An integrated GT–Kano–AHP–QFD–VIKOR framework for the sustainable design of Chinese reclaimed ship timber furniture

Abstract

Old ship timber is a wood resource that combines reuse potential, cultural significance, and distinctive aesthetic characteristics. By extending the material life cycle and promoting resource circularity, it provides potential value for sustainable furniture design. However, wood furniture design remains limited by insufficient requirement identification, experience-driven decisions, and inadequate integration of cultural values with contemporary functional needs. To address these challenges, this study focused on Chinese old ship timber furniture and proposes a sustainable design decision-making framework integrating Grounded Theory (GT), Kano model, the Analytic Hierarchy Process (AHP), Quality Function Deployment (QFD), and VIKOR. Semi-structured interviews were conducted with 15 participants to capture users’ perceptions, and GT identified five categories of user requirements—functional, visual, cultural, material, and market-related—comprising 15 elements. Kano classified these requirements, while AHP quantified their relative importance, identifying material expressiveness, ergonomic performance, and style compatibility as the highest-priority requirements. QFD translated these priorities into nine technical characteristics, and VIKOR evaluated four design schemes. Results indicate that Scheme 2, emphasizing the integration of reclaimed ship timber with contemporary living environments, achieved the highest overall evaluation score. The findings suggest that the framework supports requirement identification, technical translation, and alternative selection for sustainable furniture design.

Full Article

An Integrated GT–Kano–AHP–QFD–VIKOR Framework for the Sustainable Design of Chinese Reclaimed Ship Timber Furniture

Jiani Han ,^a Xiaohui Liu ,^b Yuanshuai Yang ,^a and Chengyue Xiao, ^c,*

Old ship timber is a wood resource that combines reuse potential, cultural significance, and distinctive aesthetic characteristics. By extending the material life cycle and promoting resource circularity, it provides potential value for sustainable furniture design. However, wood furniture design remains limited by insufficient requirement identification, experience-driven decisions, and inadequate integration of cultural values with contemporary functional needs. To address these challenges, this study focused on Chinese old ship timber furniture and proposes a sustainable design decision-making framework integrating Grounded Theory (GT), Kano model, the Analytic Hierarchy Process (AHP), Quality Function Deployment (QFD), and VIKOR. Semi-structured interviews were conducted with 15 participants to capture users’ perceptions, and GT identified five categories of user requirements—functional, visual, cultural, material, and market-related—comprising 15 elements. Kano classified these requirements, while AHP quantified their relative importance, identifying material expressiveness, ergonomic performance, and style compatibility as the highest-priority requirements. QFD translated these priorities into nine technical characteristics, and VIKOR evaluated four design schemes. Results indicate that Scheme 2, emphasizing the integration of reclaimed ship timber with contemporary living environments, achieved the highest overall evaluation score. The findings suggest that the framework supports requirement identification, technical translation, and alternative selection for sustainable furniture design.

DOI: 10.15376/biores.21.4.10886-10920

Keywords: Chinese Reclaimed Ship Timber Furniture; Sustainable furniture design; GT–Kano–AHP–QFD–VIKOR; Integrated decision-making framework

Contact information: a: Department of Environmental Design, Qingdao Huanghai University, No.1145 Linghai Road, Huangdao District, Qingdao, Shandong Province, China, NC 266555 CN; b: Department of Design, Graduate School, Hanyang University,222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea, KR; c: Hunan Polytechnic of Environment and Biology，No. 165 Wangcheng Road, Shigu District, Hengyang, Hunan Province, China, NC 421005 CN;

* Corresponding author: [email protected]

INTRODUCTION

Sustainability has become a central focus across multiple disciplines, encompassing environmental, cultural, economic, and social dimensions (Hariram et al. 2023). Among its key objectives, resource efficiency and circular utilization have become important priorities in sustainable development strategies (González-García et al. 2011). As an essential consumer product, furniture can enhance public awareness of sustainability through its widespread use in residential, workplace, and tourism settings (Li et al. 2022). Moreover, owing to the complexity of material processing and manufacturing, wooden furniture offers considerable potential for optimization throughout its production lifecycle (Lin and Huang 2016).

Wood is one of the most widely used materials in the global furniture manufacturing industry (Bumgardner et al. 2020). According to international trade statistics, the cumulative export value of wooden furniture—including bedroom, kitchen, office, and other furniture products—reached USD 345.3 billion between 2015 and 2021 (International Trade Centre. 2019). During the same period, China maintained a leading position in the global market, accounting for USD 93.8 billion in exports across these four product categories. Previous studies have consistently highlighted the importance of strengthening sustainability practices within the wooden furniture industry to reduce the approximately 10 million tonnes of waste furniture disposed of in landfills annually (Seyajah et al. 2016; Bosch et al. 2017; Vicente et al. 2017; Koszewska and Bielecki 2020). Consequently, sustainability has emerged as a key consideration in design decision-making throughout the wood processing and furniture manufacturing sectors (Bumgardner et al. 2020).

