultimately to translate that to standard practice. Specifically looking to manage risks to adoption of more advanced measures, address optimal performance and cost-effectiveness and ultimately the solutions must be both practical and profitable. Like I said, it is a tech-to-market program. None of this stuff is going to be successful until it becomes part of the marketplace.
So very busy slide here. This is a lot of information condensed down into one slide. Again, I encourage you to go and read the roadmap. Each of these boxes represents a substantial amount of work. What you're looking at here is a six-year planning horizon. This was first conceived back in I think 2014. That's why it starts in 2015.
You're looking at three general areas in this sphere or optimal ventilation IAQ, targeted pollutant solutions, smart ventilation and IAQ valuation. You see the big purple box around that bottom one because the material I'm talking about today is in that realm of IAQ valuation. You see there's a developed IAQ baselines and valuation metrics, guidance and assessment tools and 62.2 transition to IAQ equivalents and smart systems. For those who don't know, ASHRAE 62.2 is a ventilation standard put out by the ASHRAE organization for the purposes of achieving acceptable indoor air quality in homes.
It is the basis for code adoption in some cases like in California. It's being used in the weatherization program, part of ENERGY STAR.® So this ASHRAE ventilation standard is a cornerstone element of ensuring acceptable indoor air quality in high-performance homes. I will talk a little bit more about that below.
So the IAQ score – I probably should have had a score before to say why we want to have an IAQ score. So I'm just going to say it now, which is it's part of this concept of IAQ valuation is that I think at this point thankfully the concept of indoor air quality and the importance of indoor air quality is recognized by many people. People care a lot about their health. People want to create safe and healthy homes for their families. For a lot of people – first of all, we spend a lot of time at home, and then for a lot of people, if you have any kind of health ailment, susceptibility, your compromised respiratory system, asthma, elderly, et cetera, spending a lot of time at home making that environment healthy for you is critically important to your well-being.
So we all agree that indoor air quality is important. What we have lacked until now and unfortunately still lack but hopefully not for much longer is a way to put a direct score or value on that. The analogy would be so something like a HERS score for the energy performance of your home where you can actually see how your home is going to perform against other homes in your area. I'm kind of against the standard home in your area.
So what is the IAQ score? What's the vision for this IAQ score that we're creating? First of all, it's going to be an asset rating. That means we're going to rate the home, not the people in it. What do I mean by that? The actual air quality that results in your home has a lot to do with what you do.
If you smoke, for example, you're going to have terrible indoor air quality in your home. I can design a home and put things into it that help reduce the impact of your smoking, but by smoking you make a decision to dramatically and negatively impact the air quality in your home. We're trying to as much as possible take what the people actually do in the home out of the equation. What we want to see is, "Is the home set up to or designed and built to provide good indoor air quality?" So if you kind of do normal stuff in your home within the bounds of what we consider normal – that doesn't mean you do nothing.
You're going to still do activities. You're going to use cleaning products. You're going to use personal care products. You're going to cook hopefully. I certainly love to cook. You're going to do all these things that will release moisture and odors and pollutants into your home. That's OK. Your home should be able to deal with that though and still provide you good indoor air quality.
If you're barbecue grilling, if you're burning trash, if you're doing crazy stuff in your home, we can't do anything about that. So that's kind of the idea. It's about the home, not the people. We rate features based on effectiveness. How well do they control their air quality? How usable are they? How robust are they? I'll talk a little bit more about that.
The vision is it can be applied to almost all homes. Certainly to existing and newly constructed. So it's not just for new homes. But it can rate new unoccupied homes. It certainly can rate single, detached, and attached homes. Also can do multifamily units with dedicated systems. So that would be sort of individual systems. Multifamily units with shared ventilation systems and high-rise units bring in a couple of really, really big other elements. We would still like to be able to score those homes, but we have to figure out how to deal first with the most common set of challenges and then we're going to go to those kind of extra challenges.
So the scale on scoring. This is still a little bit up in the air but our rough concept at this point is that we're looking for something where 100 is excellent and most – we expect most of the space we're going to be seeing homes get rated in are going to be something between 60 and 100, that if you're below 60 you're really not doing so well. We thought it might be fun since we have this standard 62.2 that's so widely known and talked about, if that minimum kind of acceptable score was 62.2 instead of 60. We may have to play with the numbers a little bit to get that to work out but stay tuned for that one. The general idea is you're going to get points for things that are protective and you're going to lose points for hazards. Very straightforward in concept.
Components scores. So ultimately there's going to be one final score, but there's three main components that I wanted to point out. So when we're thinking about the features that should get points, the first is dealing with acute and chronic health hazards. So these are kind of the pollutants; PM 2.5, radon, formaldehyde, acrolein, NO2. I'll talk a little bit more about those in a few minutes. The other two are satisfaction and odor as one and moisture hazards as the second.
So satisfaction and odor, we're talking about things like toilet rooms. If you're in an apartment, inter-apartment transport is an odor and satisfaction. It can also be a health issue but it's first that. Cooking, nearby outdoor sources, et cetera. For moisture hazards, things like unvented bathrooms, drainage issues, obviously observed dampness or mold. Anything that would increase the likelihood of microbiological growth, mold essentially, which is a very prominent established health hazards. Then we're still working how we would roll up these components into a composite.
So what are we thinking in terms of the component scores? The reality is one of them we have worked out pretty well an objective, quantitative way to do it. The implementation is not simple but the concept is simple, which is we can look at sort of standard case of some variations and standard cases and we can calculate concentrations and pollutants that are likely to be in homes and then the effect of some feature on those concentrations. So a typical example would be we know that formaldehyde is emitted from building materials and finishes.
If you have a baseline ventilation system that's going to lower your formaldehyde levels and if you turn down your ventilation, you're going to have higher formaldehyde levels. That translates to some exposure and intake of the pollutant. Then based on how much formaldehyde you take in, there's some risk of disease, cancer, et cetera; cancer being really the most costly one. If you get the disease, if you get cancer, there's a cost per incidence of cancer. Then we roll all that up into a unit called disability adjusted life years. I'll talk a little bit more about that in a minute. But it is a measure of harm.
I just want to point out, we're still working as we're still in the early stages – with the other two we have distinct challenges. For satisfaction and odor, we need a way to quantify the harm. No one likes to have – everyone wants to be able to control the odors in their home and have the ability to get rid of them, but what's the value of that, the economic value of that? We're still working on that.
