A Preliminary Cultural-Ecological Framework for Sustainable Material Selection in Balinese Architecture

The construction sector is one of the largest contributors to environmental degradation globally, particularly through material consumption, energy use, and waste generation. According to global environmental reports, the building and construction sector contributes approximately 37-40% of global carbon emissions and produces a significant portion of construction waste annually [1]. In Indonesia, the construction industry represents a substantial share of national economic activity while simultaneously generating considerable environmental impacts due to material extraction, production, and disposal processes.

Material selection plays a critical role in determining the environmental performance of buildings. Studies indicate that construction materials can represent up to 85% of the total value of building projects and significantly influence environmental impacts throughout the building life cycle [2, 3]. The sustainability of vernacular architecture is closely associated with contextual adaptation, locally available materials, climatic responsiveness, cultural continuity, and the efficient use of environmental resources [4, 5]. Contemporary sustainable material-selection approaches increasingly employ structured multi-criteria and optimization methods to integrate environmental performance, technical requirements, life-cycle considerations, and stakeholder priorities within the decision-making process [6-9]. Consequently, the concept of sustainable architecture has emerged as an approach that seeks to reduce environmental impacts by promoting efficient use of resources, energy efficiency, and environmentally friendly materials.

However, most research on sustainable architecture primarily focuses on ecological indicators such as energy efficiency, carbon emissions, and resource consumption. Cultural dimensions of sustainability remain relatively underexplored in architectural studies. This limitation is particularly significant in regions with strong architectural traditions, where cultural values are integral to building design and material selection [10, 11].

Balinese traditional architecture represents a unique architectural system that integrates ecological, spiritual, and cultural values. Rooted in the philosophy of Tri Hita Karana, Balinese architecture emphasizes harmonious relationships between humans, nature, and the divine. This philosophy influences various aspects of architectural design, including spatial organization, building orientation, and the selection of materials derived from local natural resources.

Recent studies further demonstrate that Tri Hita Karana provides a culturally grounded sustainability framework applicable to spatial planning, vernacular architecture, tourism development, and environmentally responsive design in Bali [12].

Traditional Balinese architecture historically utilized locally sourced materials such as bamboo, natural stone, coconut wood, and thatch roofing. These materials not only reflect ecological adaptation to tropical climates but also carry symbolic meanings associated with cultural identity and spiritual values.

Despite this rich tradition, modern architectural development in Bali-particularly within tourism infrastructure such as hotels and resorts-has increasingly adopted industrial materials including concrete, steel, and synthetic finishes. This shift has resulted in the gradual loss of cultural identity and increased environmental impact associated with construction activities.

Furthermore, while regional regulations such as the Bali Provincial Regulation No. 5 of 2005 require buildings to reflect Balinese architectural characteristics, these regulations mainly focus on visual appearance rather than material sustainability. As a result, architects often replicate the aesthetic appearance of Balinese architecture while utilizing non-sustainable industrial materials.

This situation highlights the absence of a systematic framework for selecting building materials that simultaneously considers ecological sustainability and cultural compatibility. Therefore, this study addresses this gap by proposing a preliminary cultural-ecological framework that integrates measurable ecological indicators with Balinese cultural principles for sustainable material selection in contemporary tourism architecture.

The objectives of this study are threefold:

1. To identify ecological and cultural criteria influencing material selection in Balinese architecture.

2. To develop a preliminary cultural–ecological framework for sustainable material selection based on these criteria.

3. To demonstrate, rather than fully validate, the application of the model through an illustrative material-screening scenario for tourism architecture in Bali.

Through this research, it is expected that sustainable architecture can be strengthened not only through environmental considerations but also through the preservation of cultural identity in architectural practices.

The central research gap addressed in this study lies in the separation between ecological material assessment and culturally grounded architectural evaluation. Existing sustainable material assessment frameworks generally emphasize measurable ecological indicators such as embodied energy, carbon footprint, durability, recyclability, and life-cycle performance, but they rarely incorporate Balinese cultural principles as explicit assessment criteria. Conversely, Bali Provincial Regulation No. 5 of 2005 provides an important basis for maintaining Balinese architectural identity, yet its implementation tends to focus on visual architectural expression rather than measurable ecological performance, material life-cycle responsibility, or carbon-related assessment. Therefore, architects and policymakers still lack a practical framework for selecting materials that are simultaneously ecologically responsible, culturally compatible, locally contextual, and applicable to contemporary tourism architecture.

Unlike previous studies that primarily evaluate environmental performance or cultural preservation separately, this study integrates both dimensions into a single decision-support framework using Multi-Criteria Decision Analysis (MCDA), thereby providing a more comprehensive approach to sustainable material selection.

