Effective interdisciplinary stakeholder engagement in net zero building design

1.1 Stakeholder participation

The traditional roles of technical stakeholders must evolve to move critical and active modes of participation. The inclusion of new specialisms such as climate and energy engineering (Pérez-Bou et al. 2024) and the integration of non-professionals’ knowledge through participation are required (RIBA 2024). The representation of end-user groups and facility managers, for example, is critical to improved designs in the IDP (Zimmerman 2006), and thus engagement should endeavour to involve a range of technical and non-technical stakeholders. Furthermore, stakeholder participation in NZB design processes is a mechanism through which to elevate participant capacity-building as a design process outcome due to inherent collaborative activities (Myint et al. 2025), though these benefits are not elaborated upon.

The early-stage representation of diverse stakeholder perspectives, elicitation of values and subsequent integration of them into decision-support processes enables socio-technical responses to environmental challenges (Storvang & Clarke 2014; Vaidya & Mayer 2016; McKenna et al. 2018; McGookin et al. 2021; Robinson 2021). Falana et al. (2024), in a comprehensive analysis and review of the key stakeholder roles in the net zero carbon building life-cycle, identify that stakeholder partnerships early in the design stages can lead to better designs, reduced costs, enhanced knowledge-sharing and the promotion of innovation (Ohene et al. 2022).

1.2 Application in practice

The recent Engagement Overlay to The Royal Institute of British Architects’ (RIBA) Plan of Work (2024) advocates for stakeholder engagement at all stages of the building life-cycle. However, it provides generic suggestions for participatory design activities and evaluation practices. The identification of IDP-enabling attributes (or factors) during the early stages can be used to guide the selection of processes and procedures relevant to context (Ikudayisi et al. 2022). Architecture, engineering and construction (AEC) practice would benefit from developed and tested methods to holistically explore energy and carbon alongside wider sustainability implications across building life-cycles.

Successful stakeholder collaboration in the IDP for NZBs relies on client leadership, a focus on goals to sustain effort and continuity, and trust among the team (Pérez-Bou et al. 2024). Though these results were specific to the Singaporean context of Pérez-Bou et al. (2024), they provide grounds for future comparisons of the human factors driving IDP for NZBs. The transfer of best practice using comparative studies between developed and developing countries (Myint et al. 2025), where enabling conditions for the IPD in terms of NZB practice may differ, is required to progress the research domain.

Effective stakeholder engagement is difficult to achieve in practice and is often imperfect (e.g. false consensus, masking exploitation and as a means of control; Downs 2017). Any approach should be critically evaluated to track participants’ experiences (Downs 2017), as the testing of engagement methods both conceptually and practically remains a research gap in the NZB context (Myint et al. 2025).

1.3 Conceptual framework

The popularity and use of the IDP in AEC design processes suggests a decline in the dominance of the technical rationality paradigm within those design processes. However, NZB design research remains dominated by techno-centric approaches; multidisciplinary integration of stakeholders, a critical element of the IDP and that which enables socio-technical responses to complex problems, is scarcely explored for green buildings (Ikudayisi et al. 2022; Li et al. 2022), and by extension even less so for NZBs. A conceptual framework is needed to structure and inform the purpose of engagement methods.

Design frameworks that promote the IDP are iterative, compatible with participant objectives (to facilitate goal-setting) and collaborative (Pérez-Bou et al. 2024). They should go beyond multidisciplinarity and facilitate interdisciplinarity (Shen et al. 2024), flexibility and non-linearity (Abensur et al. 2023) to allow the interaction of diverse stakeholders to share tacit knowledge and elicit quantified values using a holistic, socio-technical approach to building performance, at both the building-scale and the scale of their surrounding contextual environment (Li et al. 2022).

The framework should promote effective collaboration amongst technical and non-technical stakeholders (Abensur et al. 2023) to meet the iterative briefing requirements required for statutory approval ‘milestones’ in practice. Such a framework would assume that participants are open to learning from one another’s expertise and challenge preexisting assumptions (Schön 1983), and that the integration of transient stakeholder values would be beneficial to its iterative nature in understanding how design factors must be diversified to align with the idiosyncrasy of contemporary building designs (Li et al. 2022). Alternative approaches can be useful for linear, analytic engineering-focused problem work, such as axiomatic design (Bleil de Souza et al. 2023), but are restricted by the rigidity in accommodating briefing and decision-support methods.

