In its “sustainable development” scenario, the International Energy Agency (IEA) considers energy efficiency to be the primary lever for reducing CO2 emissions (see diagram). The Intergovernmental Panel on Climate Change (IPCC) also considers energy efficiency as a key element of the ecological transition. This is also the case for all governments that have signed up to the Paris Agreement. But this strategy could prove to be flawed in that it disregards a phenomenon that has long been at work to counteract the benefits of energy efficiency: the “rebound effect”.
This results from the set of economic and behavioral mechanisms that cancel out all or part of the energy savings generated by efficiency gains. The extents of the rebound effects are difficult to quantify, but a trend is emerging within the existing body of knowledge of this phenomenon.
A recent study, to which IFPEN contributed, unequivocally demonstrated mounting evidence of a very significant rebound effect: more than half of the energy savings resulting from improved energy efficiency do not appear to materialize in reality. A key question is whether these rebound effects are properly taken into account in energy and climate models.
In the same study, four or the “integrated assessment models” used by the IPCC were examined, along with models used by BP, Shell, the IEA and the US Energy Information Administration (EIA). It was found that the majority of these models are unable to incorporate many of the mechanisms contributing to the rebound effect. This analysis therefore suggests that the models in question overestimate the energy savings that can actually be achieved. In other words, global energy demand appears to be significantly underestimated in the scenarios guiding political decision-making.
Since it appears that around 50% of energy savings are eroded by the rebound effect, there is an urgent need for the modeling community to take this phenomenon more seriously and incorporate it better into their equations. If they do not, the credibility of global climate scenarios may have to be taken with some caution, especially those that rely on a significant decoupling between economic activity and energy consumption.
 International Energy Agency, World Energy Outlook 2019, Paris, p. 79.
 P. E. Brockway , S. Sorrell, G. Semieniuk, M. K Heun, V. Court. Energy efficiency and economy-wide rebound effects: A review of the evidence and its implications. Renewable and Sustainable Energy Reviews, 2021, vol. 141, 110781.
>> DOI: 10.1016/j.rser.2021.110781
V. Court. The Conversation - 06/04/2021 :
>> La demande énergétique mondiale est sous-estimée, et c’est un vrai problème pour le climat
Scientific contact: Victor Court