Bespoke behavioural interventions led to a 414% rise in sustainable bin bag sales and a 20% drop in conventional plastic bag use.
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.
