The European Union (EU) has committed to supporting the United Nations’ efforts in line with the Paris Agreement for addressing climate change and has set ambitious targets to reduce primary energy consumption and emissions. Similar commitments have also been set by EU-27 member states. For this purpose, it is necessary to use a primary energy factor (PEF) for converting electricity use to primary energy units and for assessing energy conservation measures. Lower PEFs reflect efficiency improvements in power generation, an increased share of renewable energy sources in the fuel mix for electricity generation, and lower transmission and distribution losses. Over the past decades, there have been intensive efforts and notable progress in the EU-27 for increasing the use of renewables in the energy mix for electricity generation. However, the EU default PEF value for electricity was not regularly updated and remained at 2.5 for several years till it was finally recalculated at 2.1 in the 2018 recast of the Energy Efficiency Directive.
This paper reviews different calculation options for estimating the PEF for electricity from official annual statistics, presents the historical evolution of the calculated conversion factors, and provides simple linear correlations for projecting the PEF values that can be used to facilitate more-realistic forward-looking calculations and assess national energy efficiency, climate change, or decarbonization plans in EU-27 member states. A more detailed analysis and case studies on the impacts of this work are illustrated for Greece and Poland.
The temperature differences as a result of the UHI reach about 5.4 °C during the day and exceed 4.5 °C at night. The impacts on the buildings’ energy demand for heating and cooling are significant. For an old building, the heating energy demands showed percentage differences ranging from −33.28% to −4.51%, and the cooling energy needs showed variations from −5.33% to 93.25%. On the other hand, considering a more recent structure, variations from −37.73% to 0.22% were obtained for the heating energy needs, and differences from −2.72% to 63.31% were identified for the cooling energy demands.