Global cost in a social housing intervention

The European Union, with the Delegated Regulation No. 244/2012 of 16 January 2012 and the next document accompanying the regulation published on 19 April 2012, has defined a methodological framework for calculation of cost optimal, actually optimal levels, depending on the cost, the minimum requirements for energy performance, calculated during the estimated economic life cycle of the building or of the building element. The methodological framework is based on the European Standard EN 15459. This rule provides a method of calculating the overall cost equal to the sum of the present values of the following types of costs: cost of the initial investment; operative costs (energy costs, operative costs, maintenance costs); costs for periodic replacement of building components; disposal costs. Focusing on the energy performance of the building it is also possible to perform simulations in terms of global cost for the building, in order to take into account both energy and economic aspects. The paper discusses the results emerging from a study carried out on a social housing intervention. In particular it is investigated the economic and financial sustainability of investment costs for the renovation of existing buildings for reaching high energy performances comparable to those of energy category A. The analysis, based on the European Standard EN 15459, is conducted at the level of the global cost, in order to verify if during the useful life of the building, the savings, in terms of lower costs related to its energy management, are able to cover the higher cost of construction needed to achieve the level of energy category shown above. The results of the study shows that, in terms of global cost optimality, from the point of view of the real estate developer, it is convenient to reach an energy category B, using solutions less energy efficient for the building envelope. In fact the lower investment costs offset, during the useful life of the building, the increased costs related to its energy management.