1. EU. European Union; () [last] [Accessed November 2021].
2. International energy agency,2021
3. Directive 2002/91/EC of the European Parliament and of the Council of 16 December 2002 on the Energy Performance of Buildings;The European Parliament and the Council of the European Union,2002
4. Directive 2010/31/EU of the European Parliament and of Council of 19 May 2010 on the Energy Performance of Buildings (Recast),2010