What unsustainable behaviour needs to change:

Every online order ends the same way: a diesel van pulling up outside  your door. The last mile is the most polluting stretch of the entire delivery chain. Vans clog up residential streets, emit greenhouse gases, and create noise where people live.

Most people would happily choose a greener option if it were easy. But sustainable alternatives are rarely visible and almost never come pre-selected. The default is always the van.

The Green Nudge:

SuCoLo brought together researchers, municipalities, logistics operators, and citizens to see whether small design choices could shift delivery behaviour at scale.

The team tested several digital signals on online delivery platforms. A green leaf icon marking the sustainable option and loyalty points for choosing cargo bike delivery both performed strongly. So did a simpler intervention: pre-selecting the sustainable delivery option — cargo bike or consolidated — as the default. Shoppers could still opt for a van, but had to actively switch away from the greener choice.

Rather than asking people to seek out sustainable behaviour, each of these signals made it easier, more rewarding, and more visible. 

One approach didn’t work: urgency cues such as „only limited availability.“ Pressure felt counter-productive and the data confirmed it.

The Results: Across the platform pilots, every nudge outperformed the control group, where 22% of shoppers chose cargo bike delivery with no prompt at all:

• Customer loyalty nudge: 31% chose cargo bike delivery
• Green leaf icon: 30%
• Default pre-selection: 28%
• Urgency messaging: 18% (below even the control group)

The Business Case: Small design tweaks can shift the delivery mix without alienating customers. A green icon, a loyalty reward, or a pre-selected default each nudged shoppers toward more sustainable choices — at minimal cost. For cities, more cargo bike deliveries means fewer vans and less congestion. For brands and platforms, these signals communicate values without the need for a campaign. And the data shows what not to do: pressure tactics can actively reduce sustainable choices.

Have you tested digital nudges in your own platforms or services?
We’d love to hear what you think: hello@green-nudges.com

From Michael Thelen, Innovation Researcher at Salzburg Research, who led SuCoLo, a 2.5-year EU-funded project across Salzburg, Leipzig and Merano.

What unsustainable behaviour needs to change:

Most households own items they rarely use. A jigsaw for one DIY job. A camping stove for one weekend. A fondue set that comes out once a year. Yet buying still feels easier than borrowing.

The average power drill is supposedly used for just 12 to 15 minutes in its entire lifetime. That means it spends over 99% of its existence sitting idle. Across millions of households, that adds up to an enormous volume of goods manufactured and discarded for almost no reason. The barrier isn’t willingness, it’s visibility. We simply don’t know what our neighbours already own.

The Green Nudge:

Leihklub, a non-profit sharing club in Bremen, has devised a beautifully simple solution: a printed A2 poster mounted in the entrance hall of a residential building.

The Leihwand (roughly: “lending wall”) shows simple, easy-to-understand black-and-white illustrated icons of common household items: drills, ladders, sewing machines, camping gear, board games, bicycles. Beneath each icon, residents write their name and flat number if they are willing to lend that item out.

No app. No registration. Just a pen on a string and a poster on a wall.

The poster removes the awkwardness of knocking on a stranger’s door. It makes lending offers visible and permanent, turning everyday passing moments into quiet invitations to share. And because it sits in the hallway, it reaches every resident as part of their daily routine.

Leihklub encourages whoever hangs the poster to go first. Sign up for one or two items. That small act makes it easier for neighbours to follow.

The Results: The Leihwand is an early-stage initiative, currently running in around ten buildings in Bremen. Hard data is not yet available, but the poster is free to download, costs almost nothing to print, and the replication potential is significant.

The Business Case: For housing associations and local authorities, the Leihwand is a near-zero-cost way to support sustainability goals and strengthen community cohesion. A printed poster and a pen – that’s the entire investment. Yet its social return could be profound. For organisations looking for credible, tangible sustainability actions, this is about as low a barrier as it gets.

Do you know of any other nudges that bring the circular economy into everyday life?
We’d love to hear what you think: hello@green-nudges.com

From Leihklub Bremen, a non-profit sharing club based in Bremen, Germany. Founded by Fabian Oestreicher, Philipp Burckhardt, and a small team of volunteers, Leihklub exists to make borrowing everyday items easier than buying them. Their latest initiative, the Leihwand, takes that mission directly into the places where people already live.

What unsustainable behaviour needs to change:

Coventry is one of England’s worst-affected cities for fuel poverty, with some areas reporting more than 50% of households struggling with energy costs. Grants are available but rarely claimed. Low trust, language barriers, competing priorities, and daily pressures can limit the effectiveness of traditional council outreach, meaning that information alone is often not enough to reach those who need support most.

