In the 1960s, the Slovenian modernist architect Savin Sever designed the Mladinska knjiga printing house. It was one of the largest and most modern printing houses of its time, the modular, repetitive concrete construction representing its key architectural expression. The new owner decided to refurbish it in 2022. The biggest challenge was presented by the thermal insulation of the building. How to ensure modern climatic conditions in a building that was built with the reverse logic?