Climate Change and Health Seminar Series: “The climate and health benefits from intensive building energy efficiency improvements”

November 15, 2022

Information

Drs. Gentner and Gillingham joined the Center on Climate Change and Health to discuss their work on building energy efficiency and health.

Speakers:

Drew Gentner, Associate Professor of Chemical & Environmental Engineering; Associate Professor, School of the Environment

Kenneth Gillingham, Professor of Economics, Yale University

September 2, 2022

ID9102

To CiteDCA Citation Guide

00:00<v Host>Welcome to the first seminar of our seminar series</v>
00:04in Climate, Air, and Health.
00:06We have some online audiences joining us today,
00:09and before we get started, just wanted to let you know that
00:12this seminar is recorded, and later on,
00:15the recording will be posted on our center's website.
00:19On the monitor today,
00:20I have chosen assistant professor
00:22at Yale School of Public Health,
00:24and also the director of research
00:25at Yale School of Public Health.
00:27So, it's my great pleasure today
00:30to introduce our very first speaker, Dr. Drew Gentner.
00:35Dr. Gentner is the associate professor in the department
00:39of chemical and environmental engineering.
00:42Also, the department of the School of the Environment.
00:44He got his master and the PhD from UC Berkeley,
00:48and also he has been at the Department of Chemical
00:52and Environmental Engineering since 2014,
00:56where his research group focuses on
00:58air quality, pollution, emissions, and chemistry.
01:03His application in books and [Indistinct].
01:07And today we are very fortunate to have both Dr Gentner,
01:12and also Professor Gillingham joining us online.
01:15Today the main topic will be focusing on their recent paper,
01:21the Climate and Health Benefits
01:23from Intensive Building Energy Efficiency.
01:27So without further ado, please.
01:29<v Dr. Gentner>Thank you so much.</v>
01:31And my one request of the virtual audience
01:34is let me know if you can't hear me clearly.
01:37I will try to speak loudly and through a mask,
01:40but just chime in if you're having trouble
01:43and I'll stay closer to my computer.
01:46Alright so, you have both and Ken and I here today,
01:52and I wish he could have been here in person,
01:54but I get to present this paper that we worked on along with
01:59Professor Jordan Peccia in Environmental Engineering,
02:02a PhD student of mine, Colby Buehler,
02:04and former postdoc of Ken's
02:07from the School of the Environment.
02:08So, this was a cool project
02:11that we were really excited about because
02:12it was a true interdisciplinary science
02:15where I was excited to work with Ken
02:18to do some energy modeling, and then bring that
02:20into looking at outdoor and indoor air quality
02:24across the building envelope.
02:26And so, this brought in some expertise
02:28from Professor Peccia and I to look at air pollution,
02:32and then extend it to the health effects.
02:34This fell under the purview of, our,
02:40hopefully I can click here.
02:42Alright, of our search center,
02:45which I, Michelle Bell has been the director
02:49of up at the School of the Environment,
02:51and we're in our last year at the center now.
02:55But the overall objectives of this were to look at energy
02:57transitions and look at the the wide range
02:59of sources related to energy production use,
03:03in the context of other sources
03:04that attract urban air quality and health.
03:08And then, we paid key attention to both
03:10transitions and key modifiable factors.
03:12So which things can we change,
03:13either through policy or personal choices,
03:15so that we can make smarter decisions
03:17related to transportation, land use,
03:20our power generation, and distribution networks.
03:23So, this had a number of different
03:25projects involved with it.
03:28Ken's project was number one and mine was number two.
03:32We were doing this in collaboration with Johns Hopkins,
03:35and we had a couple other projects.
03:37And so these things,
03:38we're focused on distinctly different areas of air quality
03:45where I was focused more on source characterization
03:48and measurements in project two and Ken was doing
03:50a lot of modeling on energy and emissions.
03:52So this project represented, and this paper,
03:56one of a couple things that we were doing has inter-center
03:59collaboration within a much larger center structure.
04:04<v ->And you can check it out online</v>
04:05and see a lot of the other great work
04:07coming out of Michelle Bell's group
04:09and others at Yale, Johns Hopkins,
04:11and our partner institutions.
04:14Which span some co-PIs at Johns Hopkins, and other PI's,
04:20and Dan Esty, at the School of the Environment.
04:26So, onto this paper. So, now it's like dive in and focus.
04:30This started, I can actually remember the workshop
04:33that Ken and I were at when we were talking
04:36about this research question.
04:38Thinking about how the climate and health
04:41benefits intersect when we look at
04:44building energy efficiency measures.
04:46'Cause Ken's group was thinking about
04:49building energy efficiency scenarios,
04:51how we reduce energy use in the building sector to reduce
04:56C02 emissions and affect change for climate mitigation.
05:01And I started asking, well Ken,
05:04what about the indoor air quality on that?
05:06You know, we're gonna drop emissions of pollution
05:09outdoors from reduced energy production,
05:11but what happens with the
05:13building energy efficiency measures?
05:14And so, thus this project and this paper was born.
05:21As a brief overview of where we're going with this today,
05:24we start with the fact that buildings
05:26account for 40% of energy usage,
05:29a lot of our energy command nationally.
05:33So, it makes it a really prime target for
05:36climate change mitigation and producing
05:40both energy use and associated emissions.
05:44These are emissions of not only climate pollutants,
05:46but also air pollutants, slight particulate
05:49matter sulfur dioxide, carbon dioxide, nitrogen oxide.
