1. Directive 2010/31/EU. European Parliament and of the Council of 19 May 2010 on the Energy Performance of Buildings (recast). Official Journal of the European Union; 2010.
2. European standard EN 15316-4-5. Heating systems in buildings - Method for calculation of system energy requirements and system efficiencies - Part 4-5: Space heating generation systems, the performance and quality of district heating and large volume systems.
3. N.Surmeli-Anac, A.Hermelink, D.Jager, H.Groenenberg Primary Energy Demand of Renewable Energy Carriers. Part 2 Policy Implications. Ecofys 2014 by order of: European Copper Institute. 2014, http://www.ecofys.com/files/files/eci-ecofys-2014-pef-part-ii-policy-implications.pdf
4. E. Molenbroek, E. Stricker, T. Boermans Primary energy factors for electricity in buildings Toward a flexible electricity supply; Ecofys Netherlands BV, 2011, http://download.dalicloud.com/fis/download/66a8abe211271fa0ec3e2b07/ad5fccc2-4811-434a-8c4f-6a2daa41ad2a/Primary_energy_factors_report_ecofys_29.09.2011.pdf
5. U. R. Fritsche, H.-W. Greß Development of the Primary Energy Factor of Electricity Generation in the EU-28 from 2010-2013. IINAS, Darmstadt, March 2015, http://www.iinas.org/tl_files/iinas/downloads/GEMIS/2015_PEF_EU-28_Electricity_2010-2013.pdf