4056/2015: “Regimes for Certification, Control and Promotion of the Use of Renewable Bioenergies”. EN.2. Optimal use of energy by applying energy efficiency measures. IN 3. Improvement of the quality of the fossil fuels used. It should be noted that this measure implicitly implies technological innovation (eg improvement in the use of ultra-low sulfur fuels, requiring modernization of the vehicle fleet). IN 4. Promotion of sustainable buildings in cities. IN 5.