Mass Customization Construction Criteria

78 Environmental Product Declarations - Core Rules for the Product Category of Construction Products, 2019). PC5 can be mapped to Durmisevic material independence criteria.

79 A module is then a part assembly or a singular component that can be either assembled or fabricated first and independently of the product instance. Consequently, a module is by definition separable (2007, p. 226) and for Salvador this also extends to the possibility of disassembly. Component separability is a property of a modular system whose degree is related with the ease of assembly/disassembly.

But component separability is not sufficient to define a module of a system since to form a stable assembly it must have some form of establishing a connection with other components of the system. A second property of a modular system is component combinability which is maximized if (1) each of the modules is interchangeable with any other module of the system;

and (2) each module is a stand-alone version of the product (Salvador, 2007, p. 226). This leads to the definition of modularity in terms of component separability and combinability:

“In the domain of tangible, assembled artifacts a product system is modular to the extent that its separable components, or modules, are combinable.” (Salvador, 2007, p. 229).

Component combinability involves the concepts of interface standardization and packaged function binding. As previously stated, a component is only “connectable” with another if they share a common physical interface, but this requirement is not sufficient. They must also share a common agreement on the set of functions each component performs. This problem is frequently solved by matching interface standards with specific sets of functions (Salvador, 2007, p. 232).

Lastly, Salvador still admits the possibility of “weak modularity” for product systems that have common components, usually referred to in the literature as component commonality (i.e.(Ulrich & Tung, 1991)), but these cannot be easily disassembled (Salvador, 2007, p. 233). This is the case when two components are glued together, or in construction, when tiles or bricks are laid using mortar. The original components have a very high degree of commonality (and combinability) but are no longer separable after they are assembled without damaging or destroying the component.

4.3.2 Kent Larson Criteria

Kent Larson is one of the first authors to propose that MCC may be an appropriate paradigm to address the challenges of productivity, quality, and user choice in building construction (Larson, 2000). At the MIT, he was the principal investigator of the House_n research consortium, during which he published a series of position articles defining principles and methods for mass

80 customization of housing (Larson, 2000; Larson et al., 2001, 2004). In these articles, he proposes a systemic view of the building as a set of subsystems or components that are connected to a common platform and between themselves (Larson et al., 2004, pp. 188, 199). The separation of chassis and infill approach closely follows Habraken’s proposals of the separation of support and infill (Habraken, 1972) and of industrialized construction (Habraken, 2003).

Larson and his team propose a “standardized platform”, the chassis, and a user customizable infill which connects “in standard ways to the chassis” (Larson et al., 2004, p. 188).

These interfaces or joints of component-to-component and chassis-to-component should have industry wide acceptance (Larson et al., 2004, p. 190). In the spirit of open-source, designers and engineers across organizations and countries should “share knowledge and details and agree on common design rules” (Larson et al., 2004, p. 189).

The above criteria are achieved by “principles of modularity (where interface between systems are standardized)” (Larson et al., 2004, p. 198) and automation of fabrication processes that seeks to address “a shortage of skilled construction labour” (Larson et al., 2004, p. 189).

Both criteria would also allow for “tighter tolerances and faster onsite assembly” processes, further minimizing field labour (Larson et al., 2004, p. 189).

They recognize a balance must be established between integration of several functions in a module (Larson et al., 2004, p. 189) and disentanglement of systems to facilitate change “during design or use without affecting the performance of the larger system." (Larson et al., 2004, p.

188). Other identified criteria are the need for customization and “to efficiently accommodate new technologies and change over time” (Larson et al., 2004, p. 188).

KL1. Separation of chassis and infill (Larson et al., 2001, 2004)

KL2. Customization of infill / Standardization of platform (Larson et al., 2004, p. 188) KL3. Interoperable components across manufacturers (Larson et al., 2004, p. 188) KL4. Standardized connections component-to-component and

chassis-to-components (Larson et al., 2004, p. 190) KL5. Open-source (Larson et al., 2004, p. 189)

KL6. Disentanglement of systems and components (Larson et al., 2004, p. 188) KL7. Flexibility - provide the possibility to upgrade (Larson et al., 2004, p. 188) KL8. Speed up onsite assembly by minimizing field labour: (Larson et al., 2004, p. 188)

(Larson et al., 2004, p. 189)

KL9. Modularity (Larson et al., 2004, p. 198)

KL10. Automated fabrication processes: (Larson et al., 2004, p. 198)

KL11. Integration of several functions in one module: (Larson et al., 2004, p. 189)

81 4.3.3 Kieran Timberlake Criteria

Stephan Kieran and James Timberlake book Refabricating Architecture (2003) can be read as a manifesto for a more customizable and industrialized architecture, that departs from the Modern Movement view of mass production. The book lays out principles, criteria and methods that would allow the implementation of MCC in a quasi-propagandistic way, frequently drawing comparisons with the design and production methodologies adopted in car, computer, aviation, or shipbuilding industries.

