Making Sense of Sorting – How to nudge people to sort organic waste

Can the municipality of Copenhagen apply learnings from behavioral science to increase households’ degree of waste recycling in order to become a CO₂-neutral city by 2025?

Since 2012, the municipality of Copenhagen has invested heavily in making it possible for its citizens to sort their waste into the most common fractions such as bio, plastic, paper, metal etc.  The result has been that around 45% of household waste is sorted which roughly means that less than half of all households actively participate in waste sorting even though doing so has been made as easy as ever.

As a result, the municipality has realized that for the degree of waste sorting to increase, citizens need to be further motivated to engage in waste sorting and hereby better utilize the provided infrastructure. Since monetary incentives appealing to extrinsic motivation might be troublesome to introduce in a setting where each households’ waste production is not directly visible (as many people live in apartment buildings and dump their waste at certain stations), it is necessary to appeal to other motivators.

We therefore chose to conduct an experiment where we exposed two yards of apartment buildings to a set of interventions meant to make individuals aware of a social norm to sort waste while seeking to invoke warm glow and promote other-regarding preferences. This was done by handing out postcards to all households with information regarding the societal benefits associated with waste sorting while attaching normative feedback stickers to all waste containers in the yards comparing the households’ waste sorting effort to that of the city district.

Following 11 weeks of measurements we could conclude that our intervention had significant treatment effects leading to an increase in the level of bio waste in the treated yards in three to four weeks out of six, depending on the applied econometric model. Thus, the treated households appeared to have been positively affected by the normative feedback and the provided information.

These insights not only showcase that behavioral science can have a significant impact on individuals’ sorting behavior, they can also inform the municipality’s strategy on how to reach a high degree of waste sorting and achieve CO₂-neutrality.

Read the full report here: MakingSenseOfSorting

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Christina Gravert

Christina.gravert@impactually.se

+ 45 50 17 43 32

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