How The World Of Building Materials Is Responding To Climate Change

IRA FLATOW: This is Science Friday. I’m Ira Flatow.

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Continuing with our Degrees of Change ideas. In order to slow climate change in a world on target to warm by 2 degrees Celsius, nearly every industry will be forced to adapt, the airline industry, the fashion industry, even the unglamorous and often overlooked building materials sector, one of my favorite industries. And just like the farm to table movement, consumers are increasingly thinking about where the raw materials for their homes and their cities come from and how they impact climate change. And in response to this concern, the material sector is serving up an unusual menu option, timber.

We’re not talking about your 2 by 4s here, we’re talking about boards and panels of wood that are glued together to make ultra strong building blocks and beams out of which you can make an entire building without steel. Mass timber, it’s called. It’s the buzzword these days in the world of sustainable building materials.

Architects are crazy for it, engineers praise its excellent structural properties, and even forestry managers are in support of its use. So we asked you, would you consider living in a timber city if it meant reducing your carbon footprint, and you’ve answered. Here’s David from North Carolina. He had this to share.

DAVID: I thought about this question and decided that I would. But I also thought about living in a city that’s mostly made of stone and cinder blocks, bricks, then I remembered that the process of creating cinder blocks has a massive carbon footprint, as does cement.

IRA FLATOW: But we also heard from people like [? Pellucid ?] in South Jersey.

SPEAKER 1: Who thought of this question? We need to grow more forest, not chop them down for cities. Not only that, I’m sure that there are better materials and stronger for building cities in the face of the turbulence of global warming.

IRA FLATOW: And it is strange when you think about it. Why would cutting down trees to build homes be a greener way of building? And can wood really be sturdy enough to hold up something like a city skyscraper? Here to help answer these questions and explain why mass timber is gearing up to be the building material of choice to fight climate change are my guests. Let me introduce them to you.

Kate Simonen is director of the Carbon Leadership Forum and associate professor of architecture at the University of Washington. Welcome to Science Friday.

KATE SIMONEN: Glad to be here.

IRA FLATOW: Frank Lowenstein, chief conservation officer with the New England Forestry Foundation. Welcome to Science Friday.

FRANK LOWENSTEIN: Thank you so much.

IRA FLATOW: Casey Malmquist, founder and CEO of SmartLam North America, a cross-laminated timber company. Welcome to Science Friday.

CASEY MALMQUIST: Greetings from beautiful northwest Montana.

IRA FLATOW: Nice to have you. And we also want to hear from you, our listeners out there. Have you worked with mass timber or cross-laminated wood or used them in your home? Our number, 844-724-8255 is our number. You can also tweet us @scifri and let us know what you think.

Frank, let me begin with you. Let’s address the elephant in the room. Cutting down trees will help fight climate change? How do you explain that?

FRANK LOWENSTEIN: Well, it’s important to recognize that, just like all of us, trees have a lifecycle and they have a maturity. And so we really need to keep our forests. The forests of the world store as much carbon as all– as is in the atmosphere already, so if we lost all the forests, we would have a big problem. But the individual trees within the forest are eventually going to die, and when they die, some of the carbon is incorporate into the soil, and some is released back into the atmosphere. So wood buildings are potentially a way to harvest the trees when they’re mature and lock that carbon up for hundreds of years more.

IRA FLATOW: Kate Simonen, is mass timber movement exciting to you as an architect?

KATE SIMONEN: Yes. All buildings are exciting to me as an architect. And using materials in new ways and exploring them is part of the creative process of designing and building, so yes.

IRA FLATOW: So what in particular is exciting to you about this kind of timber?

KATE SIMONEN: Well, there’s two things that are exciting. One thing that is exciting is that it is new methods of expressing building materials, so tall wood buildings give a different expression of building. The other thing that’s exciting is that wood does demonstrate the potential for biological materials to take carbon out of the atmosphere and store them in long-life building products.

IRA FLATOW: Casey, you started the first cross-laminated timber company in North America. For those of us who can’t see what a piece of timber is like, can you explain how you make the material, what it looks like?

CASEY MALMQUIST: Yes. Fundamentally, it’s fairly simple. We take primarily 2 by 6 and 2 by 8 boards that we buy direct from mills, we lay them up basically in layers that run perpendicular to each other. We can go up to nine layers thick, which is approximately a foot thick.