China has become one of the world’s leading and most competitive furniture exporters (Li and Zhao 2023). In response, the Guidelines for the Sustainable Development of China’s Cultural Furniture Industry emphasize the role of innovative design in environmental protection and advocate the integration of digital technologies and artificial intelligence (AI) to improve design efficiency and product quality (Fan and Yi 2024; Fu et al. 2025). As an important category of recycled materials in the furniture industry, old ship timber offers considerable potential to enhance the social, cultural, and environmental value of furniture products. Old ship timber refers to wood reclaimed from dismantled wooden vessels. Originally used in the construction of seagoing ships, it typically comprises high-quality hardwoods, such as elm, merbau, ironwood, and sandalwood, which are characterized by high density, exceptional hardness, and naturally occurring oils or waxes developed over decades of growth. Long-term exposure to the marine environment contributes to distinctive grain patterns and surface textures, while the physical properties of reclaimed ship timber may vary depending on species, service history, and preservation conditions. These characteristics make old ship timber a valuable recycled material with significant cultural heritage, strong resource-circulation potential, and substantial promise for furniture design. Previous studies have demonstrated the design potential of old ship timber furniture. Li et al. (2012) suggested that reclaimed ship timber has broad application prospects in furniture manufacturing and argued that innovative designs can be effectively developed by leveraging its intrinsic material properties in conjunction with fundamental design principles. Similarly, Luo et al. (2023) examined the value of old ship timber from artistic, cultural, and ecological perspectives and proposed design strategies based on form redesign, cultural empowerment, and consumer-oriented development.

Although the circular economy and the use of reclaimed wood have become prominent topics in furniture design research, existing studies have focused on material substitution and resource recovery. Limited attention has been given to the systematic integration of design principles into user requirement identification, the translation of user needs into design attributes, and design decision-making. Moreover, the design of old ship timber furniture continues to rely heavily on experience-based approaches, with insufficient exploration of user requirements and inadequate integration of cultural values with contemporary functional needs. Consequently, the potential of old ship timber has not been fully realized throughout the product development process. Developing a systematic design decision-making framework that simultaneously addresses user requirements, cultural heritage is therefore essential for advancing innovation in old ship timber furniture design. User-centered design has emerged as an effective paradigm for addressing these challenges.

Among the available approaches, Grounded Theory (GT), the Kano model, the Analytic Hierarchy Process (AHP), and Quality Function Deployment (QFD) are widely recognized as core methods for identifying, prioritizing, and translating user requirements into design solutions. Grounded Theory is particularly effective in eliciting both explicit and latent user needs from complex social contexts (Urquhart et al. 2010). The Kano model has been applied to identify and classify user requirements in product design (Xu et al. 2009). For example, Taifa and Desai (2016) and Kapuria et al. (2020) employed the Kano model to analyze students’ needs, satisfaction, and requirement attributes for classroom furniture, subsequently proposing scientifically grounded redesign strategies. Despite its effectiveness in classifying and prioritizing user requirements, the Kano model is susceptible to ambiguity arising from variations in user perceptions. Consequently, a robust quantitative approach is required to evaluate these perceptual differences. As a decision-making method that integrates qualitative judgment with quantitative analysis, AHP effectively addresses inconsistencies associated with heterogeneous user perceptions (Chen et al. 2024). Xiao et al. (2024) integrated user requirement analysis with AHP to develop a sustainable evaluation framework for office furniture, providing valuable guidance for sustainable furniture design, management, and research. To enhance methodological integration and practical applicability, researchers have increasingly combined AHP with QFD to establish systematic requirement-to-function transformation models. Fan and Wang (2025) applied the Kano model to identify and classify consumer requirements for gift packaging, employed AHP to determine the relative importance of design criteria, and used QFD to translate these requirements into specific design parameters. The resulting sustainable packaging solutions not only satisfied users’ functional and aesthetic expectations but also significantly enhanced environmental awareness. With the growing emphasis on sustainability in design research, multi-criteria decision-making (MCDM) methods have been increasingly adopted to evaluate and optimize design alternatives. This study incorporated the VIseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) method, which effectively resolves conflicts and trade-offs among multiple evaluation criteria. As a multi-criteria optimization technique, VIKOR ranks design alternatives by jointly considering the group utility measure, the individual regret measure, and the compromise solution index (Wang et al. 2022). For example, Arıkan Kargı and Cesur (2024) applied VIKOR to support technology selection in hotel building production processes, providing stakeholders with a comprehensive multi-criteria decision-making framework for evaluating renewable energy technologies.