05:54So, with these scenarios that I'll show you in a moment,
05:58we looked at reductions in energy related emissions
06:01that would be occurring outdoors from power generation,
06:05and then translated that to its
06:07effects on indoor air quality.
06:09And, I'll talk about that feedback loop in a moment.
06:13But, the approach here is to use the Yale-NEMS model,
06:19which Ken runs up at school of the environment,
06:23to look at energy efficiency scenarios
06:25across the entire US housing stock.
06:27So we're not just studying one building,
06:30we model all the homes of the US and their changes
06:33over time with a lot of simulations
06:36and a couple models that were interconnected.
06:40Then we evaluated the outdoor
06:41indoor air quality implications.
06:43So how do the changes in emissions
06:46affect exposure and human health,
06:50both for outdoor and indoor exposure pathways,
06:52and look at the bad effects
06:53on human health, all of these together.
06:57So, I'll walk through this in a bit more detail,
07:01but we start from something where
07:03we take a reference scenario,
07:06an intermediate energy efficiency
07:07scenario just for buildings.
07:09An optimistic energy efficiency scenario for buildings
07:12and look at the changes in energy consumption
07:15and then test the carbon pricing scenario
07:18for those to see how that affects it.
07:21And we'll walk through this before,
07:23but if you fast forward all the way,
07:24you can see how we will then be able
07:27to look at projections in particular manner,
07:30emissions from that reduced energy use.
07:34So, the scenarios, without going into them in great detail,
07:39although there's a lot of information in the paper
07:41and tech would be happy to answer questions,
07:44looks at changes in both appliances and equipment
07:46and in the building shell.
07:48So we have all of this stuff indoors
07:50for heating, cooling, cooking, lighting,
07:53and other things like refrigeration
07:58and those have a certain amount of energy use with them,
08:00and that's been a target of a lot
08:01of governmental programs through efficiency.
08:03You know, you can go and buy energy star things,
08:06you see them when you go to the store,
08:09and so, there are targets related to the energy efficiency.
08:12And then in the building shell is where we start to look
08:16at the interconnections at indoor air quality.
08:19'Cause the indoor environment is really complex.
08:22The air that gets to us here,
08:23or the air in your home navigates a lot of places.
08:27Either through a forced air system or just naturally,
08:30you have some penetration coming through the walls,
08:33and some infiltration of air,
08:35and the pollutants coming in,
08:37and some ventilation of the air going out.
08:38You may do that on purpose, opening you know, a door,
08:42turning on a fan, or that might just be happening naturally,
08:46and depending on the age of your home
08:48and how well it's sealed,
08:49that could be happening at quite a high rate.
08:52So, we look at the changes in the building shell
08:56across a range of environments,
08:57and we're gonna talk more about residences today,
09:00'cause that's where we do spend most
09:02of our time and a lot of our time,
09:05a lot of our PM2.5 emissions indoors
09:09occur in our residences.
09:11So we'll look at that, and we'll look these scenarios
09:13where we have existing homes and we look at changes
09:15in efficiency that happen at slower incremental rates.
09:18And then new homes that are built
09:21to the newest specifications which follow these
09:25ambitious but demonstrated improvements.
09:29So Ken's model, which is the national energy modeling
09:34system model that is the scale installation of this,
09:38and the launch model developed by the US EIA,
09:44covers a whole lot of things in the supply side,
09:46convergence side, and demand side,
09:48electricity, and integrates it together.
09:50So, where we're gonna focus on today for this paper
09:54is looking at the changes in the residential demand
09:56and commercial demand that are derived
09:59from these changes in energy efficiency.
10:02So if we change the design of a building,
10:04we are changing the energy in the air there,
10:07and that has feedbacks to reduce demand,
10:11to increase production and thus we have changes.
10:15So, there are a lot of things that are in this model,
10:18and if you are a big fan of supplemental
10:21information sections and papers,
10:23I encourage you to check out the,
10:26somewhere around 55 pages that exist in the paper
10:31with hopefully, every question that you might have
10:36about the energy modeling system and then hence,
10:39other work using this model.
10:42And so, if we look at the scenarios,
10:44you have the reference case at the top here in red
10:49that we play around the carbon pricing initiative on there.
10:54Now we look at the intermediate energy efficiency,
10:56just for buildings here and see that that drops
10:58consumption down somewhat than a more optimistic
11:01one with without carbon pricing.
11:04The direct effects on carbon dioxide emissions are shown
11:07over here where you can actually see a pretty sizable effect
11:11on overall carbon dioxide emissions
11:13just from building energy efficiency improvements.
11:16So, this really points back to that fact that
11:1940% of our energy use occurs in maintaining
11:25our buildings and in our buildings.
11:26So, any change that we make here,
11:30a policy level has a pretty sizable effect
11:33on energy demand and related climate pollute emissions.
11:39This also has a sizable effect on air pollutant emissions
11:44like criteria pollutants for particular matter, NOx.
11:48SO2, VOCs, a sub effect on ammonia and carbon dioxide,
11:54excuse me, carbon monoxide,
11:57though today we're gonna focus mostly on PM2.5,
12:01since that is driving factor of premature mortality,
12:06and what's the key pollutant of interest for this paper.
12:12So here we've defined what the changes are
12:15for each of these scenarios over this time rise
12:19and extending to 2050 for the energy related
12:23emissions that are occurring outdoors.
12:24So if you wanna visualize it,
12:26what's coming out of the smokestack for PM2.5 emissions.
12:32So that's gonna vary a little bit across the country
12:34where we generate that power, how we generate it.
12:36And so we'll talk about that at the end
12:39of the presentation today.
