What unsustainable behaviour needs to change:

Many homeowners don’t insulate their homes — even when subsidies and support are right there. The barriers are mostly psychological: people are unaware of the help available, are sceptical of free services, and see insulation as something vague rather than a concrete next step.

The classic “knowledge–attitude–behaviour” model doesn’t hold here because informing residents simply isn’t enough to trigger action. Unconscious hesitation, low social trust, and doubts about real benefits all keep people from taking that first step toward a more energy-efficient home.

The Green Nudge:

The intervention designed by Dutch agency andc followed a three-step behavioural strategy: reduce doubt, increase motivation, and guide residents toward a clear first action.

Building on Goal Hierarchy Theory, the team identified the critical entry behaviour: booking an appointment with an energy coach. Behavioural analysis, interviews with 24 residents, and a literature review validated the key barriers for this specific target group.

The campaign „One Degree Smarter“ combined neighbourhood letters, home visits, a physical insulation house model, a shadow-board installation, and a thermal-imaging heat walk. Peer-to-peer outreach made the helpdesk visible and credible in the community. Website improvements and sharper messaging reduced scepticism around the free service.

Every intervention was grounded in behavioural insight: tackling doubt, building trust through familiarity, raising motivation, and reducing the path to one concrete step — booking that appointment.

The results: 304 home visits. 176 visits to the energy helpdesk. 250 registrations for the heat walk –reaching 300 within just two days,without any paid promotion. Residents responded enthusiastically, reporting feelings of familiarity and trust. Energy coaches became fully booked. In 2025, 497 national subsidies for home insulation and 271 local subsidies for home insulation were granted. Residents also shared positive feedback about the municipality and the insulation opportunities available.

The Business Case: Katwijk had more than goodwill at stake. Dutch municipalities are legally bound to national and EU climate targets — falling short risks losing access to climate funding. Subsidies only work when residents use them, and this campaign made sure they did.

The approach proved scalable across new target groups, with „One Degree Smarter“ now serving as a reusable platform that cuts future campaign costs.

Do you know of any other nudges that turned scepticism into action?
Get in touch: hello@green-nudges.com

From Ron Ghijssen, Partner & Behavioural Strategist at andc — a Dutch behavioural design agency. Together with the Municipality of Katwijk and the Behaviour Change Group, andc supported the launch of the Regional Energy Helpdesk (REL). The behavioural research and strategy was led by Behaviour Change Group, while andc designed and executed the interventions. 

What unsustainable behaviour needs to change:

Mobility is a key lever for climate action, yet many people stick with cars out of convenience. Bike-sharing systems are expanding, but often remain underused.

Why? Automated routines. People who commute the same route every day rarely question how they travel. Good alternatives get overlooked—not because of resistance, but because of habit. This is where behavioural science comes in.

The Green Nudge:

A field experiment by Behavioural Insights Team (BIT) in Portland for Biketown tested whether timing could unlock greater behaviour change. The nudge was simple: a flyer promoting the city’s bike-sharing scheme. But who received it made all the difference. For long-term residents, sign-up rates were just 0.31%. For people who had recently moved house, the exact same flyer boosted sign-ups to 1.14%—nearly four times higher.

Why? Moving disrupts routines. Without old habits in place, people are more open to rethinking how they get around.

BIT’s insight: Communication timed to „moments of change“—relocation, retirement, starting a new job—taps into naturally heightened openness. These brief windows make low-effort nudges far more effective–an “outsized” (unexpectedly large) impact for such a small intervention. Simply targeting the right “when” can dramatically improve results.

The results: 4x more sign-ups for the bike-sharing programme among newly moved households–from the exact same flyer. The only difference? Smart timing. This finding has since shaped mobility campaigns across multiple cities, demonstrating how behaviourally-informed segmentation boosts uptake without raising costs.

