Instant Genius - How to make buildings without harming the Earth

Episode Date: October 8, 2026

Every built environment we spend our time in, our homes, offices, music venues or sports stadiums – is designed and constructed after hours of consideration about form and function. Oftentimes, less consideration is given to the impact this has on the health of the planet. In this episode, we’re joined by Will Arnold, an environmentalist, engineer, and author, to talk about his latest book, Future Build – How Construction Can Heal Our Planet. He breaks down the huge environmental impact the five most common materials we use to construct the buildings we spend our lives in have on our planet, tells us some of the ways we could be producing these materials more efficiently and using them more thoughtfully, and looks to a future in which we can construct buildings that are more in tune with the environments they’re built in. Take your curiosity further with a subscription to BBC Science Focus magazine. Every issue is packed with fascinating insights into the science behind everyday life, the latest breakthroughs and expert analysis, delivered straight to your door. Receive an extra £5 when you subscribe using the code SF5OFF, (minimum spend £20, see full terms and conditions on our website). https://www.ourmediashop.com/bbc-science-focus-magazine-pod30 Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Discover coffee plus on nispresso.com. This episode is brought to you by Animals. How far would you go when someone threatens everyone you love? Who can you trust? From Academy Award winner Ben Affleck. Animals stars Affleck, Carrie Washington, Jillian Anderson, and Stephen Young. When a Los Angeles mayoral candidate's son is kidnapped, he and his wife are pulled into a web of deception,

forced to make choices that could tear their world apart. Watch Animals only on Netflix on October 9th. R. Hello and welcome to Instant Genius, a bite-size masterclass in podcast form. Every Monday and Friday, you'll hear world-leading scientists and experts talking about the most fascinating ideas in science and technology today. I'm Jason Goodyear, commissioning editor at BBC Science Focus. Every built environment we spend our time in, our homes, offices, music venues or sports stadiums is designed and constructed after hours of consideration about

form and function. Oftentimes, less consideration is given to the impact this has on the health of the planet. In this episode, we're joined by Will Arnold, an environmentalist engineer and author, to talk about his latest book, Future Build, How Construction Can He Heal Our Planet. He breaks down the huge environmental impacts the five most common materials we use to construct the buildings we spend our lives in have on our planet. Tells us some of the ways we could be producing. these materials more efficiently and using them more thoughtfully and looks to a future in which we can construct buildings that are more in tune with the environments they're built in. So welcome to the podcast. Thanks so much for joining us. Thanks for having me on.

So today we're talking about your latest book, Future Build, How Construction Can Heal Our Planet. So before we get into the healing bit, let's start with some of the ways that construction is harming the planet that you talk about, you know. How big is the contribution of the construction industry to things like carbon emissions, waste production, the use of raw materials, etc? I mean, without wanting to start by scaring people off, it's an industry kind of that doesn't really compare to others on this. And I think what's interesting is that the stats I'm about share. Most people have no idea of these numbers, right? So the use of materials in construction is responsible for something like one-tenth of all carbon emissions around the world.

So that's about four times the amount of emissions that come from the aviation industry. It's responsible for about a third of all waste around the world, which is a number that's only surpassed by food waste, I think. And then on top of all of that, it's responsible for about half of all raw materials that we extract from the Earth. So that's something like three times as much fossil fuel extraction every year. So these numbers are huge, And obviously those things sort of compound each other in terms of pollution and impacts that they all create.

Yeah, so let's start with materials then. You mentioned materials there a couple of times. Yeah. Obviously, if we're going to build something, we need to build it out of something. And you sort of single out the what you call the Big Five materials. So, you know, what are they? So, yeah, if you went on a construction material safari, these would be the materials you'd be looking out for, except it wouldn't take you very long, so it'd be quite disappointing.

