Exergy as a Parameter for Building Energy Assessment

Abstract

Abstract:The energy and environmental impacts resulting from the buildings sector are one of the impending problems which address the international action. The main strategies implemented to answer to this problem are the energy efficiency improvement, the CO 2 emissions reduction and the renewable energy share increase in the energy mix. The key subject discussed in this paper is the "building energy impact", aimed to leading the building sector towards the energy efficiency improvement. The paper's aim is to show that an energy assessment is not able to give a consistent evaluation of building energy use, and it could be misleading. Therefore, the paper proposes the exergy assessment as complementary evaluation method, in order to achieve a complete description of the concept "building's energy impact on the environment". In the first section, we describe the parameters currently used for the building energy assessment, focusing on the primary energy index and the CO 2 emissions index. In the second section, we introduce the exergy as a complementary index. This index is a possible answer to the problems previously identified. Finally, in the third section, we present three test-cases, analyzed through transient simulation software TRNSYS. The purpose of the test-cases analysis is to show the difference between energy and exergy assessment.