Exergy-based approaches for performance evaluation of building energy systems

Abstract

Exergy analysis is a powerful thermodynamic technique for assessing the performance of complex energy systems and optimizing their efficiency. A lot of research has been performed on exergy analysis of building energy systems, but there is still a real need to evaluate the practical application of low-exergy approaches on a building scale. One of the challenges that one faces when evaluating building energy systems from an exergy point of view is a lack of a suitable approach for a meaningful comparison of buildings with different types of energy supplier. This paper proposed three approaches, namely Inner boundary of the system, Comparative exergy efficiency and Potential solar exergy efficiency for a fair exergetic comparison of renewable and non-renewable building energy systems. To demonstrate the applicability of the suggested solutions, two case studies using a renewable and a non-renewable system are considered. A solar assisted boiler system and a conventional boiler system are used as representatives of renewable and non-renewable energy systems, respectively, and analysed based on the presented approaches. The results of the analysis show that the proposed approaches are applicable and they enable an exergetic comparison between renewable and non-renewable building energy systems to be made fairly.