What unsustainable behavior needs to change:

Amsterdam’s traffic landscape has undergone significant shifts, with increased activity and a notable rise in cyclists and pedestrians, paralleled by a decrease in car numbers. 

However, the success in reducing cars has given rise to a new challenge: approximately 25% of Amsterdammers routinely ignore red lights, heightening the risk of accidents.  Addressing this habit of disregarding red lights has become imperative to bolster road safety amidst the city’s evolving traffic dynamics.

The Green Nudge:

Commissioned by the municipality of Amsterdam, ANDC developed an intervention, known as the “gestopt-voor-rood-teller,”  aimed at reducing the number of cyclists disregarding red lights at a crossroad. 

The ‚gestopt-voor-rood-teller‘ was a visual display set up at a particular crossroad in Amsterdam. Cyclists were encouraged to engage by pushing a red button, which tallied the increasing number of cyclists waiting at the red light – visibly displayed on the screen. Additionally, a self-persuasion question, ‚you too?‘ encouraged cyclists to adhere to the newly established social norm.

The result: upon implementation of the intervention, the likelihood of cyclists stopping for the traffic light increased by 2.7 times. Even four months after the intervention’s removal, the effect remained twice as substantial.

What unsustainable behavior needs to change:

The increasing CO2 emissions from e-commerce deliveries presents a pressing environmental concern. If consumers decided to have their online order delivered to a pick-up point instead of at home, this could reduce up to 33% of CO2 emissions.

However, consumer decision-making is influenced by the mental overload and existing habits around online shopping. Consumers often multitask while shopping online (e.g., checking social media, e-mail, or news). This high cognitive load likely makes them go for the path of least resistance, such as the default or habitual choice.
To overcome this obstacle, the team designed four nudges and conducted testing via an randomised controlled trial with 1,204 participants to determine the most effective approach in altering consumer behaviour.

The Green Nudge:

To overcome this obstacle, the team designed four nudges and conducted testing via an randomised controlled trial with 1,204 participants to determine the most effective approach in altering consumer behaviour.

The four nudges included one default and three information nudges. For the default nudge, the most sustainable delivery method was automatically selected at the check-out page. For the three information nudges, CO2 impact of the delivery options was displayed: either as a green leaf next to the most sustainable option (low complexity), percentage of CO2 reduction for the most sustainable option (medium complexity), and CO2 emissions in grams for each delivery option (high complexity).

The result: The default nudge was more than 5 times as effective at steering consumers towards the most sustainable delivery option (delivered to pick-up point) relative to the control condition. While not effective in terms of shifting to the most sustainable choice, the most complex informational nudge steered consumers away from the two most polluting options – thereby potentially saving more greenhouse gas emissions than the other nudges. 

Results were replicated in a second study among more than 35,000 consumers, showing that a default nudge combined with information about CO2 impact was more than twice as effective than the control condition.

What unsustainable behavior needs to change:

Whether it’s for a cup of tea, coffee, or to fill a pot, chances are you’re using a water kettle multiple times a day. Yet, how often do you pour precisely the required amount of water into your kettle? It’s rarely accurate, often resulting in an overfilled kettle, wasted water and electricity. So, how might one reduce unnecessary water and energy use while preparing your daily hot water fix?

This seemingly minor issue is more serious than you think. Even in a country as tiny as the Netherlands, over 5.3 million cups of tea are brewed daily on average, leading to a considerable waste of water and electricity. Just to put it in perspective: boiling a litre of water consumes as much energy as keeping a light on for an entire day! Quite wasteful, isn’t it?

The Green Nudge:

To address that issue, behavioural agency, “Unravel Behaviour” devised a Green Nudge to encourage the precise amount of water required in the kettle: stickers that guide and personalise tea cup volumes.

Quantity charts on most kettles range from 1.5 to 2 litres; leaving out the precise millilitre measurement for a cup of tea. To ensure more accurate water usage, the experiment used a custom kettle sticker appliqué, specifically tailored to the volume of one’s favourite tea cup as the variable; and had one without – to serve as the control. This created nearly two identical kettles, differing only in the placement of the stickers. 

The result: Compared to the standard kettles, the stickered kettles showed 195 ml  of unused water remaining in the kettle. This means an extra glass of water, on average, was wasted in every tea-making attempt without the customised stickers. The translation of this impact: The nudge led to substantial energy savings and 1 glass of water, less wasted per person. Just in the Netherlands alone, overall, this totals 97 litres per individual, and a staggering 1.4 billion litres saved annually.

What unsustainable behavior needs to change:

The annual waste report for the Dutch municipality of Dordrecht sheds light on a specific behavioural issue: the frequent illegal dumping of bulky waste near underground containers in the Prinsessenbuurt neighbourhood of Nieuw-Krispijn. This behaviour has had significant consequences for the neighbourhood’s liveability and the efficiency of the waste removal process.

The Green Nudge:

What unsustainable behavior needs to change:

Toilets are more and more equipped with a dual-flush option. While the design varies widely between different manufacturers, the principle remains the same. There is an option to flush with a full flush (generally supposed to flush faeces) and an option to flush with a partial flush (generally supposed to flush liquids). One of the designs often seen is that of a small and a big button next to each other. While many people have learned to understand that big button =  big flush and small button = small flush, this does not hold true from a nudging point of view. 

Considering that biologically speaking, the small flushing button should be used considerably more often than the big flushing button, the nudging principles of option composition (as identified by Mertens et al. 2022) and more specifically sizing (as identified by Wee et al. 2021) are not adhered to. This is to say that the big flushing button draws more attention than the small button at the generally short decision-making time when picking a flushing button. This consequently leads to excessive use of that big flushing button. Using a full flush with often twice the amount of water as a partial flush when it isn’t necessary is a wasteful use of freshwater and should be prevented as much as possible.

The Green Nudge:

To address this issue right at the moment of decision-making prior to flushing the toilet, Chiel Verstappen developed an interactive prototype known as „The Button Nudger.“

An unmissable message was presented to the toilet user just before flushing: the nudge text (see image) – based on the principle of conveying the norm (as per Byerly et al. 2018),  was humoristic by design and had the added benefit of informing users who are not at all familiar with the dual-flush setup. In users who are familiar, it obviously acted as a gentle reminder to perform a certain action (in this case, consider the small flushing button if it would suffice) as is often the case in nudging. Next to a textual cue, an additional cue based on coloured lighting (centred around the influence of colour on mood/feeling) was given to aid the message. 

The result: The pilot test showed that “The Button Nudger” did have an influence on flushing behaviour. Some toilets showed greater effect than others, with a maximum water reduction of 10.7% and an average water reduction of 6.17%. Taking the average water reduction, a yearly water reduction of 3,180 litres per toilet could be achieved at the University of Twente.

Are you aware of any other nudges that help to conserve water? Feel free to comment or get in touch: hello@green-nudges.com