Significant but transient: The impact of an energy saving app targeting Swiss households

In Global North countries, persuasive apps supporting households in reducing their energy consumption are widespread, as promising policy tools for the energy and climate transition. Despite their growing diffusion, fed by the large-scale smart meter roll-out currently ongoing in many energy systems, rigorous studies providing evidence on their effects are still missing, especially for the long-term. We address this research gap by analysing a one-year long app-based electricity saving intervention performed in Switzerland between 2018 and 2019, involving 55 self-selected households. Adopting a quasi-experimental approach and considering four full years of energy consumption data, we estimate the app's average treatment effect over time and perform heterogeneity analyses on household sub-groups, on varying their characteristics and intensity of app use. The app reduced consumption and CO2 emissions during the intervention (average treatment effect on the treated equal to 4.95%, statistically significant at the 0.05 level; Cohen's d effect size equal to 0.35). However, one year later the effect disappeared. Our results put policies based on persuasive app use into perspective: taken in isolation, persuasive apps may exhibit limitations regarding long-lasting effects. To avoid relapse, future interventions might embed app use into broader processes explicitly aimed at redefining shared norms and conventions on household energy consumption practices, for instance within living lab processes.