Comparison of buildings’ energy consumption by means of exergy method

In this paper a new method starting from the LowEX tool, previously developed in the IEA ECBCS Annex 37 framework, in described. Following the energy conservation principle, the total consumed exergy is obtained summing the exergy exchanged in the subsystems (building envelope; distribution plant; heat generation). Finally, the efficiency of the system could be calculated, comparing the costs of energy consumption and exergy exchanges. By using the exergy approach, new (non economic) indexes could be utilized, as TOE (Tonne of Oil Equivalent), CO2 emission, or not-renewable energy uses. Therefore, the boiler would be fundamental, as well as the total amount of energy utilized, and the ratio between TOE and CO2 produced per exergy consumed in the system. The ratio between TOE produced by the boiler and the exergy used by the system represents the exergy parameter. This new exergy parameter has been finally applied in a real case history; however, it would represent a further application of exergy method to the design of new solutions.