Building on the preceding discussion, this study proposes an integrated decision-making framework based on the GT-Kano-AHP-QFD-VIKOR methodology. By integrating qualitative inquiry with quantitative decision-making methods, the framework establishes a multi-level, multi-source approach for supporting sustainable furniture design. First, Grounded Theory (GT) was employed to analyze semi-structured interview data and develop a comprehensive framework of user requirements for old ship timber furniture. Second, a structured questionnaire based on the Kano model was designed to classify user requirements and evaluate their asymmetric effects on customer satisfaction. Third, the Analytic Hierarchy Process (AHP) was applied to determine the relative importance of user requirements through expert judgment, thereby quantifying their weights within the decision-making framework. Fourth, Quality Function Deployment (QFD) was used to translate the weighted user requirements into actionable design and sustainability attributes. Finally, the VIseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) method was employed to conduct a multi-criteria compromise evaluation of alternative old ship timber furniture design schemes, identifying the optimal solution by balancing user experience, cultural heritage preservation, and design feasibility.

Although previous studies have explored reclaimed wood utilization, sustainable furniture design, and consumer-oriented product development, existing research has mainly focused on material characterization, environmental benefit analysis, or design case exploration. However, studies on how to integrate user requirement identification with systematic decision-making approaches and apply them to reclaimed wood furniture design and development remain relatively limited. This study focuses on transforming reclaimed ship timber into value-added furniture products through a user-driven and multi-criteria decision-making approach.

By integrating grounded theory (GT), the Kano model, analytic hierarchy process (AHP), quality function deployment (QFD), and the VIKOR method, this study establishes a systematic pathway from the extraction of user-perceived requirements to the optimization and selection of design concepts. Therefore, the novelty of this study does not solely lie in the application of individual evaluation methods, but rather in the development of an integrated design decision-making framework that connects cultural perception, functional requirements, sustainable value, and furniture design decision processes, providing a new research pathway for reclaimed wood furniture development.

EXPERIMENTAL

Experimental Processes

With the growing emphasis on sustainable development and increasing consumer expectations regarding the functional, emotional, cultural, and ecological attributes of furniture, traditional experience-based design approaches are no longer sufficient to address the multidimensional decision-making challenges associated with recycled-material furniture development. This limitation is particularly evident in the design of old ship timber furniture, which combines the environmental benefits of material reuse with rich historical and cultural significance and distinctive aesthetic value. To address these challenges, this study takes old ship timber furniture as the research object and proposes an integrated design framework based on the GT-Kano-AHP-QFD-VIKOR methodology to support systematic, user-centered, and sustainable furniture design decision-making.

Grounded Theory (GT) was employed to analyze the semi-structured interview data through open, axial, and selective coding. This process enabled the systematic abstraction and categorization of user perceptions, resulting in a comprehensive framework of user requirements for old ship timber furniture and improving the rigor and reliability of user need identification (Glaser and Strauss 1967). Subsequently, the Kano model was applied to classify the attributes of user requirements, determine their impact coefficients and priority levels, and identify the critical needs that should guide product design. This analysis provided clear design priorities and strategic direction for the development of old ship timber furniture while enhancing user satisfaction. The Analytic Hierarchy Process (AHP) was then employed to construct a hierarchical evaluation model. Domain experts conducted pairwise comparisons of the identified user requirements, and the relative weights of each criterion were calculated and validated through consistency testing to determine their importance in the overall design decision-making process (Saaty 2008). The prioritized user requirements were subsequently translated into specific technical characteristics using Quality Function Deployment (QFD), enabling abstract user expectations to be systematically converted into actionable design strategies. To resolve potential trade-offs among user satisfaction, sustainability performance, and design feasibility, the VIKOR method was employed to conduct a comprehensive multi-criteria evaluation of alternative old ship timber furniture design schemes. The research framework is presented in Fig. 1.

Fig. 1. Research framework

Data Collection

In qualitative research, sample adequacy is generally determined by research objectives, participant diversity, and theoretical saturation rather than a fixed numerical threshold. Accordingly, this study employed purposive sampling to recruit 15 participants from three key user groups: the traditional craftsmanship group (n=6), the modern usage scenario group (n=6), and the theoretical validation group (n=3). The participant selection was designed to ensure diversity of perspectives related to old ship timber furniture, including traditional craftsmanship, practical usage, material knowledge, and sustainable design considerations.

Semi-structured interviews, each lasting approximately 30 to 45 min, were conducted to explore participants’ perceptions and understanding of old ship timber furniture and its cultural significance. An interview guide was developed to examine four key dimensions: functional requirements, appearance and spatial compatibility, cultural and historical perceptions, and material applications. The interview protocol is presented in Table 1. All interviews were conducted face-to-face in Chinese, and the collected data were transcribed and analyzed for subsequent Grounded Theory coding.

