Using an energy-economy model that integrates behavioural and technological detail, we evaluate the impact of key policies-energy efficiency subsidies (tax credits, zero-interest loans, reduced VAT, white certificates), the carbon tax and building codes-on residential energy demand for space heating in France. We find that the carbon tax is the most effective, yet most regressive, instrument. Taking into account all possible interactions among instruments, we find that they imply on average a 10% variation in policy effectiveness. Subsidies save energy at a cost of 0.05-0.08 euro per lifetime discounted kilowatt-hour, with a leverage of 0.9 to 1.4 in 2015, decreasing over time as the potential for energy-saving opportunities is being exhausted. Targeting subsidies towards low-income households, who tend to live in energy inefficient dwellings, increases leverage, thus reconciling economic efficiency and equity. The public cost of subsidies-3 billion euros in 2013-is outweighed by carbon tax receipts from 2025 onwards. Meeting the long-term energy saving targets set by the French Government however requires increasing subsidy rates and maintaining them through 2050. In particular, an order-of-magnitude discrepancy between simulated and observed numbers of zero-interest loans points to cognitive or strategic barriers that need to be removed to increase policy effectiveness.