Numerical, experimental, and thermodynamic analysis of a nearly zero energy building

In this thesis study, a comprehensive numerical, experimental and thermodynamic analysis was conducted on a test structure designed and constructed in accordance with the nearly zero energy building (nZEB) concept. The system integrates semi-transparent photovoltaic (PV) modules, photovoltaic-thermal (PV/T) collectors, and a phase change material (PCM)-assisted underfloor heating system. The primary objective of the research is to evaluate the electricity and thermal energy production performance of these integrated renewable energy systems, assess their contribution to indoor thermal comfort, and determine their potential for energy independence. The system was operated under real climatic conditions in the city of Elazığ for one year, with measurements recorded at five-minute intervals. According to the data obtained, the system produced 4335.8 kWh of electrical energy and 8671 kWh of thermal energy annually, while the total annual energy consumption was 3033 kWh.During the winter season, the semi-transparent PV modules integrated into the façade cladding contributed to the formation of a passive indoor-outdoor temperature differential, thereby protecting the building from harsh cold weather conditions. Additionally, during the transitional seasons, the PCM-supported underfloor heating system increased indoor temperature by up to 4 °C compared to the system without PCM, providing solar-assisted heating without the need for supplementary energy input. The system achieved an annual energy self-sufficiency rate of 143%. The average energy efficiency of the PV modules was calculated as 7.45%, while the PV/T system exhibited an electrical efficiency of 13.9%, a thermal efficiency of 35.4%, and a total efficiency of 49.3%. The exergy-based efficiencies were determined as 6.89% for PV modules, and for the PV/T system, 13.9% (electrical) and 9.4% (thermal). The energy payback period was found to be 3.5 years, while the financial payback period was calculated as 8.9 years.