Table 1. Semi-Structured Interview Guide

The traditional craftsmanship group consisted of four traditional woodworkers and two artisans specializing in wood decoration. These participants were selected because of their extensive knowledge of wood properties and the symbolic meanings embedded in traditional craftsmanship. The modern usage scenario group included three users from regions where old ship timber furniture is commonly found and three cultural tourism consumers. The former provided insights into practical issues encountered during everyday use, whereas the latter offered perspectives on contemporary aesthetic preferences and market expectations.

The theoretical validation group comprised one furniture design scholar, one materials science expert, and one sustainable design researcher. The furniture design scholar ensured the logical consistency of translating user requirements into design characteristics, the materials science researcher validated the interpretation of old ship timber properties and its potential applications, and the sustainable design researcher assessed the sustainability-related implications derived from the qualitative findings.

The selection criteria were established to ensure that participants possessed relevant knowledge and practical experience related to old ship timber furniture, traditional craftsmanship, furniture design, or material applications. Participants were required to have professional backgrounds or practical experience in related fields, including traditional woodworking, furniture design, material research, cultural studies related to traditional craftsmanship, or sustainable design. In addition, participants with direct experience in reclaimed timber processing, furniture use, or cultural tourism consumption were prioritized to ensure the richness and relevance of the collected qualitative data. The detailed demographic characteristics and professional backgrounds of all participants are summarized in Table 2.

Table 2. Participant Demographics and Professional Backgrounds

The interview transcripts from the 15 participants were analyzed line by line using the Grounded Theory coding procedure. The analysis comprised three sequential stages: open coding, axial coding, and selective coding. As shown in Table 3, open coding yielded 23 initial concepts. During axial coding, these concepts were organized into related categories, and their interrelationships were examined to establish the major categories. Building on the results of the open and axial coding stages, selective coding was subsequently conducted to integrate the overall structure of user requirements for old ship timber furniture, as presented in Table 4.

The results indicate that user requirements for old ship timber furniture extend beyond basic functional considerations and constitute a multidimensional system comprising five core categories: functional, visual, cultural, material, and market requirements. To assess the reliability of the coding process, ten transcripts were selected for initial coding, while five additional transcripts were reserved as validation samples. After the initial coding framework was established, the five reserved transcripts were re-examined using the same coding procedure. No additional concepts, categories, or relationships emerged during this validation, indicating that theoretical saturation had been achieved.

Construct the Kano Model

Based on the results of the open coding stage of the Grounded Theory analysis, a Kano-based questionnaire was developed to systematically classify user requirements according to Kano categories (Jin et al. 2022). The questionnaire employed a two-dimensional evaluation approach, in which each user requirement attribute was assessed using both functional (positive) and dysfunctional (negative) questions. The functional question examined users’ feelings when a given attribute was provided, whereas the dysfunctional question examined users’ feelings when the attribute was absent.

Each question adopted the standard five-category Kano response format: “Dislike,” “Can Tolerate,” “Neutral,” “Must Be,” and “Like,” as shown in Fig. 2. These paired responses were subsequently combined according to the Kano evaluation matrix to classify each requirement attribute into Attractive (A), One-dimensional (O), Must-be (M), Indifferent (I), Reverse (R), or Questionable (Q) categories. The Kano questionnaire was subsequently administered to evaluate the identified user requirements. Stratified sampling was adopted to ensure representative participation from four stakeholder groups: industry practitioners, tourists, local residents, and domain experts. A total of 381 questionnaires were collected, of which 360 were valid, resulting in a valid response rate of 94.5%. The 21 invalid responses were excluded due to incomplete answers or inconsistent response patterns, and the valid samples were used for Kano classification of the identified requirements.

Fig. 2. Kano questionnaire structure for assessing user requirements in old ship timber furniture design

Table 3. Results of Open Coding

Table 4. Results of Selective Coding

Based on the questionnaire survey data, reliability and data suitability analyses were conducted using SPSS 27.0, and the results are summarized in Table 5. The consistency of the questionnaire responses was examined using Cronbach’s α coefficient. The obtained Cronbach’s α value of 0.782 exceeded the recommended threshold of 0.70, indicating acceptable consistency among the questionnaire responses. The suitability of the dataset for subsequent statistical analysis was subsequently examined using the Kaiser-Meyer-Olkin (KMO) measure and Bartlett’s test of sphericity. The questionnaire included 30 variables, consisting of functional and dysfunctional responses for the 15 requirement attributes, which corresponded to the degrees of freedom (df = 435) in Bartlett’s test. The KMO value was 0.684, exceeding the acceptable threshold of 0.60, while Bartlett’s test was statistically significant (p<0.001), indicating that the null hypothesis of no correlation among the variables could be rejected. These findings indicate that the dataset has acceptable sampling adequacy and sufficient correlations among variables, supporting its suitability for subsequent Kano classification and related analyses.