For moisture hazards, we have an additional challenge, which is trying to quantify the risk and then the harm. So the harm would be, "What's the cost of having dampness or mold in your home," and we know that there's some health risk that comes along with that. But first we need to figure out – to make the connection between the hazards we see. So for example, if you don't have a venting, ventilation, exhaust ventilation in your bathroom, bath or shower room, what is the risk that you're going to develop a dampness or mold problem? It's not so straightforward.
It's not known to my knowledge. If someone does know that, please let us know. It probably depends on some features like, "How many people are regularly showing in that bathroom? Do you have ventilation at other parts of the house?" Et cetera. So each feature that we're going to try to score, unfortunately for us, has a tremendous amount of complexity to it and we're going to – our overall challenge is to try to get that kind of first order or piece of that without getting lost in all the complexities.
So I mentioned disability adjusted life years. We call them DALYs. It's a combination of years life lost to premature death and then the equivalent years lost to disability. So obviously, if I die, then I lose a lot of years of my life. But if I get sick and I'm compromised in some way – I have really bad COPD or I can't walk up the stairs or whatever the issue is, that makes my life less fun to life and that's a cost, too.
So other people have worked out these costs. They've worked out – the fundamental pieces to it are there's some risk of getting disease for every increment of pollutant you take in and then there's some disability adjusted of life or DALY cost for the disease. If I multiply that out, I get DALYs per pollutant. The reason we do DALYs is because it's a way for us to compare or aggregate cost across pollutants.
So it's a way for us to compare the cost of getting lung cancer to the cost of having chronic asthma, for example. There's a reference. There's a Logue et al paper, an Environmental Health Perspectives, 2012. That journal's actually online. It's a government-sponsored activity so you can download that paper and read it.
So we did the [audio skips] _____ a few years ago in that paper where we looked at information we had about pollutant concentrations in homes and we went through that calculation for all the different pollutants that we had information about. Then we were able to aggregate that across all the homes and see kind of what we got. We got a somewhat surprising and very useful result which is – what you're looking at, the measure here is DALYs per year per 100,000 people. You see there are scientific notations. So that's on the bottom there. 100 is 1, 101 is 10, 102 is 100, et cetera.
So what you see is that PM2.5 comes out on top. So the fine, particulate matter – what's the PM2.5 is – that you breathe inside your home, if you look across the whole population, that is the air pollutant that causes the most harm across the U.S. housing stock. The second most harmful pollutant is second-hand smoke, SHS. Now if you live in a house – and second-hand smoke includes PM2.5 – if you live in a house where someone is actively smoking a lot and you're exposed to second-hand smoke, that's your biggest health hazard for sure.
The reason why across the population second-hand smoke is second is because that only happens in a relatively small number of homes. So there's a minority of homes it happens. So if it's happening, it's a really big thing, but it's only happening in whatever is it, five to ten percent of the homes. So across the population, it's not the most important. You work your way down.
Mold, moisture is next. Now that's from the EU estimate. I actually think that number may be bigger than that. Then we see radon for smokers is a really bad synergy that happens between radon and smoking. So if you're going to live in a house with high radon, don't smoke. If you smoke, don't live in a house with high radon. Of course, ideally don't do either one of those things. Formaldehyde, everyone knows that one.
There's another pollutant people don't know as well. It's called acrolein. You see these really, really wide error bars. The reason why we see big, wide error bars for acrolein is because the estimates of the disease incidents from acrolein come from animal studies. So it's a lot of extrapolation from how harmful they are from the lab rats that get fed the acrolein and get cancer to how much it is harmful to humans. So that's why this big error bar is there. So it might be extremely important and it might be not as important as some other things. Then we get to radon, ozone, NO2, et cetera.
OK, I'm going to move on. So why am I up to Input from Expert Workshop? OK, great. So score. We did an expert workshop to get input from experts, of course, about some of the key questions that we were facing early on. These were kind of high-level conceptual questions. The experts suggested or advised us to not have any mandatory features to generate a score.
So we wouldn't say, for example, "You only get a score if you have a mechanical ventilation system," or, "You only get a score if you, whatever, have a roof." Now obviously, if you don't have a roof you're not going to get a very good score, but we'll still give you a score. No measurements are required, but this is a third point that while no measurements are required, you would get much larger credits for verified equipment performance.
So if I have an exhaust fan in my bathroom, great. I get something for that. But unless someone can verify that it's actually moving enough air to be useful, then I'm going to get a lot less credit. That's just because many of the experts who participated had sort of first-hand knowledge of lots of cases where they, themselves, or they know people, colleagues who go into homes and realize that the mechanical equipment is not working as it is supposed to be.
Outdoor air quality is relevant. This is a tough one because it's going to mean that some homes are penalized for where they are. But the reality is, objectively, one of the biggest determinants of your indoor air quality is the outdoor air quality. That's where the air is coming from. So there are ways to address that. If you have polluted outdoor air and you run your ventilation air, supply air through a filter, then you can eliminate that hazard. But in the absence of that, we have to acknowledge that polluted outdoor air is going to increase risks for the indoor air.
Certainly there will be credits for contaminant control including dehumidification. It's a big issue in certain parts of the country. We have a lot of discussion about what hazards should be penalized. We said we're not rating the people but there are things that people can do to a home that go beyond their occupancy. So if I smoke in my house for 20 years, when I move out that house is terribly contaminated with tobacco smoke chemicals.
So the contamination, it's not so much that I'm smoking that's the problem. The problem is that the house is contaminated. So we did agree that anything that is going to persist beyond the people – so if I move out today, anything that's left in the house that presents a hazard to the next person that's moving in tomorrow definitely should count. I'm going to talk a little bit more – the main ones there were tobacco and mold, the emphasis of mold issues.
So let me give an example of how this is going to play out. Let me give several examples. So these are some features that will have positive or negative points and I broke it into those three categories of health, satisfaction and moisture. So for example, building a house with low-VOC materials and finishes. That's a very popular thing. It's in a lot of lean home rating systems. That would get you positive points but for health and satisfaction.