Our operation, we can do a panel up to 11 feet wide and 52 feet long. All of that, those layers are connected with a very high-tech, but very safe, innocuous adhesive. It’s all bound together under a hydraulic pressure to form a solid plate structural timber. When all of those individual boards are combine, we end up with a structural element that is equal in strength to concrete and steel for a similar profile.

IRA FLATOW: You know, I’m thinking, when I look at it, and when you talk about it, I’m thinking of a massive piece of plywood. Would I be far off on that?

CASEY MALMQUIST: No. There’s been the term plywood on steroids tossed around. It is similar in design as an engineered wood product, and it’s kind of relying on the same principles.

IRA FLATOW: Does the lamination actually make it stronger than building with steel?

CASEY MALMQUIST: Yeah. Pound for pound, the wood fiber is stronger than steel, and it has a lot of unique characteristics. One of them that I really like is what’s called ductility, particularly when compared to concrete. Concrete is very brittle, and when put under pressure and when it fails, it ruptures catastrophically, where wood has this ductility, sort of flexibility and strength.

Imagine watching a tree in a windstorm. That tree is arching across the sky several feet. That strength is not because of its rigidity, but in fact, because of its ductility. And that sort of material property translates into some of the benefits you get out of constructing with it.

IRA FLATOW: When people hear of a wood constructed building, the first thing that comes to mind is fire. How fireproof or how fire-resistant would this construction be?

CASEY MALMQUIST: Well, that’s an interesting question and very counterintuitive, and we’ve done extensive testing to prove this out. But when you mass timber together, it starts to behave very differently. And think about it, if you’re an outdoors person, when you try to create a fire, you typically have to carve the wood up into very small pieces, create surface area, and that will combust rather easily, but when you mass it together, it’s kind of like lighting a log with a BiC lighter. You won’t be able to get that to combust.

There’s a very simple process called the charring process where that combustion takes place on the very surface of the wood, it gets in an 1/8 of an inch, and it loses its combustion source and self-extinguishes. Ironically, wood actually behave better in catastrophic fire conditions than concrete or steel do, and that would actually get stronger in temperature where concrete and steel actually get weaker.

IRA FLATOW: Frank Lowenstein, you remind me of a big redwood forest, trying to light a redwood with a match, right?

FRANK LOWENSTEIN: Yeah. Yeah. I’ve certainly been on many a camping trip where I’ve put too big of a log on the fire and waited for it to catch from the little things I had burning and nothing happened.

IRA FLATOW: Are forestry managers in favor of this kind of material building?

FRANK LOWENSTEIN: Forestry managers, particularly ones who are in it primarily as a product as opposed to a lot of the small private landowners who may own forests for heritage reasons, or because they love trees, but the guys who are in it, and the gals who are in it for a product, they’re for any use that’s going to give them a new market.

IRA FLATOW: Let’s go to the phones, 844-724-8255. Dave from my Delavan, Wisconsin. Hi, Dave.

DAVE: Hi. Appreciate your time. I love wood. I love the concept. I think you briefly touched on one of my concerns, and that would be the toxicity of adhesives used and any other chemicals for, well, I was going to say fire retardant or other products, but I appreciated the comments you just made about how it behaves under those conditions. Has this stuff have been tested for off-gassing over the long haul?

IRA FLATOW: Let me ask my guests. Casey?

CASEY MALMQUIST: Yes, so our adhesive is a single part polyurethane resin. It is non-VLT, no volatile organic chemicals. Does not off-gas, has no formaldehyde. I mean, it’s kitchen grade. You can eat it. Not recommended, but yes, it has very innocuous properties.

FRANK LOWENSTEIN: And Casey, haven’t all the manufacturers now, aren’t they using a similar adhesive?

CASEY MALMQUIST: The majority of them are using them, yes. And a lot of that is guided by fire code. There are additives in that that promote fire resistance. Virtually all the producers are using that.

IRA FLATOW: We have a few tweets and a call coming in. [? Okimo ?] tweets, “I’ve worked with laminated wood structures in the South, and it’s a solid building material for most structures, ie, towers less than 12 stories or so as long as they use sprinklers. Jackie tweets, I’ve been using Parallam, a form of mass timber in my sculpture. It has a very beautiful and unique texture. It’s easy to work with, and it’s cheap. How tall can you make the structures, Casey?

CASEY MALMQUIST: Well, that’s up to the architects and the engineers. The tallest building that I’m aware of right now in place is an 18-story building. There are designs out there for buildings exceeding 30 stories, which I think will come online here fairly soon. That’s all an engineering issue. That can be resolved, again, with inherent strength, and in combination with other materials, including concrete and steel.