During the data processing stage, SPSS was used for data cleaning and cross-tabulation analysis. Based on the Kano evaluation matrix (Table 6), the paired responses to the functional and dysfunctional questions for each attribute were mapped to their corresponding Kano categories. The category with the highest frequency among the six Kano categories (A, O, M, I, R, and Q) was assigned as the final classification result for each requirement attribute. In cases where two categories showed the same highest frequency, the classification was determined by comparing the relative priority of functional requirements and the Kano evaluation logic. Reverse and Questionable responses were retained in the classification analysis and were reviewed during data screening to identify potential abnormal response patterns. This procedure generated the requirement classification matrix, and the resulting classification outcomes are presented in Table 7.

Table 5. Reliability and Data Suitability Test Results of Kano Questionnaire

Table 6. Kano Evaluation Matrix for User Requirement Classification

To further quantify the influence of each user requirement on customer satisfaction characteristics, the Better-Worse coefficients were calculated. The Better coefficient () measures the increase in customer satisfaction when a specific requirement is fulfilled, whereas the Worse coefficient () measures the increase in customer dissatisfaction when the requirement is not fulfilled. The calculation formulas for the Better and Worse coefficients are given in Eqs. 1 and 2, respectively,

where A is the Attractive value, O is the One-dimensional value, M is the Must-be value, and I is the Indifferent value.

The Better coefficient () is typically positive, with higher values indicating a greater increase in customer satisfaction when a specific functional attribute is provided. In contrast, the Worse coefficient () is typically negative, with more negative values indicating a greater increase in customer dissatisfaction when the corresponding functional attribute is absent.

Based on the calculated Better-Worse coefficients, a four-quadrant priority matrix was constructed to visualize the relative priority of user requirements for old ship timber furniture. The horizontal and vertical boundaries of the matrix were determined using the average values of the Better and Worse coefficients, respectively. Requirements located in different quadrants were interpreted according to their influence on satisfaction and dissatisfaction: requirements with high Better and high Worse values were considered high-priority attributes requiring improvement, while requirements with lower influence were assigned relatively lower priority.

Table 7. Kano Classification Results for User Requirements

The position of each requirement within the matrix provides an intuitive representation of its Kano priority characteristics and supports the identification of design priorities. The Kano priority results were further considered during the subsequent AHP-based weighting process to support the determination of design requirements. The resulting four-quadrant priority matrix is presented in Fig. 3.

Fig. 3. Four-quadrant better-worse matrix of user requirements for old ship timber furniture

Construct the AHP Model

To convert the qualitative assessment of user requirement importance into a rigorous quantitative evaluation, the Analytic Hierarchy Process (AHP) was incorporated following the Kano model analysis. An AHP hierarchical structure was established, as shown in Table 8, to provide a systematic framework for subsequent design decision-making. The hierarchy comprises three levels. The goal level represents Old Ship Timber Furniture Design. Based on the Kano classification results, the criteria level consists of three requirement categories: Must-be (M), One-dimensional (O), and Attractive (A). These Kano categories were selected as the criteria level because they represent different levels of user-perceived value and satisfaction influence, providing a structured basis for prioritizing requirements in the design decision-making process. The indicator level comprises 11 specific user requirements, each assigned to its corresponding criterion. Indifferent (I) attributes were excluded because they showed limited influence on user satisfaction and design priorities. In this study, Kano satisfaction coefficients were not directly incorporated into the AHP weighting process; instead, the Kano classification results were used to establish the hierarchical structure, and the relative importance of each requirement was determined through AHP evaluation.

Table 8. AHP Hierarchical Structure of User Requirements

After establishing the hierarchical structure, 13 experts with expertise in furniture design, materials science, and old ship timber culture were invited to perform pairwise comparisons of the hierarchical elements using Saaty’s 1–9 scale (Harker and Vargas 1988; Saaty and Vargas 2012). These experts were selected based on their professional experience, familiarity with furniture design evaluation, reclaimed wood applications, or traditional wood craftsmanship. Each expert independently completed the pairwise comparison questionnaire according to the established AHP hierarchy. Based on their evaluations, the individual pairwise comparison matrices were aggregated using the geometric mean method to obtain the group judgment matrix, which preserves the reciprocal property of AHP comparisons. The aggregated pairwise comparison matrix is presented in Eq. 3.

(3)

Table 9. Pairwise Comparison Matrix and Criteria Weights with Respect to the Goal Level

After determining the criteria-level weights with respect to the goal level, pairwise comparison matrices were constructed for the 11 indicator-level criteria, and their corresponding local weights were calculated, as presented in Tables 10 to 12. The global weight of each indicator was then obtained by multiplying its local weight by the weight of the corresponding criterion, followed by normalization. Finally, all indicators were ranked according to their global weights, as shown in Table 13.