Full bath ventilation; again, there's probably some points for health but it's more about odors. Remember, satisfaction includes odors and moisture control. Kitchen ventilation; there's a lot of pollutants that get produced when you cook using chemicals and cleaning products and things like that in your kitchen. So that's actually going to cover all three because there's odors and moisture, as well. If you have leaky ducts and your ducts are in a crawl space that's in contact with the ground, that could certainly impact your odor and satisfaction and your moisture control, as well.
If you have a sealed four-inch filter box on your heating and cooling system to enable you to put a deeper, low-pressure draw filter and it's well-sealed so you don't have pass through or you don't have air moving around the filter then you would get more points. You'd get positive points. An unvented fireplace is certainly going to have important health implications and also moisture implications. Ducted HRV with filtered air supply to the bedrooms is going to be a health positive feature.
If you have an apartment with a verified low cfm per square foot measured so you know that your apartment is tight with respect to the surrounding building that's positive for your odor and satisfaction and probably helps with moisture control, too, in terms of the robustness. Right? High outdoor air pollution is obviously a negative. So there's some examples.
Now we're getting into kind of refinements. Refinements, the feature characteristics are very important. Simplistically, you could say, "Well, if I have kitchen exhaust ventilation I should get credit." Definitely. But we probably want to break that down.
So just having the ducting for kitchen exhaust ventilation is worth something. Because maybe your range hood is really crappy, but if you have a crappy range hood but you have a low-pressure drop duct to the outdoors you can always replace that range hood with a better range hood. Right? So you probably get credit but for having the capacity for it built in and then also for having a kitchen exhaust fan. Then you could say, "Is it operational?" You can maybe break it down further there.
Is the kitchen exhaust – if it's a range hood as opposed to just a fan somewhere else, that's a positive thing. If you can verify that it has measured flow greater than 100 cfm, again, get some more points. If it has a rated capture efficiency, I gave two pluses for that, where LBL is working with ASTM to develop a capture efficiency test method. But if I've had that hood tested and know that it removes 90 percent of the pollutants generated to the cook top that's even better.
Alternately, if I know that it has a good flow rate and is quiet I'm even more likely to use it. Then if I go all the way to the fact that the hood is interlocked with the cooktop so when I turn the cooktop on, the hood turns on or there's a sensor activated [audio skips], probably even better. I have a few slides to talk about why we would do that which is an example of how these things are not so simple, which is we know from surveys that people don't consistently use kitchen exhaust ventilation even when they have it.
So this is from a California study. A few hundred respondents. What we saw is that – and these are people who are probably more likely than the common person because they volunteered to do this indoor air quality study. Even within that group, about a third of the people said that they use their kitchen ventilation about half the time or more. You see, only about 13 percent they used it all the time. About a third said they use it when needed and about a third either didn't have it or said they never used it.
Unpacking that a little bit, we see people say that they use it when they – to remove smoke, odors, a little bit on moisture and then a couple other reasons. This is consistent with the idea that a lot of people will turn it on when they per see that it's needed but not at other times. Again, very consistent, why do they not use it? They say, "I don't need it. It's too noisy. I don't think about it."
We see that coming up in survey after survey. So for these reasons, something that's quieter gets them points. But the big thing is if it's going to turn on automatically you get a lot more points because it's going to be lot more robust.
So development of score. The initial score will have to rely heavily on expert assessments for the reasons I described. We're going to build up from reference elements. Development scores for a core set of features and then other features will be scored in relation to the reference score. So with that actually is core, the core set of issues. Enable all three components to be on a single scoring basis. Then the target is to have a beta version for pilot testing in quarter two of calendar year 2017.
Some issues are still mulling over. Should pollutant measurements – they're certainly not required. Should they be considered if available? If I measure – if I take a measurement of formaldehyde in my home in a meaningful way and I see that my home has very low formaldehyde even though I didn't use low-emitting materials – it could happen – or I didn't intentionally use or I didn't verify use of low-emitting materials, should I get some credit for that? Should we give any credit for documenting what's in the home?
I'm going to talk about in a minute, a lot of people don't know anything about their ventilation systems. So if there's a printed guide somewhere, if I can go in their home and maybe it's sitting there somewhere obviously, should they get credit? If there's a maintenance schedule, should they get credit?
What to include in their hazards? I mentioned tobacco and mold. Radon would be another. Are there others? Then ultimately, we think this should correlate with actual IAQ in homes. Now it's not going to be a one to one correlation. I could have a high IAQ score for my house and still burn trash and still have really bad indoor air quality.
My home could have a low IAQ score but I could just do nothing other than just sit in the lotus position in that house and – maybe it's an older house that doesn't have any fresh materials that are emitting anything. I'm not burning anything. I live in the country. It's clean air. Maybe the IAQ is just fine even though the house is a tenth. OK, so that's that part of the presentation.
I'm going to dive in now to talk about the national baseline study. I'm hoping it's about another 15 to 20 minutes and then we'll do questions. So thanks for hanging in there. I have to tell you. Someone who does a lot of live presentations, this is a little bit interesting in the sense that I have no idea if anybody's listening now and I hope that you're all still on the line, at least a few of you.
Linh Truong:
Brett, this conference is – yeah, there are people listening because questions are coming in. So…
Brett Singer:
Great. Thank-you. OK, I'm starting to feel – OK, I won't make the political joke but I feel like up here anyway. So homes being built – why a national baseline IAQ study? What's the rationale? Well, we know that homes are being built with tighter envelopes throughout the U.S., even in places that aren't necessarily at the forefront of energy efficiency.
The industry is learning how to build homes better, which is wonderful. I think there's a consensus on the need for ventilation in tight homes, but there's a lot of discord on the details. There's certainly limited data on ventilation equipment that's going into homes and the practices that people have and how they use it. Certainly, there are really vibrant ongoing debates about various provisions of that 62.2 standard.
There are some people that say that the dwelling units rates – by the way, that means like the general ventilation or the whole house ventilation. Dwelling unit is the new term of art. So everyone really focus in; that's the term to use, dwelling unit ventilation rate. Some people say those rates are too high and they can be lowered and save energy and some people say, "No, no, no; they're too low. If you look at what the Europeans do, they have rates that are much higher. We're not adequately protecting health."
