Fighting contamination: adding friction with shape-sorting bins

What unsustainable behavior needs to change:

One of the biggest problems in recycling is the contamination of recyclables. To encourage more recycling, a common solution is to increase the numberof recycling bins. Unfortunately, this inadvertently means that people would discard non-recyclables into these conveniently placed bins, resulting in the contamination of recyclables. 

People often develop routines and habits when it comes to waste disposal, and these habits may not align with proper recycling practices. For example, if someone is accustomed to throwing all their waste into a single bin at home without considering recyclability, they may continue doing so even when recycling bins are available in another setting. 

Breaking ingrained habits and establishing new ones that prioritise proper recycling behaviours can be a key factor in reducing contamination and promoting effective recycling practices.

 

The Green Nudge:

Tommy Cheong, a Singaporean industrial designer who graduated from the National University of Singapore (NUS), came up with an idea to improve the design of recycling bins by “adding friction.”

 

 His design has three key features that tap into the principles of behavioural science.

  1. A display of contaminants: Catering to people who don’t know what cannot be recycled, the bins include a real-life display of some common contaminants; thus making it easier for users to identify what they shouldn’t put into the bins.
  2. A defensive lid: If shaping the opening of the bins to accept only very specific items wasn’t enough, the bins also have a defensive lid to prevent people from “conveniently” discarding non-recyclables into them. This disrupts people’s “System 1” automatic habit of throwing anything and everything into the bins, and activates “System 2” by forcing them to consider what exactly they should be putting into these bins. This functions like a baby’s toy where you can only fit the correct shape into the puzzle!
  3. A transparent bin housing: Just in case people still don’t know what should be placed into these bins, the bin housing is designed to be transparent, so that users can see what others are putting in the bins; therein harnessing the power of social norms!

 

The result: The trial of this bin design at shopping malls yielded a remarkable outcome, with contamination rates for plastic bottles reducing from 79% to an impressive 29%.

As you can see, green nudges can sometimes make use of more ‘friction’, especially if we are trying to discourage incorrect behaviour. And when it comes to recycling, having fewer but cleaner recyclables may actually be better than having lots of contaminated items.

 

Are you aware of any other nudges that help to keep recycling streams clean? Feel free to get in touch: hello@green-nudges.com

 

From Yee Siang who is the Behavioural Insights Lead at Singapore’s Ministry of Sustainability and the Environment. His work focuses on using behavioural science to support the ministry’s mission in making Singapore a sustainable and habitable place to live. Also read his article on how to improve recycling using behavioural insights here.

Relaxing Soundscapes in restaurants promote sustainable eating

What unsustainable behavior needs to change:

The global food system contributes significantly to CO2 emissions, and the negative impact is particularly high for meat and dairy products. Recent research indicates that food emissions alone could prevent global temperatures from staying within the safe range of the Paris Agreement’s target of limiting temperature rise to below 2°C. Therefore, there is an urgent need to make widespread changes in our collective diets by eating more plant-based foods (that are resource-efficient) and fewer animal-based products. 

Achieving the goal of eating a more sustainable diet can be challenging, especially in indulgent surroundings. Restaurants, in particular, can have a strong influence on our culinary choices, since they rely heavily on our senses of taste and smell.

 

The Green Nudge:

Dr. Sophie Attwood explores the use of overlooked sensory primes like sound to promote sustainable eating in restaurants, cafes or canteens. 

Images and indulgent descriptions are common ways to prime food choices, motivating diners to select more plant-rich meals. However, sensory primes targeting sight, smell, and sound can also nudge people towards lower-emitting foods. While taste and touch are important factors post-choice, the aforementioned can play a significant role pre-choice. 

Let’s explore sound.

Our ears have a powerful influence on our perception of food, but are often overlooked. Congruence plays a role here, with sounds that match taste expectations (i.e. a rustle of a crisp packet, crunchy white noise with fresh crudité) shown to enhance eating experiences.

Calming music and natural sounds, such as waves and bird songs, have been linked to a higher preference for plant-based foods, including fruits and vegetables. The soothing effect of music may help us avoid cognitive fatigue and encourage more thoughtful, value-driven decisions.

By introducing relaxing soundscapes in restaurants, cafes and canteens, we can hypothesise that more sustainable plant-rich food choices will follow. Implementing different soundscapes in food service and retail settings is a cheap, easy, and unobtrusive intervention that could encourage a shift from animal-based to plant-based options. Experimentation with various soundscapes could help determine which is the most effective in promoting sustainable food choices.

Are you aware of any other Green Nudges that use our senses? Feel free to get in touch: hello@green-nudges.com

 

From behavioural scientist Dr. Sophie Attwood who reveals how we can use our senses to nudge pro-environmental behaviour. Sophie’s work focuses on encouraging consumers to adopt healthier and more sustainable plant-based diets as well as reduce food waste at home.

A new default with Burger King’s “normal or with meat” campaign

What unsustainable behavior needs to change:

Eating meat is deeply ingrained in Western culture, often seen as the default choice for protein and nutrition. But this comes at a high environmental cost. According to the Food and Agriculture Organization (FAO), global livestock production contributes 14.5% of all human-caused greenhouse gas emissions—equivalent to 7.1 gigatons of CO₂ per year.

Beef, in particular, is a major emitter. Producing just 1 kg of beef releases around 60 kg of CO₂ equivalents. By comparison, the emissions per kg for other foods are significantly lower:

  • Root vegetables & apples: 0.4 kg CO₂
  • Peas: 1 kg CO₂
  • Rice: 4 kg CO₂
  • Tomatoes: 1.4 kg CO₂
  • Nuts: 0.3 kg CO₂
  • Bananas: 0.7 kg CO₂

Despite these environmental impacts, meat remains the default in many popular dishes—especially burgers. When customers order a burger, it’s almost always assumed to be meat-based. This default reinforces unsustainable choices.

 

The Green Nudge:

Burger King Austria set out to challenge this norm with its „Normal or With Meat“ campaign at its Vienna Margaretengürtel location. Instead of assuming meat, they flipped the default: customers who ordered a “burger” without specifying “with meat” received a plant-based version by default.

The results: a 270% increase in plant-based burger sales. While further research is needed to assess long-term behaviour changes, this experiment suggests that default nudges can have a powerful impact on food choices.

Changing habits is extremely difficult. But establishing a new default might nudge some people to reconsider and try new – ideally more sustainable – options. If the product experience is not worse than the unsustainable option, it has the chance to become a new habit. A new normal.