Simplified tool for the energy performance assessment of residential buildings

Building sector is responsible for approximately 40% of energy consumption and 36% of CO2 emissions in the EU. For more than a decade the Energy Performance Certification (EPC) revealed to be an effective tool to create demand for energy efficiency in buildings providing recommendations for the cost-effective upgrading of the energy performance. The EPC process is founded on a standard calculation, based on conventional climate, use, surroundings and occupant-related input data, as defined by the Technical Standard EN 15603:2008. Even if the EPC is substantially mandatory in the European Countries, differences can be found along the process in particular in terms of methodology and tools. In Italy the national regulation provides simplified methodologies that can generate results assuring a maximum deviation between + 20% and - 5% of the final non-renewable primary energy compared to the same parameters determined with the application of the national reference tool. The aim of the present article is to describe the salient features of the methodology and the technical choices necessary to guarantee the range of acceptability of the results. A case study tested the procedure and the results were compared to those of an extended calculation procedure.