IRA FLATOW: Kate, you’re an engineer, building engineer. How tall do you think you can get these?

KATE SIMONEN: Well, there’s always the question of how tall you can get something. I think there’s a little bit that it’s important to recognize how tall should you, or what’s the best use of material for the right spot. So an ultra high high-rise with wood columns would start to become ridiculous in terms of the size of the columns themselves.

And then there’s the issues of lateral stability, how does it hold up for wind and earthquakes? So I think what architects and engineers are excited about is having another material in their toolkit and being able to choose the materials that are right for the project. So I guess I’d advocate for– there’s a lot of potential for taller buildings out of wood, but we shouldn’t just be narrowly focused on that it has to be all wood.

IRA FLATOW: Diversity is good.

KATE SIMONEN: Yes.

IRA FLATOW: Let’s go to the phones. Albert in Miami, hi, Albert. I hear the waves.

ALBERT: Hows it going, Ira?

IRA FLATOW: Hi, there.

ALBERT: Yes, yes, I just wanted to bring this to your attention. I’m with Third Wave Volunteers. We were responding to Hurricane Dorian in the Bahamas, and the Abaco forest there was pretty severely damaged, and we noticed it, we started to ask some questions, and partnered with University of Miami, Perkins and Will architectural firm, and we’re kicking off a large-scale mass wood project utilizing the felled Abaco pine that’s in the Bahamas based on the old Bahamian clapboard house builds which were built by the original boat builders in the Bahamas. It’s been a useful project, and in the Bahamas, they seem to have weathered the storm better than many concrete homes.

IRA FLATOW: Thanks for that call.

FRANK LOWENSTEIN: That’s a really interesting point. As climate change progresses, it’s not only something we want to prevent, but it’s actually a threat to forests. You’re seeing rising mortality, things like the fires in Australia, but also beetle kills, the hurricane that was mentioned in the Bahamas. And so we’re going to have trees that have been damaged or killed, and what are we going to– what use are we going to make of those? If we can turn them into mass timber, use them instead of concrete and steel, which both require right now massive amounts of fossil fuels to produce, that’s a good thing for the climate, it’s a good use for the material.

IRA FLATOW: I’m Ira Flatow. This is Science Friday from WNYC Studios. And that one, that’s an interesting point that you make, because you can use wood that normally would not be available in construction, right, Casey? You can use smaller, less desirable pieces of wood.

CASEY MALMQUIST: Well, there’s a little bit of a myth with that. So small diameter in our world is probably 12 inch diameter and greater, because we do have to get to the dimensions of 2 by 6 and 2 by 8. And also, the inherent strength of that wood is important. That translates directly to the strength of the finished product.

So we are somewhat selective in getting– we can’t use garbage wood to make a high-quality product. But we do– this does not require old growth material, does not require massive trees. What we’re trying to focus– all of our product is produced from sustainable forestry practices. So all of this is– basically, it is that farm to table concept. We only are able to– we’re only going to consume what we’re able to produce.

IRA FLATOW: One last quick tweet came in from Julie, who says, can reclaimed barns wood and timbers be used for larger building projects? Can you make those into this kind of wood, Casey?

CASEY MALMQUIST: Typically, not, no. barn wood would not have– all of our product has to be graded and rated for structural properties, so some of that reclaimed probably would not– unless we use it for a face material for aesthetic purposes, but structurally, again, it has to be a graded structural material.

IRA FLATOW: Frank, you happy with the way this direction is going and using the forest this way?

FRANK LOWENSTEIN: You know, I am. I think this is a key part of the solution to climate change, and we have such a crisis in front of us. More than 10% of the world’s emissions of CO2 come from producing steel and concrete, so we’re going to need to cut that just like we need to cut the emissions of every other sector of society. This is a great way to do that, if we can use wood instead of steel and concrete.

IRA FLATOW: Well, the folks in the steel and concrete industries are also coming up, trying to be more sustainable.

FRANK LOWENSTEIN: Yeah.

IRA FLATOW: We’re going to talk about that right after the break. They have some interesting ideas that we’ll get into. But I want to thank my guests who we’ve had, my guests this hour.

Kate Simonen, director of Carbon Leadership Forum and associate professor of architecture, University of Washington. Frank Lowenstein, chief conservation officer with the New England Forestry Foundation. Casey Malmquist, founder and CEO of SmartLam North America, a cross-laminated timber company. Thank you all for taking time to be with us today.