they are concrete steel, glass, aluminium and bricks. And I would challenge your listeners to look out the window right now and see if they can't spot them because most of the time we can see these or a collection of them everywhere we look. And they, I mean, these are responsible for the sort of, you know, the foundations of human civilization, right? This is what almost every building in the world is built out of, with a few exceptions. They're incredibly useful. They're useful because these materials are, very durable, they're very strong, they keep the rain off our heads pretty adequately,

and they do so in a way that means that they don't rot away over time, you know, insects can't attack them, they're sort of like very safe and long-lasting materials. So we've become really reliant on them over the years as humanity. And what's really interesting, actually, is that when these materials were invented, when they came into common use, they were the expensive options at that point in time. You know, prior to these industrial, realised materials. We would build our homes out of earth and straw and bamboo and trees. And basically anything that either grew or that could be dug out of the ground, that's what we would use for construction. And people with a lot of money, like kings and queens and monarchs and

so on, they might use stone, you know, something a bit more, a bit more durable, a bit bigger, but obviously there's a lot of work behind that. But for, you know, for most of humanity's history, we've relied on these sorts of materials. And then over the past couple of hundred years, we've seen a rise in the big five. It's not the first time they've come about. I mean, concrete was invented by the Romans, which is about 2,000 years ago. They built a whole empire out of it.

If you go to Rome, you could be mistaken for thinking that you're looking at a lot of stone and marble buildings, but actually most of these buildings have concrete behind them or underneath them in some way or another. And an equally long time ago, the brick was invented, the fired brick, both in Mesopotamia and China at the same time.

People worked out if you fired these clay bricks. be a lot stronger. But it's only really in the past couple of hundred years that they've become super normal. And now they're everywhere. And while they were the expensive option at the start, our demand for these materials has driven prices down. And now they're not only what we rely on and what we what we see is the most useful. They're also typically the cheapest materials. And therefore, we are hooked. We are totally addicted now. Yeah. So obviously these materials, you know, you can't, most of them anyway, you can't just dig straight out of the ground. They have to be produced.

And this is where quite a lot of the environmental issues lie, isn't it? So can you give us a sort of quick rundown of some of the biggest offenders? Yeah, they do have to be produced. And effectively what we're trying to do is we are digging something out the ground to start with, and then we are trying to change the chemistry of that material into something that makes it stronger, more durable, longer lasting, and so on. To make that chemical change happen, we typically heat these materials. wheels up, and we heat them to incredibly high temperatures. So this is not the sort of temperatures

that you could use your oven for in your kitchen. We are talking the same temperatures as the base of a space rocket, typically, so somewhere in the order of magnitude of 1,500 degrees Celsius, you put an oven, oven meal near to one of those babies. It's not going to last very long. And to power these processes, we typically rely on fossil fuels to do that. The exact numbers range between something like 1,600 degrees C, but they're all in that sort of ballpark. And if we take concrete, for example, because it's the most prevalent, it's the second most widely used material on earth, second only to water. If we take the way concrete is made, what we get really interested in is cement. And cement is the sort of glue that holds everything

else together in the concrete. So the cement gets mixed with water and gravel and sand and stuff like that. But it's making the cement that's so polluting, so damaging to our environment. To make cement, you take limestone, which for anyone who's been to a limestone quarry or seen it, we would know it's quite hard, it's quite tough. You imagine trying to sort of chip that out of a quarry with a hammer. You're going to be there quite a long time. So we take thousands of tons of this stuff, this limestone, we crush it up, and we put it into what we just call a kiln. And of course, when you say kiln, people think of the things you fire potter in. You know, it's quite quaint. But a cement kiln is nothing like that. A cement kiln is the size of a jumbo jet. It's this enormous

long steel tube, it rotates slowly, and as it rotates you to feel the earth shudder underneath you. And down the middle of that tube, they fire a gigantic jet flame. It's like the length of the whole tube. So imagine a jumbo jet with a jet flame running down inside of it. And that jet flame is powered by coal for the most part. It's pulverized cold dust. That's the only way we can get the temperatures to be high enough. And then we pop the limestone in, and the chemical reaction happens and it turns it into cement. And the problem we have here, is actually twofold. So number one, we're burning cold to create all that heat, and that releases carbon emissions into the atmosphere. That's actually only half the problem,

though, which means that even if you replace the cold with something else, you're still left with half the bottom. That second half of that problem comes from the chemical reaction that happens when we turn the limestone into the cement. And effectively, we actually strip away the oxygen atoms from the limestone, and that releases more carbon dioxide emissions into the atmosphere. And we have the same problem with our other four in the big five. They're all a combination of using fossil fuels and chemical reactions that add to the problem. And roughly across all of them, it's about a 50-50 split. So somehow you have to tackle both at once.

