Prefabrication experiments - 328 - Manufacturing methodologies - 08 - Discrete manufacturing versus building construction

Discrete manufacturing is defined by strict guidelines and procedures both in terms of parts and supply management. Product’s composing constituents, parts of an industrial recipe, are either recognizable or indistinguishable at the end of the production process. In both cases, the completed objects are cohesive but can be broken down into their original ingredients. Objects made in this manner theoretically facilitate elemental replacement or repair to avoid premature obsolescence. 

 

Building construction is an interesting case study when assessed and examined in relation to discrete manufacturing. Building is probably the only industrial sector that liberally combines products, parts or components generated from disparate visions of the overall process and minimal prototyping of how edifices are assembled. 

 

A building is an example of discrete manufacturing in the same way an automobile or a computer is. However, a building also contains components that are prepared by process or batch manufacturing incorporating ingredients or outlined by specific formulas that once generated are fixed in a state that impedes disassembly. Concrete, mortar, or polymers are materials that act as glues or binders. Their production is permanent and can’t be reversed. Even through demolition the composing parts aren’t returned to their original state. 

 

Industrial building culture defined building design as a systemic organization of predetermined, premade, catalogued, and standardized parts assembled into a distinct or singular edifice produced for a particular function or use that is usually demolished at the end of its service life. Making construction even more distinct from manufacturing, certain elements are not linked to any production, for example: site or context. Buildings are set in a particular locus requiring setting-specific foundations and earthworks for their long-term stability. At best, complementary visions of production that come together in construction are a fusion and harmonization of discrete production, job and process production. At worst building construction is fragmented, entangled and leads to perpetual conflict.  

 

Offsite construction, prefabrication and industrialized building systems are designed to facilitate building assembly and speak to a type of discrete manufacturing that aims to address the longstanding fragmentation by streamlining design, fabrication and construction through a coherent product-based ideological thread that includes systematic prototyping for assembly of segments and sub-assemblies in the building process.

Discrete manufacturing from https://www.ibaset.com

Prefabrication experiments - 327 - Manufacturing methodologies - 07 - Integrated product and project delivery

 

The connexion between design (architecture) and production (construction) is often a discordant one. The design-bid-build methodology common in the delivery of buildings has been the standard form of procurement through many eras, as far back as Roman master builders, and has led to the separation of design experts from construction trades with contractual documents (drawings and specifications) being the only negotiating tool. This fragmented, conflict prone process requires comprehensive itemization and detailing for outlining systemic responsibilities. Any orphaned element in the design process becomes a fertile ground for friction among project participants. 

 

Inspired and informed by lean manufacturing principles a more integrated process can address this continuous entanglement of trades and conflicts. In this model, design criteria and project objectives are shared from the onset among stakeholders. Further, a risk-reward relationship completely reforms the antiquated design-bid-build process into a process analogous to Design for Manufacturing principles to bridge the ever-widening gap between design and construction. The separation of design from production in construction is also present in manufacturing. The disconnect is known as «over the wall» tensions; the wall separates design from engineering and from manufacturing. Design for manufacturing and assembly tackles this disintegration by incorporating production criteria, designers, and process engineers in the design of a product, eliminating the proverbial wall. 

 

In a similar way to DfMA, IPD (Integrated project delivery) fosters all project participants’ criteria from planning stages through a contractual framework that clearly defines project requirements and responsibilities. Prefabrication, off-site construction or even industrialized construction relate to the integrated process in as much as manufacturers should always be included in the design process to fine-tune detailing from predetermined and interoperable parts. Both integrated project delivery and design for manufacturing and assembly underline necessary inclusion of production and making principles in the design process.  Contemporary modelling tools are driving more integration though information sharing. Architecture is more closely related to production or even manufacturing as digital coordination between different fields is becoming the norm. All stakeholders’ conditions can be federated by BIM employing advanced modelling to collectively organize and generate the project virtually before it is built. 