The Green Nudge:

The Retrofit Rocks! project puts children at the heart of the conversation. Working with three Coventry primary schools, researchers, teachers, artists and council representatives engaged 180 pupils through energy workshops and 3D model-building of efficient homes.

Children’s work was showcased at community events where parents gathered in a familiar, welcoming setting. They spoke informally with council staff about available grants, with on-site support services to guide residents through applications.

Children are trusted messengers at home in ways no leaflet can match. Creative activities made retrofit feel personal, and a community setting replaced the formality of a council office with something far more approachable.

The Results

• Around 100 residents attended the events vs. the typical 6–12 – a tenfold increase
• Retrofit-grant webpage views tripled (peaks of 80–110 vs. baseline of 20–30)
• 130 households engaged across three schools, with 180 pupils involved
• 5 applications completed on the day; 6 households contacted Act on Energy; 4 submitted retrofit applications; 5 received social housing support
• 8 households referred to enforcement, surfacing serious disrepair for the first time
• 18 households confirmed for energy upgrades across two events (council-verified)

Early data from a pilot; further outcomes expected as participants move through the pipeline.

The Business Case: Reaching fuel-poor households through traditional channels is costly and rarely effective. Partnering with schools offers a ready-made route into hard-to-reach communities without expensive campaigns. A tenfold attendance increase and 18 confirmed energy upgrades from two events demonstrates clear value. The model stretches public funding further and ensures investment reaches those who need it most. Coventry City Council is now expanding the approach more widely across the city.

How could trusted community relationships unlock behaviour change in your sustainability projects?
We’d love to hear what you think: hello@green-nudges.com

From Dr Lory Barile from the University of Warwick. Lory worked in collaboration with Coventry City Council, local schools, artists, and community partners. Her project piloted a creative approach to engaging fuel-poor households with home energy improvements and is now being rolled out more widely across Coventry.

What unsustainable behaviour needs to change:

Most people know that climate change is a problem. Fewer know what to do – and almost nobody talks about it.

That gap isn’t apathy; It’s social silence. Research by PNAS shows that inaccurate perceptions of social norms create a „climate of silence“. When nobody around us discusses climate, we assume nobody cares, which makes acting even harder.

And conversation turns out to be a powerful trigger for action. According to the Yale Program on Climate Change Communication, people who discuss climate with family and friends are three times more likely to take action than those who don’t.

That’s exactly the gap A Brush With Climate set out to address.

The Green Nudge:

Inspired by an Australian initiative of the same name, A Brush With Climate is a University College Cork research project that turns hair salons into climate-conversation hubs. Five salons across Cork joined the pilot in March 2025 and co-created a toolkit of resources that quietly embeds climate prompts into the familiar salon experience.

• „What if…?“ cards invite clients to imagine a concrete action: „What if I switched to public transport for a week?“ or „What if I cut out fast fashion for a month?“ Each card includes a sourced fact and a QR code with practical next steps.
• Mirror stickers prime the conversation before the stylist says a word For example: „Cycling, walking or taking the bus or train is the most impactful everyday action you can take to reduce your carbon emissions.“
• Pocket-sized info cards give stylists the confidence to answer questions on the spot, backed by trusted sources.
• A digital Linktree page points clients to more information to help them take up a climate action after they leave the chair.

The results: At the end of the project, 30 clients had made 144 individual climate pledges across the five salons, with QR-code stickers remaining live until February 2026.

When asked to reflect on their experience of the project, hairstylists said they felt “inspired” and found the project “enlightening”. They highlighted how the project cemented what they already knew about climate change while also correcting misconceptions. As a result of their involvement in the project, hairstylists reported taking up more eco-friendly actions in both their salons and their personal lives – such as installing water-efficient taps and appliances, and reducing their reliance on single-use plastics. They also reported that their clients felt encouraged to behave more environmentally friendly too.

The Business Case: Hairstylists occupy one of the rarest communication environments in marketing: trusted relationships combined with uninterrupted attention. The same clients return regularly, conversations are personal, and distractions are minimal.

According to marketing scientist Karen Nelson-Field, attention is the single most critical driver of message effectiveness. Without it, there’s no chance a message will work. Add a trusted, credible sender and you have the conditions most climate communication never achieves. In the salon chair, both come together naturally, making climate-communication investments significantly more effective.

Do you know other unexpected places where climate conversations could naturally happen?
We’d love to hear what worked: hello@green-nudges.com

From Catriona Iulia Reid (MaREI Centre, University College Cork). She manages A Brush With Climate, a Research Ireland funded project led by Dr. Maria Kirrane (Head of Sustainability and Climate Action, University College Cork) in partnership with The Environmental Forum.

