The EU Buildings Climate Tracker is an index composed of a set of indicators. It is a response to the challenges of collecting and using data to monitor and assess decarbonisation progress in the EU building stock. Its starting point is the adoption of the Paris Agreement in 2015, while the objective is defined as climate neutrality by 2050. The Tracker serves as a benchmark and assessment tool for the status of decarbonisation progress in the European buildings sector and its progress towards climate neutrality by 2050. It provides evidence of the need for further action, which should be reflected in an ambitious outcome from the negotiations around the EPBD and the Fit-for-55 package. However, the Buildings Climate Tracker is not a tool for modelling the future: it rather documents the progress achieved since 2015 and puts it into perspective towards 2050, based on one scenario.