1.4 Double diamond method (DDM)

The DDM (Design Council 2005) is chosen as the conceptual framework. It facilitates a synergistic interplay between subsequent divergent thinking (exploring a problem more widely) and convergent thinking (taking focused action) to create the ‘double diamond’ shape in four stages of participatory design: discover, define, develop and deliver. The stages may be split into two phases of research (discover, define) and design (develop, deliver). The discover phase encourages creativity and exploration of the problem context, and the define stage uses convergent thinking to synthesise and refine the information to create a redefinition of the problem. The develop stage re-engages the divergent mode to generate solutions iteratively and creatively, which are tested and assessed through convergence in the deliver stage. The develop and deliver stages would comprise solution ideation, performance assessment and solution delivery through evaluation, utilising the stakeholder engagement results to achieve value-driven design for performance.

1.5 Research aims and objectives

The aim of this study is to conduct the adapted DDM’s research phase (Figure 1) with three live case study projects, constituting the development and testing of effective stakeholder engagement methods for early-stage NZBs. The ‘problem’ is the holistic balancing of technical, environmental, economic and social (TEES) design aspects, involving interdisciplinary stakeholders who hold tacit knowledge and value systems regarding how best to address the problem. This problem first requires a redefinition through a synthesis of stakeholder engagement methods (Figure 1).

Figure 1

The conceptual scaffolding of the DDM aims to promote divergent thinking (discover) for the elicitation of tacit stakeholder knowledge and values and subsequent identification of the socio-technical brief redefinition (define). Whilst the design phase is outside the scope of this paper, the complete adapted DDM framework approach serves as a possible approach for designers in promoting effective stakeholder engagement and value-driven design for performance. Case study application aims to compare the process of identifying pathways to localised solutions which balance meeting carbon targets, the provision of healthy environments, economic feasibility and social outcomes for comparability purposes.

Specifically, the study pursues the following objectives:

• the development of engagement methods to understand users, gather contextual knowledge and elicit values with respect to building performance aspects

• the testing and evaluation of these methods with three case studies and

• the identification of potential uses of the approach for AEC practice and IDP research.

2.1 Cross-case comparison

A case study approach is used to build upon recommendations in the literature to test the criticality of localised knowledge and values through engagement methods in practice for NZBs. Cross-case analysis is used to highlight the commonalities and differences between the units of analysis of the case studies (Khan & VanWynsberghe 2008). In this case, the focus is on engagement conditions, processes and results. A case-oriented approach enables conditional generalisation through the identification of commonalties in phenomena across cases (Miles & Huberman 1994). Several issues exist for pursuing generalisability in cross-case research (Khan & VanWynsberghe 2008). The present study provides comparable insights based on sufficient similarities between units of analysis. This also allows a test of the framework’s adaptability to context.

Criteria for case inclusion were therefore important to ensure likeness between cases. The selected projects were live early-stage, non-domestic, new-build design projects (RIBA/RIAI stages 2–3 or equivalent),¹ medium-sized (1000–10,000 m²), with three to four floors. Project teams were chosen for practising the IDP and having exemplary aspirations for operational and embodied carbon alongside a desire to integrate environmental and social values as design factors as part of the design brief. Both technical and non-technical stakeholders were identified for each case study from a review of the available project documentation, enabling a study of the enabling conditions of the IDP (Ikudayisi et al. 2022), in particular the human factors (Pérez-Bou et al. 2024).

Case locations were a key difference to facilitate the investigation differences in units of analysis between climatic zones and levels of development (Myint et al. 2025). This approach strengthens the testing of the framework and its use for practitioners through a triangulation of findings between evidence sources and stakeholder groups. Case studies A and B constituted examples from developed economies (Ireland and the UK, respectively) whilst case study C (Rwanda) is an example from a least developed country (UNDESA 2025). The cases are summarised in Table 1.

A variety of construction professionals, property/facility users, and policymakers and statutory body stakeholders with an active role or stake in the building’s design process were involved for each case study, and are reported alongside attendance and response rates in Appendix A in the supplemental data online. All stakeholders had a minimum of 10 years of industry experience and represented varied organisations to validate and diversify contributions.

