Maccari, A.; Zinzi, M.
July 2001
Solar Energy, vol 69-6, p. 75-92
Energy consumption in buildings is responsible for 40% of the energy end use in Italy. Most of the thermal and solar exchanges between the building and the external environment depend on fenestration. Rating schemes are useful instruments for classifying the energy efficiency of devices in many fields. For windows a rating system is largely utilised in some countries and is under study or development in many others. In Italy, single glazed units represent 80% of the total installed windows and the percentage of high quality products can be considered negligible. An energy-rating system would encourage efficient products onto the Italian market and would accelerate technical innovations in the glass and frame industries. The aim of introducing this scheme is to greatly reduce energy end use and, as a consequence, also CO2 emissions. The methodology, implemented for the residential sector, is based on the assessment of thermal performances of three reference buildings as a function of: window properties, climatic data and architectural characteristics. More than 1000 simulations, run with a building energy performance simulation code (TRNSYS), has made it possible to evaluate specific and percental heating, cooling and total energy savings as well as the reduction in CO2 emissions for the selected buildings. The simplified algorithms, which the energy-rating scheme for both cold and hot seasons is based on, have been taken from the analysis of previous results. Examples of cost–benefits analysis are presented to stress the economical and environmental advantages of the proper application of this instrument.
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