3.1 Cultural criteria for material selection

The research identified several cultural indicators influencing material selection:

•Tri Hita Karana philosophy

•Desa Kala Patra contextual adaptation

•Rwa Bhineda symbolic balance

• Sacred vs profane spatial hierarchy

These principles guide architects in determining appropriate materials for different building components.

Table 4. Summary of interview themes

Table 4 summarizes the principal themes identified from the thematic analysis of the semi-structured interviews. The coding process revealed four dominant cultural dimensions influencing sustainable material selection in Balinese architecture, namely Tri Hita Karana, Desa Kala Patra, Rwa Bhineda, and the sacred–profane spatial hierarchy. These themes consistently emerged across different stakeholder groups and served as the conceptual foundation for formulating the cultural criteria incorporated into the proposed cultural–ecological material selection framework.

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Figure 2. Qualitative coding map- research process for theme identification and material selection criteria development

Figure 2 illustrates the qualitative data analysis process employed in this study to derive the cultural criteria for sustainable material selection. The analysis began with the collection of interview data from architects, academics, government officials, and traditional craftsmen. Through a systematic coding process, recurring concepts and meaningful statements were categorized into major themes. Four dominant cultural themes emerged, namely Tri Hita Karana, Desa Kala Patra, Rwa Bhineda, and the sacred-profane spatial hierarchy. These themes were subsequently synthesized into cultural material-selection criteria and integrated with ecological indicators to establish the proposed MCDA framework

The interview data were coded thematically to identify recurring relationships between cultural philosophy and material selection. Four dominant themes emerged: harmony with nature and spirituality, contextual adaptation, symbolic balance, and sacred–profane material differentiation. For example, one architect stated that material selection in Balinese architecture should not only follow technical requirements but also respect the relationship between the building, nature, and spiritual order. A traditional craftsman emphasized that natural stone, timber, bamboo, and thatch are not merely construction materials but also carriers of local identity and ritual appropriateness. These findings support the inclusion of Tri Hita Karana, Desa Kala Patra, Rwa Bhineda, and sacred-profane hierarchy as cultural indicators in the framework.

3.2 Questionnaire-based importance of ecological and cultural criteria

The questionnaire assessed the perceived importance of four ecological criteria and one overarching cultural-compatibility criterion. The descriptive results are presented in Table 5, including the mean scores, standard deviations, 95% t-based precision intervals, and descriptive rankings for each criterion. These results are reported for the participating professional panel and should not be interpreted as population-level estimates.

Table 5. Descriptive importance ratings within the questionnaire panel (n = 45)

All five criteria received high mean importance ratings, ranging from 4.43 to 4.78. Climatic adaptation obtained the highest descriptive mean, followed by cultural compatibility and durability. However, the precision intervals overlap, particularly among the three highest-rated criteria. The ordering should therefore be interpreted as a broad panel-level priority pattern rather than statistically significant separation between adjacent criteria. The questionnaire results were subsequently used in the transparent hierarchical weight-derivation procedure described in Section 2.5.

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Figure 3. Mean importance ratings and 95% t-based precision intervals within the questionnaire panel (n = 45)

Figure 3 illustrates the ranking of the material selection criteria based on the mean scores obtained from the questionnaire survey. The results indicate that climatic adaptation received the highest mean score, demonstrating that respondents consider the ability of building materials to perform effectively under Bali's tropical environmental conditions as the most important criterion. Cultural compatibility ranked second, highlighting the importance of preserving Balinese architectural identity alongside environmental performance. Durability, carbon footprint, and recyclability were also highly rated, indicating that architectural practitioners recognize sustainable material selection as a multidimensional decision that balances technical performance, environmental responsibility, and cultural values. These findings provide quantitative support for the weighting of the evaluation criteria incorporated into the proposed MCDA framework.

The ecological ratings were not intended to represent a complete laboratory-based life-cycle assessment. Instead, they were developed as a preliminary comparative evaluation based on three sources: literature on material sustainability and embodied carbon, field observation of material use in Balinese tourism buildings, and expert/practitioner judgment collected through interviews and questionnaires. Materials were rated using a five-level scale from very low to very high. Low-carbon ratings were assigned to locally available, minimally processed, and renewable or naturally occurring materials. High-carbon ratings were assigned to industrial materials requiring intensive manufacturing, long supply chains, or high embodied energy. Durability, recyclability, and climatic adaptability were evaluated based on service life, reuse potential, biodegradability or recyclability, and suitability for Bali’s tropical climate

3.3 Questionnaire results

The questionnaire results indicate that the participating practitioners regarded both ecological performance and cultural compatibility as important considerations in material selection. Climatic adaptation, cultural compatibility, and durability formed the highest-rated descriptive cluster. Because their precision intervals overlap, the observed ordering does not demonstrate statistically significant differences between these criteria. Low-carbon performance and recyclability also received high ratings. The survey findings were used for panel-level weight calibration and should not be generalized to the entire population of architecture and construction practitioners in Bali.