The Business Case: Targeted communication during periods of transition

• Increases conversion rates by 3–4x
• Reduces waste and overall marketing costs
• Enables segmented, high-impact campaigns
• Amplifies the effect of existing programmes—without additional resources

This principle applies across many sustainability contexts: energy advice when buying a home, plant-based offers in the first week of school, public transport information when starting a job. Addressing behaviour at the right moment saves budget and accelerates transformation.

Do you know other examples where timing made the decisive difference?
Get in touch: hello@green-nudges.com

From Annalena Sommer from the Green Nudges Consulting team, featuring an intervention by the Behavioural Insights Team—a UK-based social purpose company specialising in the application of behavioural science to public policy. Founded in 2010 within the UK Cabinet Office, BIT now operates internationally, advising governments, cities and organisations on evidence-based interventions.

What unsustainable behaviour needs to change:

Cigarette butts are the most common form of litter worldwide—45 billion discarded annually. The barrier isn’t ignorance; it’s invisibility. Correct disposal is a private act with no visible consequence or social reinforcement. When no one notices the right behaviour, there’s no social norm to follow.

Traditional approaches, like more ashtrays, warning signs, or fines, underperform because they instruct people what to do but fail to show that others are doing it.

The Green Nudge:

The Behavioural Science team led by Niklas Lanninge identified the core issue: people change when the environment makes the right behaviour visible, not when they’re simply told to change.

The solution? An eleven-foot blue sculpture in a central square. Every time someone disposed of a cigarette correctly, it emitted a puff of smoke—an ancient signal repurposed for modern urban cleanliness.

The logic: social proof, made visible. Each smoke signal transforms an individual action into a public cue. Motion sensors detect the cigarette and trigger a brief, theatrical burst — a playful reward for the right choice. Smokers began to pause, watch, and gather for the next puff.

Three critical factors:

• Visibility: private behaviour becomes public
• Playfulness: humour without moralising
• Immediate feedback: instant reinforcement 

The results: Cigarette butts in ashtrays tripled — from 27.6% to 67.3%. The intervention created a new social norm through repeated, visible participation.

The Business Case: Cigarette litter creates ongoing clean-up costs and environmental damage. Enforcement through fines is labour-intensive and strains citizen relationships. The smoke signal machine changes behaviour without policing, reduces costs, and turns compliance into a positive experience. A single installation influences thousands of daily decisions — an exceptionally low cost per behaviour change compared with typical awareness campaigns.

Have you seen other nudges that make invisible good behaviour visible?
Share your thoughts: hello@green-nudges.com

From Elina Carlstein, Communications Officer and Behavioural Strategist at the City of Malmö, who used behavioural science to tackle cigarette litter through visible social feedback. 

What unsustainable behaviour needs to change:

Despite being served daily, vegetables are often left uneaten in German daycare centres. Children reject unfamiliar foods due to food neophobia, lose interest when vegetables compete with more appealing options, and lack autonomy when portions are pre-plated.

Yet daycare lunch happens in supervised, communal settings where routines repeat predictably—creating an untapped opportunity to strategically shape lifelong eating habits.

The Green Nudge:

The researchers reviewed proven nudges to identify what makes healthy eating easier for young children. These interventions can be summarized in five modules:

Module 1 – Repeated Exposure
Serve vegetables as an „appetizer“ before the main course. Colour sort them on plates. Cut them into playful shapes. These presentation changes reduce neophobia and increase intake when repeated regularly.

Module 2 – Autonomy & Self-Serving
Let children serve themselves from central bowls. Self-serving increases acceptance and teaches hunger-satiety regulation. Strategic use of vessel sizes creates visual defaults without pressure.

Module 3 – Social Modelling
Staff eat visibly alongside children, showing genuine enjoyment. Seat adventurous eaters next to cautious ones—peer influence measurably shifts eating behaviour.

Module 4 – Environmental Design
Warm-coloured walls, appropriate lighting, and clear separation between eating and play zones reduce distractions and help children focus during meals.

