K59 is a gentle renovation with a roof extension of a Wilhelminian building in Stuttgart. The gable roof, provisionally rebuilt in the 1950s, makes way for a sustainable roof extension consisting of a timber construction, recycled cellulose insulation and a copper skin applied without adhesive composites in the sense of cradle-to-cradle. A CHP unit was installed to generate heat and energy, which serves the inhouse e-charging stations and feeds the surplus electricity into the city's power grid.
The provisional gable roof rebuilt in post-war 1950s as an empty shell on top of a historic building, makes way for K59 - a copper roof extension in the spirit of cradle-to-cradle.
The aim was to show that building with existing constructions is an alternative to demolishing and re-constructing a new building. The project was intended to demonstrate that roof extensions in the sense of inner-city redensification offer great potential in the fight against ever-increasing land sealing and the resulting lack of space.
Likewise, by renovating the rest of the building, a lot of grey energy could be dispensed, and a part of Stuttgart's historical architecture could be preserved and reconsidered. Due to this subtle refurbishment, it was possible to avoid an ecologically questionable composite thermal insulation system and, at the same time, to create added value for the surroundings and the Stuttgart hillside view by preserving the sandstone façade and adding a copper-clad roof that blends into the ensemble of buildings on the hillside over the course of time and the ever-changing colours of the patina.
The traditional craftsmanship is carried out under the aspect of durability and circularity. A wooden construction with recycled cellulose insulation forms the framework for the back-ventilated and rebated copper skin without adhesive composites, which absorbs movements even in changing climatic conditions and forms a dismountable roof structure in its individual parts in the sense of cradle-to-cradle. With the installation of a biogas CHP for the own electricity and heat generation as well as the inhouse e-charging stations, it was possible to ensure a sustainable use of the material and soil resources.
The reinterpretation of the roof as a fifth façade with a contemporary design language as well as the sustainable compensation measures for the building technology give the almost 130-year-old building with a sandstone façade a sustainable and future-proof identity.
Please highlight how the project can be exemplary in this context
One of the key objectives is to take already existing buildings into account to use grey energy inherent in materials and structures.
Furthermore, the reduction of land sealing is achieved by an inner-city redensification through an additional storey activation. This intervention allows short distances to existing local amenities, culture, and public transport due to a careful search for potential spaces.
Sustainable construction methods contain the focus on durability in traditional local and regional craftmanship. These are constructions that have proven themselves many times and therefore have been applied for many decades. It is the task of planners to bring these traditional crafts and skills in line with modern regulations and ordinances.
A precise selection of construction materials such as timber from regional forest, recycled cellulose insulation for a rear-ventilated cold roof and a handcrafted copper cladding are extremely durable and can be adapted to almost any geometric form. By avoiding adhesive composites recyclability was guaranteed and the structure can absorb movements in changing climate conditions.
A combined heat and power plant plays a significant role in the building technology - its operation is used for heating. The electricity produced inhouse is available for the entire house and e-charging stations for future-oriented mobility needs. Surplus electricity is fed into the local power grid for other city residents.
The focus was particularly on simple assembly, the reduction of life cycle costs and deconstructability at the end of the life cycle. All materials used for the roof extension can be reused and recycled to decrease linear economies. Adhesive connections were replaced by smart and technically handcrafted, thus detachable joints so that the individual parts can be reused or recycled cradle-to-cradle without affecting the building’s main structure and grey energies.
Please highlight how the project can be exemplary in this context
Building with the existing includes the maintenance of idiosyncrasies and outer characteristics of the building in its surrounding. The preserved sandstone façade was integrated into the new concept with regard to the slope view. The roof structure is the result of a search for forms that explores the historical context in consultation with the city planning department and the limits of today's building regulations, as well as formulating the "fifth façade" for the eye. The roof form represents a reminiscence of the lost history in the surrounding. A key objective was to generate legibility of the building in terms of age. Visible from far across the Stuttgart valley, the copper-clad roof will change colour over time, acquire an ever-changing patina and blend into the ensemble of buildings on the hillside.
