The existing residential building with four apartments stands under historical ensemble protection. The project consists of the renovation and extension of the building with the addition of a new apartment in the attic. As a measure to reduce energy losses the entire building was provided with an external thermal insu-lation system, the old windows were replaced, and the existing balconies aborted and replaced by new, thermally decoupled ones. The original pyramid hip roof was torn down, replaced with a gable roof and raised together with the outer walls by 1 meter, to get the headroom required for the new apartment. Due to cuts in the roof two spacious terraces were created. The entire loft apartment is naturally lit by large windows in the gable ends and ceiling height windows and sliding doors that open onto the terraces. Instead of the category "C" of ClimateHouse, required to get the additional architectural volume to build the apartment, the building reaches the classification "B" of ClimateHouse (equivalent to a build-ing’s heating energy consumption under 50 kilowatt-hours per square meter annually).