Abstract:In the European Union (EU), the building sector is responsible for approximately 40% of total energy consumption. The existing building stock is inefficient and can, and indeed must be retrofitted to address this issue. The practical implementation of the European strategies requires knowledge of the energy performance of existing buildings through energy audit techniques. Application of thermography in the fields of energy are very widespread, since, through such a non-invasive investigation, and through correct interpretation of infrared images, it is possible to highlight inefficiencies in buildings and related facilities. The paper shows and discusses the results of an infrared audit campaign on 14 existing buildings located in Milan Province (Italy) made in different construction periods and characterised, therefore, by different building technologies. The U-values obtained in an indirect way through the thermography of the opaque walls of the buildings investigated, were compared with the actual known values in order to verify the reliability of the method and the possible margin of error. The study indicated that the category of buildings in which the application of this method is sufficiently reliable is that of solid-mass structure buildings, the most widespread in Italy, whereas in the case of buildings whose external walls are insulated, the percentage of deviation is very high.
The energy certification of buildings implemented in the Member States of the EU with the transposition of Energy Performance Building Directive (EPBD) has stimulated the market for high-performance buildings, normally classified as A and A+. Such energy performance, however, is evaluated based on a theoretical calculation model that defines standard operating conditions. In Italy, as in most EU countries, performance assessments are not carried out under real operating conditions. The Lombardy region is a leading player in the field of social housing. In order to demonstrate transparency to the customer, the BEST Department of Politecnico di Milano was instructed to conduct a comparative evaluation between the actual and normalised energy performance of a high performance building located in Milan. The study showed that the real performance, calculated using data from three selected flats, was consistent with that calculated during the certification procedure. However real energy consumption is different even in identical flats, due to different behaviours of the user
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