There's similarly discord or debate about the value of distributed supply ventilation. There's lots of debate about the importance of other design features, balance supply exhaust. Does kitchen need rapid distraction? I think it does. But there's some people who feel like if you can just have your ERV pick up in your kitchen and pull a constant 30 cfm or bump it up to 50 if you need to, that's good enough. There's people like myself that say, "No, the evidence suggests that you need to be able to rapidly remove the pollutants generated from cooking and other kitchen activities."
Here's one bit of data. So this is from the California New Homes Study. Bud Offermann was the lead investigator. He wrote a great report to the California Energy Commission. It's also on the California Air Resources Board website. If you have trouble finding it, let me know and I can help you find it.
But what he looked at here is measured formaldehyde concentrations. These were homes built 2002 to 2005 and then they were measured two to five years after they were built, I believe, if I have that right. So these were not brand, spanking new homes which would have even higher formaldehyde levels. These were a couple of years old. You see distributions or the concentration is across the bottom.
The cumulative frequency – so the way to read this plot is, for example, if you look at the 50th percentile – so on the left-hand side you see 50 percent. You move across that line. OK? Then what you see is at the median the 50th percentile concentration was 36mg/m3. If you look just to the left, there's a dashed line running vertically which is the Air Resources Board IAQ guideline of 33mg/m3.
So what that says is that 60 percent of the homes are above that and that's because the 40th percentile – so the 40th percent home has that concentration. The other 60 percent of the homes have concentrations higher than that. As you might guess, that was not seen as a very good thing. The interpretation or the explanation for this was that there was inadequate ventilation. If these homes had been better ventilated, we would see lower formaldehyde concentrations. LBL has done work demonstrating that when you turn up the ventilation you definitely do turn down the formaldehyde and this study also had some data to support that.
OK, so that's one bit of the rationale. Another bit is we know very little about what's being installed in homes in terms of ventilation equipment and how it works. I mentioned a few studies here. I'm going to talk a little about two of them. One was in Florida, published in 2015 by FSEC; a fine report. There was a nice report done by Washington State University that was done for the Northwest Energy Efficiency Alliance in 2015. Then there's some work done in 2012. Then also going back, that Offermann paper had some work, as well.
So first the bad news. Bad news first. The Florida report, this was done after the 2014 state code required mechanical ventilation for homes that were tighter than 5 ACH50. They did a field study, went out to 21 homes. They surveyed. They measured. They looked around. They found that there was a lot of confusion people had between the ventilation and the heating and cooling system. I can confirm.
We're doing a study now in California, which I'll tell you about that certainly still happens. Only 12 of the 21 homes had systems that were capable of operating. Only 14 percent of the homes had air flows that were near – I guess that's 3 of the 21 – had air flows that were near the design and 2 of those were turned off. So only 1 of the 21 was operating with the design air flow. OK? Sorry about the extra 3/21 there. So that was the 3 of the 21 was the 14 percent. So out of 21, 1 of them had operating ventilation that met the design criteria. So that's sad. We were sad to hear that.
Pacific Northwest, that was a much happier situation but it's because it was a stacked deck. They looked at 29 homes in Washington State. These were well-constructed homes. These were by builders that were kind of building with high-quality build tight, ventilate right. They – not typical homes. So we don't think this is reflective of all homes.
Although, we think probably in Washington things are probably a lot better than they are in Florida in large part because they required ventilation for a quite a long time. So there's been 25 years of learning. I talked this morning with a researcher from Washington State and he said that he thinks that in general they use a lot of exhaust ventilation. There's probably a lot that have reasonably close or within spec ventilation. That was Mike Lubliner from Washington State.
But even in Washington, even in these really well-built homes there was still wide variations in understanding about the ventilation systems, how to maintain them, et cetera. This study, the focus was on the effectiveness of different system designs. But the reason I put this up is because when they walked into the homes they found that ten of them had air flows that were set below the standard but that was mostly just that they were set below standard. All had proper capacity and all were operating. So it wasn't perfect but it was basically all good.
Now between those two, the question is, "What happens everywhere else across the country," and we really don't know. We're doing a study right now in California. It's a follow-up to that study I mentioned early by Offermann. The goal of this new study – we being Lawrence Berkeley National Lab. The goal of the study is to evaluate mechanical ventilation – basically whether the mechanical ventilation that was required in the 2008 code, does that adequately protect indoor air quality? So that requirement was put in before the Offermann study was completely finished in part because we already – we're seeing evidence before that there were some issues.
So the study we're doing now, two main phases. There was an online survey. We got 3,000 responses. That was from single family, townhouse, duplex built in 2002 or later and we're currently doing a field study. The goals of the field study are the characterized and mechanical ventilation equipment that's in the homes, measure air flows and then monitor equipment use and IAQ parameters over a week.
Just a couple of results in the survey. We thought they were kind of interesting. Thankfully, the vast majority of the people felt like the indoor air quality in their home was good. They were satisfied. So we had a nine or maybe – I guess it was a nine-point scale. There were – about a third of the people were kind in the middle. Then there was the relatively small number but a non-negligible number of people who were dissatisfied with indoor air quality.
Just as a reference or a context, we did ask about outdoor air quality. It broke a little differently. So in general, people were happier with their indoor air quality than outdoor air quality, which is kind of interesting. I should have mentioned I'm sure all you astute viewers have noticed that we're looking at three blocks for each of these which is the groups – homes groups which is the 2002, 2005 homes. Those would have been the Offermann homes. Not the same homes obviously but the same vintage. Homes built in between and then homes that were built to the new standards, to the new code.
This was really interesting to us. So we asked people, "What equipment do you have in your homes?" This is an all answer. We've done other surveys where we've done it as an interview and when we do it as an interview, we're able to identify when someone's confused about a question. In an online survey you can't do that.
So this really gets to not just what's in the home but implicitly what people understand about what's in the home. So thankfully, a lot of people were able to recognize that they had a bath exhaust fan in their home and that they had kitchen range hood. All of these people – because even before it was – it was still required. So all these people have bathroom exhaust fans in their home and thankfully almost 90 percent of the people knew that.
The fresh air vents – so quite a few. So don't know how many really have it but we suspect that there's a good number of people. So maybe this is a lower amount. Whole house fan. Now that's actually something different. That's in most cases probably a cooling. We were asking about a cooling thing in that case.