12:43So, we spend close to 90% of our time indoors, so,
12:51so we're thinking about exposure to pollutants.
12:54We really need to be considering that
12:55indoor environment and how it modulates our exposure
12:59to pollution coming in from outdoors,
13:02but also how it affects,
13:06how the design of that indoor environment
13:07affects our exposure to pollutants that are generated.
13:13Now, I wish I had Jordan Peccia here with me today,
13:15so he could answer all of your COVID-related questions,
13:19relating to ventilation and filtration,
13:22because that is not my area of expertise.
13:24But you can take this admissions term here,
13:28and think really about whatever pollutant or microbe
13:32or anything that you want, for your own work,
13:36and think about how that's affected by the design
13:39of your home or the space that you're currently in.
13:44This is a box model.
13:46It is actually simplified considerably,
13:49to just a singular box representing a space indoors.
13:53But yes, there's still one equation. For that, I apologize.
13:57You can ignore the equation if you like,
13:59I can try to cover it up and we can
14:01focus on the terms that are used here.
14:04So, I'm going to point out a few things
14:06on how the model connects,
14:07just to try to show how this all comes together.
14:10So first thing, we have recirculation with a filter.
14:16Now you're predominantly talking about HVAC system.
14:19So, forced mechanical air filtration system
14:22that you would have in an indoor building.
14:24You have them here, your apartment,
14:26perhaps up the east rock,
14:28that was built 80, 90 years ago may not have that,
14:33or some newer builds don't have of course, HVAC system,
14:38but that is where you would have some
14:40active particle filtration that's occurring.
14:43Now in the the era of thinking about filtering for
14:49you know, viruses and other microbes doors,
14:52whether it be COVID or otherwise.
14:54We've started to put in some affordable air filters,
14:56so you could also think about that,
14:58but we're predominantly looking at this
15:00in terms of the HVAC system.
15:02So, on the other side here you have air coming in.
15:08So, infiltration is that, what I was talking
15:10about was coming through the cracks.
15:12You have bad windows, ceiling, it's an old building.
15:15You know, there's some areas where air just gets in.
15:19If it's a newer, newer, newer building,
15:21those seals tend to be better and better,
15:23and you have fewer spots for
15:25air to infiltrate from outdoors.
15:28But then you have this,
15:29and you have a penetration factor in there
15:30for how much particles
15:31get through those little cracks.
15:33So they can get stuck on the way.
15:35It's kinda like a filter like our mask.
15:38And you have natural ventilation,
15:41so you open the window because
15:43it's hot out or if you burnt toast,
15:46and that's gonna provide some natural (indistinct).
15:51Indoors, you know, the main thing is
15:53you have emissions for cooking,
15:56you burn a toast or just you know, regular,
15:59you were frying up some eggplant for dinner,
16:01and that generated some PM2.5.
16:06Number of appliances while you're cooking,
16:08actually have a pretty sizable PM sources,
16:11but that depends a lot on cooking style,
16:13and I forget you're affected by some
16:17of the filtration over your stove.
16:20We also worked into the model,
16:21the two loss terms of the deposition of the six.
16:24So, particles go to surfaces and also
16:26they could be meddling outside.
16:30But we're thinking today about,
16:32what is the changes that happen to these terms,
16:37and how it affects the concentrations indoors.
16:40But built within this is thinking about the housing stock.
16:45So Colby Buehler,
16:46a PhD student in environmental engineering,
16:49did a literature view of the US housing stock
16:51working with Peg Long from School of the Environment
16:55to determine the filtration flow rates for
16:59homes' HVAC, and the fraction of homes with HVAC systems
17:02and also the quality of filters in there.
17:05If I was, if we were all talking
17:07about this a couple years ago,
17:08you would probably not be very familiar with the quality of
17:11filters that exists up in these systems.
17:14But there's this whole rating system
17:17for 2, 4, 6, 8, 10, 12, 14
17:20and it goes up to 16, then we get the half a grades,
17:23and that has a major effect on the efficiency
17:26of those filters and the filtration of particles,
17:30doors or air barns, microbes or dusts or anything else.
17:36And then the infiltration and natural ventilation rates
17:41are also affected by house, home aid.
17:45So you think about infiltration,
17:46a home with more cracks, more gaps,
17:49has more infiltration through those penetration points.
17:57Then, the residential energy demand consumption survey
18:00was used to determine appliance usage across all homes.
18:04So, we could look at the distribution in homes.
18:08Obviously, it comes down to how many people live in a home,
18:11but some of us are cooking all the time.
18:13We cook at home every single night,
18:15we use the toaster while we're using the stove,
18:17while we're using the oven.
18:19And some people, you know,
18:21will stop by and, you know,
18:25pick up something from the local
18:27falafel shop for dinner most nights.
18:33So, that's gonna have a huge effect on this admissions term,
18:36and it's going to propagate through this whole system,
18:38as you'll see later.
18:43So we then model over time,
18:46the changes in the US housing stock
18:49up through 2050 for this analysis.
18:52And changes in the building type,
18:56which includes the volume of home,
18:58sizes are going up,
19:00the amount of new homes that are built
19:03and the characteristics of those homes
19:06with respect to the installation of HVAC systems
19:11and filter types and all of that.
19:14So, and ultimately, the big effect that this
19:18has with the changes in the housing stock
19:21and energy creation or energy efficiency
19:24scenario is on this infiltration.
19:28So, how much ventilation occurs
19:30in your home without you actively doing that.