As I say, when we come back, we’re going to talk about the concrete and steel industries in the face of competition from timber, how they are responding to the pressure of climate change, and to evolve to becoming more green. They’ve got some interesting answers. If you’d like to talk about it, our number, 844-724-8255. You can also tweet us @scifri. Maybe you’re in that industry. We’d like to hear from you.

Stay with us, we’ll be right back after the break. This is Science Friday. I’m Ira Flatow.

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Our Degrees of Change series continues, and we’re talking this hour about how the building materials industry is responding to climate change by reducing its carbon footprint. Big industries like concrete and steel are finally responding to the threat of climate change by making these materials carbon neutral, or at least curbing emissions sustainably and substantially. Steel is one of the biggest carbon emitters in the world, not only because it’s energy intensive, but because it relies on burning coal as part of a chemical manufacturing process. So is there an alternative?

It’s a tough problem to solve, but at least one steel company is looking to overturn hundreds of years of tradition by using something else, hydrogen. Earlier this week, we spoke with Martin Pei, chief technology officer for SSAB, one of the largest steel companies in Europe. He told us, for hundreds of years, the process for making iron used in steel has been the same, iron oxide and iron ore is combined with coal in a chemical reaction that creates iron and emits CO2 as a byproduct.

MARTIN PEI: Hydrogen can do, in principle, the same job chemically. Hydrogen then can combine with oxygen from iron oxide, and then from that process, we get iron in the solid form instead of liquid form, and then the byproduct will be water.

IRA FLATOW: But one of the big hurdles in scaling up this process is getting enough hydrogen. Coal we know is abundant. Hydrogen has to be made.

MARTIN PEI: Hydrogen can be produced by using green electricity. Electricity can separate the hydrogen from oxygen atoms contained in water, and then we can use hydrogen to make solid iron from iron ore, then the solid iron is melted together with the recycled scrap, then we can make the high-quality steel products that we are making today.

IRA FLATOW: Martin Pei is chairman also of the board for a new company that was created to work on this technology called Hybrit, and they’re aiming to have carbon neutral steel ready for market by 2026. Still with us to talk about building materials and building is Kate Simonen, director of the Carbon Leadership Forum and associate professor of architecture at the University of Washington. What do you think, Kate? How is the steel industry doing with this carbon neutral idea?

KATE SIMONEN: Oh, it’s tremendously exciting. We’ll see across the building sector, from steel to cement, to even carpet, manufacturers are really innovating, not just about being more efficient, but also transforming the chemistry of how they make products with the goal of reducing carbon emissions, and ideally, figuring out a way that carbon is sucked from the air and turned into long-life building materials.

IRA FLATOW: Of course, that problem that he talked about is, well, can we get enough hydrogen? Can we make hydrogen sustainably and green so we don’t take more energy to make that energy?

KATE SIMONEN: Well, that’s a tricky question. I’m not a chemist. But what I do see is that there is growing collective momentum about both the urgency of this issue, and the potential for really positive solutions. So not one industry or one individual can have all the solutions, but if we work together, hydrogen fuel production, and the steel production, and how we design and build buildings.

The building sector, might be surprising to know, is responsible for over 40% of global greenhouse gas emissions, and if we look at new buildings built today, as much or more than half of their impacts will be from the material production. And we need to build more to have a healthy, happy world for everybody, so we can’t just stop building. We need to figure out how to build and have the building be part of a climate solution.

IRA FLATOW: And of course, you’re not talking about– as you said in the last segment, there is room for every kind of building material. You’re not talking about– or no one, I think, is talking about totally doing away with concrete or steel, but reducing it.

KATE SIMONEN: Using all of the assets that we have very efficiently at their highest, best use. So yes, everything.

IRA FLATOW: All right, let’s move on to concrete, one of my favorite topics. Concrete offers another challenge to fighting climate change. The production of cement and then concrete releases a large amount of carbon dioxide. And one person who knows a lot about how the concrete industry is tackling this issue is Jeremy Gregory, a civil and environmental engineering researcher, executive director of the Concrete Sustainability Hub at MIT. Welcome to Science Friday.

JEREMY GREGORY: Thank you. I’m delighted to be here.

IRA FLATOW: For people who don’t know how carbon intensive concrete making is, the process, give us a little thumbnail sketch.