Table 10. Pairwise Comparison Matrix and Local Weights of Indicator-Level Criteria under the Must-be Requirements Criterion

Table 11. Pairwise Comparison Matrix and Local Weights of Indicator-Level Criteria under the One-dimensional Requirements Criterion

Table 12. Pairwise Comparison Matrix and Local Weights of Indicator-Level Criteria under the Attractive Requirements Criterion

To ensure the reliability and validity of the calculated weights, consistency tests were performed on both the criteria-level and indicator-level judgment matrices. These tests evaluated the logical consistency of the experts’ pairwise comparisons and verified the validity of the resulting weighting system.

Table 13. Overall Priority Ranking of User Requirements

A value of less than 0.10 indicates acceptable consistency, demonstrating that the experts’ pairwise comparisons are sufficiently consistent and that the derived weights are suitable for subsequent decision-making (Padilla-Garrido et al. 2014).

Using the above procedure, consistency tests were conducted for both the criteria-level and indicator-level judgment matrices. The results are presented in Table 14. All calculated Consistency Ratio () values were below the acceptable threshold of 0.10, indicating that all judgment matrices satisfied the consistency requirement. These results demonstrate that the expert pairwise comparisons exhibited satisfactory logical consistency, thereby supporting the reliability of the derived weighting process and providing a quantitative basis for the subsequent Quality Function Deployment (QFD) analysis.

Table 14. Summary of Consistency Test Results

Constructing the QFD Model

Following the prioritization of user requirements, Quality Function Deployment (QFD) was employed to translate user requirements into actionable technical characteristics, thereby establishing a systematic linkage between customer requirements and technical solutions. The primary objective of QFD is to ensure that customer requirements are systematically identified, translated into engineering characteristics, and effectively incorporated throughout the product design and development process, thereby enhancing the alignment between design solutions and customer expectations (Hu et al. 2024).

To ensure the methodological rigor of the QFD analysis, user requirements were ranked according to their AHP-derived global weights. The top 80% of the ranked requirements were selected as the core inputs for subsequent technical mapping, resulting in a total of nine high-priority requirements. This strategy not only follows the Pareto principle to maximize customer satisfaction but also reduces the structural complexity of the House of Quality (HOQ), thereby improving the clarity and interpretability of the evaluation process (Dunford et al. 2014). To establish an effective correspondence between user requirements and technical characteristics, the research team synthesized evidence from user interviews, expert workshops, and representative case studies to identify a preliminary set of technical characteristics for the sustainable design of old ship timber furniture.

Based on the preliminary set of technical characteristics, an independent panel of 12 experts from diverse disciplinary backgrounds was convened to evaluate the proposed mapping scheme through multiple rounds of relevance assessment. Following iterative evaluation and cross-validation, the research team identified and finalized nine key technical characteristics for the sustainable design of old ship timber furniture. The finalized technical characteristics are presented in Table 15.

Table 15. Translation of User Requirements into Technical Characteristics for the Sustainable Design of Old Ship Timber Furniture

The House of Quality (HOQ), the core tool of Quality Function Deployment (QFD) (Das and Mukherjee 2008; Xu and Chen 2025), consists of three principal components: the customer requirements-technical characteristics matrix, the relationship matrix, and the technical correlation matrix. Together, these components evaluate the strength of the relationships between customer requirements and technical characteristics while assessing the interactions among technical characteristics. As a structured decision-support tool, the HOQ quantitatively determines the contribution of each technical characteristic to satisfying specific customer requirements and identifies the priorities and synergies among alternative technical solutions throughout the product design process.

Based on the nine selected requirements and the corresponding technical characteristics identified in the previous stage, a complete House of Quality (HOQ) model was constructed. To establish the relationship matrix, the eight frequent users were selected from participants with practical experience in using or interacting with old ship timber furniture. Together with the 12 experts described above, formed a 20-member QFD evaluation panel. Using a consensus-based rating approach, the panel evaluated the strength of the relationships between each user requirement and technical characteristic. Any differences in evaluations were discussed among panel members and resolved through consensus rather than direct averaging, resulting in the final HOQ relationship matrix. As shown in Fig. 4, the user requirements are positioned on the left wall of the HOQ, with their corresponding importance weights displayed on the right wall, while the technical characteristics are arranged along the roof, forming the engineering response structure. The roof matrix represents the correlations among technical characteristics, where “+” denotes a positive correlation and “−” denotes a negative correlation (Kürüm et al. 2021; Li et al. 2023). The central relationship matrix (i.e., the body of the HOQ) characterizes the relationships between user requirements and the technical characteristics of old ship timber furniture. Relationship strengths were quantified using four levels: ▲ = strong (5), ◆ = moderate (3), ○ = weak (1), and a blank cell = no relationship (0) (Maisano et al. 2024). Based on the completed relationship matrix, the absolute importance and relative importance of each technical characteristic were subsequently calculated using Eqs. 7 through 9,

Based on the calculated importance values from the HOQ, the technical weights were normalized by dividing each technical characteristic importance value by the total importance value of all technical characteristics. The normalized QFD weights are presented in Table 16. These normalized weights were subsequently transferred to the VIKOR evaluation.