19:35You didn't turn on the HVAC system,
19:38you didn't necessarily open the window,
19:40but you have some pressure changes in home,
19:43and air is also very good
19:45at moving through cracks and things,
19:47and it will bring (indistinct) with it.
19:52If any of you just moved to New Haven,
19:53wait until a nice cold day,
19:57go stand near a window at an older building,
19:59and you'll certainly feel that
20:01cold air moving through some of those gaps.
20:04I know I had that experience when
20:07I first moved to New Haven.
20:13So, we also look at the changes,
20:14changes in the appliance type throughout the study.
20:22I'm gonna talk about something not,
20:23I won't refer to it as a Monte Carlo analysis
20:26over and over again but I want to make the point that
20:29to constrain the uncertainty in the study,
20:33Colby Buehler ran this a lot, a lot, a lot of times.
20:38Thousands upon thousands, across the entire
20:41US housing stock.
20:42So if you go through and you simulate
20:43a whole bunch of homes with this model,
20:46and you look at all the different conditions you can have,
20:49what is the net outcome of those?
20:51So again, we're not just talking about
20:52one home with one set of conditions,
20:53or a small perturbations that
20:56we will look at one or two things.
20:57But trying to put those all together so
20:59we can show sensitivity to these different features.
21:03So, the HVAC system and what it means for emissions,
21:05and how does infiltration change
21:07with energy efficiency measures, and the age of a home.
21:17So questions before we start moving out to results.
21:25If not, good work, you just got through like lecture five,
21:29or six of my class on box models so that's great.
21:36<v Speaker>We do have a student.</v>
21:38<v Dr. Gentner>Yes.</v>
21:39<v Student>Yeah, I'm just, how confident are</v>
21:43you in modeling how the housing stock group
21:45change also changes in appliance?
21:48Like out to 2050, or did you use different scenarios?
21:53<v Dr. Gentner>So, actually Ken,</v>
21:57I'll let you answer that one.
21:59It's phone a friend time already.
22:00The question was how confident are we in the changes
22:03of the housing stock and appliance shifting over time,
22:06and how are those scenarios, model there,
22:10are there multiple scenarios in the NEMS model?
22:13<v Dr. Gillingham>That's a a great question.</v>
22:14What we do is we use,
22:16so it's built into NEMS and NEMS explicitly
22:21is modeling housing stock changes
22:23based on trends in the past.
22:26We easily could do uncertainty analyses over those numbers.
22:32I think that kind of, main takeaway on that
22:35from my understanding is that those aren't gonna be
22:39the driving forces of our final results
22:42unless you are really dramatically
22:44changing the housing stock.
22:46And I know this from another paper, not this paper.
22:49You'd have to really dramatically change
22:51the kind of core housing stock itself.
22:54And the reason for this is that there's
22:56a lot of inertia in the housing stock.
22:58So, there may be changes in how well it's insulated
23:02and you know, broader retrofits in how they're done.
23:06But the basic stock itself is quite slow moving.
23:11That said, I think you should take anything out to 2050
23:14with a grain of salt, maybe a very large one,
23:18and so I'm not gonna hang my hat on the exact numbers on
23:22the nature of the housing stock,
23:24'cause it's the full nature
23:25of the housing stock that's being modeled.
23:26And I'm not gonna hang my hat on the
23:28full nature of the housing stock in 2050.
23:30But I'm pretty confident that the numbers are gonna be
23:32pretty close to right in 2030, 2035,
23:35in that range and maybe even now out to 2040,
23:38just because of how much inertia
23:39there is in housing stock.
23:40But only a small amount of turnover actually occurs.
23:46<v Student>Just on the second part though,</v>
23:48I'd have to be more concerned about appliance type.
23:52It seems like, you know,
23:54we have possible scenarios of
23:56complete electrification, right, by 2050.
23:59Versus not doing that and still having a substantial
24:03number of gas stoves for example,
24:06would have a large effect on your conclusions.
24:12<v Dr. Gentner>So, the question's on</v>
24:14the changes in appliance tech Ken,
24:15and I'll take a quick shot at it and let you add to it.
24:19But, so that does get discussed in the paper.
24:23We don't include specific perturbations but we talk about
24:27how stoves changing up,
24:30changing to full electrification could affect that.
24:34We get into some really interesting questions
24:36then about where the emissions coming from.
24:38Are they derived from the use of natural gas,
24:42or are they derived from the process itself?
24:45If I, like your toaster is generating PM,
24:48based on what you're doing with it,
24:50not so much based on how much power,
24:51obviously, if it's not a natural gas toaster.
24:54But if we're thinking about a stove,
24:57some fraction of that PM comes
24:59from the actual burn itself.
25:01But if it's a reasonable stove,
25:05the PM is probably coming more from the cooking itself.
25:09And that's a really interesting question,
25:11and one that there was a cool paper
25:16that came out of Stanford looking at the emission rates,
25:20although they were thinking more
25:20about methane in particular,
25:22which is where you have a huge impact on (indistinct).
25:28So, on the climate side is where I think
25:32we can see a large effect of
25:33short lived climate pollutants there.
25:37And we do build in a few scenarios
25:41in there to look at some of these changes
25:43and try to bound them.
25:46Ken, can you grade my response
25:48and add anything to help there?
25:50<v Dr. Gillingham>I liked your response.</v>
25:51I wanna add a few things.
25:52One thing is this paper is explicitly
25:54about improving the efficiency,
25:57given the existing forecasted technologies in NEMS.
26:03In our scenarios, it's not about fuel switching,
26:07and I think fuel switching is a really,
26:08really important question and we actually have work underway
26:12to explore that question, where we're looking at scenarios
26:16that actually would allow fuel switching.
