Focusing on “Researchers’ Big Picture,” this series explores the future societies they envision through their work. How does their research intersect with our lives? Their visions might provide valuable insight into the path ahead for all of us.
Most of us rarely think about the environmental toll of the products we pick up off the shelves. To change that, we sat down with So and Moon, researchers working to calculate the greenhouse gas emissions embedded in everyday items. We asked how this visualization can shift public awareness and reshape society.
Interviewing:
Name:Sumiaki Kusahata
Affiliation: Department of Electrical Engineering and Information Systems, Graduate School of Engineering, The University of Tokyo (Left)
Name:Moon Dami
Affiliation: Mercari R4D lab/ Co-Researcher at Value Exchange Engineering (Right)
Keeping Products Alive Longer to Help the Planet Breathe
▶︎Could you tell us a bit about your research field, Life Cycle Assessment (LCA)?
＜Moon＞
LCA quantitatively assesses a product’s environmental impact throughout its lifecycle—from raw materials to disposal. While it covers various environmental impacts, these days it’s most commonly used to measure and evaluate greenhouse gas (GHG) emissions.
When we think about a product, GHG emissions actually start long before it even hits the shelves—beginning right at the raw material stage with extraction, refining, and transportation. From there, emissions continue to pile up during manufacturing, distribution, retail, and even after purchase, all the way to final disposal.
If we keep buying brand-new items, emissions just keep climbing because we are triggering that entire cycle over and over again. Choosing secondhand goods bypasses new manufacturing and disposal, driving down the overall carbon footprint.
To minimize our environmental impact, it is crucial to study exactly where in a product’s lifecycle we should step in with solutions. And that is exactly why LCA is such a powerful tool—it provides the framework to support that crucial research.
▶︎I’ve never thought about it as a connected process like this before. There really is a huge difference when you compare new and used products. What made you want to focus on this for your research?
＜Moon＞
Right now, cutting down on these emissions to stop global warming is a major global challenge. I believe the key to tackling this while still keeping our economy moving is to encourage people to use secondhand products. By using LCA to calculate the exact emissions, we can provide eye-opening information that gets people thinking about the environment, which I hope will motivate them to choose used items.
I have two children of my own. I want the planet to stay in a state where they can live normal, healthy lives even when they grow up. Cutting these emissions is a challenge that we, as adults, need to take on right now.
▶︎What is the methodology behind calculating GHG emissions?
＜Moon＞
When calculating emissions with conventional LCA, we set an average weight—for example, ‘one T-shirt weighs ◯◯ g’ Then, we multiply that weight by the emission factor for each material or energy source listed in databases like AIST-IDEA (such as the amount of GHG emitted to produce 1 kg of that material) to come up with the estimated value.
https://idea-lca.com/
Our goal is to calculate the product – specific GHG emissions for each and every item. For example, cotton and synthetic fibers have different emission levels during manufacturing. Even for a simple T-shirt, the numbers change depending on whether it’s 100% cotton or a cotton-polyester blend. Plus, different sizes mean different amounts of fabric used, making each individual garment incredibly complex. On top of that, emissions also happen during the ‘use phase,’ like when doing laundry. Since differences pop up based on usage history—like how many times it’s been washed—we have to apply even more variables when it comes to secondhand items.
▶︎That is certainly no simple calculation. I read the press release and noticed that you’re using generative AI. Could you tell us which specific areas you are applying it to?
＜Kusahata＞
We use a Visual Language Model (VLM)—a generative AI that processes both images and text—to automatically analyze product photos, tags, and user descriptions.
Technically, a human could check everything and input all the data to do the same calculation, but it’s just not realistic. That’s where the generative AI comes in. As a result, we found that it can identify material blends and sizes with a high accuracy of 80 to 90%. Looking deeper into the analysis, we also uncovered a major fact: when it comes to clothing, the environmental impact of the raw materials themselves is overwhelmingly larger than the impact from distribution or usage. This gave us a brand-new insight—knowing the exact material composition is absolutely essential for an accurate LCA.
＜Moon＞
We often see targets like ‘a ◯◯% reduction in GHG’ in the news, but these huge numbers can feel a bit vague and distant. I believe that seeing specific, product-level numbers—like ‘choosing this item reduces emissions by ◯◯ kg’—will make environmental issues feel much closer to home and inspire people to care. I truly hope this will be a giant leap toward a circular economy.
＜Kusahata＞
Right now, our research focuses on clothing because of its simpler material structure, but I believe this technology can be applied to all kinds of products, like laptops, electronics, and even cars. The main challenge going forward will be figuring out how to get the information that isn’t visible in photos or listed in product descriptions. Flip that around, though, and it means if we can build a system that gathers and fills in those missing blanks, we could actually automatically calculate emissions with high accuracy—even for complex products. That’s the kind of future I want to bring to life.
Unlocking the ‘Third Value’ of Secondhand Goods through GHG Tracking
▶︎I imagine there are still plenty of people who feel hesitant about buying secondhand items. How does this look from a researcher’s perspective?
