Unravelling consumers sustainable energy practices – interview
06/16/2025
4 min
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Consumer behavior will play a fundamental role in the transition towards a more sustainable and cleaner energy future. Some estimates indicate as many of 70% the outcomes of the energy transition depend on people changing their behavior. While the term ‘energy efficiency’ refers to focuses on consuming energy better, ‘energy sufficiency’ refers to actively consuming less energy in our daily activities. What drives consumers to adopt these two types of sustainable behaviors? And should we be wary of a potential “rebound effect” – when consumers who become more energy efficient may inadvertently start to consume more? These were some of the questions that *Mélodie LACHAUD looked to answer in the framework of her Master’s thesis, which recently won the ICOR Prize. We spoke to *Melodie and her thesis director, Professor **Uyanga TURMUNKH, about the findings of this work.
Why did you choose to study this topic?
Mélodie LACHAUD: I have always been passionate about environmental issues, so it felt natural to focus my Master’s thesis on a topic that aligns with my values and career goals. In France, programs like MaPrimeRénov’ have brought energy efficiency in housing into the spotlight. However, while financial incentives are widely discussed, there’s been little exploration of how they interact with other motivations.
We often assume that pro-environmental behaviors stem from strong personal convictions or moral values, but for many, it’s simply a matter of saving money. I also wanted to dig deeper into what we really mean by “environmental behaviors.” That’s why I clearly distinguished in my work between energy efficiency (consuming better) and energy sufficiency (consuming less), two concepts that are often conflated but deserve to be understood on their own terms.
Uyanga TURMUNKH: Indeed, differentiating willingness to adopt energy-efficiency from willingness to adopt energy-sufficiency is important because, while both behaviors lead to the same desirable outcome from the environmental perspective, the motivations driving these behaviors can be quite different.
Melodie’s thesis, however, goes further than studying the potentially different motivating factors behind these two types of behaviors. She uses a clever experimental design to study their interaction; i.e., whether adoption of energy-efficiency can work to reduce willingness to adopt energy-sufficiency (the so-called “boomerang effect”).
What were the main findings from your work, notably the questionnaires you sent to over 250 French consumers?
Mélodie LACHAUD: My survey showed that when consumers lack clear financial information, which replicates the status quo, they tend to underestimate the benefits of energy-efficient housing. However, when presented with concrete data, like potential monthly savings, their willingness to invest in energy efficiency increases significantly.
Interestingly, my study also uncovered a rebound effect: while energy-efficient homes lower electricity bills, this can reduce the motivation to adopt energy-sufficient behaviors, such as voluntarily cutting down on consumption, because the financial incentive becomes less pressing.
Finally, personal characteristics matter, but they don’t influence energy efficiency and sufficiency in the same way. For example, older individuals and those more concerned about climate change are more likely to voluntarily reduce their energy use. However, these factors have no significant effect on decisions related to energy efficiency. In contrast, a higher level of education is only associated with a greater willingness to invest in energy-efficient housing.
What are the main takeaways for policymakers and consumers?
Mélodie LACHAUD: For policymakers, the message is clear: energy efficiency programs in housing can be much more effective when paired with better communication. Simple improvements, like making energy labels more informative by clearly showing potential savings, can make a big difference in how consumers make decisions. Financial incentives like grants and subsidies are already in place, but they will have greater impact if people better understand the benefits of energy-efficient choices.
These insights could also be applied beyond housing, such as in the appliance market. Another key takeaway is the rebound effect. While making homes more energy-efficient reduces bills, it can also unintentionally reduce people’s motivation to cut back on energy use. This means we risk overestimating how much (the level of) emissions will actually fall. Policymakers need to factor this into their forecasts and design complementary tools such as targeted taxes or awareness campaigns to avoid offsetting the gains from energy efficiency.
For consumers, the study highlights the importance of looking beyond just the immediate financial savings. True environmental impact comes not only from choosing efficient options but also from adopting habits that reduce overall consumption.
Uyanga TURMUNKH: The takeaways highlighted by Melodie are quite interesting, and immediately actionable. For example, the EU’s energy grade labelling system for housing and for large appliances uses the system of grades from A to E. While consumers know in abstract that an A-grade product saves more energy (and money) over time compared to the B-grade product, the difference in energy grades is difficult to weigh against the difference in the upfront costs of the products (in Euros).
Melodie’s thesis showed that simply adding the monetary equivalent of the energy savings in terms of the amount of Euros saved annually can make a marked difference in people’s willingness to purchase the A-grade product. Secondly, policy-makers and managers should take into account the boomerang effect when forecasting levels of energy and monetary savings that can result from improvements in energy efficient technology. As Melodie also states, even if energy-efficient technology works to dampen financial motivations, other motivations (e.g., conservation) can be appealed to prevent the boomerang effect.
*Mélodie LACHAUD is now a graduate of IÉSEG.
**Uyanga TURMUNKH is Associate Professor of Economics at IÉSEG and a member of the School’s iRisk Research Center on Risk and Uncertainty.