So that's a – which is a very big fan that quickly extracts air from the house, blows it up into the attic so you can – when it gets cooler in the evening you can turn over the air very quickly in your house for energy savings. Some small numbers with kitchen exhaust fan. This is the one we thought was interesting. The continuous ventilation exhaust fan. Certainly in 2000 – that last group, 2010 to '15, almost everybody has one of these or at least the majority of people. That's the most common ventilation system they can put in and very people knew that they had it.
Now it could be that enough of – many, many, many of the people have turned it off. So they're like, "No, I don't have anything continuous. We turned that off years ago." But many of them should have it. HRV/ERV was as we would expect small numbers. Probably a few more people than that have them but we would be surprised if it was large numbers.
OK, so getting back to the national baseline study. I brought up some of that California stuff because it kind of, again, helps motivate what we're recommending nationally. The goal is to collect data on pollutant air flow, building and HVAC systems in recent construction, occupied homes and varied climates around the U.S. The idea of doing this is to inform standards and technology development, to protect IAQ as new homes are built to more stringent efficiency standards. It's all in the service of – from the Department of Energy's perspective, it's primarily about being able to make energy efficient homes.
Now everyone wants to see healthier homes, but the Department of Energy is an energy business. So we want to make sure that we maintain protection as we make the homes more energy efficient. Then there's also a goal of comparing 62.2 compliant homes to non-62.2 homes.
Specific objectives; measure humidity, air pollutants and ventilation equipment use; track activities that impact emissions and removal; characterize mechanical ventilation designs, et cetera, investigate associations. Very similar to what we're doing in California but with a more of an interesting humidity when we start going to other parts of the U.S.
Study elements. We certainly were always reviewing and compiling existing information. We still hope there will be a survey element to this. Even with people being unsure or unclear, we still get really useful information out of the survey although linking it to something where we can link a survey, web-based survey responses to some kind of interviewer or ground truth thing is always helpful. There will be a stage of data collection in homes and the study will be modeled after the study in California with a similar aim but there will be some differences in the implementation.
Pollutant measurements. We're recommending measuring time-resolved PM2.5 by light scattering. Do I have it all on one slide? Let me just go right through this slide. It's summarized here but look better. So there's time-resolved. This means we can see kind of what's happening over time. PM2.5 using light scattering, that's not a direct math measurement but it gives it a pretty good estimate of PM2.5. CO2 we're not measuring as a pollutant per se but we're measuring as an indicator of occupancy and bio effluents, what's coming out of the people. When you see high CO2 then all the other stuff that's being emitted by people is going to be a high concentration.
Certainly temperature and relative humidity are important. We'll be looking to do ozone, NO2 and CO2 using sensors. We may not do a lot of CO measurements. That will be dependent a little bit of the house. If it doesn't have gas appliances, there's almost no need to do the CO. If it does have gas appliances, then we do it. But unless we see kind of unvented appliances we usually don't see any CO. Then temperature, humidity in bathrooms. I mentioned master bath because there's other pollutants in a central location and in some cases bedrooms.
Then we use some time integrated stuff. We do NOX, NO2 with an integrated sampler. Formaldehyde and acetaldehyde, speciated volatile organic compounds. That allows us to look at individual chemicals. Then radon probably will be in areas that are – if any sampling happens in designated high-radon areas, then I can't imagine that we wouldn't do that in those homes but it's probably not going to be needed in all the homes.
System diagnostics and monitoring. So we look at the things you'd expect; air leakage, duct leakage, exhaust fan flows, clothes dryer vent, et cetera. So we measure the flows and then we also monitor how they're used.
So how does this fit into the Building America process? The request that has gone in is that the FOA that will be released this fall would request proposals to conduct that field study around the country for teams that are interested in conducting the field study. LBNL in our operating plan has been submitted for FY17, which starts in a couple of days. Our operating plan involves or includes some technical support work where we will help the program further develop the study protocols and then when teams are selected, again presuming that that plan gets approved, when teams are selected then we'll work with the teams to finalize study protocols, et cetera, kind of all the details.
I'd say if you're listening to this and you think you might be interested in proposing to be one of those teams, the thing to do is just to watch for when the FOA comes out in the fall. Anything that I tell you now is my understanding of what's happening in the process, but nothing is official until there's actually a FOA released. Then when the FOA is released, you should respond to what's called for in the FOA. So if there's anything in the FOA that's any different than anything I've said today, ignore me and pay attention to the FOA because that's where the official word is. I'm just a researcher from LBL who's taking up a couple hours of your afternoon.
I think that's all of my prepared material. I would be thrilled to answer questions.
Linh Truong:
Great. Thank-you so much, Brett. As we go through these questions I'm going to start at the very beginning. So I'm going to let you keep control of the slides, and if you need to refer to one of your slides in answering your question, feel free to do so. Just as a reminder to the audience, if you haven't done so already, please feel free to continue submitting your questions. We will go through as many as we can today.
A few of you have raised your hand. Unfortunately, due to the number of folks on the line and the questions that we're going to be going through we won't be able to unmute you at this time. But feel free to submit your questions through the question pane. So Brett, let's go ahead and start with the first question. The first question relates to the data that you alluded to at the very beginning. "Is there any data that correlates to the benefits of effective IAQ such as improved health or lower healthcare costs?"
Brett Singer:
It's an excellent question. So there are lots of studies that look at exposure to pollutants and health outcomes. Most commonly these are looking at health-compromised people because you want to look at the sub-population where you're going to see the most effect. So for example, there are studies showing that asthmatic children who live in homes that have higher NO2 measured concentrations or who have more use of unvented cooking, gas cooking, they have more asthma symptoms. So the frequency and the severity of their asthma symptoms are worse when they're exposed to more NO2 in their homes.
So we take from that the benefits of reducing NO2. Now if you're a perfectly healthy person, you get an important monetary benefit from reducing NO2. That's highly uncertain. We don't have data as to that. There's some other data going the other way where studies have looked at outcomes, health outcomes, for example, of implementing filtration. So putting portable air filters in bedrooms of, again, asthmatic children and some of those are even very nice slate designs where there's a fake air filter.
So there's something else that – they have a box that's always moving air through it. Sometimes they drop a filter in and sometimes they take a filter out. They look at the asthma symptoms and those studies have found if you reduce exposure to particles then you improve asthma outcomes. So there's lots of data like that. Building America is not a health research organization. So we have to rely on the NIH research and other research funders who – researchers who do that primary research. What we do is we have those data or those study results linking exposures to pollutants in your home and either positive or negative health outcomes. Then from that we infer that if you can reduce the pollutant levels you're going to get those benefits.