＜Kusahata＞
I feel like people’s choices between new and used are starting to shift, depending on their budget, purpose, or how long they plan to use the item. On the other hand, new products—especially appliances—come with a manufacturer’s warranty, better energy efficiency, and less risk of breaking down. When you look at the total picture, it’s also understandable that many people still lean toward buying new.
＜Moon＞
While the secondhand market is steadily growing, our research shows that this wave hasn’t quite reached the people who traditionally avoid used goods. It’s true that many still feel a strong hesitation. On the other side, the rise of smartphones, ICT, and e-commerce platforms has made secondhand items much more mainstream. Now that product conditions and prices become more transparent, the barrier to entry has definitely dropped. Baby products, for instance, have become one of the top choices for practical parents who align their purchases with their needs, leading to a steady rise in demand. The key challenge going forward is figuring out how we can expand this kind of ‘rational and positive choice’ to society as a whole.
▶︎To open up the secondhand option for that demographic as well, what kind of initiatives are you working on under Value Exchange Engineering?
＜Moon＞
It would be wonderful if more people started choosing secondhand goods as a part of their daily lives, regardless of how long or for what purpose they plan to use them. To make that happen, shifting our mindset around consumption is key. Right now, the secondhand market is growing based on two values: the ‘scarcity value’ of vintage items and the ‘financial value’ of being cheaper than new. By adding a “third value”-the environmental benefit of choosing secondhand-we can truly shift consumer mindsets.
＜Kusahata＞
Testing and finding out exactly what kind of approach will actually change user mindsets is a challenge we are about to tackle. Once we are confident in the reliability of our emission calculations for clothing, we will move on to studying what information to disclose and the best way to present it.
＜Moon＞
I believe that displaying an item’s GHG reductions on the Mercari product screen has the potential to create that ‘third value.’ However, to truly weave this into society, I believe that researchers showing the numbers/data is not enough and we also need to approach consumers by creating experiences that help people truly recognize and feel the impact.
As part of this effort, Mercari hosted a ‘Green Friday’ event. People brought in clothing they no longer needed for a swap meet, and we displayed the CO2 savings right on the spot so they could personally feel their contribution to the planet. I hope events like this will inspire people to shift their mindset from ‘throwing away’ to ‘passing it on’ to the next person.
https://about.mercari.com/press/news/articles/20251121_greenfriday
▶︎An interactive event like that sounds really exciting! What do you think is needed to connect this kind of hands-on experience to people’s everyday behavior when using Mercari?
＜Moon＞
When people are looking to let go of their belongings, they aren’t all just trying to throw them in the trash. In fact, many are probably thinking, ‘It’s such a waste to throw this away, but I have no other choice.’ For those people, it’s crucial to help them realize that using Mercari not only gives them a sense of fulfillment from contributing to society , but also genuinely connects to protecting the environment. As the number of listings grows, it will attract more buyers, and the culture of using secondhand items will become even more deeply rooted in society.
＜Kusahata＞
To further boost that sense of fulfillment from helping the planet, I think designing an incentive system like ‘Eco-Points’ would be highly effective. The more you use the Merari platform, the more points you earn to use within or possibly outside of the platform. By adding this kind of concrete benefit, I believe we can turn a one-time experience into a steady, everyday habit.
The future beyond our research, where a circular economy is fully realized
▶︎Once this research truly weaves its way into society and changes how people think about shopping, what kind of future will we see?
＜Kusahata＞
Right now, the driving force behind purchasing is heavily dominated by personal desire—what people want and how to get the best deal. When it comes to buying with the environment in mind, the reality is that we are still relying on individual goodwill. Once our research with Moon-san bears fruit and displaying things like GHG reductions becomes the norm everywhere, these vague environmental issues will finally feel real and hit close to home for everyone. As a result, it will be much easier to trigger a shift in mindset, prompting people to naturally consider whether to choose new or used before making a purchase.
＜Moon＞
As the choice to buy used instead of new spreads, the secondhand market will grow even further. On top of that, manufacturers will likely start to see this market as a fresh opportunity to boost their own value through environmental care and social responsibility. Through this, I hope we can transition from a resource-consuming social model—which has long relied on continuously producing and consuming new goods—to a circular economy model where production and consumption are in perfect balance. Ultimately, my wish is to realize a true circular economy and leave a beautiful planet for the children of our future.
▶︎I always feel like I should live with the environment in mind, but to be honest, I’d never really thought about how much skipping a single plastic bag at a convenience store actually helps reduce the environmental footprint. Once your research with Moon-san and Kusahata-san bears fruit, I think it will be a wonderful catalyst for people to start seeing environmental issues—which often feel too massive to grasp—as something close to our lives. Society fully realized the circular economy might be not only sustainable but also empathetic, where caring for both the planet and each other happens naturally.
Thank you so much for such a wonderful time today.
Value Exchange Engineering PR, Kawanaka
Related Link
https://www.t.u-tokyo.ac.jp/press/pr2025-09-12-001