“Replay Program” Hits Sustainability Home Run
What unsustainable behaviour needs to change:
At large sporting events, beverage consumption often leads to a mountain of single-use plastic waste. In U.S. stadiums, disposable cups are still the norm—used only for a few minutes, yet last for centuries. Most cups end up in landfills after just one game, contributing to environmental degradation and greenhouse gas emissions. Plastic production already accounts for 3.4% of global emissions—more than aviation—and is projected to double by 2060.
Germany’s Football League (Bundesliga) offers a powerful compelling alternative: Many German football clubs have used returnable cup systems for years, with strong fan support. FC Bayern Munich alone saves around 20 tonnes of waste annually through reuse. Since 2023, German law mandates that all stadiums offer drinks in reusable containers—proof that sustainability can scale without compromising fan experience.
Reuse systems like these offer a practical, high-impact way to cut stadium waste while preserving the ritual of the game-day drink.
The Green Nudge:
The Replay Program at Oracle Park replaces single-use cups with durable, reusable ones for alcoholic beverages from German reusables company Vytal. Fans receive their drinks in these cups and return them to designated bins before leaving. Cups are then collected, washed, and returned for circulation—creating a closed-loop system that slashes waste, water, and emissions when compared to disposables.
Each Vytal cup can be reused up to 200 times. After just 10 uses, it already outperforms single-use cups in terms of energy efficiency, water usage, and carbon footprint.
What makes this especially effective? The name. “Replay” is baseball lingo for reviewing a play—a moment fans already associate with second chances and fairness. By borrowing that familiar term, the programme makes reuse feel like a natural part of the fan experience. It sends a clear message: this isn’t just good for the planet—it’s part of the game. That framing fosters pride, not sacrifice—key to lasting behaviour change.
The Giants have been laying the groundwork for this approach for years, using playful baseball language to promote sustainability. Campaigns like “Waste Zero,” featuring slogans such as “Make a Giant Difference,” encouraged fans to sort waste more effectively—showing that when climate messages speak the language of sport, they resonate more deeply.
Do you know of any other nudges that promote sustainable practices at large events? Let us know: hello@green-nudges.com
From Vytal Global, a Cologne-based company pioneering smart, reusable packaging systems across Europe — and now expanding into the United States. As Vytal brings its reuse expertise to new markets, recognising and respecting cultural nuances is key. The “Replay Program” at Oracle Park reflects this approach: integrating sustainability into the rhythm and rituals of American baseball culture, rather than adding it from the outside.
Meat with a Warning: Climate Labels Can Change What We Eat
What unsustainable behaviour needs to change:
For many consumers, choosing meat isn’t a conscious decision—it’s a default. Meat often anchors the meal, reinforced by social norms, tradition, and routine. This habitual consumption pattern persists despite growing awareness of its environmental and health impacts. Livestock farming alone accounts for nearly 15% of global greenhouse gas emissions, while high meat intake is linked to obesity, heart disease, and certain cancers. Yet, when faced with a menu or supermarket shelf, many people instinctively reach for meat-based options.
This automatic behaviour limits the uptake of more sustainable alternatives and underscores the need for subtle interventions that interrupt the “meat-as-default” mindset and open the door to more conscious choices.
The Green Nudge:
Researchers from Durham University tested a subtle but powerful intervention: visual warning labels on meat-based meals, inspired by those used on cigarette packaging. These graphic labels, which highlighted health, climate, or pandemic risks, aimed to trigger emotional reactions and disrupt automatic, habitual choices—especially in fast-paced environments like canteens or online menus.
The researchers suggest that these warning labels work by making the hidden consequences of meat consumption—such as its contribution to climate change—visible. The imagery also evokes a negative emotional response, which can automatically shift attention and preferences away from the labelled product.
The results: In a large online study with over 1,000 UK meat eaters, published in Appetite (2023), the labels reduced meat meal selections by 7.4–10% compared to a no-label control group. Climate-focused warnings performed best overall: they effectively decreased meat choices while being met with neutral public reactions—unlike pandemic or health warnings, which were more emotionally intense but less credible and more divisive. This makes climate warnings a particularly promising tool for encouraging sustainable eating without provoking resistance.
It would be valuable to test these labels in physical retail environments as well—such as on product packaging in supermarkets—where real-world shopping habits and brand cues come into play. Such trials could reveal how warning labels function in more complex, high-stakes decision contexts.