Fig. 4. House of Quality (HOQ) Model for the Sustainable Design of Old Ship Timber Furniture

Table 16. Normalized Weights of Technical Characteristics Derived from QFD

To prioritize the technical characteristics for the sustainable design of old ship timber furniture, the importance values derived from the QFD analysis were used to establish a relative priority ranking of technical characteristics. The normalized QFD weights were further used to compare the relative contributions of different technical characteristics. Based on the ranking results, a prioritized hierarchy of technical characteristics was established to identify the key design directions for sustainable old ship timber furniture. As shown in Table 17, the resulting priority hierarchy was further used to support the subsequent design evaluation and functional deployment strategy.

Table 17. Priority Ranking of Technical Characteristics for the Sustainable Design of Old Ship Timber Furniture

Level I functional analysis

Level I functions represent the First-tier priority group identified from the QFD-based ranking and define the core value of the sustainable design of old ship timber furniture through three key dimensions: the preservation of material characteristics, integration with contemporary living environments, and the expression of regional cultural heritage. D6: Natural Ship Timber Grain Preservation was identified as the highest-priority technical characteristic. By preserving the natural grain patterns and weathered textures developed through prolonged marine exposure, it reinforces the material identity of old ship timber while preserving its historical and cultural significance. D5: Contemporary Interior Integration Design focuses on enhancing the compatibility of old ship timber furniture with modern living environments. Through the application of contemporary design language and spatial adaptation strategies, it improves product versatility and market acceptance. D8: Translation of Regional Cultural Elements facilitates the reinterpretation of ship timber culture and regional cultural symbols in contemporary furniture design, thereby strengthening the product’s cultural identity and emotional value. Collectively, these Level I functions establish the core framework for the sustainable design of old ship timber furniture, providing a foundation for balancing cultural heritage with contemporary market demands.

Level II functional analysis

Level II functions represent the Second-tier Priority group identified from the QFD-based ranking and focus on enhancing user experience and sustainability performance. D4: Adaptive Design for Multiple Usage Environments improves the adaptability of old ship timber furniture to diverse climatic conditions and usage scenarios, thereby enhancing environmental resilience and extending product service life. D2: Ergonomic Support Design enhances user comfort during prolonged use by optimizing structural dimensions and the ergonomic interface between the user and the furniture. D9: Circular Application of Recycled Materials embodies the principles of the circular economy and sustainable design by improving the utilization efficiency of recycled materials, thereby contributing to enhanced resource efficiency and potential environmental benefits. Collectively, these Level II functions complement the Level I functions by improving product performance and further reinforcing the sustainable design value of old ship timber furniture.

Level III functional analysis

Level III functions represent the Third-tier Priority group identified from the QFD-based ranking and primarily support product realization and market implementation. D1: High-Stability Structural Design enhances furniture safety and durability by optimizing structural connections and load-bearing systems, thereby ensuring long-term structural reliability. D7: Modular Functional Design improves functional flexibility and spatial adaptability, enabling the furniture to accommodate diverse user needs and usage contexts. D3: Cost-Effective Composite Material Design explores the potential application of composite materials and optimized production strategies to support manufacturing feasibility and market competitiveness while maintaining the functional requirements of old ship timber furniture.

Although these technical characteristics occupy relatively lower positions in the QFD ranking, they remain important for improving manufacturability, cost-effectiveness, and market implementation of old ship timber furniture.

RESULTS AND DISCUSSION

Design Scheme Generation

To translate user requirements into implementable design solutions, this study integrated a Large Language Model (LLM) with diffusion model-based image generation within the QFD framework to establish a hybrid design workflow. This workflow was designed to improve the semantic consistency, functional completeness, and conceptual expression of concepts generated during the early stages of product development (Chen et al. 2024).

Fig. 5. Hybrid AI-assisted design workflow and candidate prototype library for old ship timber furniture

The nine key technical characteristics identified during the QFD stage, together with their corresponding importance weights, were used as the core semantic inputs. These inputs were integrated with a three-dimensional semantic framework comprising functional attributes, usage scenarios, and sustainability considerations to generate design prompts. Based on these prompts, ChatGPT Image 2 and Nano Banana were employed as AI-assisted visualization tools to automatically generate a series of conceptual visualizations of old ship timber furniture, facilitating the exploration and refinement of preliminary design concepts. Through multiple rounds of iterative optimization, a set of candidate conceptual designs was generated, resulting in the establishment of a preliminary concept visualization library (Fig. 5).

