Koch, DavidDavidKochBalve, PatrickPatrickBalveGerdes, Jan-NiklasJan-NiklasGerdesHertwig, MichaelMichaelHertwigKröll, MarkusMarkusKröllLentes, JoachimJoachimLentes2024-08-122024-08-122024https://publica.fraunhofer.de/handle/publica/473056Rising energy and resource costs, as well as regulatory requirements, are driving industrial companies to become more sustainable and environmentally friendly. To this end, the concept of ultra-efficiency has been developed and promoted by Fraunhofer in recent years. It is characterized as a concept for creating a loss-free, emission-free, energy self-sufficient and climate-neutral factory that blends into and enriches its urban environment and provides a human-centered workplace for its employees. In many cases, neighboring companies are more successful in meeting these challenges by working together than by acting individually. Therefore, the concept of ultra-efficiency has been extended from a single factory to multiple factories in industrial zones and, more recently, to agriculture in mixed-use urban districts. In this context, we have selected three completed projects and analyzed their specific challenges and opportunities. We conclude with a list of lessons learned that can help companies and other private and public actors in their quest for greater sustainability.enUltra-EfficiencyIndustrial SymbiosisSustainabilityIndustrial Parkconference paper