Have you come across other nudges that make climate impacts more visible at the point of sale? Let us know: hello@green-nudges.com
From Mario Weick, Milica Vasiljevic, and Jack Hughes from Durham University. The team explores how behavioural interventions can steer everyday decisions—like meal choices—towards greater sustainability. Their 2023 study, “Impact of pictorial warning labels on meat meal selection”, published in Appetite, provides new evidence on how visual cues can disrupt default behaviours and promote lower-impact food choices.
Free, persuasive, and green? Yes, yes, and yes.
What unsustainable behaviour needs to change:
Despite growing awareness, private cars and fossil-fuel-based transport still dominate urban journeys. In the UK, transport is the largest emitting sector, responsible for nearly 25% of total greenhouse gases. And yet, most city trips are under 5km—ideal for walking or short enough for a bike ride, yet still overwhelmingly dictated by cars.
Several behavioural barriers hinder the shift towards more sustainable choices:
- Status quo bias keeps people stuck in their routines—driving simply because it’s what they’ve always done.
- Skepticism toward “free” or shared services, often leads people to view them as lower-quality or unreliable.
- Lack of perceived individual impact, makes e people feel that their choices won’t make a meaningful environmental difference.
These psychological factors create real friction, even when sustainable alternatives are readily accessible.
The Green Nudge:
Enter the bike company forest’s London campaign–a smart example of how behavioural science can drive sustainable action. Rather than relying on a single technique, the ad campaign layers multiple interventions to encourage behaviour change:
- The Power of Free: “10 minutes free daily” taps into our natural preference for zero cost. Free offers dramatically increase participation, with one study showing a 69% spike in purchase intent (Ariely, 2008).
- Costly Signalling: forest states it would be £11 million richer without this offer, signaling commitment and credibility– increasing the perceived value of the service.
- Specific Number Bias: “51,899,782 free minutes” seems more believable than a rounded figure. Specific numbers feel more accurate and persuasive. In one experiment, panhandlers who asked for an exact amount—like 17 cents—instead of “spare change” saw a 60% increase in donations (Hey Buddy, Can You Spare Seventeen Cents? Mindful Persuasion and the Pique Technique, Santos & Leve, 1994).
- Noble Edge Effect: forest presents itself as a purpose-driven brand, aiming to make zero-emission transport affordable. Research shows that when companies act with genuine social responsibility, customers respond with greater trust and loyalty.
- Variable Rewards: A bike placed beneath the ad offers “100 free minutes” via a QR code—but the bike itself isn’t usable. This small surprise creates a moment of novelty, increasing engagement. One study found that people were more likely to complete a task when the reward was uncertain rather than guaranteed (The Motivating-Uncertainty Effect, Shen, Fishbach & Hsee, 2015).
These interventions don’t just promote a service—they help change habits. forest’s campaign is a strong reminder that behavioural science deserves a central place in sustainable marketing. If we want green options to become the default, we need fewer well-intended awareness campaigns and more insight-driven strategies that create real change.
Know any clever ways to make sustainable travel the easy, obvious choice? Share your ideas or get in touch: hello@green-nudges.com
From Phill Agnew, host of the UK’s top marketing podcast “Nudge.” With senior marketing experience at Brandwatch, Hotjar, and Buffer, Phill brings behavioural science to life for marketers and sustainability changemakers alike.
Restaurant Menu Engineering Boosts Plant-Based Choices
What unsustainable behaviour needs to change:
India has long been one of the world’s most vegetarian-friendly countries, with plant-based eating deeply rooted in cultural and religious traditions. However, rising economic prosperity has driven higher meat consumption. Between 2000 and 2020, India’s per capita meat consumption nearly doubled, fueled by urbanisation, increased disposable income, and evolving food aspirations.
This shift comes at a high environmental cost. Animal agriculture is a major driver of deforestation, water consumption, and greenhouse gas emissions. As India is projected to become the world’s most populous country, its dietary choices will have significant global environmental implications. The challenge is not just awareness but fostering meaningful shifts in daily food habits—a challenge behavioural nudges can help address.
The Green Nudge:
At Gracias Granny, a Mexican restaurant in Mumbai, a real-world experiment tested whether menu nudges could encourage diners to choose more plant-based meals.
The interventions included:
- Descriptive Enhancements: Adding vivid, appetizing descriptions to plant-based dishes led to a notable increase in plant-based orders, especially in takeaway sales.
- Promotional Offers: A free churro incentive for plant-based meals boosted selection, proving that ‘perceived value’ can be a stronger motivator than sustainability messaging.
- Menu Structuring: Featuring a plant-based „Burrito of the Day“ resulted in 100% of orders from this category being plant-based– without reducing overall sales.
