Energy retrofitting of listed buildings requires a rethink as it is economically and technically complicated to retrofit. The Technische Universität Berlin has 47 buildings with a total net floor area above 500.000 m2 in its central campus, and 60% of them are listed. In Germany, optimizing the energy efficiency of such buildings has not to fulfill the requirements of the energy efficiency regulations. On the one hand, this situation is not corresponding to the national objectives regarding climate adaptation. On the other hand, they have to be retrofitted because of issues like poor energy efficiency and user comfort, and not privileged with special regulations. However, instead of changing the regulations, it is possible to solve the problem by changing the way of thinking. In this regard, rather than retrofitting such buildings directly, a new approach has been developed where the surrounding climatic conditions are optimized. Hereby, a simulation-based concept has been developed with an external transparent envelope. This “climate envelope” creates an intermediate space between outdoor and indoor, where through controlled air movement and passive solar gains, the balance in seasonal energy efficiency can be kept economically without any implementation on the buildings according to the building thermal and CFD simulations. This overall approach activates the yet not exploited capacity of energy savings by listed buildings using intelligent design and saves up to 30% more of primary energy.