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.