However, not all nudges were successful:
Messaging nudges that highlighted the environmental impact of meat consumption unexpectedly led to a drop in plant-based choices. Instead of motivating change, these messages reinforced existing food habits, showing that positive framing (focusing on taste and value) is far more effective than guilt-based appeals.
These findings demonstrate that subtle, experience-driven nudges—rather than moral arguments—can be a powerful tool for shifting food behaviour toward sustainability.
Do you know of any other nudges that encourage sustainable dining? Feel free to get in touch: hello@green-nudges.com
From Rashmit Arora, co-founder of Gracias Granny, a Mexican restaurant in Mumbai; Chris Bryant, founder of Bryant Research; Billy Nicholles, Researcher at Bryant Research; and Charlotte Flores, a Food Systems Researcher. Conducted by Bryant Research, this study combines academic insights and real-world restaurant data to identify which menu nudges and promotions encourage plant-based choices—and which do not.
Think Pink: Compostables in the Right Bin
What unsustainable behaviour needs to change:
Compostable packaging—like cups, cutlery, and salad boxes—can be a more sustainable alternative to plastic, but only if disposed of correctly. If placed in general waste or recycling, it can’t be composted and may even contaminate other waste streams.
In UK workplaces using Vegware packaging, research based on the Behaviour Change Wheel (Michie, 2011) identified three key barriers to correct disposal:
- Compostables are difficult to distinguish from conventional plastics;
- Bin signage is often unclear or inconsistent;
- Motivation is low when composting feels abstract or irrelevant.
While closed-loop composting infrastructure is not yet widespread in the UK, it’s steadily growing—particularly in workplaces and community projects. Where these systems exist, correct disposal is essential to unlock their full environmental benefits. Behaviourally-informed interventions can help ensure that infrastructure delivers on its promise.
The Green Nudge:
The research team, in partnership with Hubbub, developed a behaviourally-informed intervention to improve compostable waste disposal in three UK office canteens. The intervention addressed disposal barriers through a series of targeted nudges:
Bright pink labels with clear icons and the message “Put in compostables bin” were added to all compostable items;
- Matching pink signage was placed above compost bins;
- A short motivational video explained the benefits of composting in relatable terms;
- Compostable bins were introduced in one of the canteens;
- Managers were briefed to support consistent implementation.
The results: Waste audits by Recorra showed that before the intervention, compostables made up just 32% of bin contents. After one month,this rose to 61% and after two months reached 77% —demonstrating a clear shift in behaviour.
Managers praised the intervention, describing the signage as “amazing.” The findings highlight how consistent visual cues and emotional engagement can significantly improve composting behaviour in workplace settings.
Are you aware of any other nudges that help to keep waste collection streams clean? Feel free to get in touch: hello@green-nudges.com
From Dr Nicola Buckland, a psychologist and Senior Lecturer at the University of Sheffield. This research was conducted in collaboration with colleagues at The University of Sheffield, Dr Sara Bru Garcia, Meghann Matthews, Thomas Webb and Sarah Greenwood, Rosie Sharp from Hubbub, Tom Mockridge from Recorra, and David Dyce MCIWM, Lucy Frankel from Vegware.
Nudging Greener Bin Bag Habits in Norway
What unsustainable behaviour needs to change:
Plastic bags, primarily derived from petroleum products, contribute significantly to environmental pollution and can take up to 1,000 years to decompose. Acknowledging this challenge, the EU aims to reduce annual plastic bag usage to 40 bags per person by 2025. Norway has acted on this through awareness campaigns and price increases, successfully lowering plastic bag consumption from 135 per person in 2022 to 104 in 2024.
However, most households still repurpose plastic shopping bags as bin liners, limiting further reductions. While recyclable bin bags offer a more sustainable alternative, their adoption remains low.
The Green Nudge:
In partnership with a grocery store and funded by the Norwegian Retailers‘ Environment Fund, Nudgelab implemented a series of behavioural interventions to promote sustainable bin bag use:
- Visibility & Convenience: Sustainable bin bags were strategically placed in large containers near checkout areas, making them easy to spot and pick up.
- Cost-Framing Effect: Posters highlighted the cost savings of using sustainable bin bags, reinforcing the perception of a “smarter choice.”
- Increased Friction for Plastic Bags: Plastic bags were stored under self-checkouts, making them less accessible. Additionally, small signs reminded customers of the high cost of plastic bags, further discouraging their use.
- Reframing the Checkout Default: Staff replaced “Do you need a bag?” with “Do you have something to carry your groceries in?”, prompting customers to rethink their need for a plastic bag.