26:18So, say switching from burning natural gas in your range,
26:22to an induction range, right? Electric induction range.
26:26So, that type of fuel switching, we hold constant in this.
26:31So we don't, any trends that are in
26:34the baseline in NEMS, we continue,
26:37and we don't focus on those,
26:38our scenarios are very much about improving the efficiency.
26:42I think in reality,
26:44you may end up seeing both
26:46happening somewhat at the same time.
26:48But it depends on the policy direction.
26:51You could see a world in which you do see a lot of fuel
26:53switching and not much efficiency or vice versa.
26:56And I think from a intellectual perspective
26:59it's really helpful to parse those out,
27:01and understand them separately.
27:03So that was sort of the,
27:05some of the thinking behind it,
27:07how it plays out in what we do here in this analysis.
27:12But it's a really great question
27:13and a really important point.
27:15I think it's becoming increasingly important as we move
27:18forward because of the IRA, you know, the recent act,
27:23and other efforts to lead to electrifying the home.
27:27There's been a real push in that direction, so I think,
27:31but this framework that we've set up is reasonably
27:34well suited with some modifications to understanding
27:37the implications of some of those questions, too.
27:42<v Dr. Gentner>Right, thank you for the questions.</v>
27:44Just so I don't have to skip slides at the end,
27:47I'm gonna move forward.
27:49Johan, to answer your question,
27:51the exact materials that are used to change
27:54the building efficiency in terms of insulation
27:56are not explicitly worked in here,
27:58but they are part of changes in building shell efficiency.
28:02So we look at, in the paper we discussed,
28:04how changes in installation versus
28:06changes in building ceiling
28:08could affect the ultimate outcome.
28:11Alright, so, participation time.
28:15How many people in the room have an
28:18HVAC system in their home or apartment?
28:23Alrighty, so we're talking,
28:25alright so that number came in at about 10%.
28:28I don't know, hands were really kind of low on there.
28:30So, now is where we have like,
28:32a choose your own adventure moment in the presentation.
28:35So for those who are in homes that do not have,
28:43it's gonna come back I promise. Alright.
28:48Recirculation with filtration,
28:50here are the overall results for
28:52the entire US housing stock,
28:55comparing the reference scenario
28:57here in the reddish orange color
29:00to the intermediate case in blue.
29:02And then green is the optimistic energy
29:04efficiency case for buildings.
29:06On the bottom here, you're looking at
29:08the indoor emissions percentile.
29:11So the far left,
29:14this is the person who picked up
29:16falafel for dinner every night then.
29:19Hopefully, they got different toppings but they
29:22did not do much cooking in their home,
29:24and breakfast they got on the way to campus.
29:27And on the far right here,
29:28this is the person who wanted deep fried cauliflower
29:31three times times that week, and is cooking a lot.
29:36Maybe it wasn't deep fried cauliflower,
29:38but you get the point.
29:39Here is where there's a lot more indoor emissions.
29:41So it's what you could imagine a home that is,
29:44has more PM generated from various appliances,
29:49but ends up being an an important one,
29:51And on the far left,
29:52this one you can think as a cleaner home
29:55just in terms of the indoor emissions.
29:56So, if you're all the way here on the left side,
30:00you're seeing actually a benefit
30:04compared to the reference case of building tighten.
30:09So reducing that infiltration actually yields you a benefit.
30:12And the reason is, any of the PM that is outside
30:16is not making it indoors because your home is sealed off.
30:21You have a very, you have a tighter box that you live in.
30:24So you are just living with your own emissions,
30:26and you don't have as much
30:27infiltration of particles from outside.
30:29If you move to this other side here,
30:32and you can see where it is worse than the,
30:37oh excuse me, this is with recirculation.
30:39I said before this is without,
30:40this for the 10% of you that have an HVAC system.
30:45Here on this side is showing
30:48if you're doing a lot of cooking indoors,
30:50you actually see a penalty from
30:52those energy efficiency measures.
30:54'Cause now you have bottled up your home,
30:57you have filled all the cracks,
30:58maybe not every last one of them but you haven't improved
31:04the ceiling through your home to the point that you
31:06spend a longer time with any of your emissions indoors.
31:12So, the bummer is that that toast
31:15that you burnt lingers longer,
31:18or any other combustion source that you have indoors.
31:21And so, thus you would have more exposure to that.
31:25Or it could be a continued source of something,
31:27if you had a bad pilot light or something
31:29else in your home then that continues, or persists along.
31:35So, when you're looking at this,
31:39the reference case models the building stock without
31:42any changes from the energy efficiency scenario.
31:45So what is the current inertia,
31:46and everything that we talked about.
31:48And then this represents the change,
31:51where the left shows some benefit,
31:53and the right where you get about
31:56the reference case line shows a detriment indoors.
32:00So, for those of you,
32:04the 90% in the room that don't have an HVAC system,
32:08or other recirculation with filtration,
32:12this is what it looks like.
32:13So, everything is the same here.
32:15The only difference is now we're looking at the 38 to 45%
32:19of homes depending on the scenario that have
32:25no filtration or HVAC system at the home.
32:28So, now you can see this effect is exacerbated.
32:30There's a smaller fraction of homes that see a benefit
32:34for their indoor pollution from
32:37these energy efficiency measures,
32:39and a larger fraction that get
32:40greater exposure to particulate matter,
32:44because they spend more time with those emissions.
32:47So this shows two things,
32:50the importance of the indoor emissions
32:54in determining your indoor exposure
32:57and target ventilation there.
