Primary Energy Factors and the primary energy intensity of delivered energy: An overview of possible calculation conventions

The related concepts of Primary Energy and Primary Energy Factors (which describe how much Primary energy is contained in each unit of delivered energy) are used for international comparisons of national energy use and have become increasingly important regulatory and statistical metrics, especially in relation to the European Energy Performance of Buildings Directive. As concepts they contain a mixture of technical, political and economic dimensions, so it is perhaps unsurprising that reported values from different organisations and countries do not seem to be calculated in the same way. This review aims to clarify the origins of such differences by identifying, summarising and commenting on alternative conventions that are or can be applied. In particular, it aims to provide a starting point for the development of a transparent means of reporting the procedures and conventions that are employed. Such a framework would provide a basis for understanding the reasons for differences. The review does not recommend specific conventions or procedures – preferences will vary, depending on a number of factors. Practical application: Primary Energy Factors are central to international comparisons of national energy consumption and to several aspects of European energy policy. In the context of buildings, they are especially important to the newly revised Energy Performance of Buildings Directive which requires primary energy to be the primary metric, rather than, for example, carbon emissions. It is known that different countries use different methodologies and that this can have substantial repercussions. The methodologies used are rarely reported and range of possible options has not previously been set out. This paper sets out to do this in order so that choices can be made with greater transparency and clarity