The results: Over the six-week trial, sales of sustainable bin bags increased by 414%, while plastic bag consumption fell by 20%—a stark contrast to the 14% rise in plastic bag use nationwide. These findings confirm that making sustainable choices easier and creating friction for less sustainable options can drive meaningful behaviour change.
However, interventions like this only succeed when integrated into a well-functioning system. In Norway, plastic recycling infrastructure is well-developed, enabling the effective processing of recyclable bin bags. Yet, consumer behaviour remains key—if these bags are not disposed of correctly, they won’t be recycled and could still contribute to environmental pollution. In regions lacking such infrastructure, interventions promoting recyclable alternatives may fail to deliver their intended impact.
Do you know of other nudges promoting sustainable bin bag use? Share your insights or get in touch: hello@green-nudges.com
From Dr. Irmelin Bergh, a behavioural psychologist and partner at Nudgelab in Norway. She has extensive experience in behaviour change, having worked as a researcher at the University of Oslo and as a strategic consultant at Netlife Design. During her doctoral studies, Dr. Bergh spent time at UC Berkeley and Stanford, gaining unique insights into applying behavioural psychology and “nudging” within major Silicon Valley companies.
Breaking the stigma: An unbiased taste of plant-based food
What unsustainable behaviour needs to change:
Despite growing awareness of sustainability, plant-based foods continue to face deep-seated stigma. Many consumers dismiss these options without trying them, assuming they are inferior in taste or nutrition. This reinforces a heavy reliance on animal-based products, which significantly contribute to greenhouse gas emissions, land degradation, and water consumption.
Research indicates that “expectation bias” plays a major role in food choices. When individuals perceive plant-based foods as less desirable, they are less likely to consider them—regardless of actual quality. Addressing these psychological barriers is essential for accelerating the transition to a more sustainable food system. Rather than requiring drastic dietary changes, the key lies in making plant-based foods an appealing and natural choice.
The Green Nudge:
A blind taste test experiment was conducted in Thailand using chocolate to remove preconceived notions about plant-based ingredients. Participants sampled two types of chocolate without knowing which one was plant-based and which one was dairy-based.
Here’s how it worked:
- Participants tasted Chocolate A and rated it out of 5.
- They repeated the process with Chocolate B.
- After both chocolates were scored, participants guessed which one was plant-based—before their blindfolds came off, revealing the truth.
The results: the plant-based chocolate was rated slightly higher, receiving an average score of 3.9, compared to 3.6 for the dairy version. While the difference was modest, it challenged common assumptions that plant-based alternatives are inferior in taste.
Several participants expressed genuine surprise when discovering which chocolate was plant-based. Many admitted they wouldn’t have expected to enjoy it as much had they known in advance. This highlights how expectation bias—not actual flavour—is often the biggest hurdle to adopting more sustainable food choices.
Addressing these psychological barriers is essential to accelerating the transition to a more sustainable food system. Rather than requiring drastic dietary changes, the key lies in making plant-based foods feel like an appealing and natural choice.
Know a smart nudge that challenges food-related bias or boosts plant-based choices? We’d love to hear about it: hello@green-nudges.com
From Setthawut Fang (Steven), Head of Behavioral Design Lab and UX/UI Designer at Sand Studio & Co., a digital design studio in Bangkok, Thailand. Outside his professional role, he is an active member of the Global Shapers Community, an initiative of the World Economic Forum that unites young changemakers to drive social impact and sustainability.
How a ‘protected nature’ sign keeps roadsides litter-free
What unsustainable behaviour needs to change:
Littering along roadsides is a persistent problem. These spaces, often seen as a ‘no man’s land,’ exist in the transition between inhabited areas and travel routes. Many motorists lack a personal connection to them, making it easier to discard waste from their cars without a second thought. The anonymity of roadside spaces leads to psychological detachment from responsibility.
This behaviour stems from the ‘tragedy of the commons’—when shared spaces suffer because no single individual feels accountable. Additionally, ‘out of sight, out of mind’ plays a role: once rubbish leaves a car window, it’s no longer the driver’s problem.
The Green Nudge:
To shift this perception, Fama Volat collaborated with a local forester to reframe the roadside as a protected nature reserve. The intervention was simple: a brown UNESCO-style sign declaring the roadside a „Protected Natural Area.“
Why does this work? People litter less in places they perceive as valuable. A nature reserve signals an environment worth protecting, subtly encouraging motorists to keep their trash inside their cars.
The results: In multiple Dutch municipalities, the Protected Roadside sign has led to a more than 50% reduction in litter. The intervention gained media traction and is now being tested in Belgium, where the first municipalities have begun trialling the approach.