Module 5 – Imaginative Menus
Rename dishes with playful language—“grass-green frog soup“ instead of „pea soup.“ Post illustrated menus in hallways. Use stickers to highlight vegetables and water.

The Results: Combinations of nudges are more effective than single interventions—low-cost implementations (under €5 per child) deliver substantial behavioural change when designed systemically.

The Business Case: This approach delivers measurable outcomes at minimal cost. By reducing food waste, it lowers disposal and catering expenses. At the same time, higher vegetable intake improves children’s eating behaviour. For educators, it offers simple, evidence-based tools that integrate into daily routines without added workload. Parents, in turn, see tangible commitments to health outcomes. Overall, the system is scalable, low-barrier, and designed for real-world implementation.

Do you know of any other nudges that help to drive plant-based adoption?
Share your thoughts: hello@green-nudges.com

From researchers from Albstadt-Sigmaringen University and the University of Potsdam. Led by PhD Student M.Sc. Jo-Ann Fromm in the team of Prof. Dr. Andrea Maier-Nöth, with contributions from Prof. Dr. Astrid Klingshirn, Prof. Dr. Gertrud Winkler, and Prof. Dr. Petra Warschburger, the team systematically reviewed evidence-based interventions tested in German daycare settings as part of the „Start Low“ project funded by the Federal Ministry of Food and Agriculture.

What unsustainable behaviour needs to change:

Tourism accounts for around 8% of global greenhouse gas emissions, with hotels responsible for roughly 2%. Yet sustainability communication often underperforms in travel contexts.

The key barrier is inertia. Holidays are hedonic by nature: tourists prioritise comfort, ease, and enjoyment. Traditional sustainability messages—especially moral or instructional ones—often feel like lectures that interrupt the holiday experience. As a result, guests stick to familiar habits such as overusing water and energy or ignoring recycling, even when they care about sustainability at home.

The Green Nudge:

Researchers found that humour works particularly well in tourism because it fits the leisure mindset. Across five studies—including field experiments in Chinese parks and hotel-like settings, plus eye-tracking analysis—humorous signs using wordplay, incongruity, or wit consistently outperformed neutral messaging. They captured more attention, reduced perceived effort, and made sustainable actions feel easier rather than preachy.

Based on the research findings, three design factors appear critical:

• Relevance: the joke must connect directly to the behaviour („Fish look for fish, shrimp look for shrimp, garbage goes back to its own home“ for recycling)
• Clarity: a simple, visible instruction
• Placement: exactly where the decision happens (bins, taps, light switches, towel hooks)

But the real insight is this: it’s the humorous sign itself—not just putting people in a good mood—that drives behaviour change.

The results: The field experiments showed that humorous recycling signs increased correct disposal from 66.25% to 83.75%—a 17 percentage point lift. Eye-tracking confirmed that these humorous signs attracted significantly more visual attention than the neutral ones. Survey data also showed lower perceived effort for recycling, water saving, energy conservation, and towel reuse when humour was used.

The Business Case: Hotels face a structural mismatch: guests control consumption, while operators carry the cost. Fixed pricing removes any incentive to save water or energy—making moral messaging largely ineffective. Humorous signs cut through this impasse. They change behaviour without incentives or enforcement, making sustainability campaigns more effective without touching the guest experience—and especially powerful in fixed-rate and all-inclusive settings.

Do you know of any other nudges that use humour to make sustainability communication more effective?
Share your thoughts: hello@green-nudges.com

From the Green Nudges Consulting team drawing on research by Ming Lei, Yatong Li, and Makarand Mody, published in the Journal of Sustainable Tourism, examining how humorous signs influence sustainable behaviour in tourism settings.

What unsustainable behaviour needs to change:

Tenants usually assume that rooftop solar is only for homeowners. When people picture solar power, they imagine installing their own PV modules — something renters cannot do. This mental model forms a strong barrier: solar is not for me.

