The goal of the research was to improve the energy efficiency of nearly zero energy buildings in the Mediterranean using renewable energy systems. The researchers combined an Earth – Air Heat Exchanger, an Underground Tank, and a Solar Thermal Collector to meet heating needs. By integrating these systems, they achieved a 131% coverage rate in Oran, Algeria, surpassing the individual systems' coverage rates of 49.3% and 41.7%. The combined systems saved 37.9 € and reduced CO2 emissions by 21.1 tons during the heating period.