The exergy approach for the evaluation of heating and cooling technologies; first results comparing steady state and dynamic simulations

Energy saving and emissions reduction are both af¬fected by the energy efficiency of the built environment and the matching between the quality of the energy car¬rier and the quality of the required energy. To take into account qualitative aspects of energy leads to the intro¬duction of the exergy concept. Heating and cooling of buildings require low valued energy, especially if low temperature heating systems and high temperature coo¬ling systems are used. Nevertheless space conditioning is usually provided through high exergy sources. This study is related to the IEA ECBCS Annex 49 “Low Exergy Systems for High Performance Buildings and Communities”, in the framework of which a research for comparing different technologies for heating and cooling, from both the energy and the exergy perspec¬tive has been started, assuming steady state conditions. After that, dynamic simulations have been carried out in order to evaluate the effects of climatic conditions, systems behaviour and envelope’s thermal response on exergy performance. First results in terms of comparison between the steady state and dyna¬mic approach in exergy calculation are presented.