2.2 Discover

The discover stage of the research phase comprised three methods for collecting and integrating interdisciplinary knowledge and values into the IDP. The following section will outline the content of the consultation survey, contextualise workshop and priority weighting workshop. The discover stage’s conceptual scaffolding of divergence is used to inform the development of the three methods. Designers view knowledge generation, creativity and innovation as integral to the IDP, but require support in creating conducive environments that support equitable, creative contributions and interactions between client/project managers (Barrett 2018).

2.2.2 Contextualise workshop

The goal of the contextualise workshop was to gather tacit knowledge from the technical and non-technical stakeholders alike. The workshop goal was for stakeholders to propose and discuss the key drivers and barriers for maximising building performance and consider the systemic interconnections of items in response to context. The activity goes beyond typical ‘site analysis’ exercises used in AEC practice and traditional drivers and barriers research (which typically uses rigid, closed surveys) taking an exploratory approach to building performance related aspects at building and site level across TEES categories.

The open-ended approach aims to capture similar benefits of the grounded-theory style (non-prescribed) approach to the drivers and barriers exercise by reducing the bias toward fixed alternatives and encouraging more comments to be made (Donglong & Clarkson 2022). The activity also shares similarities with force-field analytical tools deployed in research (Rebalski et al. 2022) by including impact scores (six-point scale) to establish positive–negative distinctions in variables. Combined with the categorisation of variables using TEES, the systemic importance of variables was identified. This study also addressed the temporal element by assigning a building’s life-cycle stages to perceived impact timing.

During the workshop, participants were asked to complete three stages of the task: (1) identify drivers and barriers; (2) categorise them according to TEES; and (3) assign an impact score (on a 1–3 scale, where positive = driver and negative = barrier). The authors added temporal detail by assigning the variables to phases of a typical construction project timeline. The workshop template is shown in Figure 2.

Figure 2

2.2.3 Priority weighting workshop

The analytic hierarchy process (AHP), developed by Saaty (1990), is a multi-criteria decision analysis method that allows individual and group preferences to be mathematically calculated based on the completion of a pairwise comparison matrix, and a well-established tool in eliciting and analysing stakeholder preference (Arafat et al. 2023; Bhyan et al. 2023; Gashaw et al. 2023; Li et al. 2023). The second workshop comprised an application of the AHP weighting exercise for a problem hierarchy for maximising building performance. The hierarchy built upon the TEES categories used in the contextualise workshop, incorporating additional levels of detail.

The AHP is adopted here as a tool for value elicitation (priority weighting). The exercise aimed to ascertain the relative importance of building performance aspects according to stakeholders when endeavouring the maximising building performance. The complex task of balancing TEES performance aspects was the hierarchical goal. The sub-criteria of meeting carbon targets (technical), provision of healthy environments (environmental), social outcomes (social) and financial feasibility (economic) comprised the next hierarchy level. Detailed criteria for building performance were derived from a literature review and the authors’ knowledge of both quantifiable and less tangible elements of building performance to fill in any gaps (Figure 3) and comprised the final hierarchy level. The hierarchy aimed to be holistic and was validated by screening with stakeholders. No changes were suggested in any case studies.

Figure 3

The AHP exercise was completed individually by stakeholders using the online software AHP-OS (Goepel 2018). The consistency ratio (CR) was calculated to enable later removal of inconsistent judgements (CR < 10%) if necessary.

2.3 Define

The progression of the DDM from the discover phase to the define phase required the organisation and sharing of results generated in the discover stage with the case study groups. The organisation encompassed the strategic analysis of the results of the three activities ensuring a central stakeholder knowledge and value narrative (Design Council 2019). Key quotations from stakeholders regarding the carbon square were highlighted from the consultation survey alongside the ranking results, to formalise stakeholder motivations in the AEC industry. The categorical, temporal and impact score data were combined visually for the contextual drivers and barriers to highlight systemic connections and identify pathways to maximising performance. Finally, individual weighting scores were aggregated into group averages to align the group’s design intent. The results were collated and shared via online presentations with stakeholders, highlighting narrative themes across methods.