32:59And the importance of recirculation
33:01with filtration, just for PM2.5. Yes?
33:05<v Student 2>This might be a silly question, but,</v>
33:06is there, is like the,
33:10it's hard for me to to believe,
33:11to understand how building efficiency,
33:15have that much impact over HVAC.
33:17Like I would think that homes have the circulation system
33:22would be filtering air more than like,
33:26having cracks in the wall,
33:27and like, not as great of efficiency
33:30would like, have an impact on this.
33:33Does that make sense?
33:34Like, just looking at the reference line there.
33:36So like, if there were no
33:37improved efficiency in the building,
33:39you would still be having this kind of like,
33:41being close to the one to one line
33:43if you had a lot of indoor air emissions.
33:46But then, you improved, like how is the HVAC not filtering?
33:54<v Dr. Gentner>Improving?</v>
33:55<v Student 2>Yeah, I guess, or I guess, yeah.</v>
33:56I just think of it as like constantly pulling air out,
33:59and like, pushing fresher air back in.
34:02So that was the, how is the increased
34:05efficiency of a building making that almost worse.
34:08Does that make sense?
34:10<v Dr. Gentner>It does, and it's actually</v>
34:11a great opportunity to make a clarifying point here,
34:17that in the current paradigm of building temperature,
34:24climate control, infiltration, this is a closed one.
34:28Your HVAC system takes air, conditions it,
34:31and puts it back into your home.
34:34So, it comes down to the efficiency of that filter,
34:37rather than if saying, we're gonna give you
34:39completely fresh air from outside,
34:41to get rid of all our air
34:43from the inside and put it outdoors.
34:45This is where we're starting.
34:47We'd be thinking about like, next generation things.
34:51Is there any opportunities to get fresh air while
34:55not paying the penalty for having to completely
34:57recondition, well I say recondition,
35:00I mean, change the temperature of all the air coming in.
35:03<v Student>Perfect, yeah.</v>
35:04<v Dr. Gentner>No problem, that's a good point to clarify,</v>
35:06so thank you for that.
35:07The only major everyday example for a lot of us,
35:13or exemption to that would be in some of our labs,
35:16we have a fume hood obviously,
35:17we'd dump all of that out the building,
35:20we don't recirculate that.
35:22And there were some changes in various buildings,
35:27like on campus I know where the percentage of fresh air
35:30versus recycled air has changed over the past couple years.
35:35So, alright, so,
35:43If we think about this effect,
35:45this is looking at the overall effect,
35:47the entire housing stock for these two cases,
35:52or two types of homes across old and existing.
35:57Then we have this result where we end up
36:00at steady state having higher overall concentrations.
36:03If you wanna visualize this more,
36:05as what's happening for any singular event,
36:08you can think about the response time to something.
36:11So if you just look at this as a singular case,
36:14let's say here,
36:15you, oh, stick with the burning toast scenario,
36:20you burnt toast or you were frying something,
36:23you generated really high concentrations
36:24and then you stopped.
36:26How long does that take to decay down?
36:29And specifically, we think about that as the folding time,
36:32so down to one over just 37%, to keep it going on.
36:40And, so we look at that in the different scenarios
36:43with and without filtration.
36:45One other point, actually I wanted to make
36:47about your quick filtration question
36:49is in a lot of homes,
36:52we're not recirculating air
36:55at a range of like, the entire house
36:56over 6 points or something.
37:01During COVID we increased some of
37:04those ventilation rates for public spaces.
37:06Marketing air exchange rate of 4 or 5,
37:09those are probably the goal ones.
37:11So air exchange per hour,
37:13but we're not changing everything.
37:17<v ->So, that's why there are differences</v>
37:19here with the filtration and recirculation
37:22for dropping it quicker,
37:24in the cases of having an HVAC system.
37:26And then you can see, you know,
37:29as we tighten up the building more and more
37:30in the optimistic energy efficiency case,
37:34you know, that time that you're spent with the burning
37:38of be it toast or whatever else,
37:41that happen indoors increases,
37:44and you can see the theory we're approaching.
37:48(indistinct)
37:53So, that helps to visualize what's happening,
37:55just in terms of the time.
37:57Hopefully, that's a useful comparison.
37:59<v ->So, but we know that the system</v>
38:03is sensitive to outdoor PM concentration.
38:07So, we did all this modeling,
38:09and then we did a couple case studies
38:12within it across all different outdoor PM concentrations,
38:16and looked at how the system responded to outdoor PM.
38:23Because if we go back to that box funnel,
38:25and I won't put it back on the screen again,
38:28but you know, remember we have
38:28the concentrations of PM outside,
38:31and that's trying to come in
38:32and then we have our indoor PM and that's going out.
38:34So we have this really complex game
38:37that's happening over the building.
38:39And so, if we keep our indoor emissions on the bottom.
38:43So, again, this is the home of the most indoor emissions
38:46and this is the home of the least,
38:48and we look at the outdoor
38:49concentrations on the Y axis here.
38:55So this is the ambient outdoor PM2.5 concentration.
39:00The national average is here,
39:02the annual standard is here,
39:03and then the 24 hour standard's up there.
39:07So, depending on where you live,
39:08and even time of year or if it's a pollution event,
39:11you're going to fall on different spots.
39:16This graph vertically and that ratio of what it is
39:20in the optimistic energy efficiency case,
39:22versus the reference case is shown here.
39:26Where red has just energy efficiency measure
39:30increasing the indoor concentrations,
39:34and blue shows it decreasing the indoor concentrations.
