Reorganizing Construction with 3D Printing

 Combining Offsite, Onsite And Nearsite Manufacturing In Construction  

  

 

The current mix of onsite construction and offsite manufacturing has become a well-

developed and efficient system of production, but the level of efficiency and productivity achievable is limited by the lack of significant economies of scale in a project-based industry. With 3D printing and digital fabrication this is no longer the case, and a new off/on/nearsite production mix that combines offsite mass production with onsite and nearsite manufacturing is possible. This introduces a new option in the organization of construction.

 

Can the industry greatly increase the share of components manufactured onsite or nearby, and do so while reducing embodied carbon and increasing choice and quality for clients? Could a significant share of components be manufactured onsite or nearby, using automated machinery to provide just-in-time delivery of structural elements as well as fixtures and fittings?

 

 

The Current System Combines Onsite Work and Offsite Manufacturing

 

Onsite construction is a project-based activity to deliver a specific building or structure in a specific location. It is a dense, highly regulated network of industries, utilising standardized materials and components to deliver buildings and structures using well understood processes. The system may not be elegant, but it is flexible, sophisticated and resilient, and coordinates many firms in a widely distributed value chain. Because this is an efficient system, any new technology will have to perform extremely well to have any significant effect on an industry as large and diverse as construction.

 

Mass production of standardized products justifies the capital investment in plant required for products where market demand is well known and stable, unlike the highly variable demand for buildings which rises and falls with the business cycle. However, while there are factory made structures and components, the number of standard buildings is limited and onsite production is organized around standard parts and materials. Manufacturing, in contrast, is organized around standardized products and continuous production runs. 

 

The current system is therefore an efficient mix of onsite work and offsite production of prefabricated and manufactured components, with the combination varying depending on the type of project and location. The alternative that has been attempted many times with varying degrees of success is to replace onsite work with assemblies like panels, pods and modules that are manufactured offsite. However, the economies of scale of offsite manufacturing (OSM) are counterbalanced by the significant capital and transport costs involved, and OSM is not yet a viable alternative for many projects, at a time when improving the productivity of construction is a crucial element in addressing current issues in delivering housing and the energy transition. 

 

Is there another alternative to OSM? What would a different way of organizing construction look like? What would be the effect of increasing the amount of work done onsite by manufacturing more, or most, of the structure and components on or around the construction site? How can that be done? 

 

 

Onsite and Nearsite Manufacturing with Digital Fabrication

 

Over the last decade digital tools such as building information modelling (BIM), digital twins and design for manufacture and assembly (DfMA) have become widely, although not universally, used in construction. While these have been applied to OSM, they have not solved the fundamental problems of limited economies of scale and large capital requirements. However, instead of reducing the amount of onsite work, these tools can be used to produce many of the components of a building anywhere, using new production technologies based on digital fabrication. 

 

Digital fabrication turns design information into physical products using automated processes, providing the cutters, printers, millers, moulders, scanners and computers needed for designing, producing and reproducing objects. The tools include traditional subtractive ones for cutting, grinding or milling, but the focus has been on research into new methods of additive manufacturing using different methods of layering materials using 3D printers. The information needed to create a 3D blueprint is generated during design, and it is a relatively small step to move from a digital model to instructions for a 3D printer. Printing of metal, ceramic and plastic objects from online design databases in fabrication laboratories (fabs) has found industrial applications.

 

There are three methods for 3D printing: stereolithography, patented in 1986: fused deposition modelling, patented in 1989: and selective laser sintering, patented in 1992. It didn’t take long before research into 3D concrete printing (3DCP) began, focused on developing the equipment needed and the performance of the materials used. By 2022 the commercialisation of 3DCP was underway, with two types of systems available. One using a robotic arm to move the print head over a small area, intended to produce structural elements and precast components, the other a gantry system for printing large components, walls and structures. In November 2023 the Additive Manufacturing Marketplace has 44 concrete printing machines listed, ranging from desktop printers to large track mounted gantry systems that can print three or four story buildings.

 

Figure 1. Concrete printers

 

Clockwise from top left: COBOD, Cybe, Luyten, Kamp, Black Buffalo

 

Once a BIM model of a project has been created it can be used to provide instructions for production of both the structural elements and other components of a building. When a concrete printer is used to build the walls it is an example of onsite production, but 3DCP can be used to make stairs, columns or other elements onsite as well. Producing components onsite from bags of mixture avoids the cost of handling and transport, and for large items avoids the load limits on roads and trucks. However, site space and access is often restricted, so setting up a fab nearby would still take advantage of the lower transport costs of bulk materials and a shorter distance for delivery while maintaining control over the production process. That is nearsite production. Local suppliers offering manufacturing on demand with print farms (factories with many machines) and many different printers that can produce large runs and specialised components is a nearsite form of production rather than OSM. 