During the generation process, the prompts were constructed based on the prioritized technical characteristics and design requirements obtained from the QFD analysis. Iterative refinement was conducted by adjusting semantic descriptions related to material characteristics, functional attributes, spatial scenarios, and cultural expression. No copyrighted or confidential third-party images were used as input references, and the generated concepts were derived from original textual descriptions based on the research findings.

Building on this workflow, the generated design concepts were comprehensively evaluated based on functional coverage, semantic consistency, and design completeness. An expert review panel comprising five specialists, including two furniture design researchers, one materials science expert, one old ship timber culture researcher, and one sustainable design researcher, assessed the candidate concepts. The candidate concepts were screened according to their alignment with the prioritized design requirements derived from the QFD analysis, including functional attributes, material expression, cultural representation, and sustainability-oriented design considerations. Based on the evaluation and screening results, four design concepts that best matched the prioritized design requirements were selected for further conceptual development. These concepts were subsequently refined and optimized from three design perspectives: the expression of material characteristics, integration with contemporary living environments, and cultural sustainability-oriented innovation, ultimately resulting in the final conceptual design outcomes of this study.

Scheme 1. This design scheme is centered on the preservation of ship timber cultural heritage, emphasizing the reinterpretation of the historical traces and maritime cultural memory embodied in old ship timber. As shown in Fig. 6, the design preserves the natural grain patterns, selected weathered cracks, and aging marks developed through prolonged marine exposure, while these surface characteristics are retained only after necessary material inspection, cleaning, stabilization, and safety evaluation. Traditional structural features, including ship hull components and planked hull construction, are reinterpreted using a contemporary design language. Cultural details, such as ship rivets and vessel identification numbers, are incorporated to reinforce the furniture’s cultural identity and narrative character. The overall color palette retains the natural dark-brown tones of old ship timber together with the subtle chromatic variations produced by long-term oxidation, creating a restrained and historically evocative aesthetic. This scheme is intended primarily for cultural exhibition spaces, boutique homestays, high-end cultural tourism projects, and the collectible furniture market, emphasizing the integration of cultural value, emotional resonance, and collectibility.

Scheme 2. This design scheme focuses on integrating old ship timber with contemporary living environments, aiming to achieve a harmonious balance between the material characteristics of reclaimed ship timber and modern interior spaces. As shown in Fig. 7, the overall form adopts a clean, streamlined contemporary design language. Optimized proportions and structural configurations aim to reduce the visual heaviness traditionally associated with old ship timber furniture. Metal framing and upholstered elements are incorporated to create a visually lighter appearance and support potential user comfort, while preserving selected areas of the natural ship timber grain as distinctive visual features. This scheme is intended for modern residential, office, and commercial environments, targeting younger consumer groups and the contemporary furniture market, with particular emphasis on aesthetic compatibility and market acceptance.

Scheme 3. This design scheme focuses on spatial adaptability and functional flexibility, emphasizing modularity and adaptability to diverse usage scenarios. As shown in Fig. 8, the design adopts a modular architecture with standardized connection mechanisms, enabling the flexible combination and rapid reconfiguration of sofas, coffee tables, and storage units. Individual modules can be rearranged or expanded according to spatial requirements, aiming to improve space utilization and functional versatility. Ergonomic principles are integrated throughout the modular configurations to support user comfort across different usage modes. This scheme is intended for modern residences, apartments, shared workspaces, and creative cultural spaces, effectively addressing the growing demand for flexible spatial solutions and multifunctional furniture.

Scheme 4. This design scheme is founded on the principles of circular resource utilization and sustainable design, emphasizing potential for efficient reuse of reclaimed old ship timber through sustainable design strategies. As shown in Fig. 9, reclaimed old ship timber is used as the primary material and combined with recycled wood-based panels and recyclable metal components to form a composite structural system. This material strategy is intended to promote resource utilization while providing potential considerations for structural performance and durability. The design further aims to reduce material waste and potentially improve manufacturing efficiency, thereby exploring potential environmental and economic benefits. This scheme is intended for green residential environments, eco-hotels, and sustainable demonstration spaces, demonstrating the innovative potential of old ship timber furniture within the framework of the circular economy.

In summary, the four proposed design schemes represent distinct design pathways centered on ship timber cultural heritage preservation, integration with contemporary living environments, modular functional design, and sustainable design, demonstrating the proposed framework’s capacity to address diverse user requirements. All schemes were derived from the AI-generated prototype library and subsequently refined through semantic filtering, structural evaluation, and iterative optimization. This process ensured a high level of consistency among functional priorities, implementation feasibility, and sustainability objectives. The resulting generation-screening workflow highlights the complementary capabilities of Large Language Models (LLMs) and generative image models in user-centered furniture design, providing a novel methodological framework and technical pathway for AI-assisted furniture prototype development.

Fig. 6. Old ship timber furniture design concept (Scheme 1)