JEREMY GREGORY: Well, as many people know, concrete is made up of cement, which is like a powder, that you mix with water and then sand and gravel, so concrete is the mixture of those four ingredients. Now, making cement relies on digging up limestone from the earth, heating it up to very high temperatures, and then turning it into this powder that we call cement. So actually, on a per unit weight basis, concrete is pretty cheap and has a low environmental impact. But the issue is that we use more– we use concrete more than any other material in the world, except for water. So on a per unit weight basis, it has a low impact, but because we make so much of it is why we should really be focusing on it as an opportunity to lower greenhouse gas emissions.

IRA FLATOW: And are there are experimental methods or methods that are being used to lower the CO2?

JEREMY GREGORY: There are lots of opportunities available today to lower the CO2 of cement and concrete. Some of them are about using what we call supplementary cementitious materials. There are waste materials, such as fly ash from coal-fired power plants, and slag from steel production, those can be ground up into powders that can be used as a binder like cement in the concrete.

So those are pretty simple things that are available today. But there are also some exciting opportunities about technologies that are being developed, and also in the marketplace today that use captured carbon dioxide from industrial sources, such as cement plants or power plants, and using them in the production of concrete or aggregates. And what’s exciting about that is with some other opportunities, we can then create concrete that has a net zero or even negative carbon footprint. And so capturing that carbon dioxide from one source, putting it into concrete, and then it’s permanently sequestered then in the concrete, so that’s a maybe newer exciting opportunity.

IRA FLATOW: That is interesting. I never heard about that. We hear about CO2 being locked up in wood, but not in concrete.

JEREMY GREGORY: Yeah. Yeah. I think it is something that’s an opportunity that people don’t talk about. And like I said, there’s a lot of researchers that are looking at if carbon capture is an important part of our greenhouse gas mitigation strategies, what do we do with that captured carbon?

And a lot of people look at sequestration, geological sequestration deep in the earth, but those are problematic because the carbon dioxide can often leak back out. Whereas what’s interesting about using it in concrete is that, like I said, it’s permanently sequestered. And studies have been done show that by value, and then also just by pure mass, if we can put that– if we can put that captured carbon dioxide in concrete and aggregates, we can make a real significant dent in greenhouse gas emissions.

IRA FLATOW: Kate, do you think– the public is looking for things that are green. They’re shopping for green clothing. Do you think that if they had a choice between a greener building and one that’s just built the way it is now they would opt to buy or live in something like that?

KATE SIMONEN: I think it’s the responsibility of us as design professionals to show people what is truly possible, and that’s buildings that perform really well, and that are part of climate solutions. I think that it’s incredibly inspiring to see the youth movement around engaging on this topic. I’ve worked with middle school and high school students who are looking at creating information about the carbon impact of building materials and spreading the news. I expect that we’re going to see a rapid transformation of understanding of the importance of buildings in climate and a willingness to engage in really testing out new solutions.

IRA FLATOW: Let me go to the phones to David in Springfield. Hi, David, welcome to Science Friday.

DAVID: Oh, thank you, Ira. And thank you for what you do. The thing I’m not hearing come up here with these guys, and maybe your concrete guest can address this.

Right now, in France, they’re developing Hempcrete, and they’ve actually finished some buildings made out of a concrete hemp mixture. They’re developing hemp wood now to build the fiber products that your other guest was speaking about. And I just don’t think cutting down trees is the way to fix the climate.

IRA FLATOW: All right, let me ask. Thanks for that call. What about hemp as a building material, Kate?

KATE SIMONEN: Well, there’s a lot of interesting materials that are really agricultural waste products, so the straw and materials like hemp that are fast-growing, and reusing bamboo. Biobased materials really do need to be looked at from a whole systems perspective, and what happens in how they are growing, so forest management, and how long– how long their typical rotations are, and where do we taking? The best use would be things that are dead or dying already, but there’s a broad range of opportunities here.

IRA FLATOW: Jeremy, can I go to my local home fix it store and buy a bag of this new kind of concrete, the cement?

JEREMY GREGORY: You can’t go to the local fix it store, but there are a lot of concrete producers that are already using these technologies that incorporate captured carbon dioxide into the concrete. The other thing, I think, that’s pretty basic, as Kate knows very well, the architects and engineers just have to start asking for it. And I think it’s sort of a really basic thing that when it comes to a lot of construction, we just don’t ask for what’s the environmental footprint of your concrete, and I think that’s something, just a really basic first step we got to do. We’ve got to show there’s demand.

IRA FLATOW: I’ve got to make sure–

KATE SIMONEN: Can I add into that?

IRA FLATOW: Yes, please, Kate.

