1. Buildings – European Commission, (n.d.). (Accessed 28 November 2018) https://ec.europa.eu/energy/en/topics/energy-efficiency/buildings.
2. M. Economidou, B. Atanasiu, C. Despret, M. Economidou, J. Maio, I. Nolte, O. Rapf, Europe's buildings under the microscope, (n.d.). (Accessed 17 May 2017) http://bpie.eu/wp-content/uploads/2015/10/HR_EU_B_under_microscope_study.pdf.
3. European Commission, Energy Efficiency Directive - European Commission, (n.d.). (Accessed 21 December 2018) https://ec.europa.eu/energy/en/topics/energy-efficiency/energy-efficiency-directive.
4. New Energy Performance in Buildings Directive comes into force on 9 July,2018
5. European Commission, Nearly zero-energy buildings - European Commission, (n.d.). (Accessed 18 December 2018) https://ec.europa.eu/energy/en/topics/energy-efficiency/buildings/nearly-zero-energy-buildings.