Linh Truong:
Great. Thank-you. The next one is a comment and then a question. "When you're working on scoring the satisfaction and odor points, you may need to look at outside sources of odor and locational issues. For example, a farmhouse might have odors from the farm, which the owners might accept but visitors might object to. What are your thoughts in dealing with issues like that?"
Brett Singer:
Can I go to the next question? That's a really tough one, right? Cooking is another one. So I'm going to pile on myself here. Certainly a lot of people cook for the very reason of – for the whole point of creating odors in their home because they want to smell that bacon or they want to smell those whatever it is, muffins baking. So what we're looking for is we're looking for homes that have the capacity to deal with those odors so that the occupants can choose whether or not they want to implement those controls.
I'm going to stop at that answer. I recognize that might not be entirely satisfactory but if you live on a farm and you like the smell of the farm, great. If the question was, "Are we going to penalize a home for being on a farm because of the odors of the farm," that's a tougher one that we haven't dealt with. We were thinking more along the lines of being in maybe congested urban areas where there's like a lot of odors from traffic-related stuff or if you're down-wind of an industrial site. Farm's a little tougher one. We just haven't discussed that.
Linh Truong:
OK. I hope this next one's a little bit easier for you. "What household items does acrolein come from?"
Brett Singer:
Good question. It comes from some wood products. So it's a natural reaction product to some of the chemicals that's in wood. It's also emitted – probably the biggest slug of it comes from cooking oils. So it's a breakdown product of the cooking oils when you heat them to high temperatures. There's some others – I'm not an expert but those are the two. So it's kind of wood-based construction materials and oils. I think there's some others, as well. Those are the big ones, though.
Linh Truong:
OK. Then on slide 11 you had information on formaldehyde. They were surprised by the high number related to that. Were you surprised? Want to make any comments about that number related to formaldehyde?
Brett Singer:
Oh, if you think those numbers are high, go hang out in some FEMA trailers from even later than that or go back 30 years. Formaldehyde levels have been coming down. It came to kind of public consciousness as we started building tighter homes for energy efficiency. Then a lot of insulation was produced with formaldehyde urea resins and the formaldehyde emissions were a byproduct of that production. We recognized that there was a health hazard. At high levels, it's an irritant. At low levels, it's still a carcinogen. But they've been basically coming down over the years.
Was I surprised that – California numbers are actually very consistent with numbers that we see from other studies when you put in that historical trajectory. What I'll tell you is that – I wanted to add this slide; probably should have. We do see that – two things. One is when you build a home with low-emitting materials you see lower formaldehyde. So materials that they're sort of certified low emitting.
One of the things they're low-emitting of is formaldehyde. We did a study. The first author was Hult, H-U-L-T, and published in Building – no that was an indoor air study I think, the Journal of Indoor Air. That study, we found that building with low-emitting materials meant that your homes had much lower formaldehyde. I think it was like going to be 40 percent lower than conventional.
California passed an air toxic control measure that reduces formaldehyde emissions from manufactured wood products. That was in the 2000s. Then the federal government passed the Formaldehyde Control Act, I think is what it was called, maybe in 2012, that modeled that California regulation. The regulatory structure of enforcing that as a federal law is still I think not yet finalized but hopefully close.
So what we expect to see is that from those two things, formaldehydes sort of come way down. From the first few homes we've been looking at in this newer California study we are seeing those, as well. It looks like new homes in California have much lower formaldehyde then they did back when Offermann did his study.
Linh Truong:
OK. The next question is, "What are the qualifications for the experts determining the IAQ score for a home?"
Brett Singer:
The short answer is to be determined. It's one of the open questions about, "Should we make a recommendation about that or should we leave that to the marketplace where we put the score out and then it's up to the market to figure out who should be allowed to use it?" I think what we expect or envision is it's most likely going to be people like HERS raters. It's going to be people who – now I don't know if you're going to need as much training as you need to be a HERS rater, but it's certainly something that could be kind of an additional training for somebody that has that kind of training.
That would be a good time to do it, right, because you're going out in the home and making measurements already of air flows, et cetera. You're checking for a lot of equipment. So those people could probably do it very efficiently. Whether it will be put out there in a way that any homeowner could go and score their own home, I don't – we haven't made any firm decisions about that. I'm reluctant to even venture a guess as to how open-ended the scoring community will be.
Linh Truong:
The next question is, "How about credit in new construction if the exhaust supply and return ducts are sealed during construction?"
Brett Singer:
Sounds like a good thing for me. So yeah, I mean that's the kind of thing. If you're saying well-sealed ventilation ducts, yeah, that's something that we think is kind of a robustness issue. So I don't know if it will be a lot of points but I can see giving points for that.
Linh Truong:
What, if anything, is being done to rate CO risk?
Brett Singer:
To rate CO risk. We have things about CO. It's, as people know, mainly an acute issue. We do know that unvented combustion can produce CO levels that can exceed standards. There is a DALY mechanism for doing it. So we've used it.
We've done it before. I think we've done it before. I'll have to check on that. I'm going to stop there. The acute – what I will say, is the acute – the DALY analysis I showed before was for chronic exposure. We've done some estimates of acute exposure and the cost of the _____ [audio skips] didn't do them directly with DALYs. We did them with incidents of specific health outcomes. The reason is because we did them with a very few pollutants.
I think we did it with NO2 and CO, actually. That wasn't a DALY analysis but that was a health impact analysis. Really what we're looking for is to try to credit for the reducing the likelihood of having CO ever exceed the acute health standards. I don't know if we need to do that with a DALY analysis or if we can do that otherwise.
Linh Truong:
Next question is, "What about the value of humidity control as it relates to defining the comfort zone?"
Brett Singer:
Can you repeat the question? The comfort – repeat the question, please.
Linh Truong:
What about the value of humidity control as it relates to defining the comfort zone?
Brett Singer:
Comfort, yeah. There's another Building America team that's working on a comfort score. So we're trying to stand clear of that, recognizing that comfort and indoor air quality – comfort and satisfaction with the indoor air quality are closely linked. So when people are uncomfortable they rarely say that they think the air quality is good. But in general, we're trying to – when we talk about moisture we are looking for kind of dampness and mold risk, not comfort.