A core design task for these authors is to reduce the complexity of the on-site assembly by aggregating parts into preassembled modules. This would serve the purpose of achieving

“higher quality, better features, less time to fabricate, and lower cost: more art and craft, not less.” (Kieran & Timberlake, 2003, p. 79).

The previous design challenge requires a clear subdivision of the building into modules.

Working with a modular system requires a framework for understanding the whole and this is

“the originating act of the design process” (Kieran & Timberlake, 2003, p. 64). Digital technologies allow the coordination of these efforts across teams that may then focus on designing specific modules, it would also allow the possibility of simultaneous production of the modules, a process that the authors compare to quilting (Kieran & Timberlake, 2003, p. 56).

The key criteria to consider in deciding how to divide the building into modules are exchangeability (Kieran & Timberlake, 2003, p. 77), that must be provided where there are: (1)

“difference[s] in life cycles in construction and technology, between dumb and smart” (Kieran &

Timberlake, 2003, p. 77); (2) reduce the number of components for final assembly at the site (Kieran & Timberlake, 2003, p. 47); (3) reduce number of joints or interfaces, which will provide

“more precise tolerances and better working conditions with less accumulation of parts in the final assembly area" (Kieran & Timberlake, 2003, p. 87); and (4) non-linear assembly (Kieran &

Timberlake, 2003, p. 75).

For these authors the purpose of modular joining is manufacturing efficiency, dependent on “geography, on the location of the plant where the materials are actually joined" (Kieran &

Timberlake, 2003, p. 93), more than to reduce the number of parts in a module. Yet, they consider that there is also the opportunity to redesign these modules into monolithic components, thereby reducing weight and number of parts (Kieran & Timberlake, 2003, p. 80).

Another important criterion when considering the subdivision into modules is integration of functions, instead of dividing the modules according to trades and functions (Kieran &

Timberlake, 2003, p. 91).

82 This modular logic operates at several nested levels which in turn implies that there are different types of joints depending on where these modules are assembled, the authors speak of connection and system joints (Kieran & Timberlake, 2003, p. 101).

KT1. Reduce the number of parts per module by redesigning them into monolithic elements (Kieran & Timberlake, 2003, p. 80)

KT2. Exchangeability (Kieran & Timberlake, 2003, p. 77)

KT3. Modules defined by life-cycle (Kieran & Timberlake, 2003, p. 77)

KT4. Reduce the number of components: (Kieran & Timberlake, 2003, p. 47) (Kieran

& Timberlake, 2003, p. 96)

KT5. Reduce number of joints or interfaces (Kieran & Timberlake, 2003, p. 87) KT6. Modularity for manufacturing efficiency (Kieran & Timberlake, 2003, p. 93) KT7. Non-linear assembly (Kieran & Timberlake, 2003, p. 75)

KT8. Simultaneous production of components (Kieran & Timberlake, 2003, p. 56) KT9. Integrate functions (Kieran & Timberlake, 2003, p. 91)

KT10. Site and factory joints (Kieran & Timberlake, 2003, p. 101)

4.3.4 Merging Mass Customization Construction criteria

MCC enables the possibility of delivering customized solutions to specific contexts efficiently. Its authors also have a large set of overlapping criteria. Integrating several functions within one module is discussed by both authors (KT9, KL11), as is its' tradeoff criteria of disentangling systems (KT3, KL6) for exchangeability in design, production, and future change (KT2, KL7). Separation of chassis/infill (KL1), interoperable component across manufacturers (KL3), standardized interfaces (KL4), open-source (KL5) and modularity (KL9) can be considered strategies to achieve exchangeability (KT2). Likewise, reducing the number of components (KT4) and interfaces (KT5), and defining site and factory joints (KT10) and non-linear assembly sequences are all strategies to minimize field labor (KL8).

Although the concepts of open-source (KL5) and chassis-infill (KL2) are not explicitly discussed by Kieran and Timberlake as a criterion, there really is no disagreement since open-source for Larson is limited to the interface and chassis standards. Shared interface standards are also discussed by Kieran and Timberlake, but instead of the chassis and infill approach, they discuss several different strategies present in different industries to divide the products into modules, e.g., “grand blocks” or “smart modules” of the shipbuilding industry.

The term module is sparingly used by Larson and strictly to signify spatial structural units, which is more in line with the conventional meaning within architectural circles (Rocha et al.,

83 2015). The term component is interchangeably used with module and is also used to signify either complex assemblies of parts or the parts themselves. Kieran and Timberlake mostly use the term module for the latter meaning, while the expression “grand blocks” is used to signify large building components which offer support for “smart modules”. Thus, while the terms are different the concepts behind them are the same.

The fundamental difference between both authors lies in how the decision on the modular framework is made. For Larson this something that is arrived at by industry consensus, while for Kieran and Timberlake this is something that the “tier 1” product manufacturer can decide.

4.4 Negotiating criteria for customizable and disassemble able