Energy efficiency is a key part of sustainable energy development, not the least in Central and Eastern Europe (CEE), where the previous communist systems neglected energy efficiency for decades. The examples show how to increase energy efficiency in transformation (cogeneration of heat and power) as well as in usage. They also show different ways at which energy-optimization efforts might be organised: by the user (Oncology Institute), by an energy service company, and by a NGO, along with public owners that rent out the buildings. These examples also demonstrate that financing is a limiting factor.