Linh Truong:
OK, great. What is an acceptable indoor PM2.5 measurement?
Brett Singer:
What is an acceptable measurement? Is that what the question was?
Linh Truong:
Yeah. What is the acceptable indoor PM2.5 measurement is the question?
Brett Singer:
The answer to the question as framed of what's an acceptable measurement is a device that we think has been validated to report quantitatively, which doesn't mean perfectly but quantitatively a concentration that would correspond with the reference measurement, which would be a mass measurement. That would be taking a filter and weighing the filter to see how much the weight, the mass, the micrograms of particulate matter that are available for each or that were captured for each meter cubed, mg/m3, for each meter cubed of air that was drawn through the filter and there were certain devices, which have been validated for doing that. I think that's the answer to the question as framed, though.
I'm guessing what they want to know if really what's a desired PM2.5 level concentration. We don't have a simple answer to that. The health effects literature is mostly based on outdoor PM2.5. So when we frame the PM2.5 health effects, we know it's an imperfect analysis because the data that we have, the response functions essentially are based on measurements of outdoor PM2.5 and then the resulting health outcomes, cost, people going to the hospital for various diseases, people dying, et cetera. Those are usually framed as a change in health effect per increase of 10 mg/m3 of PM2.5.
Now whether there's a threshold level below which we can say there's no problem, we wouldn't have that. We would be doing it all on an incremental basis. So that I guess the answer to the question of what's a good number is lower is better is 10 – there are outdoor standards. There's like a 24-hour standard. There's an annual standard. The U.S. EPA has a standard. California has a standard. So I'd say refer to the standards as kind of ballpark numbers. But in terms of the score, we'll be crediting things that will change the concentration rather than getting to an absolute level.
Linh Truong:
The next question is, "Do you possibly consider the effects from destratification ducting such as potentially transferring moisture from roofs and ceiling to basement?"
Brett Singer:
Will we consider the effects of the benefits of destratification? Is that the question?
Linh Truong:
Yeah, destratification ducting.
Brett Singer:
Destratification ducting. So you're saying – the question, duct work that achieves mixing to reduce stratification? Whoever asked that question, if you could clarify the question. I'm not quite getting what the question's asking. So maybe we can move on and then they can email back.
Linh Truong:
That sounds great. "Thermal comfort is usually one of the top homeowner complaints and one of the most valued factors. Some building programs calculate thermal comfort in the hours of overheating. How can we rate a home for these parameters?"
Brett Singer:
Once again, I'm going to defer on that question. There are – evaluating comfort is tricky business and there's another group that's working on that. What I'll say is there's – if you look at hours of overheating, that's kind of a performance measurement. Also, for comfort a lot of the same issues that come in is we have for indoor air quality which is there's what your home is capable of providing in terms of the service and then what it actually provides based on how you operate it. Right?
So the classic example of comfort is if you're someone who needs it warm, you don't thermos-regulate. You're 90 years old. You're otherwise in great health but when you're 90 your thermo-regulation doesn't work the same as when you're 30. You might really want it, need it to be warmer than if you're 30 years old. So that temperature might be outside of the national comfort zone, but if your home can allow you to reach that warmer temperature that you desire then the home is maybe better suited to your comfort needs.
Again, it's not something we're doing but I'll just point out that for comfort there are a lot of the same issues that come up of what the home can provide. A home that's well-insulated with good mechanical heating and cooling systems is going to provide better comfort than one that's not. I think that's some of the considerations that are going in although there's another group working on it and I would refer you to that other group.
Linh Truong:
OK. Another question about user behavior. "Will the IAQ ranking be resilient to user behavior? Things like exhaust ventilation in a bathroom or range hood is only helpful for IAQ if it's operated. Will the ranking give significant increased points in proportion to increased mechanical ventilation above 62.2 minimum or give points to future performance based systems that ventilate based upon sensor readings?"
Brett Singer:
OK, so as I mentioned, this is about what the home can do, not what the people do. So we won't give points or drop points for people not using their ventilation system. If you walk into a home that's all moldy because people haven't used their ventilation system, then there's another problem that's been created. So you have to kind of – the mold is there and that's a health hazard. But otherwise, we wouldn't be crediting what people do.
Now what we'll do is we'll credit systems that are easier to use, more clear to use. For example, if the whole house system or the dwelling unit system is on a switch that's unmarked so someone could just turn it off and not know that they're turning off the dwelling unit ventilation, that would be a negative point. If there's a clear sign there that says, "This is your dwelling unit ventilation; if you turn if off you might expose yourself to more pollutants indoors," then we say, "OK, that maybe gets a point." The next question was about the sensors, I think. Do we envision giving points for systems that are linked to sensors? I actually do envision that's going to be part of the score at some point.
Whether that's part of the version one is an open question still and partly because or maybe mostly because it brings a whole other set of questions about how reliable is that sensor and what features do you have in place to determine when that sensor is no longer reliable. So for ventilation – the first one I think we're likely to see is something that's like a demand control. It exists in some places already. It certainly exists in commercial buildings where you measure CO2 and if CO2 gets too high you turn ventilation up or conversely if CO2 gets really low you turn ventilation down because you don't need it.
What we've seen is that from the first, the early generations of those sensors that were put out into commercial buildings, lots of them didn't work right out of the box. Lots of them failed and there were lots of mechanical ventilation systems that were doing all kinds of crazy things because they were being operated by sensors which were not measuring anything meaningful. The new CO2 sensors are a lot better. They probably are more accurate right out of the box, lasts longer, et cetera. There's still a big variation in quality.
So we will definitely get to a point where you will be able to operate your home on sensors much the same way your car operates on sensors or I should say your home will operate on sensors, taking you out of a lot of the equation. I don't think we're there yet. In terms of how we credit it in the interim, we're still working that out.
Linh Truong:
Great. Thanks, Brett. I think we have more questions than you have time to answer today. So we'll go through a few more.
Brett Singer:
I'll try to be shorter, too. I'll try to – let's knock off a few quickly.
Linh Truong:
No, I think your answers are definitely appreciated and appropriate because the more you talk the more questions come in.
Brett Singer:
Oh no. We have _____.