Yeah, so obviously, as you mentioned there, we've been using these for these materials or the ideas behind them, at least anyway, for thousands of years. So replacing them is going to be a big challenge, even just in terms of infrastructure and things like that. So what are some alternatives that we have at the moment to these? and, you know, is there any chance of those taking off? Yeah, I mean, the exciting thing,

the reason why I still get out of bed in the morning and haven't completely given up hope on my industry, is that we actually have solutions to all of these problems. This is no longer a technical challenge. This is a challenge to do with adoption, to do with normalising, to do with bringing costs down. So the construction industry and its use of materials is kind of at a similar point in time

to maybe where solar panels were at the turn of them, millennium. You know, they worked technically, but they didn't work financially, or they weren't widespread. Not enough people were making them. And this is why I have hope that we can make change happen. So if we take steel, for example, to start with the different materials, steel is made by taking iron ore out of the ground, which is a mixture of iron atoms and oxygen atoms. And then again, we fire it with coal, and that strips away the oxygen, which gives us these emissions. That leaves us with iron, and we turn the iron into steel. There are ways to do this, which is already happening around the world that instead of using coal uses natural gas. And that makes up something like

7% or so of all steel making around the world uses gas instead of coal. And it has now been proven that you can change natural gas out for hydrogen. And of course, if you can make the hydrogen using renewables, you end up with steel made with no fossil fuels. And about three years ago now, a consortium of companies in Sweden called Hybrid actually did this and for the first time produced steel from iron ore without any fossil fuels being involved and therefore without those associated emissions. You could hold it in your hand and they're in the middle of building a new furnace that will, when it comes online and it should be this year or next, it'll be capable of producing something like a million tons of steel per year. And there's similar other companies doing the same now.

There's one being built in Namibia and at least one being built in China. So we know that this stuff can be done and it can be done at scale. It's just a case now trying to sort of to accelerate that change. How about the option? So you mentioned there's sort of timber and bamboo and things like that. So how about the option of sort of looking backwards to go forwards and, you know, returning to these materials that we traditionally relied on for our structures? Yeah.

No, it's really a point. And there's an argument here about, you know, the need to put the right material in the right place. And so if I'm building foundations for a tool building or a train station or maybe I'm building a tunnel, I'm going to be relying on concrete for that because of its strength, because of its durability and so on. If I'm building a house, you know, a two-story house in the middle of the UK, which is a fairly sort of, you know, we don't have earthquakes, we don't have typhoons, fairly sort of easy place to build in. I don't need to build that house on a concrete.

And yet at the moment we do in the UK, most houses have concrete blocks and fired bricks as their main superstructure. And it's not needed. There are loads of these examples where we could use other materials. You're quite right. And in the book, I, I try and pull out examples of people using these sort of materials in the past, but in modern ways. So one of my favorite examples is the Sagrada Familia, which is the world's largest church, and it's down in Barcelona. And it's very famous because the famous architect, Anthony Gaudi, famously started this project, 100 or 200 years ago, I forget. And it's taken a very long time to complete. And actually, when engineers were contacted about finishing off of about 10 years ago, the default assumption

had started to become that the rest of the Sagrada Familia would be built using concrete and steel and maybe clad in stone, so it would look like it was made out of stone, but really it would be a bit of a facade. And actually, the engineers were quite brave, and they turned around and said, well, it's not what Gaudi envisioned. It's not really faithful to the original idea. And we think we can make it better if we make it out of stone. But we don't want to make it out of stone in the way that, you know, medieval castles were made out of stone. We're not going to pile blocks on top of each other. We want to do something better. And so what the engineers did was that they came up with a system where they trimmed stone blocks down to about a third of the width,

