U-Value: A key role parameter for sustainable buildings
Keywords:energy efficiency, sustainable building, thermal insulation, U-Value
Buildings have a considerable environmental impact that corresponds to almost 30% of the global carbon footprint, with a prediction for further growth, and to 40% of the final energy consumption in the EU. The EU therefore has set a goal to reduce primary energy use by 20% by 2020, which is one of the five headline targets of the European 2020 Strategy. Moreover, the European Commission has established since 2002 a common policy for sustainable buildings and low environmental impact materials promoting energy efficiency and reduction of greenhouse gas (GHG), based on a series of directives and regulations. A key role parameter for sustainable building construction, is the appropriate building envelope’s thermal insulation in order to reduce its thermal losses. This was firstly introduced in Greece, with the Regulation of Building Insulation in 1979. Therefore, the paper focuses on the implementation of thermal insulation at buildings in compliance with the Greek national legislation framework during the last forty years. In this line of approach, measurements of the U-values and of the internal and external surface temperatures were carried out, in residential and office buildings. The sample consisted of buildings with construction dates that mirrored the development in legislation and in the building practice.