Check out the episode:

You can find the shownotes through this link.

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Are you interested in embodied carbon accounting?

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Our summary today works with the white paper titled Measuring embodied carbon in the residential sector: Barriers and opportunities from 2024, by Tom Petty, published on the CarbonTrace website.

This is a great preparation to our next interview with Tom Petty in episode 306 talking about embodied carbon and its accounting.

Since we are investigating the future of cities, I thought it would be interesting to see the opportunities for the building industry regarding embodied carbon emissions. This white paper investigates different embodied carbon measuring methods and defines one for the residential sector.

[intro music]

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Welcome to today’s What is The Future For Cities podcast and its Research episode; my name is Fanni, and today we will introduce a research by summarising it. The episode really is just a short summary of the original investigation, and, in case it is interesting enough, I would encourage everyone to check out the whole documentation. This conversation was produced and generated with Notebook LM as two hosts dissecting the whole research.

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Speaker 1: We’re talking about the hidden carbon footprint of our houses, the embodied carbon. You know, all that buzz about energy efficiency, using less power day to day. Well, there’s a whole other layer of emissions baked in before we even turn on the lights.

Speaker 2: It’s kind of like this. People tend to fixate on the energy their homes use daily, you know, the operational carbon. But there’s this hidden impact from all the materials used to build it, like think concrete foundations, timber framing, the whole shebang.

Speaker 1: Yeah, and it’s not small potatoes. By 2050, this upfront embodied carbon could be a massive 85 percent of a building’s total footprint here in Australia. That’s crazy,

Speaker 2: right?

Speaker 1: It really shows how the focus is shifting. As we decarbonize the energy grid, the emissions from those initial building materials become the dominant factor. It’s like we’ve been working on one side of the equation, and now this other piece, the one we often overlook, is becoming glaringly obvious. So today we’re unpacking all of this. We’ll break down the barriers to understanding embodied carbon and explore some solutions that are popping up. Whether you’re a homeowner now or dreaming of that future place, this is going to give you some serious food for thought.

Speaker 2: And this is particularly important for Australia now. We’ve got these ambitious emission targets and we need to build more homes, but we can’t just ignore the environmental cost.

Speaker 1: Absolutely. Okay, so let’s jump into the first big idea from this paper. They call it embodied carbon, the invisible elephant in the living room. It’s like we’ve been so busy making our homes energy efficient, we totally forgot about the impact of, well, building the darn things in the first place.

Speaker 2: The paper does a great job comparing the commercial building sector to residential. And it really highlights the unique challenges we have when we try to measure and manage embodied carbon, especially for individual houses.

Speaker 1: Yeah, it’s not like a massive office building where you can just assume each floor uses the same stuff. Every house is different. So how do we even begin to measure this embodied carbon? Is it as simple as like counting the bricks? Unfortunately, it’s much more complicated. There are three main variables that make it tricky. First, there’s the scope of the analysis. What exactly are we including in our carbon calculation? Just the house itself, landscaping, appliances. Or, the whole life cycle, from construction to demolition.

Speaker 2: It’s like those Russian nesting dolls, right? Layers upon layers.

Speaker 1: Exactly. Then you have to think about the data on the carbon footprint of each material. Problem is, different databases use different methods. So the carbon footprint of, let’s say, a steel beam, can vary, depending on where you get your information from. It leads to inconsistencies, makes comparisons tough.

Speaker 2: So even if we agree on what to count, the numbers themselves might be all over the place. That sounds like a recipe for confusion.

Speaker 1: It definitely can be. And then there’s the third variable, which is figuring out how much of each material is used in a particular house. This is where it gets really tricky, especially in residential construction.

Speaker 2: Because every house is unique. It’s not like a factory made product where everything’s standardized and this lack of standardization and how we build homes makes collecting accurate data a real headache.

Speaker 1: So how does measuring this compare to, say, figuring out the embodied carbon in a skyscraper?

Speaker 2: Well, in commercial construction, you often have dedicated sustainability gurus and all this fancy software to analyze everything. They’re equipped to handle the complexity.

Speaker 1: They’ve got the high tech tools and the know how.

Speaker 2: Precisely. But your average residential builder. They might be a smaller operation, you know, what the paper calls a dog and a ute kind of set up. They don’t necessarily have the resources or the, let’s face it, financial incentive to dive into complex carbon calculations.

Speaker 1: That analogy is perfect. And the paper points out this isn’t just an Australian problem. It’s global. Residential construction everywhere is wrestling with this.

Speaker 2: It is. And that brings us to the biggest pain point, actually getting the data to do these calculations.

Speaker 1: Right, so if figuring out how much of each material we use is the challenge, what options are there? Where do we even look to get this data?