the typical stone block. They drilled holes at the middle of them. And they effectively threaded blocks together on thin steel rods. So there's a small amount of steel at the middle, holding it all together. It's a bit like one of those push toys you might have had as a child where you sort of push up the bottom and the anthelope falls over, whatever it was, except obviously, in Sigrada familiar, we keep it all in the sort of tightened position. And as a result of this, not only were they using stone instead of concrete and steel with just those thin rods, and therefore they're using a far less damaging material, they weren't even using as much stone because they were applying these modern engineering ideas to it. And so the carbon

footprint was much lower. They're building as much lighter, which has advantages in somewhere like Barcelona, which has minor earthquakes, it was quicker to build, and yet it's retained this sort of original vision. So there's ways to use these old materials without necessarily having to give ourselves what might be thought of as like an old-fashioned building. We can build a future using the same palette, but using modern methods, modern technology. New from Nespresso. Blend wellness into your coffee routine with a coffee plus range, infused with functional benefits. Choose the coffee you love with added B vitamins,

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is sort of, you know, cost effectiveness versus environmental impact and other impacts. And of course, that's a big question to be asked of the buildings that we construct. So it turns out that actually we could be doing a much better job of using the materials more effectively, but it's more cost effective to do that. So we're sort of stuck in this sort of war between the two. Yeah. We've seen a trend over the past few decades where buildings have got heavier and heavier. And it comes from a shift where the costs of labour has gone up for good reason.

It means people are being paid more fairly. And the cost of materials have come down. And again, that's generally seen as a good thing because it means we've got more efficient with our methods of making them and so on. But as a result of this shift, we've gone from. a world where it used to be the case that if you could minimize the amount of material and use lots of labor to make it, that would be cheapest. Now we're in a position where you're trying to minimize your use of labor. And it doesn't matter if that takes more material. So for anyone who

enjoys a bit of architecture, maybe sort of 70s, 80s, brutalist architecture, if you go down, say, the South back in London, or even any car park built during that period, if you look up above your head, you'll quite often see concrete that looks a bit like a waffirm. that you might have for breakfast with jam on it or something. And we call these waffle slabs, and they are incredibly efficient in terms of their use of material. Because actually what you're looking at in each of those waffle shapes, in those indentations, you're just looking at fresh air.

There's no concrete there. And so it uses something like half the amount of concrete, less even, than compared to, say, just a completely flat slab, which is what we build everything out of today. So the equivalent today would be totally flat, totally uniform. in my personal opinion, very boring to look at, and it'd be far heavier, but it'd be quicker to make, and it uses less labour. And this is what's driving decision making today. Now, what's interesting is that I think the industry has started to, well, for a long time,

it's been thinking, well, in order to drive costs down, I therefore have to, you know, thicker and heavier and just quicker to make, and that's all this is there in this, and therefore being more sustainable is going to cost me money. and actually what people have started to realize, particularly over the last five years or so, when we've had a real push to change things in the UK to try and make construction more sustainable, people have realised there are ways to use less material and reduce cost at the same time. So the classic example of this is how far apart the columns or the walls are in a building. So if you think of the house that you live in and you think of the wall from one side of your house to the other,

if we take, say, a terraced house, those walls might be something like five, meters apart. If we look inside an office building that was built maybe five years ago before we started thinking about this, you might see columns that are more like 12 or 15 meters apart. There was this big drive for big open plan spaces and columns are further and further and further apart. Now, slightly counterintuitively, if your columns are further apart, you may have fewer columns, but the building ends up weighing a lot more. And that's because most of the material is not the stuff in the columns, it's all the beams and floors that go between them. It's a bit like if you went to the gym and you were asked to do a press up or hold the plank position,

and you were given the option between resting on your knees or resting on your feet. Now, if you rest on your knees, the distance of your body has to span is from your knees to your hands. It's about two-thirds of the length of your body. If you were told to take your knees up off the floor by your gym instructor, all of a sudden your body has to go much further. It has to be much stronger to hold it there. We have the same problem when we move our columns further apart. The structure above has to get much stronger, and it gets bigger.

and it gets heavier. And so over the years, as we've, you know, pushed and pushed to make our spaces more and more open plan, we've seen less and less columns, or fewer, fewer columns, but the beams and the slabs and everything above them have just got heavier and heavier and there's become a realisation in recent years that actually there's some simple fixes, like bringing the columns closer together, that all of a sudden make the building a lot more light, a lot more efficient. And this can be coupled with other things, you know, basements, add a huge amount of material for often not a lot of value. And, you know, silly eye-catching,

I'm catching sort of wavy-shaped buildings with big, you know, you know, petrusions out the side and stuff. Again, often adds a lot of material without creating a huge amount of value. And so I think that, you know, there's becoming an awareness that if we want to create low-carbon buildings and we want to do it in a way that also saves money and time, we need slightly simpler approaches to the way that our buildings are built and constructed. we need to be slightly more sensitive in terms of things like columns and so on.

