1. United Nation Environment Programme, Environment for development, available at http://www.unep.org/sbci/AboutSBCI/Background.asp;
2. U.S. Department of Energy, Building energy data book, available at http://buildingsdatabook.eren.doe.gov/ChapterIntro1.aspx.
3. European Commission, data available at http://ec.europa.eu/energy/en/topics/energy-efficiency/buildings;
4. Directive 2010/31/EU of the European Parliament and of the Council of 19 May 2010 on the energy performance of building;
5. Directive 2012/27/EU of the European Parliament and of the Council of 25 October 2012 on energy efficiency, amending Directives 2009/125/EC and 2010/30/EU and repealing Directives 2004/8/EC and 2006/32/EC Text with EEA relevance.