Speaker 2: There are a few ways to go about it. Cost data is easy to get, but it doesn’t always reflect the actual quantities of materials. A fancy toilet and a basic one might have very different prices, but their carbon impact could be pretty similar.

Speaker 1: So the cost isn’t the best indicator. What else can we look at?

Speaker 2: Another option is using detailed design documents, like those BIM models. They’re digital blueprints that contain detailed lists of materials. These are becoming more common in large commercial projects, but residential construction is slower to adopt them.

Speaker 1: Yeah, smaller builders might not have the budget or the expertise for that kind of fancy software. What about looking at past projects? Can we learn anything from those?

Speaker 2: Retrospective analysis can be useful for understanding broader trends, but it doesn’t give us real time information for a specific project. We need something more immediate, more actionable. And that’s where the idea of using Nathers data comes in.

Speaker 1: Nathers. That’s the energy rating system for houses here in Australia, right?

Speaker 2: Exactly. It’s mandatory for new homes. And as part of the assessment, they gather data on the building materials, walls, roofs, floors, all that, to assess energy efficiency.

Speaker 1: So the aha moment here is that we could use that data to estimate embodied carbon. It’s like a hidden goldmine of information just sitting there.

Speaker 2: It’s a pretty clever approach. The paper even mentions that CSIRO, Australia’s science agency, actually developed software called ECO2 to do just this, but it was abandoned a while back.

Speaker 1: Really? Why’s that? It seemed like a good idea.

Speaker 2: There were concerns about potential bias in how it calculated the carbon impact of different materials. There wasn’t a clear agreement on which database to use, and the CSIRO didn’t want to be seen as favoring certain materials over others.

Speaker 1: That makes sense. But the whole conversation around embodied carbon has really picked up steam since then, hasn’t it?

Speaker 2: Absolutely.

Speaker 1: But data is only useful if we can actually make sense of it.

Speaker 2: Exactly. First, it creates what they call a relative performance benchmark. Remember how we talked about comparing different houses? It was tricky because every house is unique in terms of its design and materials.

Speaker 1: Yeah, I was getting a data headache just thinking about it.

Speaker 2: Their algorithm goes through the data, calculates the embodied carbon intensity of a house, and then compares it to a huge database of other homes in the same area, by postcode, by state, even nationally.

Speaker 1: So you can finally see how your house stacks up against the Joneses, but in a carbon conscious way, kind of like those neighborhood energy reports, but for the building process itself.

Speaker 2: And if your house isn’t doing so well, that information can encourage you to make greener choices in the future, whether it’s a renovation or building a new home from scratch.

Speaker 1: Knowledge is power, right? What’s the second way to use this data?

Speaker 2: They’ve developed a really user friendly platform that lets you model the carbon impact of different design choices. This is especially useful in the early stages of a project when you have the most flexibility.

Speaker 1: So if I’m planning a renovation or building a new place, I can play around with different materials and see how they affect the overall footprint. Takes all the guesswork out of building green.

Speaker 2: It empowers everyone involved, homeowners, designers, builders, to make smart choices that can significantly reduce those upfront emissions.

Speaker 1: Okay, now this is where things get really interesting to me. The paper talks about how this data can connect to green financing. Now that’s a game changer, right?

Speaker 2: It’s a perfect match. Think about it. There’s all this money out there set aside for sustainable projects, but to access it, you need a solid way to assess the environmental impact. And that’s been the missing link, especially for homes.

Speaker 1: It’s like having a key but no lock to put it in.

Speaker 2: But we now have that key. We can link a house’s embodied carbon performance to tangible financial benefits.

Speaker 1: How would this actually work in the real world?

Speaker 2: Picture this. You walk into a bank to get a mortgage, and they offer you a green loan with a lower interest rate if you build a home that meets specific embodied carbon standards.

Speaker 1: Wait, so building a greener home could actually save me money on my mortgage? That’s incredible.

Speaker 2: It is. It’s a win win for everyone. Homeowners save money, builders can get access to green financing for their projects, and suppliers of low carbon materials see a surge in demand, which drives innovation in the industry.

Speaker 1: It’s like this chain reaction of positive change, all thanks to being able to measure and track embodied carbon.

Speaker 2: And the paper specifically mentions the Climate CBI, as an international framework that could be used to link green financing to home building.

Speaker 1: So a house with a low carbon footprint could actually help a developer secure green bonds for an entire housing project.

Speaker 2: Precisely. Imagine the impact if that became the norm. It would motivate developers to make sustainability a top priority from the very beginning.

Speaker 1: It feels like a practical roadmap to changing how we build.

Speaker 2: And the best part, we’re not starting from scratch. We’re using existing frameworks and data, which makes it doable and scalable.