KATE SIMONEN: That asking is not just the rule of the professionals, that’s the asking of the public. So the public can ask these questions, and that helps drive change. Owners are more– owners, particularly owners who are making large-scale global climate commitments, are starting to ask these questions. These questions will need to be asked by everybody.

IRA FLATOW: So if I go to my Lowe’s or my Home Depot and say, I would like you to find a way for me to build with this cement made out of the sustainable cement, they would listen and maybe that would help move the wheel a little bit, Kate?

KATE SIMONEN: Yes. When I talk to manufacturers, they are discouraged by the lack of people being excited about their innovation. Lowe’s and Home Depot and the people that are selling you your flooring all need to be asked. They may not have an answer right now, but if enough people ask, they will figure out how to move their market.

IRA FLATOW: All right, number, 844-724-8255. Let’s go to Orlando. Steve, hi, there. Go ahead, Steve.

STEVE: Yes, hi, Ira.

IRA FLATOW: Hi, there.

STEVE: I’m calling in from Orlando, and I design homes here in Florida and around the country, and I’ve done some in foreign countries too. One of the problems here in Florida is termites, and it’s the number one cause of insurance claims here in Florida, as well as fires and tornadoes. So insurance is a big issue.

People who have their homes designed and built out of concrete block save a substantial amount of money when they build out of concrete block as opposed to wood. This is not to say that we’re not going to have any wood products within the project, we have wood trusses, we have wood furring, we have wood interior walls, wood cabinets, and they’re all important and necessary within the architecture of the housing industry. But as far as the main superstructure of the house, we try to use concrete block wherever possible, and that saves a lot of money in insurance, and I just wanted to make a comment about that.

IRA FLATOW: Well, don’t go away, because I have a question I want to ask you right after I tell everybody that I’m Ira Flatow and this is Science Friday from WNYC Studios. Our guest, Kate Simonen, has been saying, if we want to change things, we have to ask for them. Would you, as a construction engineer or someone who builds homes, would you be willing to ask for concrete block that is made out of more sustainable concrete?

STEVE: Well, absolutely, yes. Sustainability of concrete is getting better and better all the time. And one of the things I’ve noted from specs that I’ve seen from ACI, the Concrete Institute, is that adding more fly ash to the concrete strengthens it, thereby reducing the need for some of the Portland cement that goes into it. And I’m not an engineer, I’m a designer, but one of the things that I’ve noted is that as concrete products have evolved over the last, say, 15 or 20 years, is that it is more and more environmentally stable and sustainable within the design and construction field.

IRA FLATOW: Well, thank you for phoning in and telling us about your work. You’re just backing up what Jeremy and Kate have said. Jeremy, a guy in your industry.

JEREMY GREGORY: Well, I mean, there are a lot of people who know about the many benefits of building with concrete, but I think one of the things that Steve raised that is important is that there are– there are different ways that you can make concrete. People sort of think maybe it’s just those four things that I mentioned, but there’s really almost infinite combinations of different types of binders and aggregate that you can mix together.

They will have some trade-offs in terms of different properties that you’re looking for, whether it’s strength, or stiffness, or time it takes to achieve some of those properties, but once again, just comes back to asking people to say, not only am I looking for that kind of performance, but I’m also looking for a low environmental impact as well.

IRA FLATOW: So you’re agreeing, concrete, as I’ll call it, is as strong and will last as long as what we have now?

JEREMY GREGORY: You mean these more sustainable concrete? Absolutely. Absolutely. If not better.

I mean, there’s a reason that we still have concrete left around from thousands of years ago that the Romans were making.

IRA FLATOW: The longest structures that we have.

JEREMY GREGORY: Exactly. Exactly?

IRA FLATOW: Last word, Kate, on concrete?

KATE SIMONEN: Well, I think that the caller brought up a really important point, is that it depends on where you are and what you’re doing what’s the best material to use. concrete. Has opportunities for improvement, steel, wood, all of these materials, we need to be driving towards climate smart solutions as we’re building. And it’s both the material choice, who makes the material, and how we configure, and even what we build. The lowest carbon footprint building is one that we retrofit and reuse and maintain over long periods of time.

IRA FLATOW: There you have it, Kate Simonen, director of the Carbon Leadership Forum, associate professor of architecture at the University of Washington. Jeremy Gregory, a civil and environmental engineering researcher, executive director of The Concrete Sustainability Hub at MIT. And special thanks to Martin Pei, CTO of European steel manufacturer SSAB, where he spoke with us earlier in the week.

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