Zero-interest green loan programs (ZIGL) are gaining traction to address the tremendous financing needs implied by climate change mitigation. One such program, the French Éco-Prêt à Taux Zéro, significantly under-performed the expectations the government had for it at its inception in 2009. Using a difference-in-differences design applied to a panel survey of 10,000 households, we find that the program had a substantial, yet short-lived, impact on home energy retrofits. On the extensive margin, eligibility to the program significantly increased the rate of renovation by 3-4 percentage points (+25%) in the first two years, but not thereafter. The effect is strongest (7-8 p.p.) for low-income homeowners. On the intensive margin, the amount spent on renovation significantly increased only for the second year of the program, with at least an extra €1,100 (+9%). Our results are robust to a range of robustness checks, including placebo regressions and propensity score weighting. Our analysis points to unexplored barriers in both the demand and supply that can explain the short-lived effect of loans for home energy retrofits. (joint work with Louis-Gaëtan Giraudet and Mariona Segu)