Within the Energy Performance of Buildings Directive the Primary Energy Factor (PEF) is used when calculating the energy performance. The PEF accounts for the energy losses of electricity generation and transport when comparing electricity use with other types of energy use in the building. But a recent Ecofys study warns that PEFs are not an unambiguous scientific value. Edith Molenbroek, researcher at Ecofys said: “Calculation methods are not transparent, harmonised and consistent and are not always adjusted to higher shares of large-scale renewable electricity.”