 

The potential of 3D printing in construction is not limited to concrete. The Additive Manufacturing Marketplace had 1,852 printers listed, and many of those printers could be used to produce fixtures and fittings for buildings. Suppliers offering manufacturing on demand with print farms for local production of building components might include the established manufacturers with specialized fabs producing metal, plastic and ceramic finishes, fixtures and fittings. A modular fab in a container customised for construction, or even a specific construction project, can be set up onsite to produce components as the schedule requires. Larger sites might need a fleet of fabs. Restorations and repairs can be done with replacement parts made onsite from scans of the original.

 

This does not suggest the end of mass production of all standardized components, economies of scale are the economic equivalent of gravity, but onsite and nearsite manufacturing using digital fabrication does not have to achieve the same economies of scale needed for mass production. The price of a mass-produced item includes its packing, storage, transport and delivery, costs that local just-in-time production avoids while providing more control over the supply chain. Then there are the potential economies of scope from integrated design-production-installation processes, which could be provided through platforms developed by companies like PT Blink and Project Frog, or the UK Product Platform. 

 

The view here is that, over the next decades, the diffusion and spread of new production technologies will deeply affect how construction delivers buildings and structures. The options available between onsite, nearsite and offsite production will broaden considerably as 3D printing and digital fabrication capabilities increase, and the choice will be determined by the economies of scale and installed cost of local versus offsite manufacturing. The tradeoff between the cost, time and quality of the current onsite/offsite production mix and a new off/on/nearsite production mix will vary greatly across locations and projects, so this new way of organizing construction will coexist with the current system for many decades to come. 

 

Figure 2. Print farms

 

Clockwise from top left: Zortrax, 3D Systems, Design 3D Print, Formlabs, Optomec

 

The combining of robotic and automated machinery with 3D printing of parts will open up further possibilities. Site processes can be structured around components and modules designed to be assembled in a particular way, and machines to assemble those components and modules can be fabricated for that purpose. The FBR bricklaying machine below is an example of this, designed to use custom made blocks larger than conventional bricks. Another is the RoBIM robot making wall panels from prefabricated components. 

 

Designing an automated production process that includes the machines and equipment needed to move and install parts produced by printers and robots puts digital fabrication at the core of an integrated system of design, manufacturing and assembly. This can work as well in construction as in any other industry. 

 

Figure 3. Construction automation

 

From left: RoBIM wall panel robot, Hilti Jaibot for M&E fixing, ABB robot team, FBR bricklayer

 

Production technologies based on digital twins link localised digital fabrication with online design databases and, as well as concrete, materials like steel, ceramic and plastic can be used to make components and fittings. The robotic and automated machinery and equipment being developed for construction is also based on digital twins, as are the various types of drones used to layout and monitor construction sites. 

 

 

Combining Offsite, Onsite and Nearsite Production 

 

The combination of digital twins and digital fabrication will be transformational if it significantly alters existing economies of scale in the industry. Digital fabrication is a technology whose use has a high probability of becoming ubiquitous as the cost of fabs falls and the supply chain of raw materials continues to develop. Advances in automation and mechanization have the potential to significantly increase onsite and nearsite production in construction, using 3D printers to make and finish both structural elements and a wide range of fixtures and fittings.

 

This introduces a new option in the organization of production for delivery of buildings and structures. The current choice between onsite work and offsite manufacturing is a well-developed and efficient system, but the level of efficiency and productivity achievable is limited by the lack of significant economies of scale in a project-based industry. With digital fabrication this is no longer the case, and a new production mix that combines onsite and nearsite manufacturing with onsite construction work is now possible. 

 

Construction AI

Three industry scenarios

 

McKinsey’s Artificial Intelligence: Construction Technology’s Next Frontier (Agarwal et al 2018) is one of a series of recent papers from the management consultants on AI, automation and infrastructure. They identify five AI-powered applications, and use cases that have already arrived in other industries, that can be applied to construction. This is a practical approach that seems to target major contractors, and is a different approach to previous reports that could have been primarily intended for public sector clients. McKinsey has been seriously developing their infrastructure practice for some years now, positioning themselves for the global infrastructure boom they forecast over the next few decades. The five industry applications are:

•  Transportation route optimization algorithms for project planning optimization;
•  Pharmaceutical outcomes prediction for constructability issues
•  Retail supply chain optimization for materials and inventory management
•   Robotics for modular or prefabrication construction and 3-D printing;
•  Healthcare image recognition for risk and safety management.

Each of these has a short discussion with some examples of crossover potential. They are all plausible extensions of current technology, and in robotics, 3-D printing and drones, leading construction firms are already well advanced. Using AI for optimization is obvious (Gans 2018), and is addressed below (see figure 2), but construction firms typically contract out specialized tasks such as design and logistics, rather than invest in the hardware and software development needed (Manly and XXX). Its questionable whether McKinsey makes a convincing case for using AI in construction. Are these are the pathways into construction for AI, or the only ones?

McKinsey also looks at some machine learning algorithms that are relevant to contractors, and briefly assesses their potential engineering and construction applications. Despite their extensive reporting on BIM elsewhere there is no discussion of the potential use of AI in design and engineering, or in restructuring processes. They do have a generic framework for types of machine learning, and they suggest algorithms will be useful for: refining quality control and claims management; increasing talent retention and development; boosting project monitoring and risk management; and constant design optimization.

