Summary form only given. The implementation of high quality solutions enables a significant reduction in the energy demand of historic buildings. But for monuments it has to be established, that all refurbishments are specifically targeted and adapted to the particular case. That's why the ongoing FP7 EU project “3ENCULT Efficient Energy for EU Cultural Heritage” recommends the collaboration within an experienced multidisciplinary team. The “3ENCULT Monument Information System” is based on the “Raumbuch” (room book), an inventory documentation tool, which is well established in heritage preservation praxis. It enables the structured documentation on urban and building level down to the single room. Thus users can “move” through the building on different levels of detail. The stocktaking with a “room book” not competes with other methods of acquisition, like a restoration survey, but it gives the possibility to involve the different information at one common platform. To support a constructive discussion across disciplines the heritage related information of the objects is cross-linked to energy issues. The user can compare the different options and finally select the best one for the specific building. The implementation of catalogues, e.g. for materials, construction elements or windows greatly facilitate and speed up the working process. The database was implemented as a web-based system. The technical demands for the 3ENCULT architecture were kept to a minimum. This innovative digital tool can be used for all energy retrofit cases of historic buildings. The comprehensive documentation of the as-it-is-state and all interventions is extended with a post-evaluation. The archiving of this information gives the possibility to reuse it in the future - for monitoring the building itself but also as a guideline for comparable constructions.