As part of the Replacement of Heat Water Exchangers at Units 1 and 2, the heat exchanger station building was digitized and a BIM model was created. This model was created already during the geodetic surveying of the existing load-bearing structure and was gradually supplemented with the necessary machine technologies. It has become an invaluable helper already in the design of spatial layouts, when it was possible to check all alternatives for handling, operation and installation of the equipment still before the start of the design phases. The BIM model has gradually grown into a comprehensive information model, where, in addition to the position and shape of individual machine technologies, piping distributions or other equipment, important data can be read regarding various descriptions, KKS markings and other technical information according to the customer's specific assignment and wishes. The BIM model was also very useful during implementation, where it saved assembly time, especially during the unit shutdown.