2.4 Participant evaluation

Stakeholders were asked to screen and assess the importance of evaluation criteria (see Appendix A in the supplemental data online) relating to their participation. The criteria used were based upon the established use of universal and local criteria and adapted into local criteria for this context. Establishing these criteria a-priori is an important step in good practice evaluation (Reed et al. 2018) and enables the transparent longitudinal assessment of participation in the devised activities (Rowe & Frewer 2004).

A brief online survey was sent to participants after workshop completion. Analysis comprises a comparison of the calculated mean scores of pre-rated participation criteria to the reflective ratings post-completion of workshop activities 1 and 2 using a ‘success profile’, coupled with any additional written feedback from stakeholders about the performance of the workshop activities.

3.1 Consultation survey

The ranking of the carbon square variables (Figure 4) demonstrated that case studies A–C each responded to the addition of carbon to the traditional construction project management triangle of time, cost and quality by generally elevating it to the second most important driver of a construction project. Whilst quality consistently received the greatest number votes as the most important driver, carbon received the second most for case studies A and C. Case study B placed it third most important behind cost. Time received the least votes across the case studies.

Figure 4

Alongside its consistently high ranking, the indication of the fundamentality of quality to a project’s success was present across the case studies in the open-ended response mechanism; multiple quotations were given for each case study on the importance of quality. Across cases, the inexplicable link between quality and longevity according to stakeholders is commonly highlighted (Table 3). Stakeholders across case studies B and C inferred that a higher quality building is believed to reduce carbon. This was stated directly about maintenance cycles and indirectly about refurbishment or replacement.

Considering carbon specifically (Table 4), it is perceived as a variable that must be top of the agenda, and used as a tool for education in championing high quality and sustainability (architect, case study A). A case study B engineer took a different view, separating it entirely from the design process and considering it as an external pressure originating from a global crisis. These parallel but contrastingly scaled views both pay attention to a final perspective (architect, case study C): designers have a collective responsibility to channel their own awareness into educating clients through a demonstration of the sustainability of material choices.

3.2 Contextualise workshop

Case study A generated 25 drivers and eight barriers (see Appendix C in the supplemental data online). Whilst the drivers were spread across TEES categories, no social barriers were identified and were therefore a mix of TEES items. Most items discussed were attributed to the design stage, whilst the remaining items were spread almost evenly across the concept, construction and operation stages. No items were suggested for the end-of-life stage (Figure 5).

Figure 5

Case study B generated 30 drivers and 28 barriers (see Appendix D in the supplemental data online). Drivers were generally spread across the TEES categories, with a prevalence of social and technical items. Technical barriers were the largest response category. Most items discussed were attributed to the design and operation stages, whilst the remaining items were across concept and construction. One item was suggested for the end-of-life stage (Figure 5).

Case study C generated 19 drivers and 24 barriers (see Appendix E in the supplemental data online). The items discussed were generally within the design and construction phases, with a smaller proportion in the concept and operation phases, whilst no items attributed to the end-of-life stage were discussed (Figure 5).

In case study A, an action-minded client was important for maximising technical (impact score = 2), environmental (3) and social (3) building performance (see Appendix C in the supplemental data online), whilst in case study B, the items relating to the design team declaring a climate emergency (technical = 3; environmental = 3; social = 3) and the council declaring a climate emergency (technical = 2; environmental = 3; social = 3) were the most impactful drivers (see Appendix D online). Whilst case study C also highlighted the developer driving the sustainability of the master plan as the most important driver (see Appendix E online), it also proposed numerous drivers relating to local capacity-building. These included: reducing barriers to sustainable design through local material use for future projects was an important driver (economic = 3; environmental = 3; social = 3), improving the local school supply chain specifically (economic = 3; social = 3); using local, sustainable materials to educate within the school (see Appendix E online); and the development of new local institutions to deliver sustainable, local building materials (environmental = 2; social = 2).

Stakeholders expressed frustration at a lack of regulatory mechanisms (no defined reward for NZB; technical = 1; economic = 1; environmental = 1); and a lack of regulation on embodied carbon (technical = 1; environmental = 1; and current policy does not support low carbon buildings) in case study B.

In case study A, certification issues relating to circular economy potential (technical = 2; economic = 1; environmental = 1) were the most important barrier to maximising building performance. It was also noted that the stakeholders in case study A reinterpreted the impact scale to their context and were keen to stress that barriers with an impact score of 1 or 2 were generally not seen as negative, but more so as challenges that would enrich the design upon engagement and research into them.