K59 is based in the threshold between Stuttgart city and nature what is likewise visible in the interior. The front façade with a terrace faces the city centre, opera and railway station while an additional terrace on the back has a view into idyllic garden greenery. Different room qualities generate versatile spatial experiences and conditions rich in variety. This is reached by various room heights from 3.2 to 4.5 metres that create an airy living feeling. In addition to those, different pitches of the roof and light conditions from sidelight to skylights were designed.
Working with existing structures has a great potential for strong identity-establishing aesthetics for both residents in K59 and the surrounding. Small and additive interventions give the possibility to concentrate on unique and subtle details and construction methods. Qualities of experience change through time within K59 and show an ongoing traditional development searching for contemporary additions.
Please highlight how the project can be exemplary in this context
When building with the existing the outer appearance of K59 was mainly set by including the historic context. The subtle roof extension, however, was carried out in close cooperation with local craftsmen.
Nevertheless, K59 maintains a universal design including working and dwelling spaces in multi-functional floor plans. The term cradle-to-cradle can therefore not only be mentioned in terms of materials but also in terms of function. The 170 square meter roof extension contains the possibility of a single residential or office unit or subdivision into several independent units. For that reason, it adapts to different kinds of needs such as dwelling for families, shared flats, and co-working spaces.
Accessibility is constituted by a barrier-free access into the building and a lift that has been installed over seven floors. In addition to that K59 is situated close to local amenities, culture, and public transport to reduce dependence on others.
The flexible floor plan allows people to configure an appropriate floor plan. The roof elevation is currently used as a shared flat.
K59 can be exemplary in this context because it deals not only with the cradle-to-cradle approach in terms of sustainability but also in terms of adaptability for different needs.
Please highlight how this approach can be exemplary
Very often aspects such as sustainability, spatial qualities and social compatibility are paradoxically divided into different categories and in consequence of this phenomena these categories are thought, developed, and implemented separately. K59, however, is conceived, developed, and implemented holistically. Individual construction measures combine the most diverse aspects into a strongly networked and cross-aspect building. Working with existing structures does not only turn out to be a necessary construction method in regard of sustainability, but also proves to be a recognisable and familiar place for both house and city residents. These aspects, however, are created solely through constructional interventions influenced by architects and planners.
The approach is necessary for holistic thinking or system thinking. Rather than thinking analytically or in specifics, one can see patterns and concepts that umbrella details. Interconnectedness is therefore representing a more extensive system of occurrence in each building project.
K59 is a great example how sustainable, aesthetic, and social dimensions lead to a holistic concept and a resulting building as a crucial local impact to face global challenges.
K59 does shape a circular industrial ecosystem and support life-cycle thinking in a variety of aspects such as sustainability, architectonical and spatial strength and social conditions by highlighting the concept of cradle-to-cradle.
In the K59 project, one cannot exclusively see the appearance of a building over the course of an intervention and roof extension. Even existing and unrenovated buildings influence the way the substance will be treated. The almost 130-year-old building after renovating and extending still offers the possibility of being able to deal with different effects in the sense of further development and conversion. It is not seen as a linear product, but rather as a concept to be adopted in the future.
The focus in this project was particularly on simple assembly, the reduction of life cycle costs and deconstructability at the end of the life cycle. All materials (copper, cellulose, wood, glass, steel) used for the roof extension can be reused and recycled to decrease linear economies. The value chains of the materials are traceable.
Adhesive connections were replaced by reliable and technically handcrafted, thus detachable joints so that the individual parts can be reused or recycled cradle-to-cradle without affecting the building’s main structure and grey energies. K59 has the potential to be treated as an example showing how holistic and transdisciplinary approaches are developed and implemented. Sustainability has not only to do with a lifespan of materials but also with durability and future adaptability. The floor plans are flexible dependant on residents needs and other changes, as well as resources yet available.
Please also explain the benefits that derived from their involvement.
This project involves the preservation and subsequent careful renovation of a historic and existing building structure. Stuttgart citizens long for places that create identity and therefore support the preservation of buildings that are historically significant. However, after the second world war there are not yet many characterising structures left. For this reason, the task was rather to establish a discourse with the planning departments at administrative levels. In coordination with various disciplines within the administrative apparatus, it was finally possible to find a way to preserve the building. Herby the building is steeped in history, and it is an example for many buildings which can be treated as K59 by adding a contemporary element for the sustainable future yet to come.
