Mandatory energy efficiency disclosure policies are increasingly being used by governments around the world to reduce information-driven market failures. We exploit two policy changes in Flanders to study the causal effect of mandatory energy efficiency disclosure policies on house prices. We find that the introduction of mandatory energy performance certificates in 2008 that include an energy efficiency score did not affect the association between energy efficiency and sales prices, indicating that the policy change did not reduce information frictions. However, the introduction of EPC labels in 2019 affected the willingness to pay for energy efficiency.