If McKinsey has a more nuanced story to tell on pathways for AI into construction it might look something like the scenarios depicted by the World Economic Forum and the Boston Consulting Group in their Future Scenarios and Implications for the Construction Industry (WEF/BCG 2018). This scenario analysis is the second, final step in their Future of Construction project, which has involved people from industry and researchers from a wide range of organizations, after the Shaping the Future of Construction report (WEF/BCG 2016). They use infrastructure and urban development Industry (IU) to describe what has elsewhere been called the built environment sector.

The three future scenarios the WEF describe make technological context central to the future form of the industry. The scenarios depict three extreme yet plausible versions of the future. Each scenario is used to extrapolate implications for the industry, identifying potential winners from technological transformation, and the range of examples and ideas shows the value of such a widespread collaboration between industry, government and academia. The WEF does not say how far into the future they are looking, although it seem to be a lot further than McKinsey:

1.       In Building in a virtual world, virtual reality touches all aspects of life, and intelligent systems and robots run the construction industry. Interconnected intelligent systems and robots run the IU, software players will gain power, and new businesses will emerge around data and services.

2.       In Factories run the world, a corporate-dominated society uses prefabrication and modularization to create cost-efficient structures. The entire IU value chain adopts prefabrication, lean processes and mass customization, with suppliers benefiting the most from the transition and take advantage of new business opportunities through integrated system offerings and logistics requirements.

3.       In A green reboot, a world addressing scarce natural resources and climate change rebuilds using eco-friendly construction methods and sustainable materials. Innovative technologies, new materials and sensor-based surveillance ensure low environmental impacts, so players with deep knowledge of materials and local brownfield portfolios thrive on the new business opportunities around environmental-focused services and material recycling.

It is important to keep in mind that scenarios are not predictions of the future. Rather, they outline a broad spectrum of possible futures. In the real future, the construction industry will most probably include elements of all three, as the supply side of changes in demand for different types of building.

One issue is where the industry is at in regard to technology take-up, now that there is widespread recognition of the reality of a digital future. Will construction industry development over the next decades absorb the impacts of new technology and be gradual, changing industry practice over time without significantly affecting industry structure or dynamics? Given the entanglement of economic, social, political, and legal factors in the construction technological system this might be the case, however there are good reasons to think this may be wrong. Machine learning, AI, automation and robotics are an interconnected set of technologies that are evolving quickly, enabled by expanding connectivity and the massively scaleable hardware available today.

 

In 2016 a scenario analysis called Farsight for Construction, looking at the future of the building and construction industry in Queensland, Australia, was released (Quezada et al, 2016). The scenarios describe “four plausible futures for Queensland’s construction industry over the coming two decades, with a focus on impacts for jobs and skills. Each scenario consists of a description of Queensland’s construction industry in the year 2036, a narrative of how the scenario came about, and a commentary on plausibility.” In the figure below Australia is substituted for Queensland.

Figure 1.

Source: Quezada et al, 2016.

If we think of the structure of the construction industry as a pyramid of different sized firms, there is a broad base of tradesmen and small firms at the bottom, followed by a deep layer of medium sized firms, and a small top triangle with a few large firms. Some of those large firms, and some of their major clients, are clearly on the technological frontier, and their investment in capability and capacity should deliver significant increases in efficiency and productivity, and probably scale. Some medium-size firms are also making these investments, and also have access to technologies like algorithmic optimisation, platform-based project management, robotic, VR and AR applications and so on. The WEF Shaping the Future of Construction report (WEF/BCG 2016) included snapshots of what a range of firms at the frontier were doing. These examples reflect the diversity of the industry, and were missing from McKinsey’s high level analysis.

A period of technology-driven restructuring of the building and construction industry may be about to start, similar to the second half of the 1800s when the new materials of glass, steel and reinforced concrete arrived, which led to new methods of production, organisation and management. There are many implications of such a restructuring. Some firms are rethinking their processes in response to developments in AI, robotics and automation as capabilities improve quickly and the range of new products using these technologies expands. Many firms, however, are not. Meanwhile, firms at the frontier are exploring new technology and pushing the boundaries of what is possible, and are inventing new processes.

 

References

Agarwal, R., Chandrasekaran, S. and Sridhar, S. 2016. Artificial Intelligence: Construction Technology’s Next Frontier, McKinsey & Co.

Quezada, G., Bratanova, A., Boughen, N. and Hajowicz, S. 2016. Farsight for Construction: Exploratory scenarios for Queensland’s construction industry to 2036, CSIRO, Australia.

WEF/BCG, 2016. Shaping the Future of Construction: A Breakthrough in Mindset and Technology, World Economic Forum and the Boston Consulting Group, Geneva.

WEF/BCG, 2017. Future Scenarios and Implications for the Construction Industry, World Economic Forum and the Boston Consulting Group, Geneva.