Combined with low involvement, ‘switching friction’ and the invisibility of electricity (“power just works”), many tenants stick with generic grid electricity even when cleaner, cheaper power is generated right above their home.

The Green Nudge:

By borrowing a beloved Scandinavian rooftop figure, the German energy brand Karlssonn from energy provider ALVA creates instant emotional closeness: ’something on the roof‘ feels warm and personal, not technical or exclusive.

The tagline „Your power from the roof“ frames the core promise — you don’t need to own a house to have your own power. Even the name itself does some cognitive heavy lifting: the strong consonant opening (punchy first sound), light wordplay and distinctive spelling boost salience (help it grab attention), make it more memorable and likeable.

Plain-language explainers clarify that no installation is needed. Pre-filled signup forms and building-level activation create soft defaults. Behind the scenes, a bias-aware communications toolkit addresses ‘status-quo inertia’ (sticking to what’s familiar), ‘present bias’ (favouring the short term) and ‘complexity aversion’ (avoiding what feels complicated).

The results: Early adopter buildings reached 60%+ tenant uptake, far above the 35–40% market baseline, with new buildings achieving up to 90%. The brand and explainers also significantly improved understanding of tenant-accessible rooftop solar, closing a critical awareness gap.

The Business Case: When the brand itself removes barriers, commercial performance follows naturally:

• Higher asset utilisation: More tenants choosing rooftop solar lifts self-consumption and speeds up PV payback.
• Lower acquisition costs: A memorable, behaviourally designed brand compresses the funnel and replaces costly switching pushes.
• Lower churn: Tenants feel a sense of ownership (‚my power from my roof‘), strengthening loyalty compared with generic utility offers.
• Scalable model: The brand-led nudge is transferable across buildings and cities, supporting revenue growth without eroding margins.

Karlssonn proves that when behavioural insight shapes brand strategy from the start, it becomes a core business lever.

Which other brands could use storytelling to make sustainable choices feel personal?
Share your thoughts: hello@green-nudges.com

From Nicolai Shimmels, Director of OH, BEHAVE c/o ressourcenmangel, where he brings behavioural strategy and creative brand building together to make sustainable choices intuitive for mainstream audiences. He and his team specialize in the energy sector, helping utility and energy providers design behaviour-led solutions. 

What unsustainable behaviour needs to change:

For over a century, mined diamonds have been promoted as the ultimate symbol of eternal love. From the famous slogan „a diamond is forever“ to family traditions, social norms still push couples to choose natural stones. Yet the costs are high: diamond mining is carbon-intensive, damages ecosystems, and often carries the legacy of „blood diamonds.“

Lab-grown diamonds—real diamonds produced in controlled conditions replicating natural processes—offer an identical alternative without these harms. Yet awareness remains low, and even when people know about them, cultural biases create hesitation. For many, naturally mined diamonds represent authentic romance, while lab-grown ones are stigmatized and feared as symbols of lower status.This gap in knowledge, combined with cultural attachment to mined diamonds, perpetuates an unsustainable norm.

The Green Nudge:

In a study with 551 participants, each imagined being in a jewellery shop where a customer was choosing between a mined and a lab-grown engagement ring. When shown a simple informational prompt—“Lab-grown: smaller environmental footprint, conflict-free“—perceptions shifted notably.

The lab-grown option was not only rated more positively but also seen as socially acceptable, with participants believing others would approve too. The message narrowed the perceived gap between mined and lab-grown diamonds, making the sustainable option seem equally, or even more, desirable. Both personal willingness to choose lab-grown and perceived social acceptance increased measurably.

For jewellers, this shows the power of subtle prompts: emphasising the ethical and environmental benefits of lab-grown gems in displays or advertising could accelerate acceptance. Over time, lab-grown diamonds could evolve from an alternative into the new norm.

