How green is your house? Mandatory energy performance certificates and energy consumption

Mandatory energy performance certification for buildings is increasingly used in many countries and is seen as a key policy instrument for reducing energy consumption. Despite the widespread use, empirical evidence on whether or not mandatory certification reduces residential energy consumption is nonexistent. I study the introduction of mandatory energy performance certificates since November 2008 in Flanders, Belgium. I find that houses that were sold after mandatory certification consume 6% less energy. The lower energy consumption is mainly due to lower expenditures on fossil fuels. The results are robust to a whole range of possible alternative explanations such as pre-trends and changes in energy prices or subsidies over time.