In case study C, stakeholders identified two significant technical challenges in a lack of technical skill (technical = 3; social = 2) and the height of the building requiring concrete (technical = 3; economic = 1), whilst no defined school stakeholder present for the school was another highly ranked barrier (technical = 3; social = 2).

3.3 Priority weighting workshop

The results for the AHP demonstrated similarities between group judgement across level 1 hierarchy elements (see Appendix F in the supplemental data online). The provision of healthy indoor environments (environmental) was consistently the most important aspect of maximising building performance for case studies A and B. It scored second most important for case study C. In Appendix F online, the AHP summarises the results before and after inconsistent judgement removal, showing that environmental aspects remain the most important (case study A = 0.303, case study B = 0.340), whilst in all cases, social becomes more important (case study A = 0.254, case study B = 0.340, case study C = 0.455). Technical aspects are more important to the case study A (0.189) group than case studies B (0.122) and C (0.103).

At level 2 of the hierarchy, operational carbon (case study A = 0.729, case study B = 0.645) is deemed relatively more important than embodied carbon (case study A = 0.271, case study B = 0.355) at a similar weighting ratio or equal (case study C = 0.500) (see Appendix G in the supplemental data online). Similarly, IEQ (case study A = 0.613, case study B = 0.614) is deemed more important than outdoor environmental quality (case study A = 0.387, case study B = 0.386), and equal for case study C (0.500). Economic rankings demonstrate a preference for economic resilience (case study A = 0.350, case study B = 0.408) and energy costs (case study C = 0.357) as the most important aspect of performance. User health and wellbeing remains the most important social aspect for case study A (0.414) and case study C (0.413), whilst community wealth-building remains the most important social aspect after inconsistent judgement removal for case study B (0.386).

Environmental aspects receive the highest group priority ratings. Occupant comfort related aspects of indoor air quality for case study A (0.142), thermal comfort for case study B (0.084) and urban heat island effect for case study C (0.152) are the most relatively important. Economic aspects, such as economic resilience, receive relatively high importance for case study A (0.060) and case study B (0.081), but have the lowest relative priority for case study C overall. Case studies A and B placed a moderately high importance on occupant-related social aspects, namely physical health and mental health; case study C rated all social aspects, in particular these two aspects, highly. Technical aspects consistently rank the lowest between case studies A and B, particularly those relating to carbon. It was observed that operational energy-related aspects rank the highest of the technical aspects (space-conditioning for case study A = 0.066, appliances and equipment for case study B = 0.028) and end-of-life carbon ranks the lowest of all aspects (case study A = 0.011, case study B = 0.008). Case study C ranks technical aspects relatively low, with operational carbon receiving the highest relative rating (0.330). Case study A places a particularly high relative weighting for IEQ and other environmental impacts aspects, whereas there is more observed spread in relative importance for case study B. Case study C places a particularly high relative importance on environmental and social aspects (Figure 6).

Figure 6

3.4 Participant evaluation

The evaluation of the activities is shown in Figure 7 through a presentation of the pre-framework criteria screening completed before engagement and the workshop participation evaluations. For the full question list, see Appendix B in the supplemental data online.

Figure 7

The first observation was the appropriate selection of participation evaluation criteria for this context of evaluating participatory design process activities. All criteria screened with the case studies received above-neutral (3.0) scores from the calculated medians, indicating that they are suitable for future application in participatory design exercises. The second observation to note was that relative to the screening exercise, both workshop activities received positive evaluation scores across all criteria for all case studies (Figure 7) for attainment, with the exception of attitudinal impacts for case study B scoring 2.5 for each workshop.

For case study A, all criteria received positive scores both workshops. It achieved evaluation scores of ≥ 4.0 for all criteria across both workshops, with the exception of representativeness at 3.5 for the contextualise workshop. In both workshops, a score of 4.5 was given for incorporation of values, and in the priority workshop for conceptual impacts and iterativity (Figure 7). For case study B, scores > 4.0 were given for representation and incorporation of values for both workshops. Whilst scores were positive for conceptual impacts (contextualise = 3.5, priority = 3.0) and iterativity (both = 3.5), they were below screening rankings. Attitudinal impacts was the only criterion to score below neutral (2.5) for both workshops (Figure 7). For case study C, scores of 5.0 were recorded for both workshops for representation, incorporation of values and compatibility with objectives. A score of 4.5 was given for attitudinal impacts and iterativity. Conceptual impacts received a score of 3.0 (Figure 7).

