Nudging, a definition

The holy grail of energy efficiency demands drastic changes in the overall energy-related behaviour of consumers.

  • We need to better understand all those factors that determine the consumers behaviour and the decisions they make about energy consumption matters,
  • Since the 1970s, monetary or in-kind incentives (e.g. discount plans and bonuses) have been used as motivation for affecting consumption decisions, 
  • Recent studies have identified ways in which behaviour can be affected without resorting to financial provisions or incentives of any kind, 
  • By far the most influential of these studies, the work of Richard Thaler and Cass Sunstein in 2008 introduced the notion of Nudging, as: “any aspect of the choice architecture that alters people’s behaviour in a predictable way without forbidding any option or significantly changing their economic incentives”.

First used by public authorities to improve the welfare of society, now nudges are more widely spread in diverse areas such as health, transport, taxation, finance, while the implications of nudging techniques for policy design have been explored extensively, also at the highest possible governmental level both in the US and UK. 

Nudging is a soft push, that can make people act or react — and consume less energy — because they are told their neighbours or peers do so for instance or by changing the default settings of energy devices.

Examples and instances

Nudges may be classified into six categories: 


Nudges that facilitate desirable behaviours by diminishing the physical or mental effort of individuals.


Nudges that seek to prevent an unwanted behaviour by instilling doubt about it.


Nudges that draw on humans’ desire to comply with what they perceive as others’ expectations from them.


Nudges that attempt to generate fear and uncertainty.


Nudges that reinforce behaviours.


Nudges that favour desirable behaviours by deceiving users’ perception about alternatives.

Instances of all six categories of nudges, together with other types of interventions, will be designed and tested in the NUDGE project. To this aim, a set of five heterogeneous trials (also referred to as pilots) have been carefully selected to demonstrate effective interventions in various scenarios of energy consumption.

The pilots feature widespread geographical coverage across different EU states (Greece, Belgium, Portugal, Germany and Croatia) and build on pre-existing consumer communities with population much bigger than the population expected to participate in the planned activities (direct participants).

Nudge category Description Example nudge relevant to the project

Facilitating Nudges

Default Change the preset option Temperature setting
Opt-out Consent is opt-in instead of opt-out Consent to automated management or switch to manual
Suggesting Suggest alternatives for decisions Personalized push notifications through the apps

Confront Nudges

Throttling mindless activity Implement time buffer between decision and action Provide time buffer before a non-energy efficient setting is activated
Reminding of consequences Provide information on consequences of actions between decision and action Prompting users through personalized messages, right before taking an action

Social Influence Nudges

Leveraging public commitmentLet people formulate a certain (public) commitment Prompt users to follow individual targets for a period and remind them to follow their commitment (Goal setting)
Raise the visibility of user's actionMake actions of users visible to others Quantify the impact of energy decisions on own energy bill or in a combined dashboard with others
Enabling social comparisonsCompare behavior with family, community, friends, etc. visible Comparison chart with social community (family, neighbours, classmates)

Fear Nudges

Resources scarcity Create perception of scarcity Inform that free PV energy will be available for 2 more hours
Temporal discounting Provide discount now instead of on the long run Provide discount on installing monitoring equipment, so that they can save energy later

Reinforcement Nudges

Just-in-time prompts Point out desired behavior at a suitable time Identify changes in the context (temperature setting) and prompt the user on time
Instigating empathy Provoke feelings of compassion to stimulate desired behavior Environmental impact highlighted through examples to create emotions of compassion

Deceive Nudges

Deceptive visualizations Create optical illusions that alter people's perceptions and judgments Visualizing the non-energy efficient choices impact through dramatic visualizations

Nudging techniques in NUDGE pilots

A preliminary attempt to identify nudges relevant to the scope of the five NUDGE pilots, together with an indication of the category (facilitating, confront, social influence, reinforcement, fear, deceive) they belong to was realized.

These choices will be further iterated upon in the early stages of the project to conclude on the most meaningful and promising set of nudges for each pilot. Then, they will be implemented through tool adaptations and functionality additions that will ease the assessment of their effectiveness in changing the energy-efficient behaviour.

These nudges will be executed sequentially, i.e., each pilot participant will be exposed to a single nudge mechanism during a certain timespan (minimum 2 nudging techniques per pilot). At the same time, and depending on the pilot at hand, more traditional policy mechanisms will be tried out; for example, pricing policies in the case of the German pilot.

Indicative nudging interventions currently envisaged for each of the five NUDGE pilots:

Efficient heating and DHW preparation for Natural Gas consuming boilers in Greece

  • Facilitating: Change the default temperature setting of available heating schedules
  • Deceive: Visualize the environmental consequences of non-efficient actions (e.g. overheating)
  • Social Influence: Comparison with similar households in the same neighborhood, city, etc.

Interdisciplinary project-based education on home energy consumption for children in Belgium

  • Facilitating: Provide easy, understandable information on own household consumption
  • Social Influence: Social comparison with households of classmates
  • Confront: Define impact of a certain action in monetary or environmental measures

Optimization of EV charging with self-produced PV power in Germany

  • Facilitating: Suggest alternative periods for EV charging
  • Reinforcement: Point out that EV charging is advised during periods of high PV production
  • Reinforcement: Provoke feelings of environmental responsibility to drive efficient EV charging

Healthy homes for long-lasting energy efficiency behaviour in Portugal

  • Social Influence: Prompt users to follow individual targets towards improving health conditions for their family
  • Facilitating: Suggest alternative means for improving indoor environment conditions that take into account the impact on overall energy use (e.g. ventilation to reduce indoor pollutant concentrations when outdoor temperature/humidity conditions permit)
  • Fear: Inform parents that prevailing outdoor air quality is not optimal for energy-efficient house ventilation

Promoting distributed self-production for local Energy communities in Croatia

  • Social Influence: Social comparison with members of the cooperative
  • Social Influence: Leverage commitment of individuals to common goals of the cooperative
  • Social Influence: Invoke feelings of reciprocity by advising members to consume when PV energy is available