Heavy Rotation - The Recurring in Architecture

In loose succession, we publish here contributions from the discourse section of the current yearbook of the department. In it, members of the department address the significance of cyclical processes in architecture.

von Felix Heisel, Karsten Schlesier und Prof. Dirk E. Hebel

About reusing and recycling
The Mehr.WERT.Pavilion at the Federal Horticultural Show (BUGA) 2019

by Felix Heisel, Karsten Schlesier and Prof. Dirk E. Hebel

The recurring has determined the emergence and discourse of architecture in all its facets, scales and speeds since then. Since industrialization, however, important of these natural cycles have been lost or abandoned in favor of a linear economic understanding. With the research of closed material cycles and (re)construction technologies, as well as the search for new business models of the circular economy, the KIT Department of Sustainable Construction questions in particular the materials and construction methods of today's building industry. The hypothesis is: all resources required for the production of a building must be completely reusable, recyclable or compostable.

At the Federal Horticultural Show 2019 in Heilbronn, the department succeeded in realizing a prototypology that consistently puts into practice the theoretical claim - materials used are not consumed and subsequently disposed of, but rather borrowed from their technical or biological cycle for a certain time and later returned to it. The design was developed by KIT students in the course of the design semester Building from Waste in the winter semester 2017/18. Lisa Krämer, Simon Sommer, Sophie Welter, Katna Wiese and Philipp Staab then took over the elaboration of the design for the building project in close cooperation with the departments of Building Technology Prof. Dr. Rosemarie Wagner (static form finding) and Load-bearing Structures Prof. Matthias Pfeifer (test statics).

The Federal Horticultural Show Heilbronn 2019 is for the first time a garden and city exhibition at the same time and poses the question of resources that will still be available and sustainably used in the future. In the light of dramatically diminishing natural resources, it is no longer a question of improving the status quo, it is a question of a paradigm shift in the construction industry in order to be able to satisfy the future demand for building materials at all.

The Mehr.WERT.Pavillon project demonstrates an innovative and sensible use of existing resources. All materials used in the project have already gone through at least one life cycle, either in the same or in a different form. Likewise, all materials are used in a single-sort process and are completely separable after dismantling. No adhesives, silicone joints, paints or other impregnations are used in the project. Thus, on the one hand, the project makes use of the existing urban mine, but at the same time it represents a storehouse of materials, the resources of which will be completely available again after the Federal Horticultural Show.

Conceptually, the project is based on material layering: the supporting structure is made entirely of steel, most of which comes from a dismantled coal-fired power plant in North Rhine-Westphalia. The façade features recycled glass materials from the glass container, such as glass ceramics or foam glass. The ground surfaces in the garden and under the pavilion are covered with mineral building demolition materials, which come directly or in processed form from recycling yards. Examples include broken clinker and porcelain, but also StoneCycling bricks, which are produced directly from construction waste by a young start-up in the Netherlands. Furniture and fixtures are made from recycled plastic materials. Here you can find 3D-printed chairs made from household waste or a worktop made from former kitchen cutting boards.

Materials used in construction are subject to numerous national standards and regulations. When used in load-bearing elements, however, the requirements are particularly high. Approval of a material for a structural load-bearing application requires strict quality assurance during production. It also requires a comprehensive study of its mechanical and physical properties, as well as knowledge of its behaviour under different loading situations and climatic conditions. Recycling of steel scrap has long been established without stimulation or subsidy due to economic incentives. The recycling rate is 88%. Direct reuse of structural steel, on the other hand, is currently practiced only to a small extent, with a reuse rate of 11 %. In addition to careful dismantling from existing buildings, knowledge of the material quality (classification) and previous use is required here. It is necessary to determine what defects and damage are present in the dismantled element after use.
The steel structure of the pavilion consists largely of steel pipes dismantled from a decommissioned power station. In addition to a close visual inspection to determine possible damage to the elements, the steel was examined for various properties. Tests for tensile strength, elasticity, impact strength and chemical composition made it possible to make the necessary statements about the material quality. In the end, the steel quality proved to be equivalent to that of a standard structural steel (S235), which allowed the direct reuse of the elements in a new construction.

The use of glass in structural applications is regulated in Germany by national standards (DIN 18008, Glass in Construction). However, the standards only apply to the use of certain glass products approved for this purpose. However, the panes of recycled glass used for the Mehr.WERT.Pavillon do not fall within the scope of the standard. For this reason, it was essential to apply for so-called approval in individual cases for use in the building project. The approval was based on the specifications of the existing glass standard; likewise, the static proof was provided in accordance with the design philosophy of the standard. The limit stresses determined by standardised tests carried out by independent, accredited testing laboratories provided the basic data for the design stresses. In accordance with the glass standard, an additional mechanical protection measure was applied by means of a close-meshed steel net underneath the linear mounted glass panes of the roof. Furthermore, the manufacturer was obliged to issue a declaration of conformity for the quality control of the production through standardized mechanical tests.

The Mehr.WERT.Pavilion proves the applicability of reused and recycled materials also in structural applications. However, the process of designing and building in the circular economy currently has many administrative, financial, legal, and physiological hurdles that need to be addressed quickly to enable a paradigm shift. Common barriers to reuse and recycling include a lack of confidence in the quality of recycled materials, a lack of documentation on material composition and history, a mismatch between supply and demand (both in terms of quality and quantity), inadequate timing of audits and deconstruction work, a lack of facilities and expertise, and the often low value of products in high volumes.

The Mehr.WERT.Pavilion is therefore not only a storehouse of materials, but also a public demonstrator intended to serve as a model and inspiration for other construction projects. It can be shown that we are already capable of operating in closed cycles in the construction industry today, if certain framework conditions were better regulated. The aim is to discuss important issues of construction and the associated use of resources with decision-makers from politics, construction planning and implementation, and to develop new innovative concepts, applications and methods from this, both in practice and in teaching.


A Recycled broken and bottled glass, Reused scrap steel, Recycled plastic waste, Reused and recycled mineral building rubble
B The Mehr.WERT.Pavilion at the Federal Horticultural Show 2019 in Heilbronn, Germany
C D Detailed views (recycled steel, recycled glass)


Zooey Braun

Project sponsor:

Waste Management Services of the City of Heilbronn, Ministry for the Environment, Climate and Energy Management Baden-Württemberg, Bundesgartenschau Heilbronn 2019 GmbH.

Project participants:

Design: Lisa Krämer, Simon Sommer, Sophie Welter, Katna Wiese, Philipp Staab, Department of Sustainable Construction (KIT).
Planning, structural analysis and execution: 2hs Architekten und Ingenieur PartGmbB: Dirk E. Hebel, Felix Heisel, Karsten Schlesier, Lisa Krämer, Simon Sommer
Structural design: Prof. Dr. Rosemarie Wagner, Department of Building Technology (KIT)
Laboratory Research Group West University: Arnold Mager
Test engineer: Prof. Matthias Pfeifer, Karlsruhe
Building construction: AMF Theaterbauten GmbH
Electrical and lighting design: Udo Rehm/FC-Planung GmbH
Lightning protection: Gebr. A. & F. Hinderthür GmbH
Electrical installation: Elektro-Scheu GmbH
Furniture construction: Kaufmann Zimmerei und Tischlerei GmbH
Landscape architecture: Frank Roser, landscape architects PartGmbB
Landscaping: GrünRaum GmbH
Exhibition concept: Idee-n Büro für nachhaltige Kommunikation


GreenCycle GmbH,
Der Grüne Punkt - Duales System Deutschland GmbH (DSD),