This field trial tested whether a simple, non-financial intervention could influence real-world charging behavior of electric vehicle users. In collaboration with a housing cooperative in Ghent, Belgium, we installed a "smartboard" displaying real-time signals about renewable energy availability. Charging activity in this garage was compared to a control site without the intervention, using a pre-/during-trial baseline and a linear regression model with a triple interaction (intervention × trial period × lamp signal), equivalent to a difference-in-differences-in-differences design.
Across the trial period (Aug 2023-Apr 2024), we observed 9,854 charging operations (88 MWh) from 563 badges, in addition to 5,353 operations (44 MWh) from 382 badges in the pre-trial year. The analysis shows that, relative to both its own pre-trial baseline and the control garage, the smartboard garage shifted charging significantly toward renewable-abundant hours and away from carbon-intensive times. Emission calculations indicate that this behavioral change reduced charging-related emissions, a 16-22% decrease compared to counterfactual patterns.
Beyond results, the trial offers practical lessons: the importance of close collaboration with local partners, the need to ensure signal salience, and the trade-offs between research design and day-to-day system operation. We find that visible, real-time informational cues when salient and convenient can complement financial demand-response measures and support sustainable mobility transitions.