Interviews

98 costs may vary with time and thus are always going to be an imperfect forecast of future disassembly cost (Sassi, 2008).

Criteria JT2, JT8 and VF1 do not evidently belong to one of our criteria and sub criteria proposed above because these criteria are intervention specific and not characteristics of a specific construction system.

99 4. What are the obstacles to the adoption of demountable and reusable construction

systems?

5. Is independence between components and constructions systems with different life cycles, and particularly partition walls from the rest of the building, an important criterion to consider?

6. Is the integration of digital design and fabrication, with its instantaneous and flexible links between design and production an adequate fit to the challenges of building renovation?

7. Considering that the partition wall to be developed is meant to be assembled and disassembled by users without previous construction experience, which criteria should be included?

8. Which criteria make a demountable partition wall system more flexible?

9. Which performance criteria should be met by the partition wall system in development?

10. Beyond production and building cost which other costs should be considered?

All authors agreed that building renovation will tendentially increase in relevance in the medium term. In terms of difficulties in adaptation to building renovation, interviewees highlight:

1. Need for site adjustments not compatible with rigid contractual and AEC procurement process, i.e., the drawings are contractually binding (AR).

2. A model that includes builder and designers in the same team is more sensible (AR).

3. Lack of room for design experimentation (BS)

4. Low budgets make digital fabrication uncompetitive (BS)

5. Construction companies and sub-contractors were not prepared, lack technical know-how and builders use construction methodologies for new buildings in the rehabilitation of old ones (JAF, NCREP, VF)

6. The mindset to maximize the reuse of the pre-existence is not there (JAF, NCREP) 7. Speed in the process is not compatible with careful studies (VF)

8. Lack of sector specific regulation (VF)

In terms of reconciling automation and pre-fabrication with building renovation, VF, JAF and BS agree that there should be separate solutions for the pre-existing building and the new system. NCREP suggests that this prefabrication will be less standard and JM that lack of standardization in existing buildings is an important obstacle. JT and PM discussed the need for

100 social, and environmentally balanced solutions. Lastly, AR stated that context-aware design-to-fabrication models are the key.

Regarding question 4, most of the authors consider reusing building components is not something society is yet ready to pursue, either because there is a lack of habits, are not informed of the need, or construction tradition prevents it (AR, JM, JAF, PM, NCREP, VF). BS points to some issues that are not specific to DfD but are a general problem of circular economy solutions, e.g., lack of supply chain information, resistance to the use of recycled materials in new products because of reduced technical performance and know-how. JT calls for taxation on construction waste sent to landfill and argues for a mix of Design for Durability with high quality design. PM further adds higher cost and barriers to the adoption of self-renovation in social housing as obstacles of DfD solutions.

All but BS agree that independence of partition walls from the support is an important aspect. JT extends the requirement to materials. Yet, JAF cautions that the aim of independence is not to reuse components since these systems are hardly reusable in different contexts because there is a lack of standardization. PM disagrees with JAF and argues that walls should be more like furniture, further stating that even if users or building owners do not take advantage of the extra flexibility it is always preferable to have it. While BS did not explicitly disagree, he exposed a similar view as JT in the question 4, that good design can increase the product lifetime.

All interviewees agreed that the integration of digital design and fabrication is an adequate fit to the challenges of building renovation. AR stated that the advantage would be to shorten the design to production cycle. BS talked of the capacity to respond to shorter production runs.

PM, BS, and JM discussed the capacity to respond to context specific variations. VF cautioned that integration is easier in new construction and JT that digital fabricated solutions must integrate with the pre-existing. Lastly, JAF stated the transition will have to start at universities and progress to design stakeholders before it reaches contractors and subcontractors.

Table 4-6 summarizes the issues discussed with each interviewee and maps those issues to the proposed criteria in the previous section.

Table 4-6: Mapping of discussed issues during the interviews to the proposed criteria

101 Regarding criteria for assembly / disassembly by users without experience the interviewees highlighted the following criteria: Simplicity (NCREP, JM, PM, BS), Practicality (PM), Symmetry in assembly/disassembly - Separability (JAF), Communication (PM, AR), and Combinability (AR).

Replying to question 8, interviewees discussed Modularity - Combinability (AR, JAF, JM, PM), Modularity - Separability (BS, JAF, JM, PM), Independence - Material (BS), Personalization (JAF, PM, NCREP), Simplicity (NCREP), Practicality (NCREP), and Geometric Flexibility (NCREP)

Regarding performance issues AR, JAF, JM, PM, and VF place safety requirements first as a sine qua non condition. AR, JM identify acoustic as important, NCREP considers it is a differentiation factor. VF considers acoustic, thermal, and hygrometric demands should be characterized to allow a performative selection and not be criteria.

Lastly, replying to question 10, AR considers that automating production will reduce costs, BS mentions all the product development (design, prototyping, optimization, certification) and marketing costs. JAF and VF mentions LCA cost should consider initial cost, cleaning and disassembly and further propose that the evaluation of reuse cost should consider a percentage of global cost reduction. JM focuses on production and distribution costs. PM proposes the user could be informed of the estimated assembly times even if those are not costs of the product but only if providing this information is obligatory can it then be considered criteria.

Some interviewees observations which are not answers to any specific question are also worth highlighting. AR stated that lack of labor is a current concern and a driver their efforts of increasing pre-fabrication and automation. BS considers that architectural offices currently are in position to offer architectural products ranging from building components to houses. He further stated that the difficulty in adoption is related with education but also with the

Criteria Subcriteria AR BS JT JAF JM PM NCREP VF

ER Renewable/recyclable materials X X X X X X

EIM Independence - material X X X

EIF Independence - functional

EEC Low embedded carbon and energy X X

AS Simplicity X X X X

AP Praticality X

AC Comunication X X

FG Geometric flexibility X

FS Services integration X

FMS Modularity - Separability X X X X X X X X

FMC Modularity - Combinability X X X X X

FP Personalization X X X X

PA Acustic comfort X X X X

PS Safety and Acessibility in use X X X X X

PJ Joint durability X

PT Thermal confort X

PH Hygiene, health and environment X

PF Fire safety X

CI Initial cost X X X X X X

CR Reuse cost X X

Separability Subsystem X X X X X X X X

Separability Component X X X X X X X

Independence Material X X X

Environmental

Assembleability

Flexibility

Performance

Cost

102 maturation of computational design knowledge by designers which must span from conception to materialization of design.