39:41And that's just because again,
39:43here you are preventing the PM from outdoors coming in.
39:49Imagine it's a wildfire scenario,
39:52and you know, you're living in the northwest
39:55and your home is really tightly sealed,
39:59so your concentrations are really high outdoors,
40:02and you're up in this space where your home
40:03is more well sealed so less stuff gets in.
40:07If you go all the way to the right of this
40:09and you're in cleaner conditions outdoors,
40:11but you have a lot of indoor sources,
40:14now that tighter building with with less infiltration
40:18actually increases your indoor content.
40:21So point says, interesting interplay between outdoor
40:25and indoor PM and how that interacts.
40:29So, if there's anything you take away from today,
40:33whether it be for particulate matter
40:34or other atmospheric public health considerations,
40:38I hope it's thinking a little bit about that
40:41interaction between outdoor and indoors.
40:43So, in summary for this slide,
40:49which it literally has a lot of different
40:52information on it and colors.
40:54The impacts of these energy efficiency measures
40:56on indoor air quality are partially dependent
40:59on outdoor air quality,
41:01in addition to the in-home emissions.
41:03So if you were to translate this to Delhi,
41:07or another city that has higher outdoor concentrations,
41:11have to help how you approach this.
41:15There are some studies that were done,
41:17just looking at a few homes back in Beijing.
41:22And, probably like a decade ago,
41:24(indistinct) at Berkeley looked at the changes
41:27in home infiltration and ceiling and how that actually
41:31affected imperfect air concentrations to outdoor ratios.
41:36So, it does have an impact in other locations,
41:39and it can be different than what we're showing here.
41:44Okay, so to wrap this up and look at it together.
41:50I said we wanted to look at the outdoor effects
41:52and the indoor effects.
41:53We spent a little bit more time on the indoor stuff today,
41:58but we get this huge gain
42:02from the reduction in outdoor PM2.5.
42:06This is really like the energy related PM2.5.
42:09So we've dropped the energy demand for buildings
42:13considerably with the cases here.
42:17So intermediate, optimistic, optimistic with carbon pricing.
42:21And so we have a few benefits
42:24in reduced premature mortality that's avoided in 2050.
42:30We just talked about the complexity of indoors.
42:34And so overall, we see a detriment indoors
42:42but this is not for every home,
42:45'cause there's many homes that see a
42:46health benefit from the energy efficiency improvements
42:50based on this modeling.
42:53And so it's those high emissions homes,
42:55high indoor emissions homes that
42:57drive the overall effect negative.
43:02So, those graphs that I showed you before
43:03that had the lines across them for HVAC and non-HVAC
43:08were showing that, you know,
43:09there's a fraction of homes that see a detriment
43:12and need to see a benefit from this as well.
43:16But overall, the indoor effect offsets
43:22this positive outdoor effect,
43:24but it's weighted towards a
43:25subset of homes and a subset of the population.
43:29We look at this on net for those three scenarios.
43:33Intermediate, optimistic, optimistic with carbon pricing.
43:36We see that we get a net benefit from energy efficiency
43:39for avoiding premature mortality for PM2.5.
43:44This is stacked on top of all of the benefits
43:46that we get from the reduced climate pollutants.
43:54So, we get a climate benefit in terms
43:56of reduced CO2 emissions,
43:59and we get a benefit in terms of improved public health.
44:05And that's driven by a large decrease
44:08in energy-related pollutant emissions,
44:10and to some degree,
44:13some of the homes that have poor indoor air quality.
44:17But we do see some of the negative effects
44:19on indoor air quality overall.
44:23That's what I said in summary.
44:27And then, we wanted to test how the effect
44:31of HVAC usage or or filtration system's effectiveness.
44:37So, if we look at the case where we actually upgraded
44:41all homes to have 100% good HVAC systems.
44:44So boost that investment up,
44:47actually increases the health benefits that occur.
44:52So, basically if we improve indoor air quality
44:55through improved filtration indoors at PM2.5,
45:01we can achieve a larger benefit there.
45:07This can be put up as a summary.
45:12Here, where reductions in outdoor emissions,
45:15yielding that benefit across the entire building stock.
45:21And, the observed changes indoor air quality,
45:25due to these energy efficiency improvements,
45:28really require us to think about
45:30improvements to our indoor PM2.5 emissions,
45:36the targeted ventilation of those emissions.
45:38So, better ventilation of cooking emissions,
45:41improving the PM2.5 filtration efficiency.
45:44So, upgrade your filters, get better efficiency
45:47for those of you who can.
45:49And then, careful consideration of these energy efficiency
45:53policies and how we look at ventilation in buildings.
46:01And this is yet another time
46:02where I wish I had Jordan Peccia
46:06on the line as well, to make a few comments on that.
46:09Because it is a really interesting, important topic
46:13for how design, building ventilation for quality of life,
46:18wellbeing and thinking about a range of pollutants.
46:21So we present this today in the paper,
46:24through the lens of PM2.5.
46:27And we include some discussions in the paper
46:28about different pollutants,
46:31I think for indoors, and we did it in various amounts,
46:35so that goes through the range of criteria pollutants.
46:38We can even start to think about radon
46:39in some areas of the country.
46:42We can start thinking about disease transmission.
46:47No worries, it has nothing to do with this paper,
46:49but it does come up against the space
46:53where we think a lot about
46:54building design, and filtration and ventilation.
46:59So, looking at these benefits across the country pay.
47:05The graduate student who was working,
47:06sorry, the postdoc who was working on this,
47:09modeled it spatially and across various geographic regions.