3.4 Multi-Criteria Decision Analysis weight derivation, material scoring, and sensitivity

Table 6 reports each numerical step used to derive the global MCDA weights. The procedure first determines the relative balance between the ecological and cultural dimensions and then assigns weights to the subcriteria within each dimension. This hierarchical procedure prevents the ecological dimension from receiving a mechanically larger total weight merely because it contains several questionnaire items. It also makes explicit which weights are data-derived and which represent neutral methodological assumptions.

Table 6. Transparent hierarchical derivation of the Multi-Criteria Decision Analysis (MCDA) criterion weights

The dimension weights were derived directly from the questionnaire outputs. This produced nearly balanced weights for the ecological (49.356%) and cultural (50.644%) dimensions. Within the ecological dimension, climatic adaptation received the largest local weight, followed by durability, low-carbon performance, and recyclability. Equal cultural subweights were used as the baseline because no defensible quantitative evidence was available to distinguish their relative importance. The sensitivity analysis evaluates the effect of this assumption.

Ecological criteria include carbon footprint, durability, recyclability, and climatic adaptation, whereas cultural criteria comprise Tri Hita Karana, Desa Kala Patra, Rwa Bhineda, and the sacred-profane spatial hierarchy. The assigned weights represent the relative importance of each criterion, as determined through the integration of literature review, qualitative thematic analysis, and questionnaire findings.

This weighting structure provides a systematic basis for evaluating and comparing alternative building materials and serves as the foundation for the subsequent scoring and ranking process within the proposed MCDA framework.

The worked-example scores were assigned during a structured author-consensus session conducted after the scoring rubric had been finalized. The authors reviewed each material–criterion combination against the operational anchors in Table 2 and the available literature, field-observation records, and interview-derived contextual evidence. Discussion continued until one consensus score was agreed for each cell. The resulting consensus matrix was retained as the illustrative input to the MCDA calculation. The questionnaire respondents were not asked to score individual materials.

Because only consensus values were retained and no independent rater-level score matrix was available, between-rater variance and an intraclass correlation coefficient (ICC) could not be calculated. The absence of an independent reliability estimate is explicitly treated as a methodological limitation. Future validation should require independent scoring by a multidisciplinary panel, retention of individual rater-level scores, and reporting of an appropriate absolute-agreement ICC following established reliability-reporting guidelines [16].

The criterion-level scores and the resulting composite material evaluations are presented in Tables 7 and 8. Table 7 reports the score assigned to each material under each ecological and cultural criterion, thereby making the material-performance inputs fully traceable. Table 8 presents the corresponding ecological and cultural composite scores, overall weighted scores, and illustrative material rankings derived from the weighted-sum aggregation procedure. To evaluate the robustness of the material rankings to changes in criterion weights, a sensitivity analysis was conducted under four alternative weighting scenarios, as presented in Table 9. The scenarios comprise the baseline data-derived weights, an ecology-emphasis scenario, a culture-emphasis scenario, and an equal-criteria scenario.

Table 7. Illustrative criterion-level material score matrix

Table 8. Recalculated dimension composites, overall scores, and illustrative rankings

The analysis examines whether reasonable changes in the relative importance of ecological and cultural criteria alter the resulting material rankings.

Table 7 makes the material-performance inputs fully traceable by reporting the score of each material under every criterion. Table 6b reports the within-dimension composites and the final weighted score. The ecological and cultural composites are not independently assigned values; they are calculated from the criterion-level scores using the normalized within-dimension weights. The overall score is then obtained by multiplying every criterion score by its global weight and summing the eight weighted contributions.

As shown in Table 9, the rank order remained unchanged across all four principal weighting scenarios. Bamboo consistently ranked first, followed by natural stone, timber, reinforced concrete, and steel. The one-at-a-time sensitivity analysis, in which each global criterion weight was independently increased and decreased by 20% and the complete weight vector was subsequently renormalized, also produced no rank reversal. These results indicate that the illustrative material ranking is stable under moderate variations in criterion weights. However, this robustness applies specifically to the illustrative author-consensus score matrix and should not be interpreted as external validation of the framework.

