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Circular construction is the sustainable circular economy in the construction industry that enables a careful use of resources. Whether recycling bricks, window glass or steel: the “cradle-to-cradle” future trend requires digital solutions.
The age of the linear building culture is over. The future demands circular construction. The idea behind this is to imagine the building as a material store and to understand the building of the future as a continuous cycle of recyclable materials in terms of cradle to cradle. The implementation of a circular economy in construction requires numerous digital technologies and new planning methods, from material databases, BIM, and the digital twin to digital construction sites. digitalBAU 2024 will showcase the many options for circular construction.
On August 2, 2023, the Earth’s natural resources account was at zero. Since then, the whole world has been living “on credit” – and we continue to work with rare earths, sand, ores, and other materials that the Earth cannot provide as abundantly as we consume them at an accelerated pace. For the past 50 years, Earth Overshoot Day – the day on which the Earth’s annual quota of renewable resources is used up – has been moving ever closer as the year went on.
As one of the largest consumers of raw materials, the construction industry bears great responsibility. In Germany alone, it processes more than 70 percent of all raw materials mined in this country, according to the Federal Environment Agency (source). The picture is similar across the EU: in 2020, this resource-intensive economic sector accounted for 37 percent of EU-wide steel demand (source), and sand is now the most widely used raw material in the world – used mainly in construction (source). Like construction sand, aluminum, iron ore and gypsum are also becoming increasingly scarce.
Against this background, circular construction is becoming more and more significant: in view of the continuing growth in demand, it is increasingly important to conserve existing resources and recycle building products and raw materials. Unlike the linear construction method used in the past, materials are to be recycled rather than disposed of at the end of the structure's life. Considering the Earth’s limited resources and the effects of climate change, a circular economy in the construction industry is really the only feasible option that is left for us.
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The way out of this dilemma therefore relies primarily on circular construction, also known as cradle to cradle. But what exactly does this mean?
Circular construction could be described as a continuous closed-loop principle. Biodegradable consumer goods are returned to the natural raw material cycle. After their use, technical consumer goods should be broken down into unmixed starting materials and returned to the technical cycle. The aim is to maintain the quality of the chemically safe materials so that no more waste is produced.
If this principle is applied to the existing building stock in terms of circular construction, it becomes a valuable material store or raw material inventory. Every piece of wood, every window, every screw and every door represents a materially and financially significant item that is to be rebuilt and reused or recycled after the end of its initial use in terms of urban mining.
In addition to recycling, circular construction relies in particular on urban mining, the specific recovery of construction resources from urban waste materials. Consistent registration, use and optimization of existing materials in the construction industry is sustainable and conserves resources. Recyclable materials are thus used intensively and in closed cycles in the long term. Pilot projects like the city of Heidelberg are setting a good example.
In addition, circular construction takes environmental and health aspects into account and consciously relies on durable products. Recycled materials are either directly installed in a new building – for example, in a new facade or a new roof. Alternatively, goods are refurbished and modified to such an extent that they can be assigned to the new task.
In this way, complete buildings can be constructed with second-hand components from smart recycling. Examples of circular architecture with existing materials are the recycling house in Hannover and the recycling extension in Kelsterbach. Sustainable construction is guaranteed with solutions such as this.
In addition to carefully dismantling and separating the different building products, circular construction is based on a modular principle. This is the case, for example, with modular or serial construction. This means that the building is no longer constructed completely on site. Instead, elements or complete modules are prefabricated in a factory and assembled at the construction site.
The spectrum ranges from serially produced exterior walls to fully equipped bathroom modules delivered “on site”. Even a whole house, including ceilings, roof and facade, can be made of prefabricated modules. An example of this is a modular housing complex for hospital employees in Esslingen.
In addition to sustainable materials and advanced constructional engineering, a circular economy in construction also requires digital solutions for planning and materials management. Digital platforms and automated tools facilitate resource-efficient and circular construction by enabling all parties involved to design the construction process transparently from the planning stage through to the turnkey building. These solutions enable raw materials and products to be labeled and traced, for example, and processes to be documented. This also includes management of important data such as construction details and building materials used – for consistent and transparent planning and construction site processes.
In order to evaluate product sustainability and consider environmentally relevant aspects in the context of circular construction, materials and products must be categorized. Relevant data includes, for example, technical information, details of the respective life cycle modules, environmental parameters and, where applicable, test results. Environmental Product Declarations (EPDs) are “fact sheets” for assessing product sustainability. The exact evaluation of the construction product must be carried out within the framework of a holistic life cycle analysis. The PCDS (Product Circularity Data Sheet) provides reliable data about circular product properties.
Comprehensive documentation is a basic requirement for a circular economy in the construction sector. The material data obtained in a continuous digital planning process can be collected in material or building passports, which are stored virtually on material platforms such as madaster.de, in the Digital Building Resource Passport of concular.de or the DGNB Building Resource Passport.
Planners and real estate or construction companies use it to virtually record the materials and products that are processed in a building – whether new or existing – and thus virtually pay the monetary value of the beams, doors and windows into a material account. By linking a material and product database developed by EPEA with the Madaster platform it is also possible to calculate CO2 emissions and the recyclability of buildings. Information on material origin and recycling is already stored in the data record.
Once the building in question has been dismantled, the materials can be recycled or returned to the material cycle in accordance with the cradle-to-cradle principle. Considering the finite resources of our planet, these materials can then be used to reduce the CO2 footprint or – in view of rising material costs – can even result in a financial benefit from their renewed use.
Circular construction and the associated circular economy of the construction industry will become an all-round success when digital planning and documentation go hand in hand with digitally controlled manufacturing and production. Geometric data, materials and product properties generated with BIM and 3D planning can be stored in the building model and be supplemented and adjusted during the tendering process and during construction. This creates a transparent building model that maps all the resources tied up in the building.
As an “as built” model, it allows the data to be reused for the operation of the building so that this can be carried out in a resource-saving and sustainable manner – until the end of the life cycle, when it is time to dismantle and recycle the building. Then the cycle starts all over again.
digitalBAU 2024 will showcase the wealth of digital tools and services related to the possibilities of circular architecture and circular construction in detail in numerous presentations, various discussion panels and at the booths of highly specialized exhibitors.
Among other things, the focus is on contemporary planning methods such as BIM, which can be used to create digital and reliable building models, the “digital twins”. By using digital planning, coordination and execution tools, sources of error can be identified and eliminated in advance of construction, and the quality of planning and execution can be increased considerably. Material and raw material consumption or the consumption of building products can be further optimized in this way.
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