Multi-objective optimisation of a seasonal solar thermal energy storage system combined with an earth – Air heat exchanger for net zero energy building

Abstract Net Zero Energy Building (NZEB) is a high performance building concept that integrates passive design and renewable energy systems. The aim of this paper is to analyze the performance of multi-integrated renewable energy systems for nearly zero energy buildings in the Mediterranean context. Taking into account the particular technical characteristics of net-zero energy buildings, this study focuses on three different systems: 1) an Earth – Air Heat Exchanger (EAHE), 2) an Underground Tank (UNT) and 3) a Solar Thermal Collector. The first step of the methodology was to study the energy efficiency of the combination between EAHE and UNT for heating needs. An experimental facility equipped with monitoring sensors was constructed. For the second step, we propose a numerical study of the energy performance of the UNT coupled with a solar thermal collector and combined with an EAHE in order to improve the coverage rate of heating needs. The results show that the combination of the three systems satisfied all the needs with a rate of 131% for the climatic conditions of Oran, Algeria. On the other hand, the EAHE and UNT systems operating separately covered 49.3% and 41.7%, respectively. Combining three systems simultaneously saves 37.9 € (or 232.8 kWh of energy needs) and reduces by 21.1 tons of CO2 emissions during the heating period.