Abstract
The Directive 31/2010 has recommended to the Member States to establish new minimum energy performance requirements according to the cost-optimal approach both for new buildings and renovation. According to the Commission Delegated Regulation EU 244/2012, the member states have to determine “statistically representative” reference buildings and to compare the cost-optimal set of retrofits with the current energy performance requirements in order to define a new and more stringent prescription. In the present paper, this approach is applied to a basic module whose initial configuration is varied, in order to simulate different possible reference buildings. It has been considered an uninsulated single-storey model of 100 m2, with different glazings sizes, window orientations and S/V ratio. A total of 18 different reference buildings were obtained from the combination of the above alternatives each analyzed in three climatic regions of the North of Italy (Belluno, Milan, and Pisa). The cost optimal configuration has been found for each reference building combining improvements: on the opaque envelope (different levels of external insulation), on the transparent component (double or triple glazings, with low or high SHGC), on the ventilation losses (ventilation with heat recovery), and on the energy production system (different boilers and solar collectors). Globally, 360 improvement packages, given by the combination of the above measures, have been analyzed for each reference building. The cost optimal configurations and the respective energy requirements have been compared in order to evaluate their variability depending on the characteristics of the corresponding reference building.