And then we bring the beauty and the value of our buildings in with the materials that we finish these things in. So, you know, the materials that they're clad in, what we make the doors out of, what we make those, all those pieces of a building that you touch and you look at that stick in your mind, that's where the value needs to be added, not in some big heroic thing where the columns are so far apart. You can place a jumbo jet between them. Yeah, so let's have a look at that then. Because, you know, another consideration, not commonly, but amongst certain buildings, you know,

there's a desire to build, you know, what you'd call iconic buildings, like these giant huge structures. And often the kind of, some of them are, you know, really well thought out from an environmental perspective. But quite often it is kind of about, you know, what it looks and the statement it's making is one of the primary considerations. especially when you've got these sort of the type of clients behind them that want that to make that sort of statement. So, you know, where do they fit into this picture? Are they doing more damage than others about the same less? Is there anything we can do about that? Well, I think, yeah, I mean, I think the sort of irony here is that because we don't currently put any cost against the environmental impact and all the things that go with it.

We only cost the creation of the materials. Everything else is sort of externalised. it means that to create something that's bigger and bolder and maybe hangs over a motorway, we'll use a whole load more material, but the true costs of that are not taken into account. Going, you know, doing big, crazy shapes and so on, almost always adds more material, creates more damage, creates more emissions, more waste, more pollution, and so on. There's very few circumstances where that's not true. So taking a more efficient approach to the way we construct our buildings and creating the value and so on,

in other ways, has to be a really cool part of this. There's a really great book by Thomas Heatherwick called Humanise. And in that book, he talks about how buildings are, they need to be considered from three different distances. And I'm going to get this slightly wrong, but I think it's something like three meters away, 30 meters away and 300 meters away. And he argues that from each of these sorts of distances, far, medium and near, the building has to be, you know, considered in terms of its surrounding and what you look at

and what creates interest and so on. But he makes the point that the distance that matters the most is what he calls, either calls it door distance or door handle distance or something like that. And it's the really close one. It's the one way you're about to go into the building. And I don't think there's many people out there

where the main thing that sticks in their memory is the view of the building from afar once they've been into it. Once you've been into it, all you remember is what it's like to be inside, what there's space is like. That does not require you to do something silly with a building. It requires you to,

you know, have enough quality and care and consideration behind the materials inside that you're coming into contact with, that it leaves a, you know, leaves a good impression with you. And I think what's really interesting with this is this then takes us on to the bigger question, which is why are we building new buildings at all? Because actually, if you refurbish an old building, quite often, you get a lot of this quality in this tactile nature and this stuff that sticks in your head. You get it for free because it already exists. There's a slight irony in that you see a lot of these new developments, and the cafes at ground floor will have this sort of four meter floor to ceiling heights, and all the structure will be exposed above your head, and there will be all these ducks and these pipes and, you know, the plumbing and stuff will all be on show as if to create this illusion that this is a sort of like industrial warehouse-esque space and that it's all been, you know, left there over years of evolution of the building. And the reality is somebody's just designed it that way to make it look that way.