Still, a caveat applies: this study measured attitudes and stated preferences, not actual purchases. Engagement rings are emotionally charged decisions, often influenced by social expectations. Whether these nudges translate into real-world choices remains an open question, calling for future research.

The Business Case: Lab-grown diamonds make timeless beauty accessible. Once reserved for the wealthy, synthetic diamond rings are now an affordable, sustainable option for mainstream buyers—typically 40–70% cheaper than mined stones. In 2023, lab-grown diamonds accounted for around 46% of U.S. engagement ring centre stones (Rapaport, 2024). This shift opens the market to younger and more diverse consumers who value ethics and transparency over rarity.

Which other sustainable products do you know of that are replacing  problematic “traditional” ones?
Get in touch: hello@green-nudges.com

From Kerem Güclü, Master’s student in Industrial Economics at TU Berlin, with support from the Berlin Social Science Center (WZB). His research explored how a simple social-responsibility message can shift perceptions of lab-grown engagement rings.

What unsustainable behaviour needs to change:

High meat consumption is one of the most environmentally damaging dietary habits. Livestock farming accounts for roughly 16 % of global greenhouse-gas emissions, takes up 80 % of agricultural land, and drives deforestation, biodiversity loss, water pollution, and the risk of animal-borne diseases.

Yet in efforts to reduce meat intake, one intervention has dominated: carbon labelling.

Dr Chris Macdonald, Director of the Better Protein Institute (BPI), argues that carbon labels — while well-intentioned — often underperform. They’re cognitively demanding, hard to interpret during quick decisions, and rely on complex calculations. Despite these limitations, they remain popular — something Macdonald attributes partly to “environmentalist bias”: prioritising ecological framing over consumer understanding.

The BPI takes a different approach: start by talking to the end user.

The Green Nudge:

In a UK study published in Frontiers in Sustainable Food Systems, Dr Macdonald and his team surveyed over 1,500 consumers and uncovered a key barrier: people believed plant-based meals lacked protein. He called this the “insufficiency illusion” — the mistaken belief that meat-free options fall short nutritionally.

This insight drove a large-scale experiment with over 3,000 participants. Menus were updated with a simple, factual label showing that plant-based options contained comparable protein to meat-based ones.

The results: when protein content was highlighted, meat-free meal selection more than doubled — jumping from under 25 % to over 50 %. The effect held across genders, making the meat-free option the majority choice.

This subtle label is what Macdonald calls a “nudge by proxy” — an indirect cue that shifts behaviour without highlighting the environmental problem. Rather than prescribing what to choose, it provides the specific information people feel they need.

The Business Case: For food operators, this small label delivers measurable results. Since plant-based meals are generally cheaper to produce, every additional sale contributes to higher margins. The change requires no staff training or marketing investment—just a small adjustment to menu design. And by grounding sustainability in evidence rather than ideology, it helps strengthen trust among customers and employees alike.

Do you know of any other nudges that help to promote planet-friendly food?
Feel free to get in touch: hello@green-nudges.com  

From Dr Chris Macdonald, a behavioural scientist, author, and founder. Dr Macdonald is a Fellow and Lab Director at Lucy Cavendish College, University of Cambridge; a Fellow at the Institute of Corporate Responsibility and Sustainability; a Supervisor at the University of Cambridge Institute for Sustainability Leadership; and Director of the Better Protein Institute. He was recently named one of the 40 Under 40 in Science and Innovation.

What unsustainable behaviour needs to change:

Speeding trucks on unpaved construction roads stir up large amounts of dust, posing serious health risks. Truck movement can contribute up to 50% of PM10 emissions—fine dust particles small enough to enter the lungs— on-site (Giunta et al. 2019). Yet on many sites, speed limits are ignored due to weak enforcement and low awareness.

At the Gurugram (part of the National Capital Region) pilot site—an active Indian construction zone grappling with air quality concerns—only 16% of heavy-duty vehicle drivers followed the 10 km/h speed limit. With no reminders from guards, dust control wasn’t seen as a priority.

