On the cost-optimal levels of energy-performance requirements for buildings: A case study with economic evaluation in Italy

The European energy policies about climate and energy package, known as the “20-20-20” targets define ambitious, but achievable, national energy objectives. As regards the Directives closely related to the 2020 targets, the EU Energy Performance of Buildings Directive (EPBD Recast- DIR 2010/31/EU) is the main European legislative instrument for improving the energy performance of buildings, taking into account outdoor climatic and local conditions, as well as indoor climate requirements and cost-effectiveness. The EPBD recast now requests that Member States shall ensure that minimum energy performance requirements for buildings are set “with a view to achieving cost-optimal levels”. The cost optimum level shall be calculated in accordance with a comparative methodology framework, leaving the Member States to determine which of these calculations is to become the national benchmark against which national minimum energy performance requirements will be assessed. The European standards (ENs- Umbrella Document V7 (prCEN/TR 15615) are intended to support the EPBD by providing the calculation methods and associated material to obtain the overall energy performance of a building. For Italy the Energy Performance of Building Simulations EPBS must be calculated with standard UNITS 11300. The energy building behaviour is referred to standard and not to real use, nor climate or dynamic energy evaluation. Since retrofitting of existing buildings offers significant opportunities for reducing energy consumption and greenhouse gas emissions, a case study of retrofitting is described and the Cost- Optimal Level EU procedure in an Italian context is analysed. Following this procedure, it is shown not only that the energy cost depends on several conditions and most of them are not indexed at national level but also that the cost of improvement depends on local variables and contract tender. The case study highlights the difficulties to apply EU rules, and allows verifying whether this methodology could be used as thermo-economic analysis for investment decisions in energy efficiency improvements and refurbishment in Italy or similar regions. In the case study here analysed, the choice of the best energy efficiency measures derived from the Cost Optimal level methodology underlined the importance of the building typology, the reference market and also the building location in applying this methodology.