Part I focuses on the theoretical framework of each of the areas involved in this research organized in a top-down way: open building renovation, mass customized construction, design
CHAPTER 4 Towards framework of criteria for customizable and disassemble-able partition systems
4.5 Assessing and setting design goals
4.5.1 Cost-effective digitally fabricated systems
4.5.1.2 Elsayed Low-Cost Housing
Elsayed’s LCH system is composed of parametric elements, wall, ceiling, and floor, which combine structural and skin functions, and a prefabricated core for wet spaces. Only the wall system is detailed in the paper (Elsayed 2017). The authors consider the system to be “modular parametric” meaning that the wall system components may be dimensionally adapted to context specific circumstances.
A thorough analysis of the proposed wall system reveals that there are in fact two types of straight wall components – male and female (Figure 4-13). We identify 5 different types of connections: 2 structure-to-panel connections, 1 spacer-to-panel connector, stud-to-stud connections, component-to-component connections; and 11 component types, assuming there is axial symmetry: 2 straight wall components, 3 L-components and 4 T-components. If the identified components are to be assembled onsite, as the authors propose, the system complexity increases. Each L and T component has 8 panel and 2 stud variants, with two panel and stud types for each straight wall section.
Figure 4-13: (Left) Assembled components with male straight wall, Male/Female T-Wall and female L-Wall, (Right) Application of Female-Male logic to original diagram (Adapted from Elsayed 2017)
109 The authors suggest the wall components are completely assembled onsite, which reduces simplicity of onsite assembly. Nevertheless, the system has a smaller number of part types, when compared to WFG, and there is potential for the components to be pre-assembled offsite.
Elsayed system assembly sequences can be classified as horizontally bidirectional for component assembly, it requires simple tools for friction-fit joints and no tools for snap-fit ones.
The full heigh wall section is 700x2800mm. The selected material has a reported specific weight of 720kg/m3. It is not clear how the assembly process is conducted but assuming the wall section component is assembled on the floor, each fully assembled component weights 63,87kg and requires two people to erect it and connect the wall sections together.
No information is provided regarding how assembly/disassembly sequences are communicated to onsite assemblers nor if a specific part labeling scheme is used. Considering the low number of component types, instructions would be significantly reduced as compared to WFG.
The system provides level I geometric flexibility due to the selected connection types. It can be considered a type III in terms of services integration. Obtaining access to the wall voids is theoretically possible with local panel disassembly. In practice this should be difficult to achieve since there is no points to grab and pull the panel apart from the structure, also it is unclear if the system remains stable after the disassembly of the panels. Regarding separability, it is a type VII system, meaning that the disassembly sequences are still unidirectional. Removing a specific wall section does not seem to be possible.
Assuming that the height is constant from house to house the system would have a high combinability. But with changing heights only the connectors and the lower sections of the external sheathing are reusable between system instances. The vertical runners would have to be produced specifically for each system instance. Components can be combined in different arrangements but are limited by the male-female component-to-component connection logic.
Elsayed system suffers from the same issues as WFG regarding both functional independence and personalization. Although a more modular approach is adopted, the panels still perform structural functions. Also, regarding personalization, the protruding joint complicates adding different finishes to the system and the snap-fit joint is not as widely applicable as the friction-fit joints.
We use the case-study reported by Sass, a room with 7,3 sqm surface area, and the diagram presented in Figure of the LCH system, with 16,19 sqm building footprint, to analyze the systems.
Table 4-10 summarizes the analysis regarding the specified criteria with all scores normalized.
For simplicity and combinability, we chose to assume a theoretical optimal value of 1, which
110 follows Salvador approach. LCH case is double the area of WFG case but only the number of operations is proportionally affected by this change, all the other metrics are system specific.
Table 4-10: Evaluation of WFG and Low-Cost Housing according to the defined criteria
Thus, although the number of site operations in WFG is similar to that of LCH, the more modular approach reduces the number of different operations by one order of magnitude.
Similar effects are seen in Combinability component types and in a smaller degree in connection types, which contributes to a significantly increased overall combinability score for LCH. The increased modularity in LCH comes at the cost of geometric flexibility, the joining solutions can only be applied to orthogonal geometries, which might be an issue at the system boundaries in building renovation. Regarding Practicality, there is no improvement regarding assembly and disassembly sequences between both cases.
The analysis revealed that there are opportunities: (1) to explore the interrelations between different criteria in practice, particularly those of Modularity (FMS, FMC), Simplicity (AS), Practicality (AP) and Functional Independence (EIF); (2) to determine how specific system design choices impact each of the criteria and ultimately influence the reuse potential; (3) to determine which design patterns may exist in systems which are more open and reusable; and (4) to determine how digital fabrication may meet the complex and diverging challenges of open system partition walls.
Lastly, some aspects of the analysis beyond the framework of criteria should be highlighted.
Surveys are sine qua non first steps for adequate building renovation (JT1). Delivering context specific solutions, as required by JT3, JT4 and JT9, on a global scale demands multiple building systems. This requirement is also a corollary of EE criteria, it is not realistic to expect the scope of a single partition wall system to include all possible variations of material combinations.
Hence, multiple customisable and disassemble-able partition wall systems of smaller scopes are
111 needed, which underscores the need for criteria and design principles but also demands MCC systems capable of addressing the design level.
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