By changing how people view roadsides, this intervention turns scattered stretches of land into a collective, nationwide nature reserve—one that we can all help to protect.
Are you aware of any other nudges that help to reduce littering? Feel free to get in touch: hello@green-nudges.com
From Fama Volat, a Dutch creative agency dedicated to using creativity to drive behavioural change. Their work tackles urban challenges and promotes sustainability through innovative solutions.
How a simple pop-up makes dinners more plant-based
What unsustainable behaviour needs to change:
The burgeoning meal kit delivery industry offers a unique opportunity to reduce dietary greenhouse gas emissions. However, many consumers habitually select meat-based meals, often overlooking plant-based alternatives. This tendency is influenced by habitual behaviour and default choices, where individuals stick to familiar options without considering more sustainable possibilities.
Additionally, there’s a concern about compensatory behaviours—for instance, choosing a salad for lunch might lead to indulging in a heavier, meat-based dinner, negating earlier sustainable choices.
The Green Nudge:
To address this, researchers introduced a pop-up message on an online meal kit platform. After customers selected their lunch, but before choosing their dinner, the message highlighted the environmental impact of their choices:
„Did you know that by opting for a plant-based dish, you could save greenhouse gas emissions equal to the energy needed to power your phone for two years? Choosing plant-based reflects a commitment to a more environmentally friendly lifestyle.“
This intervention significantly influenced dinner selections:
- For customers who chose a plant-based lunch, the message reinforced their environmentally friendly self-identity, leading to a 51% increase in plant-based dinner choices.
- For those who selected a meat-based lunch, the message created a sense of cognitive dissonance, highlighting the inconsistency between their choices and the positive identity described. This led to a 27% reduction in meat-based dinner selections.
By leveraging behavioural spillover, this nudge encouraged sustainable choices across meals, showing how a well-timed reminder can reinforce eco-friendly habits.
Do you know of other nudges that promote sustainable food choices? Feel free to comment or get in touch: hello@green-nudges.com
From Dr. Sophie Attwood, Dr. Sebastian Isbanner, and Dr. David Fechner, who collaborated on this study to explore how subtle behavioural nudges can reduce meat consumption in meal kit choices. Their research examines how small interventions can create lasting shifts toward more sustainable eating habits.
- Sophie Attwood PhD is a behavioural science consultant dedicated to fostering a healthier, more sustainable future for people and the planet. Learn more at www.behaviorglobal.com
- Dr. Sebastian Isbanner is a research fellow and consumer behaviour expert at Technische Universität Berlin, Germany, with a focus on decision-making and sustainable consumption.
- Dr. David Fechner is a research fellow and behaviour change expert at Griffith University, Australia, specialising in interventions that promote environmentally friendly choices.
Mainstreaming Pre-Loved Fashion for Everyone
Why Sustainable Fashion Still Isn’t Mainstream:
For many, traditional sustainable fashion can still feel out of reach, often seen as a more expensive or niche option. The affordability and accessibility of fast fashion make it a go-to for those on a budget or with limited resources.
While second-hand shopping provides a sustainable alternative, traditional thrift or vintage stores can feel cluttered, unorganised, and unappealing—more like rummaging through leftovers than an enjoyable shopping experience. This “messy bargain bin” image puts off many consumers who might otherwise choose pre-loved fashion.
Amid rising living costs and the climate crisis, it’s high time we make sustainable fashion accessible and appealing to all.
The Green Nudge:
A new generation of second-hand fashion stores is changing the game, making pre-loved shopping just as appealing, effortless, and stylish as buying new. Good London, Ada & Albert, and Verso Vintage Shop are leading the way, proving that second-hand doesn’t have to feel second best.
Good London, for example, sits seamlessly between high-end brands in London Bridge Station. Its sleek layout, curated collections, and premium feel make shopping second-hand an aspirational experience—without the waste or high price tags. This shift isn’t just about sustainability; it’s about mainstreaming and elevating pre-loved fashion so that choosing second-hand is the natural, desirable option for everyone—not just those already in the green bubble.
Do you know of other nudges that help mainstream sustainable shopping? Feel free to comment or get in touch: hello@green-nudges.com
From Dr. Moira Nicolson, a behavioural scientist and climate change expert. As Lead Behavioural Scientist at the UK Cabinet Office, she specialises in applying behavioural science to complex social challenges, with a focus on climate strategy, public engagement, and crisis response. With over a decade of experience spanning government, academia, consulting, and clean tech, Dr. Nicolson also holds leadership roles in climate initiatives, including the Welsh Government and Carbon13.