A behavioural science approach helped Katwijk turn scepticism into trust, fully booking energy coaches, and unlocking 100+ insulation subsidies.
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 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.
Dutch cities installed rain sensors at traffic lights that automatically shorten waiting times for cyclists during wet weather.