The project aims to convert an industrial building into an office building. We propose a simple and economical solution to adapt the factory’s spaces to new uses, while highlighting the architectural principles that led to the original construction. The intervention focuses on the facades. Large windows, originally intended for industrial activities, are subdivided to facilitate the partitioning of interior spaces. By subdividing the existing constructive frame, the new windows give the building its office building status. The windows are subdivided with vertical mullions. They are equipped with white aluminum chassis to increase the coefficient of natural light in the office spaces and prevent from thermal bridges. Positioned in the upper part of the window, aluminium sunshades protects the occupants from too much direct lighting and optimizes the working atmosphere.