The medians for both workshops were used to highlight the successful characteristics of the stakeholder engagement approach generally. All criteria scored above neutral, with most criteria scoring > 4.0. The highest scoring criterion was incorporation of values (contextualise = 4.8, priority = 4.7). The lowest scoring criteria were conceptual impacts and attitudinal impacts (both workshops = 3.5) (Table 5).

Participants also provided written feedback based on the completion of the workshop exercises. These comments are presented in Table 6 and discussed further below.

4.1 DDM to promote the IDP

The DDM’s conceptual structure during the research phase to use (first) divergent thinking (discover) modes effectively accommodated three briefing methods for interdisciplinary knowledge generation. The research phase then used convergent thinking modes (define) of interdisciplinary knowledge synthesisation using the key outputs of the discover phase. An explanation of the envisaged uses of the discover and define outputs tested in this work via IDP collaboration for AEC practice will now be outlined.

4.1.1 Discover

The consultation survey prompted the technical participants to reflect on and appreciate the projects’ position of responsibility within a changing AEC industry. Responses from the stakeholders echoed a shared sentiment of the importance of carbon relative to the logistical and economic factors of construction. AEC practitioners might find use in this reflective survey in establishing the motivations of technical team members. In turn, this can be used to justify the necessity of promoting interdisciplinary work through the IDP, where collaborative work requires additional budgetary and resourcing allowances than conventional design activities.

Whilst evidently suitable for cases at both stages 2 and 3, case study A scored the contextualise workshop exercise the highest for iterativity potential (case study A was the only project at stage 2). Projects in the later RIBA/RIAI stage 3 or equivalent may require stronger evidence for the quantification of systemic interconnections to enable knowledge utilisation than the subjective impact scoring undertaken here. The following example from case study C of systemically addressing regional low carbon building materials (compressed stabilised earth blocks) provides a basis for discussion (Figure 8).

Figure 8

As projects mature, the integration of stronger quantitative evidence is needed to match the greater liability risk involved in decision-making. Systems thinking provides a conceptual and methodological approach for modelling systemic relations and interdependence. Note here the potential use of the contextualise workshop as a means to building qualitative causal loop diagrams (CLDs) noting the structural similarities in Figure 8 with that of a CLD. Quantitative modelling of the interconnections (systems dynamics) could use decision-analysis methods, such as ex-ante building performance modelling, to provide evidence of trade-offs between operational and embodied carbon, occupant comfort, and economic performance, amongst other metrics for use in such models to test feedback loops and leverage points, which could be of significant use to decision-makers.

A platform for equitable value elicitation was demonstrated using the AHP’s weighting function to establish individual priorities in maximising building design. Considering building performance holistically across its component TEES elements, the provision of healthy environments dominated the AHP results across all cases when group averages were taken. This might be expected to be the result of the group average weighting when including technical and non-technical stakeholders. However, when sorting case study B stakeholders into the construction professionals (n = 1) and property/facility user (n = 2) groups, it was observed that the groups shared the most consensus across technical and social categories in terms of the low relative weightings given to the components (Figure 9).

Figure 9

The removal of inconsistent judgements was necessary to perform such an analysis, and this significantly reduces the available sample. Increasing sample size to diversify further the stakeholder responses could be achieved in practice by iteratively surveying project teams (suiting the transient nature of project team personnel), enabling longitudinal assessment of the transience of group priorities with the inclusion of varied expertise and knowledge. This is evidenced in the present study as the exercise was rated strongly for iteration (see Section 3.4) and through written stakeholder feedback (Table 6):

I feel there would be significant value in this exercise at the beginning and throughout a project.

(case study B)

The limits of participation in this study are discussed further below.

4.2 Evaluation of stakeholder participation

4.3 Cross-case diversity

Initial observations on the diversity of the case studies are presented below. These will be explored further upon completion of the design phase of the DDM.