Linh Truong:
Which is a good sign usually. But so the next question is, "In the current California study, is LBNL tracking formaldehyde and other pollutant concentrations as a function of the time integrated combined infiltration ventilation rate?"
Brett Singer:
We are measuring time-resolved formaldehyde. It's not on a minute by minute basis. It's like a half-hourly basis. That's through use of a new sensing technology that's been out for a few years now. So if there are diurnal variations or if there are big variations with ventilation system use, we'll see it. We are also tracking ventilation system use. So we're measuring environmental parameters.
In that study we're actually – I should have mentioned that. We're actually asking people to keep their windows closed for the duration of our monitoring. We argued back and forth over that quite a lot, whether – we all agreed that it was very valuable information to get window – understand how people use windows in ventilation but we didn't have – it wasn't a big enough study that we could do both those things at the same time. So that study really is focusing on whether the base mechanical ventilation system provides adequate protection when people keep their windows closed as many people do for substantial parts of the year. So the short answer to the question is yes and the long answer is all the other parts I gave.
Linh Truong:
"After a home is scored, especially if it is determined to be poor, will there be an associate recommendation for a particular ventilation system improvement and what type of system – what system type do you believe to be the most effective?"
Brett Singer:
Thank-you so much whoever asked that question. That was a point that I was supposed to make that I didn't, which is one of the motivations for the score and maybe even the biggest one is to give people guidance of what they can do to make their homes better and that would be builders building homes, contractors retrofitting homes or people just trying to improve their own home. So yes, most definitely envision that the score would lead to recommendations. How that's going to play out, we don't know quite yet.
The obvious way is you'll be able to – someone doing the score will be able to look down the list and say, "OK, what does this home not have that could most improve its score?" So for example, if you live in a place with really bad outdoor air quality and there's some way of filtering the air on the way in, or if you lack one of these really basic features like a bathroom exhaust fan, that's going to really negatively impact your score. In terms of filtration, in terms of what I recommend, I don't have a global recommendation because it really depends a lot on your situation. What I will say is that you should pay attention to the fact that there's two parameters that are important, which is the effectiveness of the filter at removing particles from the air stream that's pushed through it and then how much air you push through it.
So we see, for example, there are one of the filtration configurations is a HEPA bypass. So it takes a small amount of air coming through your air handler and routes it through a HEPA filter and then back into the duct. Then you remove 99.99 whatever percent of the particles with that HEPA filter. The reason why it only does that with a small amount of the air or a fraction of the air is because it's such a high pressure drop. You can't do that with all the particles – with all the air.
In general, you're probably going to do a lot better with a MERV 13 filter or maybe a MERV 16 filter if you need it or something in between that you filter all the air through a filter that's not as high a quality, although MERV 16's pretty high quality. That would be a better scenario than doing a bypass to perfectly clean a small amount of air. So imperfectly cleaning a larger amount of air more quickly is probably better than perfectly cleaning a small amount of air. So pay attention to those features.
One of the things in a lot of homes, the quick bang for your buck is portable air cleaners. They can be very efficient. You're not paying for the energy of pumping air through the duct work. The central systems have the advantage that you get kind of free filtering. So having a good filter in your central system is almost always a good idea. But if you're looking for something more advanced then maybe you want a MERV 11 filter on your center system and a MERV 16 filter on a portable that you can take around to the rooms where you're hanging out.
Linh Truong:
OK, let's do one more before we wrap up for you. "Is LBNL planning to study the change in IAQ from brand new homes with no occupants to – and retest after a few years of occupancy?"
Brett Singer:
The question is, "Have we ever done a study where we've looked at brand new homes and then gone back to look at the same homes after they've been lived in after a few years?"
Linh Truong:
Yes.
Brett Singer:
No. We did do a study where we – we didn't do that study. We did a study where we went back to homes and measured air tightness after a period of time. So these were homes that had had an air tightness measurement when the homes were new. We returned. I think that's reported by Reggie Chan, C-H-A-N, and looked at kind of the degradation of air tightness. We haven't looked at the change in indoor air quality over time in occupied homes.
Linh Truong:
Do you know of any plans for LBNL to be doing that in the future?
Brett Singer:
We don't have plans. There has been some work in Japan and I think somebody did it here although I don't remember who, looking at – actually, no. We did something like that. We tried to do that. We tried to do a study where we were going into homes when they were new pre-occupancy measuring the VOC concentrations and then coming back a couple of times after that.
We did a couple pilot homes in that study and it didn't actually go anywhere in part because it was really hard logistically to get into homes that were new and to do it at the time when they were pre-occupancy but finished. That's because a lot of people, there's a pressure all around to get people into homes, the people have a pressure to get into the home. So they move in as soon as possible. So waiting to have people wait to move in it wasn't really feasible. Having said that, there's a researcher at Harvard, Gary Adamkiewicz, who I believe was trying to do some measurements of homes when they were maybe renovated, maybe not new and then do some pre-occupancy and post-occupancy as a variation of that. I don't think that work is yet out but you can look for that. But it's not something – we're interested to know the answer. We just haven't done it and there's not a lot of work in that area.
Linh Truong:
Great. We appreciate so much of your time and your expertise, Brett. Before we go to our concluding slides with the Building America website and that type of thing, do you have any closing remarks for the participants today?
Brett Singer:
No. Just thanks for anybody who's still listening. Thanks a lot for hanging in there. Hope you got something out of it.
Linh Truong:
Yep, Thank-you so much for your time, Brett. So we'll go ahead and wrap up the webinar today. If we did not answer your question today, we'll reach out to you independently and reach out to you after today's webinar. But we wanted to go ahead and make sure that you are aware. Thank-you very much for your time and also be aware that the webinar today is being recorded and it will be posted on the Building America website.
We want to make sure that if you have any additional questions, feel free to reach out to us. Otherwise, it will take a few days for the presentation itself to be posted and then once the audio is available – it will be available in the next week or two. If you are interested in receiving updates on news and events and other things that are happening in the Building America space, please sign up for the newsletter, which goes out once a month. The second Thursday of every month. The second URL that you see on the slide will give you a link to how to subscribe to that.
Otherwise, Thank-you very much for your time. We appreciate, Brett, your time as well as all of our participants. You've been a great audience with great dialogue. So have a great week everyone.
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