Introduction
Nestled in the heart of Stuttgart's city center, the Calwer Passage introduces lush greenery into the cityscape while preserving heritage-listed building sections. The greening of façades and rooftops establishes a high-quality urban space with a natural, healthy climate, providing an architectural answer to the climate change challenges. The rich diversity of species generates a vibrant and ever-changing appearance.
Architecturally distinctive, this pioneering project significantly enhances the resilience and appeal of the city.
Project Description
The redesign of the Calwer Passage involves the replacement of a 1970s building's upper volume with a new, lushly greened structure, while partially preserving the existing lower levels. The new development's elongated silhouette stands approximately 27 meters tall and spans over 133 meters. It comprises six floors above ground with residential units and office spaces, a blend of retail and small restaurants at street level, while the basement levels serve as an integral component of the Stadtmitte S-Bahn underground station.
The façades are densely adorned with climbing and hanging plants, following a finely balanced system. The selection of plants aligns with the concept of a façade-integrated system featuring year-round active vegetation. The greenery is accommodated in containers along windowsills, forming evolving bands around the building. Steel cables and nets stretched between the floors serve as climbing aids: some plants cascading from the vessels, others reaching upwards in a rich and diversified vegetation arrangement. The multifaceted green façade features alternating densities – moderate in front of the office windows to allow for optimal incident light without obstruction, intensifying in front of the stairwells.
An expansive hillside landscape with shrubs and herb meadows crowns the rooftop. A striking aspect and notable feature are nearly 40 large trees strategically planted on and around the building - a small mixed forest shaping a distinctive contour, visible from afar.
The abundance of vegetative elements contributes to a dynamic and constantly evolving visual allure. Diverse foliage, various fruit arrangements, and a range of flower shapes and colors offer year-round variety in both forms and hues. The natural cycle of seasons further enhances this vibrant atmosphere.
Impact
The greened envelope is an essential design element of the Calwer Passage. Following a comprehensive phytotechnological concept, this fusion of nature with architecture presents a modern urban solution to address climate change. Acting as energy converters, its green surfaces maintain a cooler temperature than the surroundings, mitigating the urban heat effect while shielding against summer sun rays, enhancing overall well-being. They also serve as crucial contributors to the city's microclimate by sequestering carbon dioxide, minimizing dust and noise, fostering biodiversity, facilitating rainwater retention, closing the gap in the water cycle and naturally preventing an overload of the public sewerage system.
The Calwer Passage's refurbishment sparks vital discussions about the significance of urban greenery, emphasizing its invaluable role in city landscapes. This innovative project challenges conventional urban developments, introducing vibrant, living greenery into an otherwise rigid and dull mineral environment. It serves as a testament to the importance of bold initiatives in advancing architectural culture and sustaining meaningful discourse in urban planning.
Background
The inauguration of one Germany's most advanced shopping center in 1970 aligned with the comprehensive transformation of the Calwer Street into a pedestrian zone. The green transformation upholds the original vision of urban rejuvenation, advancing the evolution of downtown revitalization. Maintaining its structural heritage, the Calwer Passage continues to offer place for around 20 independent boutiques and owner-managed stores, fostering opportunities for local businesses in the heart of the city, otherwise dominated by large high-street retail chains.
