Located beside the spa park in the centre of Bad Dürkheim, Germany, the transformation of the Salinarium by 4a Architekten expands an existing leisure pool into a contemporary thermal spa and sauna complex. Rather than replacing the original facility, the project adopts a strategy of preservation and extension, using the existing building as the basis for a more energy-efficient and socially inclusive public wellness environment.
The intervention upgrades the spatial and environmental quality of the complex while maintaining continuity with the existing leisure pool and surrounding park landscape. Through carefully integrated additions, durable material systems, and energy-conscious building technologies, the project demonstrates how public recreational infrastructure can be renewed through transformation rather than demolition.
Extending the life of existing structures
A defining sustainability principle of the project is the decision to retain and develop the existing leisure pool rather than replace it. This approach conserves the embodied energy stored within the original structure, reduces demolition waste, and preserves a familiar civic environment within the city’s collective memory.
The new thermal spa and sauna areas are connected to the original complex through a reorganised circulation system beginning at a redesigned entrance marked by a broad cantilevered roof. A long transition corridor links the entrance with the quieter spa areas deeper within the site, gradually shifting the atmosphere from active recreation to relaxation. Existing facades at key junctions were refurbished and integrated into the new architectural language, allowing the distinction between old and new construction to remain legible.
Spatial organisation and passive environmental quality
The thermal spa is organised through a series of curved forms that create flowing spatial sequences and intuitive wayfinding. The extension spans three levels, combining bathing facilities, sauna areas, lounges, restaurants, and relaxation spaces that open towards outdoor terraces, gardens, and roof areas. These layered indoor-outdoor relationships create spatial variety while supporting natural daylight and visual connection to the surrounding parkland.
Generous floor-to-ceiling glazing allows daylight to reach deep into the interiors while supporting passive solar gain during colder periods. Outdoor spaces, including a sauna garden and roof terrace, extend the usable area without requiring additional enclosed floor space, contributing to a more resource-efficient spatial strategy.
Durable materials and long-term performance
The architectural language of the thermal spa differs from the more active leisure pool through the use of calm and restrained materials. Interiors are defined by timber slats, exposed concrete, porcelain stoneware, and ceramic finishes in muted tones chosen for durability, longevity, and ease of maintenance. The pools are also finished in grey ceramic tiling to reinforce a quieter atmosphere and reduce visual intensity.
The external cladding references the golden tones of matured Riesling wine, connecting the building to the cultural identity of the region. Continuous facade bands unify the extension while expressing the relationship between retained structures and new additions.
Energy systems and operational efficiency
The project incorporates an environmental strategy focused on reducing long-term operational demand. A high-performance building envelope with improved insulation and airtight detailing lowers heat loss compared with the original facility. Ventilation systems with heat recovery and demand-controlled operation improve efficiency while maintaining indoor comfort in humidity-intensive spa environments.
Additional systems, including pool covers, separate pool water circuits, process-water heat recovery, and central building management, further reduce energy and water consumption. Heat is supplied through district heating, providing a stable, low-emission energy source for the complex.
Renewable energy generation is integrated through photovoltaic panels positioned on facades and roofs, while extensive green roofs contribute to rainwater retention, microclimate improvement, and roof longevity. Together, these systems support operational efficiency and long-term performance.
