The Leuphana University of Lueneburg changed to renewable energy supply with the first climate-neutral energy balance for heat, electricity, cars and business trips in 2014. The heating network is based on two biomethane-powered combined-heat-and-power (CHP) units of 525 kW_el. each. A total of 720 kW_p photovoltaics with 95% self-consumption covers > 20% of the electrical demand. We present the campus development and transformation to provide a best-practice example for conversion to exergy-efficient renewable energy systems.The new central building provides a large auditorium, seminar rooms, offices, a cafeteria, machine hall and space for exhibitions and events. It uses low-grade heat at 58 °C for optimized integration of short and long term heat storage installations. The architecture and façade design significantly lower cooling demand (≈ 2.5 kWh/m²a), modern lighting systems and user integration allow for superior overall energy efficiency. Exergy efficiency, storage options and emissions of the campus system as well as energy efficiency of the buildings were analysed. A high-temperature aquifer thermal energy storage (HT-ATES) installation perfectly matches the low-exergy heating demands and increases the share of CHP-heat, resulting in an additional surplus of 2.3 GWh/a of renewable electricity and additional savings of 2.424 t CO₂-eq./a.