What unsustainable behaviour needs to change:

Most consumption systems still nudge people towards replacement rather than repair or refill. Even consumers who value sustainability tend to default to buying new. Research shows this gap isn’t driven by attitudes but by behavioural barriers: people overestimate the effort and cost of circular alternatives, underestimate their convenience, and rarely encounter repair or refill options at the exact moment decisions are made (Kremel, 2023).

Yet these decisions increasingly happen in digital and hybrid environments — online stores, in-store touchpoints, and checkout flows — creating a powerful opportunity to redesign defaults.

The Green Nudge:

Recent studies show that default settings, salience cues, social norm messaging, and friction reduction consistently shift consumer decisions at the moment of choice (Khound & Mishra, 2025). Circular behaviours increase when repair and refill options are made visible, easy, and socially normal.

Instead of moral appeals, effective interventions subtly reshape the decision environment:

• Reduce Friction: one-click access to repair guides, refill services, or local providers directly from product or checkout pages.
• Shift Defaults: surface „repair“ or „refill“ before „replace,“ without removing freedom of choice.
• Use Social Norms: frame circular actions as what most people do already, especially when the behaviour is unfamiliar.
• Align with Identity: position repair and refill as desirable and status-signalling rather than a sacrifice.

Companies play an active role: embedding circular pathways into customer journeys can systematically shift consumption patterns at scale (Bücker et al., 2025).

Real-world example:

In 2024, Visa’s Recommerce Behavioural Insights Lab partnered with Selfridges to test a simple idea: could the right message, placed on mirrors in the beauty hall, get shoppers to choose refill products? Three variants were tested: „More people are buying refill,“ „People are switching to refill,“ and „Be one of the first. Start a trend.“

Overall, refill sales declined across the category; wider market pressures were too strong for messaging alone to overcome. But two brands stood out: one saw a +16% uplift, another saw refill sales double. Small copy changes. Real behavioural differences.

The Business Case:

Circular nudges reduce waste, extend product lifecycles, and strengthen brand trust without incentives or moral pressure. For businesses, this means measurable sustainability impact through smarter design rather than heavier messaging. And, as the Selfridges experiment shows, even imperfect results generate strategic intelligence that sharpens the next intervention.

Do you know of any other nudges that make repair and refill the obvious choice?
We’d love to hear what worked: hello@green-nudges.com

From Sofia Held Ruiz, who works at the intersection of technology and human behaviour. Her contribution draws on recent research exploring how digital choice architecture can promote circular economy behaviours– specifically repair, refill, and recommerce. 

What unsustainable behaviour needs to change:

Cycling rates drop when it rains. Precipitation is one of the strongest negative predictors of cycling frequency. Even moderate rainfall leads to statistically significant ridership declines (Kane & Kythreotis, 2024). Not because people don’t want to cycle, but because bad weather magnifies every small friction point. Standing at a red light in the rain feels longer and more uncomfortable than it ever does on a dry day. For many, that discomfort is enough to reach for the car keys.

And yet this is the exact moment when infrastructure design can make a difference. Rain doesn’t have to mean a worse cycling experience.

The Green Nudge:

Cities including Rotterdam, Groningen and Enschede have installed rain sensors at key intersections, particularly along school routes. When the sensor detects rainfall, the algorithm automatically adjusts and cyclists get the greenlight sooner and wait less.

The intervention works on two levels: it reduces objective discomfort, and it signals something more powerful: the city is on your side, even when the weather isn’t. In Rotterdam, a small indicator light on the traffic pole makes the system visible to cyclists. This matters. It transforms an invisible infrastructure change into a felt experience, reinforcing cycling identity (Thaler & Sunstein, 2008; Akerlof & Kranton, 2000).

The logic is simple: car drivers are dry. Cyclists are not. So when it rains, cyclists get priority.

The Results: Rotterdam’s evaluation shows cyclist waiting time drop from 48 seconds to 33 when sensors are active – a 31% reduction (Gemeente Rotterdam, n.d.). Car waiting times increase modestly, from 21 seconds to 29. In Amersfoort, 28% of surveyed cyclists said they would cycle more often with smart light infrastructure, and 20% said they would leave their car at home (Gemeente Amersfoort, n.d.). In Rotterdam, bike traffic has grown 10% in the past year alone with rain sensors among one of the 40 measures fueling that momentum.

The Business Case: The Netherlands moves on bikes, accounting for over 27% of all trips nationally. When rain pushes cyclists towards cars, that modal share doesn’t vanish: it moves onto roads already strained. Every percentage point lost to the car means more congestion, more emissions, more pressure on infrastructure never designed to absorb it. At €5,000 per intersection, the rain sensor is one of the cheapest ways a city has to protect the modal mix it has spent decades building.

