By bringing together more than 80 studies from academic publications and technical reports, the paper analyses a wide range of environmental behaviours, from energy and water usage, to recycling and waste reduction. So what works and what doesn’t? Here is a summary to guide you in the choice of your next intervention.
1. Education & Awareness: Useful but not on their own
Based on the knowledge-deficit model, it refers to the provision of information and is often the default approach to change behaviours. It is used in most interventions.
Telling people what to do or simply informing them about environmental issues has little impact. However, messages that reduce the psychological distance and highlight local environmental problems perform better.
The most successful interventions contain tailored information, such as comparative feedback with other households, and achieve even better results when combined with public pledge or commitment to pursue conservation efforts.
Providing information close to a point or moment of consumption (e.g. such as water-efficient stickers in the bathroom) can effectively reduce water and energy usage.
Environmental information can be overwhelming. In addition to information on the topic, people should be provided with support and resources to avoid feelings of disempowerment.
Education and awareness interventions are particularly effective on individuals that are already motivated by an interest in environmental behaviours but lack information. Their impact is more limited on the rest of the population.
Success rate based on the studies reviewed: 66%. Education and awareness interventions have the lowest rate of success across the studies examined. It is however the most studied type of intervention, probably because of its ease of application and the fact that it requires limited resources.
2. Outreach & Relationship Building: A complete but resource-intensive tool
These interventions aim to raise awareness of multiple environmental issues, based on creating relationships within communities and among stakeholders. They tend to respond to real-life problems using a practical approach. Examples include workshops, focus groups, training sessions, or public engagement activities and meetings.
They are particularly effective to change sets of pro-environmental behaviours associated to general topics such as climate change or sustainable lifestyles.
They work when used in conjunction with robust stakeholders and inter-community relationships and where the sense of belonging is strong.
Building these relationships is difficulty and requires a significant amount of time, money, community liaisons and organisational activities.
Rigorous measurement of their impact is difficult. Organising control groups to evaluate an intervention that takes place at a community-level can be hard. Their assessment tends to be qualitative rather than quantitative.
Success rate: over 80%. These interventions obtain the largest success rate as they often combine combines different interventions, such as education or social influence, with relationship buildings. They are however less studied in the literature.
3. Social Influence: A safe bet
Interventions that inform about the behaviours of other people (family, friends, community) to influence pro-environmental behaviours. Examples include campaigns via social networks, social or group comparisons or public commitment.
These interventions are often time and cost effective.
They work well on specific behaviours and in private context (such as water or energy use).
Face-to-face methods such as public commitment and block leaders seem to be work better than comparison feedback.
However, comparative feedback and social norm statements can help sustain their effect over time.
Identifying the right reference group is key to success.
Their long-term effect is difficult to determine as follow-up studies are often difficult to implement.
Success rate: 78%. Because they are relatively easy to implement and cost effective, these interventions are the second most studied in the literature. Studies show that they perform better than Education and Awareness interventions.
Dr Gianluca Grilli, co-author of the paper, tells us:
“Given that the ultimate goal of a project is to achieve an improvement in the environmental quality, the choice of the behaviour to change is very important. Small changes to some key behaviours may be more beneficial than large improvements of secondary behaviours.”
4. Nudges: Not for everyone
The tools that change the context of the decision - or choice architecture - to stimulate behaviour change in a predicted way. Examples include changing the default option and making the sustainable option more visible.
Nudges can be successful in motivating pro-environmental change. Changes in infrastructure, such as making recycling bins more visible or providing reusable cups for free, all had a positive outcome.
Small changes in the choice architecture can sometimes be enough to sustain environmental behaviours in the long run.
Financial nudges, such as offering free goods, are costly, and cannot always be sustained over a long period of time. Pro-environmental behaviours might not be last after the end of an intervention.
Nudges are less successful in private contexts where it is difficult to work on the choice architecture. They have a limited impact on waste and energy consumption for example.
Nudges raise ethical concerns. Environmental nudges should be based on the urgency of solving environmental issues, be transparent, and complement rather than substitute institutional changes.
Success rate: 75%. Nudges based on infrastructural changes appear to be efficient, but their use to encourage pro-environmental behaviours has rarely been studied to date.
5. Incentives: As a last resort
Incentives include monetary or non-monetary motivations to perform pro-environmental behaviours. Examples include cash bonuses, discount fees, gifts or coupons.
Monetary and non-monetary incentives have been successfully used in areas such as waste, water and energy reduction, but there is no consensus on which of those two approaches to use.
They could be particularly appealing to local authorities to promote environmental behaviours associated with the provision of public service, such as recycling or the use of eco-friendly transport.
The sustained long-term impact of incentives is still debated.
These interventions can be expensive to implement and there is a lack of specific guidelines regarding their use.
Financial incentives do not stimulate environmental awareness or intrinsic motivation, but simply reward individuals for specific actions. This appeal to economic interests and egoistic values can backfire on the long-term and generate behaviours that participate in the degradation of the environment.
Success rate: over 80%. These interventions have been less studied and, despite a high success rate, do not appear more effective than other interventions. According to the authors, there is no reason why they should be preferred over less expensive and equally effective methods.
“Carefully select behaviours and concentrate on the behaviours that make a real difference on environmental quality.” Dr Gianluca Grilli.
Tips for Practitioners:
Define and select the most impactful behaviour: Choose the behaviour that will have the most beneficial impact on the environment. When possible, consider the environmental problem to be tackled before deciding on the behaviour to change. Do not forget to consider potential barriers to pro-environmental behaviours such as cost, convenience and practicality prior to designing interventions. When barriers are institutional, behaviour change at the individual-level might not be the solution.
Tailor your intervention to the behaviour targeted. There is no default option when it comes to intervention. Each intervention should be context-specific and chosen depending on the objectives targeted and on the resources available. For instance, information and social influence might be more appropriate when you are aiming to change specific or private behaviours whereas outreach and relationships might work better to influence general sets of behaviours. Don’t forget that these interventions can also be used in a complementary way (ex: block leader to start and EEA to sustain).
Conduct sound research: Use a control group and pre-test your intervention on small samples. Measures of success and measurements tools should be clearly defined as they will prove useful to anticipate long-term environmental impacts. As practitioners, it is crucial to work towards a large-scale replication of successful interventions, especially when it means positive environmental outcomes!
Think long-term and regularly assess the impact of your intervention. This will allow you to provide stimuli to reinforce behaviours as needed. Studies usually focus on the first phase of behaviour change programmes but rarely assess the evolution of pro-environmental behaviours over time. While practical considerations can make it difficult to study the long-term effects of an intervention, obtaining these insights will help both academics and consultants to identify the most efficient tools to promote environmental behaviours.
The interventions reviewed, most of which were found in academic publications, are subjected to publication bias that tends to focus on successful interventions. Research is still needed to assess the long-term impact of each of these tools.
In addition, this article illustrates that, like most research to date, research on pro-environmental behaviours is WEIRD and focuses on White, Educated populations living in Industrialized, Rich and Democratic Countries. 73% of the studies reviewed here were conducted in Europe and America and only 2% in Africa, 7% in Asia and 3% in Oceania. Individual changes will only be beneficial to our planet if environmental behaviours are encouraged across the world and tailored to different populations.
Grilli G. & Curtis, J. (2021) Encouraging pro-environmental behaviours: A review of methods and approaches. Renewable and Sustainable Energy Reviews, 135, pp. 1-14.