and we can do all of that for free by just taking a space like that that already exists and sticking a cafe in it. And some of the coolest places you can think of to go for a drink or go and meet your friends and restaurants, they're quite often these like old Victorian buildings or their little warehouses or, you know, maybe a church that's been converted into a library. And these buildings, they don't just come with all the materials for free, but obviously they have baked into this, the sort of the story of the place,

the people who have been behind them, there's a rich nurse, you know, they've been locked into the community for so much longer. And I think that as well as the industry realizing that we don't need to do big, bold statements, they're also realizing we don't need to do everything from scratch. And actually, if we move towards a reuse first mentality, kind of like we're doing with cups when we go to Starbucks and shopping bags when we go to Tesco's, right? You know, it's always bring your own for those. We don't want to throw away a cup, but wouldn't it be great if we also never threw away a building? And, you take the weight of a cup and you take the weight of a building,

you can see where the sort of difference lies. So we need to move in that direction as well. And in a country like the UK, where we have such a rich existing stock of buildings, it's even more important than in other parts of the world. Yeah, so let's have a look at another sort of possible way of attacking this, sort of mainly the efficiency issue, I suppose. And that's to take inspiration from nature,

which is often called biomimicry. So, you know, how does that work in, terms of construction and architecture? So, yeah, there's a sort of, as a rule of thumb in nature, nothing is ever flat, nothing is ever straight. And so that flat slab that I described before, that's less efficient than the waffle, you'd never see a flat slab in nature. And the exception that proves the rule is obviously that bit of rock you managed to find a sit to eat sandwiches on last time you went for a hike. But except for that particular rock doesn't exist anywhere. And that's because the way that nature has evolved over the millennia that we've existed on this planet,

is that anything that's sort of useless material has been stripped away through evolution. And so when you look at a tree, it's thickest at the basin, it's thinnest at the tip. And within that, all the branches do the same thing. And all of the bits that have the leaves on, they do the same. And this repeats and repeats and repeats. And it's nature losing excess material through evolution. the bits that are needed are kept and everything else is shedded away as that evolution happens. And we can apply this same logic to the way we design our buildings.

And whether it's the logic of the tree that gets thinner up its height, or you take, say, bubbles, soap bubbles, which are, you know, the minimum possible shape for the volume of air, which they have inside. Take roofs of caves, you take spiders webs. All of these things we find in nature, we can use all of those to teach us more efficient ways to design our buildings. Now, there's loads and loads of really cool examples out there, mostly of roofs to large buildings that have employed these methods.

If you went to the London Olympic Park and you went to the Velodrome, which was designed by the company I work for now, Expedition Engineering, the Velodrome's got this roof that's sort of shaped like a pringle. And if you go inside and you look up at it, it's incredibly thin. And the reason it works when it's so thin is that it's actually just a series of cables. It's like a big net. It's like a piece of stocking that's been stretched around this circular ring that runs around the outside. And that was strong enough and stiff enough.

We could then put roofing material on it. And the weight of that roof is like nothing compared to some of the other projects that have been built in the same area. Because its entire form was driven by this question of what the most efficient sort of nature-inspired approach would be. There's loads of these roofs and they're quite often in the sort of world of sports. What excites me even more than this is we now have people trying to apply that same, that same logic, that same approach to the way we design our floors. And the floors of our buildings is where most of the material is. Therefore, it's the biggest sort of opportunity to move forward.

And we've had quite a few companies and initiatives pop up in recent years trying to take the arch or the dome as a sort of structural form and create it in a way that it's flat on top and it's domed underneath. So when you stood on top of the floor, you can still walk on it, and your wheelie chair doesn't slide in any one direction. But from the underside, it looks incredibly graceful and elegant because it's sort of domes and it springs between columns. And there's a few of these systems out there in existence today. There's a couple that are being sold on the market, and they reckon that they are cheaper to buy than creating the flat slab from scratch. And so I think it's inevitable that we'll go in the direction where we see more and more of these products.

where we're stripped away, stripped away, the sort of useless material. And what's really interesting is once you've seen one of these things in real life with your own eyes, and I've been to see this stuff in Switzerland and so on, you then go back to like a quote-unquote normal building. Gosh, they look heavy. You know, you go back to what we consider normal and you just think, what is all this material? How did this get here? We don't need this. It's quite mind-changing. Thank you for listening to this episode of Instant Genius, brought you from the team behind BBC Science Focus. That was Will Arnold.

To discover more about the topics we've just discussed, check out his book, Future Build, how construction can heal our planet. If you liked what you just heard, then please do consider subscribing to Instant Genius on your preferred podcast platform. If you'd like to see our guests and hosts in person, then why not check out our YouTube channel at Science Focus.

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