Which other nudges could make sustainable transport more resilient?
We’d love to hear what worked: hello@green-nudges.com

From Annalena Sommer from the Green Nudges team, highlighting one of 40 measures from Rotterdam’s local government to stimulate cycling.

What unsustainable behaviour needs to change:

Most Western homes still run on gas or oil fuels whose price is determined by global energy markets rather than at home. In H1 2025, heat pumps overtook gas boilers as the most-installed heating system in Germany for the first time. Yet Germany has only 54 heat pumps per 1,000 households. Norway has more than 600.

The barrier is often behavioural rather than technical. According to Keleher and Hansen-Connell, over 75% of homeowners in the coldest US regions knew little to nothing about heat pumps. Status Quo Bias does the rest: when the old boiler breaks, people replace it with the same thing.

The Green Nudge:

Working with the Minnesota Air Source Heat Pump Collaborative, researchers tested a range of promotional messages: comfort, reliability, climate impact, rebates. None outperformed one simple comparison: „Heat pumps are 2 to 4 times more efficient than conventional heating systems.“

A reference point people can calculate with immediately. The study tested cost framing explicitly but autonomy comes with it for free: understand the efficiency gap, and you understand that your heating bill is no longer hostage to global gas markets.

German renovation research confirms both motivators. Reducing heating costs is the #1 driver for energy upgrades. Cost framing and autonomy framing work together. Climate messaging, by contrast, should be used sparingly. Only a small minority named carbon emissions as their key motivational driver, even among eco-conscious homeowners. 

The results: Messaging preferences were consistent across all segments — no targeting required. Broad awareness outperformed precision messaging. Once the financial case is understood, adoption accelerates. The tipping point has arrived. Communication just needs to catch up.

The Business Case: Homeowners are ready to act on financial self-interest and protect family finances from price volatility they cannot control. They just need the right reference point to do the maths.

• Lower bills: 2-4x efficiency often reduces heating costs by 30-60%
• Energy independence: every heat pump keeps an average of €16,000 in the local economy over its lifetime instead of flowing to foreign gas suppliers
• Works in existing buildings: most installations happen in retrofits, often requiring only larger radiators or targeted insulation measures
• Subsidy windows close: acting now locks in current incentive levels

Have you worked on campaigns for heat pumps or home energy upgrades?
We’d love to hear what worked: hello@green-nudges.com

From Matthias Höppner from the Green Nudges Consulting team, drawing on a 2024 study by Anna Keleher (The Behavioral Insights Team Americas) and Maddie Hansen-Connell (Center for Energy and Environment), conducted with the Minnesota Air Source Heat Pump Collaborative, complemented by market data from Norway, Germany, and the US: Rewiring America (2023), Zukunft Altbau/BDH (2025), and the toom Baumarkt/forsa survey (2025).

What unsustainable behaviour needs to change:

Most sports clubs are built around peak hours — and they pay the price for it the rest of the day. Facilities sit idle, energy keeps running, and pressure grows to expand or rebuild rather than make better use of what’s already there. Meanwhile, participation has become increasingly individualised and car-dependent, disconnected from the neighbourhood life that once made sports clubs matter.

The underlying driver is status quo bias: clubs default to a service-provider model, members default to consumption, and sharing rarely happens. The result is fragmented communities and facilities used in extractive ways that consume resources while offering little social return and undermining environmental sustainability.

The Green Nudge:

Kjøbenhavns Boldklub introduced a Senior Membership that does something deceptively simple: it opens underused daytime hours to older members, shifting the default from isolation to shared movement. The communal sauna acts as a behavioural anchor: an informal space where spontaneous interaction replaces programmed activity and social distance gives way to dialogue.

The nudge works on two levels at once. Seniors get back into active community life. The club gets better utilisation of infrastructure that was already there and already running. No new build required.

Together, these create a self-reinforcing loop where longevity, wellbeing, and efficient resource use become the daily default rather than the exception.

The results: Idle facilities have become active social spaces. Seniors previously at risk of inactivity have re-entered daily club life, increasing daytime utilisation without additional infrastructure or energy demand. Intergenerational contact has deepened local attachment to the club extending both the functional and social lifespan of its existing assets.

The Business Case: The Senior Membership doesn’t require new infrastructure, expanded capacity, or higher energy use. The same facilities deliver more social value across more hours of the day, lowering the cost per member served and reducing the pressure to expand or rebuild.

Do you know of any other nudges that unlock more value from existing infrastructure?
Share your thoughts: hello@green-nudges.com

From Mikkel Sølbeck, infrastructure project manager at Denmark’s national rail authority and volunteer sustainability lead at Kjøbenhavns Boldklub. Through his newsletter Unlocking The Future Game, Mikkel explores how regenerative thinking can transform sports clubs into resilient community ecosystems.

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.