In the context of EPBD-regulations, and in particularly in the ASIEPI project, the results of which this article is based, innovative systems are defined as: a) systems that most probably give a better performance in terms of energy performance of buildings than the commonly used systems b) the performance of which cannot be assessed by the national EPBD calculation methods. Thus, according this definition some systems can be innovative in some countries and not in others. In context of regulations, and on particular in the ASIEPI project, the principle of equivalence is defined as the procedure to assess the energy performance of innovative systems. In some countries the principle of equivalence is not limited to EPB regulations. As the Energy Performance of Buildings (EPB) regulations cannot cover all possible new technologies, Member States have to develop "principle of equivalence" procedures, in order to allow the assessment of systems not covered by the standard calculation procedures. This article discusses the overall context and describes the approaches used in some countries.
