1. Consumption of Energyhttp://ec.europa.eu/eurostat/statistics-explained/index.php/Consumption_of_energy
2. Promoting renewable energy sources for heating and cooling in EU-27 countries
3. ČSN 73 0540, Thermal Protection of Buildings—Part 3: Design Value Quantities,2005
4. UNE-EN 673 Glass in Building—Determination of Thermal Transmittance (U Value)—Calculation Method,2011
5. BS EN ISO 10077-2, Thermal Performance of Windows, Doors and Shutters. Calculation of Thermal Transmittance,2017