SPIE contributes to the transformation of the Star-Shaped Bastion at Château du Haut-Kœnigsbourg in Orschwiller, Bas-Rhin

Cergy, 16 December 2025 – SPIE Building Solutions, a French subsidiary of SPIE, the independent European leader in multi-technical services in the areas of energy and communications, is contributing to all the technical electrical facilities in the new areas of the Star-Shaped Bastion, the emblematic architectural feature of the Château du Haut-Kœnigsbourg. Headed up by the European Collectivity of Alsace, this project delivers technical expertise while ensuring compliance with the restrictions imposed by a listed historic monument.

Complex technical work to restore an historic monument

Dating back to the 12^th century, the Château du Haut-Kœnigsbourg is a tourist hotspot in the Alsace region, welcoming some 600,000 visitors every year. These high visitor numbers have helped the site undergo several restorations.

The current renovation of the château, together with the building of an extension, involves creating new commercial spaces to be completed in 2027. These include a restaurant, a kitchen, seminar rooms, offices and external toilets. The restaurant, which will have capacity for over 270 covers, will considerably increase the attractivity of the site, enhancing what is currently on offer.

The teams from SPIE Building Solutions, who were selected following a call for tenders in late 2024, will be involved in all the technical electrical facilities. This work includes the installation of high- and low-voltage networks and the establishment of a security and communications system within the building. The technical building management system (BMS) will be fully modernised to optimise the site’s automation systems, while centralised technical management (CTM) will be set up for real-time monitoring of consumption and optimisation of usage patterns.

SPIE Building Solutions has made use of various low-consumption materials to meet the challenges of the site’s energy transition, including LED lighting, low-temperature electric underfloor heating with room-specific control, heating devices with KNX-standard thermostats for accurate control in line with the actual usage of the rooms, and electrical switchboards with an energy optimiser.

Once complete, these facilities will enable one of the most visited tourist sites in Grand Est to benefit from state-of-the art installations, bringing together automation systems, efficient electrical installations and optimised management of electricity consumption.

Heritage status means unique restrictions

This project site, characterised by the technical restrictions associated with the special nature of working on such a unique site, benefits from the proximity of the SPIE teams from Colmar and Holtzheim and their experience in restoring listed historic buildings. Each intervention is subject to prior approval from the Regional Directorate of Cultural Affairs (DRAC) and the official state heritage architect (Architecte des Bâtiments de France) with responsibility for the project.

The layout requires specific technical resources supervised by a team of archaeologists as the Château du Haut-Kœnigsbourg, and by extension the Star-Shaped Bastion, were built on a rocky outcrop. This complicates the interventions, while the proximity of the castle wall makes access to the project site difficult. As a result, the use of shared, adapted lifting apparatus was required to position the equipment and ensure the safety of the teams during the delicate handling stages.

The work, which began in early 2025, will continue until 2027 and the Château du Haut-Kœnigsbourg will remain open while work is ongoing.

“Working on a monument as emblematic as the Château du Haut-Kœnigsbourg is a source of particular pride for our teams. Our regional proximity has allowed us to develop recognised expertise in heritage conservation. The renovation of the Star-Shaped Bastion perfectly illustrates our ability to rise to even the most complex of technical challenges, while demonstrating how modernity can be harmoniously married with heritage preservation,” says Sébastien Diebolt, Business Administrator at SPIE Building Solutions.