This paper analyzes the impact of building characteristics, economic factors, and climate conditions on residential energy consumption in France. We use two complementary approaches: a regulatory change in Energy Performance Certificates (EPCs) on the one hand, and granular weekly electricity consumption data from smart meters on the other hand. Relying on log-log regression models, both strategies estimate energy consumption elasticity to insulation, boiler efficiency, household income, energy price, surface area or heating needs. Even though relying on two totally different datasets, our findings converge. Incorporating interaction terms evidences that, while insulation can be effective to deliver energy savings, its impact is contingent to several factors such as boiler efficiency and heating needs. The study provides evidence that integrated policy approaches combining retrofitting incentives, energy pricing mechanisms, and support for efficient heating systems like heat pumps are necessary to achieve meaningful reductions in residential energy use and advances towards carbon neutrality.