Effect of Reference State Characteristics on the Thermal Exergy Analysis of a Building ✠

The exergy analysis is a way to assess the impact of an energy system on the natural resources. In a previous paper the Authors developed a building exergy model, called ⬓Thermal Exergy analysis of a building⬽. The exergy allows to assess a building from a Thermodynamics Second Law point of view. However the assessment result is function of the reference state chosen. In this paper the Authors explore the effect of the reference state thermal properties on the assessment result. To this purpose, an existing building has been modeled through the transient simulation software Trnsys. The model shows that the result changes when describing the reference state through hourly temperatures, monthly average or yearly average. The difference is low if the temperature of the energy flows is far from the reference state temperature and high if their temperature is close to that of the reference state.