Speaker 1: It’s like you said earlier, working smarter, not harder. But there’s one thing that keeps popping into my head as we’re talking about all this. We’ve talked about measuring embodied carbon and using it to access green financing. But who’s ultimately responsible for cutting down these emissions? Is it the homeowner, the builder, the designer?

Speaker 2: The question of responsibility. That’s a big one. And it’s something the paper explores in detail.

Speaker 1: Right. It’s like trying to figure out who left the fridge door open. So when it comes to the embodied carbon in our homes, who’s actually holding the hot potato?

Speaker 2: The paper does a good job of breaking down all the different players involved and how they connect to these emissions. We’ve got the homeowner, the builder, the designer, the engineer, even the banks. Each one has a role to play, but it gets tricky when you try to pinpoint who should be doing the heavy lifting when it comes to reducing it.

Speaker 1: Let’s start with the homeowner. They’re the ones living in the house. Enjoying it. Does that mean they own the emissions?

Speaker 2: Technically, yes. It’s similar to the idea of Scope 3 emissions for businesses. You know, those indirect emissions from sources they don’t directly control, like the emissions from manufacturing the products they sell. Well, in the same way, the emissions linked to building a house could be considered part of a homeowner’s footprint.

Speaker 1: So it’s like companies thinking about the emissions from all the stuff they buy. Homeowners should be thinking about the emissions from all the stuff that goes into their house.

Speaker 2: Exactly. But here’s the thing. Homeowners aren’t held to the same standards as companies when it comes to reporting these things.

Speaker 1: So they might technically be responsible, but there’s not much incentive for them to care about embodied carbon unless they’re really motivated or they see a financial benefit like those green loans we talked about.

Speaker 2: Right. And that’s where the other players come into the picture. The builder, for example, knows a lot about the materials and the whole building process.

Speaker 1: So maybe they should be the ones held accountable.

Speaker 2: It’s tempting to point the finger there, but remember, builders are often working within the constraints of a design that’s given to them. They’re basically following a blueprint, and changing things up can cost more money and take more time.

Speaker 1: Okay, so does that put the designer in the hot seat?

Speaker 2: In many ways, yes, the designer makes those initial choices about the structure, the materials, the whole approach, all of which have a big impact on the embodied carbon footprint.

Speaker 1: But just like the builder, the designer is also working within certain limits, the client’s budget, what the site’s like, and often the client’s own style preferences.

Speaker 2: Absolutely. It’s a complicated web of factors. And then you’ve got the engineer who’s responsible for making sure the building is structurally sound. There are decisions about things like foundations and materials also have a major impact on the carbon footprint.

Speaker 1: It’s like a chain reaction. Every decision has a ripple effect.

Speaker 2: It really is. And let’s not forget about the developers who are setting the vision for whole housing projects and making decisions that can either promote or hinder sustainable practices.

Speaker 1: Oh, and then there are the banks, who are becoming more aware of something called financed emissions. It’s like they’re realizing that the carbon footprint of the projects they’re financing actually reflects back on their own sustainability goals.

Speaker 2: It’s this multi faceted. Headed web of responsibility and like the paper highlights, just pointing fingers isn’t gonna get us anywhere. The key is to create a system where everyone has a reason to work together to reduce embodied carbon,

Speaker 1: and that’s where this whole new approach we’ve been talking about comes in, connecting those emissions to real, tangible benefits, financial incentives. Green financing options and even just recognition in the market can really push things in the right direction.

Speaker 2: Exactly. It’s about making reducing embodied carbon a smart business decision, not just some moral obligation.

Speaker 1: And that’s why I find this carbon label idea so fascinating. What if every home came with a label like super clear and easy to understand showing its embodied carbon footprint?

Speaker 2: It would empower everyday people to make informed decisions about the homes they buy or build. Builders would have a reason to compete on sustainability. And suppliers would have a real incentive to develop and market low carbon material.

Speaker 1: It could be a real game changer. If we had to sum up the main takeaway from our deep dive today, what would it be?

Speaker 2: The way we build has a huge impact on global emissions, and homes are a big part of that. But the good news is we’ve got the knowledge and the tools to make a real difference.

Speaker 1: We have companies proving that measuring this stuff is possible. We’ve got financial mechanisms already in place that could reward sustainable building practices and we’ve got the power to come together and demand a more sustainable future for housing.

Speaker 2: It’s a future where reducing embodied carbon isn’t just an afterthought. It’s a core part of the whole process from the very beginning of the design to the actual construction.

Speaker 1: That’s a future I want to be a part of. So here’s a thought to leave you with. What if choosing a low carbon home became as normal as choosing an energy efficient appliance? How would that change what we value, how we think, and ultimately how we design and build the places we call home?

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