47:14And you can see for the intermediate
47:16energy efficiency pace, the optimistic one.
47:18And then when we employ carbon pricing
47:21and carbon pricing with the optimistic
47:23case where the benefits occur.
47:27And these differences come down in many ways
47:31to how power is, generator,
47:33how electricity is generated in
47:35various areas of the country.
47:37So where we see some of the largest
47:40benefits depending on the case.
47:43So, carbon pricing is gonna have a sudden different effect
47:46than on the optimistic case on it's own.
47:50It's going to change the
47:52underlying fuel that we're using for generator outlets.
47:56So, you know, we think about
47:58the midwest and the northeast here,
48:01the types of fuels that we're using for power plants.
48:05So, using that demand is going have a larger effect,
48:12where there's a higher amount of renewables.
48:15So, in summary, and then we'll open it up to questions
48:17with whatever time we have.
48:20The study used the NEMS model coupled
48:23with The Monte Carlo analysis.
48:25Indoor air quality box model across
48:27the entire US housing stock.
48:29We see a 6 to 11% reduction in carbon dioxide emissions.
48:34and a 18 to 25% reduction in
48:37outdoor energy-related emissions of PM2.5.
48:42So, this is not including other PM2.5 sources.
48:47These reductions are complimentary with carbon pricing.
48:49It takes the pressure off as we're
48:52trying to decarbonize electricity going forward.
48:55So these building event, energy efficiency measures
48:59provide a huge opportunity,
49:01but they require attention to indoor PM2.5 emissions,
49:06and improving PM2.5 filtration,
49:09and thinking about how we implement
49:11these ventilation-grouping policies
49:14that get at some of the nuances that
49:16you're talking about with
49:18fresh air exchange and energy recovery.
49:23And so, in all the majority of homes see improvement
49:28or little change to indoor air quality,
49:30with these energy efficiency improvements.
49:33A subset of homes have increased
49:34PM2.5 concentrations indoors,
49:38which there, overall are driving
49:40health effects going forward there.
49:44And we're seeing that benefit in total, outdoors.
49:47So with that, we are at 12:50,
49:51so I'm happy to take any questions that people have.
49:54I have Ken here to answer all the tough ones
49:56that I can't or don't wanna answer,
50:00and thank you so much for you time
50:01today and for the invitation.
50:07(indistinct)
50:09<v Host>So, I think we have two questions.</v>
50:12<v Dr. Gentner>Okay.</v>
50:13<v Host>I guess each student</v>
50:14already prepared some questions.
50:15So, and what would you want to ask?
50:18<v Student 3>Hey could you go back to</v>
50:19the health impact slide?
50:23Sorry, yeah, thank you.
50:27First, if there was a bar on there
50:30for no, like without the energy efficiency,
50:35like, whereabouts would it be?
50:41<v Dr. Gentner>So this is all comparisons</v>
50:43to the reference case.
50:45So to the current trajector.
50:48So, this is the changes that occur on top of
50:52whatever we expect to happen
50:55in the absence of these standards.
51:03<v Student 3>I guess I didn't consider, (indistinct)</v>
51:10<v Dr. Gentner>It does.</v>
51:18Though, it doesn't include a distribution
51:22of clients saying you know, across different subsets
51:25of the population who is spending more or less
51:30time at their residence.
51:33But it does scale for them.
51:37<v Student 4>I was wondering if there are plans</v>
51:41to put your study off to different groups,
51:43so looking at how (indistinct)
51:54You know, what are the,
51:55are there plans to study the specific (indistinct)?
52:02(indistinct)
52:21<v Dr. Gentner>Yeah, so-</v>
52:23<v Host>The online audience is gonna hear the students-</v>
52:26<v Dr. Gentner>Oh, okay.</v>
52:28Yeah the first question, prior to that
52:30was about the half of the slide that's up.
52:35What the zero line is,
52:36and that's the comparison to the reference case.
52:38The question was just posed is is how much does
52:43or do we have plans for another study
52:46or set of studies looking at gas phase pollutants?
52:49And so we include some commentary in the paper about some of
52:52the factors that need to be considered.
52:54And it does, it comes down to how much
52:57the emissions current indoors
52:58versus outdoors.
53:00The other for Nox,
53:03you already really got out one of
53:04the huge factors there, is there is no,
53:09there's not a readily available filter that we already have
53:11in all the homes that filter NOx with
53:14the kinda efficacy that we have with particle filters.
53:17So, that adds a really interesting thing that makes it
53:21so that HVAC system doesn't have as
53:23large effect on that gas phase pollutant.
53:27So, Ken and I have have some things
53:29that we're thinking about and working on,
53:31although NOx is not one of 'em at the moment.
53:35Unless Ken's gonna send me an email later today,
53:38telling me to start writing.
53:40But yes, there's a lot of interesting things here.
53:45Yeah, we're just kinda scratching the surface
53:48to thinking about how other pollutants
53:49behave in these changes.
53:52And Jordan Peccia spends a lot time thinking about moisture,
53:56and how that's going to affect
53:56microbial activity at home.
53:59So we think about holes, and other standpoints.
54:01That's an area of interest.
54:03I encourage you to try to catch up with
54:06Jordan, because he'd love it.
54:09That is a real important factor on developmental health.
54:16Great. <v Host>Thank you everybody.</v>
54:18And because we have across right of us, so we're happy,
54:21and thank you everyone for coming.
54:22Thank you again Ken and Drew.
54:24<v Dr. Gentner>Thank you Ken.</v>