Architecture has an influence on several of the many global challenges and can therefore make a major contribution. We are aware of this responsibility and want to provide a local contribution to global problems with our approach.
The project addresses sustainable development and climate change and the related question how sustainable development can be achieved for all people while addressing global climate change to the discipline of architecture. Fortunately, there is fundings by major governmental and financial institutions to invest and implement technological solutions such as a decentral combined heat and power station (CHP). Another way to face the climate change is by reducing carbon capture by reusing and working with existing materials and structures in K59. The reduction of energy per unit of GDP is therefore achieved.
Further the challenge of population and resources is challenged. The UN Urban Agenda is implemented into the design process to bring population and resources into balance.
The above-mentioned CHP faces the challenge of growing energy demands by designing K59 as a building producing more electricity than needed and to lead for energy conservation and efficiencies – e.g., surplus electricity is fed into the power grid for other city residents.
Science and Technology is another challenge that links research agendas to human needs and threats. K59 explores ways to limit destructive purposes and to decline linear economies.
The innovative aspect in K59 in comparison to mainstream practices is to recognise innovation not exclusively as a technology-driven part but to have a holistic approach to achieve sustainability. Innovation is therefore a process that involves multiple activities to uncover new ways to face challenges. K59 has the approach of a further development of existing structures to preserve grey energies and in the sense of cradle-to-cradle extend existing structures while implementing proven technologies for new demands to come.
New construction of working and living space is particularly necessary in growing cities like Stuttgart, where the supply of living space must be increased. Technical or social developments that fundamentally change the requirements for residential real estate are also often associated with increased new construction activities, accompanied in this case by demolitions of existing buildings.
For us, the future of construction is inherent to work with the existing fabric of cities.
The original assumption is questionable: Is demolition followed by "sustainable" new construction always more economical and environmentally friendly? In 90% of the buildings, it is worthwhile to repair and find alternative solutions.
Working with existing buildings also requires working with local craftspeople with local knowledge and the ability to adopt to and repair the future past. This will reduce large scale mobility und will maintain local identities through the reduction of prefabricated elements form different sources. The preservation of regional craft execution deserves further attention. In this context, a durable authenticity of buildings and cities is manifested – beside the significance of historic structures. K59 stands out from other projects in its innovative approach in terms of the integration of existing structures, the sensitive approach, and the structural intervention through local craftmanship.
Please provide clear documentation, communication of methodology and principles in this context.
K59 shows great potential for both architects and building owners to face global challenges on a local scale by thinking, designing and building with the existing and local craftspeople. This approach does not only have climatical advantages, but also social, aesthetic, and economic benefits.
Transferring K59 results into other contexts does not mean to copy and paste. Results may appear completely different dependant on the encountered material, social aspects and surrounding. It is always a strong analysis and renegotiation of the existing and subtle contemporary adding.
The strategy is to find potential buildings and to make an inventory of the existing building and its components: architectural-constructive issues, static-constructive issues, waterproofing issues, energy issues, noise issues, hazardous materials remediation, and others. A further step is then to build in the existing building inventory.
This strategy and approach of cross-scale and cross-disciplinary are capable to be transferred to different scales of building projects but can also be applied to other disciplines and show an immense impact on sustainability, quality of experience and inclusion.
Within the project of K59 we consider ourselves as a planning manufactory that works between contemporary action and respect for tradition. We see the individuality of each project and each client as the motivation for our architectural exploration with a wide range of scales and disciplines.
In this context we always try to continue the adventure of architecture and city together with innovative ideas. An architecture suitable for everyday use between invention and memory, between art and science, between contemporary action and genuine respect for tradition is created in our planning manufactory for the cultural resource of local craftsmanship and depicts an architecture of the target state and pragmatic beauty, which escapes the material- and area-greedy "normal building" and can age gracefully.
@STUDIO CROSS SCALE, 2020
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