The Green Nudge:

To reduce dust, a simple strategy was introduced: guards were trained to verbally remind incoming truck drivers about the 10 km/h speed limit and explain its role in improving air quality. Posters reinforced the message visually, and drivers were invited to voluntarily commit to following the rules.

Why did it work? People are more likely to comply when reminded by someone credible,when they actively commit to a behaviour, and when consequences are made concrete. Guards fit this role perfectly, reinforcing site rules with authority and clarity. This approach combined salient cues, social reinforcement, and personal accountability.

The results: This low-cost nudge raised compliance from 16% to 63%. As trucks slowed down, dust pollution dropped–PM10 by 11%, PM2.5 by 29%—regardless of weather conditions.

The business case: Less dust means healthier workers, fewer sick days, and stronger regulatory compliance—all achieved with minimal investment and no new infrastructure required.

Do you know of any other nudges that reduce construction site pollution and thus cut health costs?
Feel free to get in touch: hello@green-nudges.com

From the Clean Air team at the Council on Energy, Environment and Water (CEEW), Delhi: Arvind Kumar (behavioural science), Dr. Mohammed Sahbaz Ahmed (air quality modelling), Dr. Arpan Patra (urban pollution compliance), Sandeep Narang (sustainable construction), and Dr. Abhishek Kar (Senior Programme Lead). The team combines behavioural science, air quality modelling, and on-ground interventions to tackle urban air pollution—from construction dust to transportation emissions.

What unsustainable behaviour needs to change:

It’s Friday afternoon. You’re tired after a long week, rushing through the supermarket on autopilot. You have good intentions — to eat healthier, shop more sustainably — but in the moment, those values are quickly overridden by fatigue, convenience, and price cues.

Sound familiar? This everyday scenario reveals why good intentions often fall short in the grocery store. Despite growing climate awareness, most of us still grab the convenient, familiar choices. The problem isn’t that we don’t care—it’s how our brains respond under pressure.

Here’s why:

• Mental shortcuts under pressure (decision fatigue): When we’re tired and rushed, our brains default to familiar patterns
• Too much information (cognitive overload): With thousands of products competing for your attention, we can’t process what’s truly sustainable
• Bold price tags win (price salience bias): Eye-catching sale stickers trigger our deal-seeking instinct, regardless of actual value

Traditional campaigns often miss the mark on promoting more sustainable choices because they expect people to be deliberate. But most shopping is reactive– shaped by fast, unconscious judgments, not slow, rational decisions.

The Green Nudge:

In a study with a Danish supermarket, Krukow Behaviour Change tested a remarkably simple intervention:

• Yellow dot stickers were added to healthy, everyday vegetables like cabbage, potatoes, and broccoli.
• The dots mimicked „sale“ tags, using price cues to trigger the brain’s deal-seeking instinct — but without changing the price.
• These items were placed in high-traffic areas, making them easy to grab without extra effort.

The results: Shoppers who encountered the yellow dots were 46% more likely to choose the healthier option.

No discounts. No education campaign. No added friction. Just a subtle visual cue that leveraged our brain’s automatic assumption that visually prominent items offer special value (price bargain heuristic).

The intervention cost virtually nothing to implement and required no staff training or system changes. This shows how design tweaks—not big budgets or awareness campaigns—can shift real-world behavior.

The Business Case: The yellow dot acts as an evolutionary nudge that drives purchase behaviour through instinctive attention cues — raising sales without eroding margins or requiring promotion spend.

What other clever in-store nudges have you spotted that actually work?
Feel free to get in touch: hello@green-nudges.com

From Sille Krukow, a global leader in Behaviour Design with over two decades of experience helping organizations like Procter & Gamble, Electrolux, and the European Commission turn behavioral insights into measurable sustainability outcomes. She’s a frequent keynote speaker and guest lecturer whose design based methodology shows how small environmental cues can drive big shifts in decision making.