Above: DfMA; Below: IPD; both showing effort and involvement in planning

Prefabrication experiments - 326 - Manufacturing methodologies - 06 - Is architecture, job, batch or flow ?

 

Prefabrication and industrialized construction intellectualize edifices and their parts as products resulting from harnessing the efficiencies of manufacturing principles. The spectrum of manufacturing processes that have been related to building include job (offsite produced prototypes), batch (mobile homes) and flow (modular building). The methodologies vary from completely customized to mass produced. Job production is most closely related to construction. Materials, labour, and tools are set up or arranged to fabricate a unique object or product according to a predetermined design. Objects generated in this way are usually complex, errors can be corrected along the way and a prototype is the result. 

 

Architecture and construction are a type of job process and perhaps here lies the challenge of industrializing their production. Industrial processes are based on continuous and repeating methods and materials to realize economies of scale. Batch and flow, both serial production, include prototyping as part of the design process, not the result. Supply chains and production strategies are studied to design for productivity. Batch production determines an amount after which each subsequent collection can be tweaked to further increase efficiencies. This requires a high level of standardization. Flow processes are related to the batch process but tuned to a just-in-time methodology as tasks are organized to allow each step of production to be tweaked and optimized. 

 

Mobile homes, modular and panelized construction have proven that putting a building together can become, ideologically, more like production. Singularity, however, is still a strong concept that impedes high levels of industrialization in most cultures. Building edifices as prototypes is part of the problem. Prototyping is part of an industrial process that once optimized makes batch and flow production both feasible and fruitful. Aiming to include industrial prototyping in construction, Virtual Design and Construction using information technology is the current way of testing before building. The knowledge gained from prototyping is augmented from project to project, fostering integration and decreasing fragmented decision making which has become the emblem of construction inefficiencies. Architecture could benefit from this outlook that is closer to making things from of a design for production process. 

job, batch or flow in industrialized architecture and construction

Prefabrication experiments - 325 - Manufacturing methodologies - 05 - From mass to lean production

Production at the beginning of the twentieth century was defined by Henry Ford's model of mass production: the assembly line. The value of Ford's system was founded on dominating the supply chain and insisting that suppliers lower costs from raw material to market to realize economies of scale. Drastically reducing manufacturing costs of the Model T from 825$ in 1908 to 360$ in 1914 is a testament to Ford's successful vision.   Characterized by a continuous flow of repeating tasks, components, jigs and moving constituents through a linear process, vehicles were verified and validated at the end of their production cycle which sometimes led to accumulated inefficiencies and errors. 

 

Another manufacturing revolution came in the 1930s from another automobile manufacturer.  Influenced and inspired by Japanese craftsman culture, Toyota introduced a collaborative and cellular approach to making automobiles. The Toyota Production System harvested value from within manufacturing as well as from output.  Lean manufacturing or Lean production were outlined on key principles: the first, improving productivity of every task; which meant looking for errors, waste at all stages and from every individual. Arguably the most important nuance from Ford's model was the integration of the suppliers in a type of coordinated cooperation. Producing in smaller batches also made it possible to correct errors and glitches as they presented themselves. Finally, Just-in-time production, using and making things as required increased the agility of the manufacturing process. 

 

Often related to prefabrication and offsite construction, Lean construction is described as the Toyota model applied to building construction. These theories have been proposed for improving lagging productivity since the 1970s.  Lean implies a comprehensive and integrated practice where all stakeholders are invested in improving both the product and the process, arguably, tasks that are easier achieved within a factory setting. Conventional delivery of construction projects is bogged by conflicts between design professionals, trades and contractors. The systemic fragmentation and entanglement of design and construction is a clear area for a Toyota inspired process to redefine architecture and construction from two disparate spheres to architecture and construction as part of a streamlined and optimizable continuum of waste reducing and value adding actions. 

Middle Table from https://explorescm.com/lean-manufacturing/ consulted on April 4, 2022