Table 9. Sensitivity of illustrative material scores and rankings to alternative weighting scenarios

For example, the overall score for bamboo was calculated as:

$\begin{gathered}S_{\text {bamboo }}=5(0.121781)+4(0.124732)+5(0.118830) \\ +5(0.128219)+5(0.126609)+5(0.126609) \\ +5(0.126609)+5(0.126609)=4.875\end{gathered}$

This calculation replaces the untraceable composite-score procedure used in the earlier version. Under the illustrative baseline scenario, bamboo obtained the highest overall score, followed by natural stone and timber. Reinforced concrete and steel received high durability scores but lower low-carbon and cultural scores. These results apply only to the stated early-stage screening context and should not be interpreted as evidence that one material universally substitutes for another in primary structural applications

The rank order remained unchanged across the four principal weighting scenarios. Bamboo, natural stone, timber, reinforced concrete, and steel retained ranks one through five, respectively. The one-at-a-time analysis, in which each global criterion weight was increased and decreased by 20%, and the complete weight vector was renormalized, also produced no rank reversal. Across these perturbations, the score ranges were 4.854–4.898 for bamboo, 4.617–4.648 for natural stone, 4.488–4.514 for timber, 2.890–2.993 for reinforced concrete, and 2.619–2.735 for steel. The results indicate that the rank order is stable under moderate changes in the assumed weights for this illustrative score matrix. This robustness should not be interpreted as external validation because the material-performance values remain scenario-based author-consensus scores.

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Figure 4. Transparent Multi-Criteria Decision Analysis (MCDA) weighting, scoring, aggregation, and sensitivity process

Figure 4 illustrates the proposed MCDA framework developed to support sustainable material selection in Balinese architecture. The framework integrates two complementary dimensions, namely ecological performance and cultural compatibility, into a unified decision-making process. The ecological dimension evaluates materials based on carbon footprint, durability, recyclability, and climatic adaptation, while the cultural dimension assesses their consistency with the Balinese architectural philosophies of Tri Hita Karana, Desa Kala Patra, Rwa Bhineda, and the sacred-profane spatial hierarchy. These criteria are subsequently assigned relative weights according to their level of importance, followed by the scoring of each material alternative against all evaluation criteria. The weighted scores are then aggregated to generate a ranking of the available material options, enabling the selection of materials that achieve an appropriate balance between environmental sustainability and cultural preservation. Accordingly, the proposed MCDA framework provides a transparent and systematic approach for supporting material selection decisions in contemporary Balinese architecture, particularly within tourism-oriented development projects.

Table 10. Trade-off analysis between ecological and cultural performance

Table 10 interprets the ecological-cultural trade-offs generated by the illustrative worked example. Under the stated screening context and baseline assumptions, bamboo, natural stone, and timber received comparatively high scores in both dimensions. Reinforced concrete and steel received high durability scores but lower low-carbon and cultural scores. These outcomes should not be interpreted as a universal prohibition on industrial materials or as evidence that natural materials can replace structural concrete or steel in every application. Structural safety, fire performance, code compliance, exposure conditions, availability, and maintenance requirements remain mandatory project-specific constraints. Where reinforced concrete or steel is technically necessary, the framework supports mitigation through material-volume optimization, recycled content, lower-carbon production, local sourcing, durability planning, and integration with culturally meaningful materials.

Figure 5 illustrates the trade-off relationship between ecological performance and cultural compatibility in the evaluation of building materials for Balinese architecture. The horizontal axis represents ecological performance, ranging from low to high, while the vertical axis represents cultural compatibility, ranging from low to high. Materials located in the upper-right quadrant, such as bamboo, natural stone, and timber, demonstrate superior performance in both ecological and cultural dimensions, indicating that they are the most suitable alternatives for sustainable architectural applications. In contrast, reinforced concrete and steel are positioned in the lower-left quadrant because, although they provide high structural strength and durability, they exhibit relatively higher environmental impacts and lower compatibility with traditional Balinese architectural values. The quadrant analysis demonstrates that sustainable material selection requires balancing environmental responsibility with cultural preservation rather than optimizing a single criterion. Consequently, the proposed MCDA framework provides a systematic mechanism for evaluating these trade-offs through weighted criteria and integrated scoring, thereby supporting more transparent, balanced, and context-sensitive material selection decisions for contemporary Balinese architecture.

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Figure 5. Illustrative ecological-cultural trade-off under the baseline weighting scenario

The quadrant provides a visual interpretation of the illustrative score matrix rather than an independently validated material classification. Its principal function is to identify materials that combine favorable ecological and cultural scores and materials that require mitigation or restricted application. The position of a material may change when the building component, technical requirements, measured environmental data, or stakeholder preferences change.

3.5 Application in tourism architecture

Observations of hotel and resort buildings indicate that:

•Local materials are often used in façade elements.

•Structural systems frequently rely on concrete.

•Decorative elements simulate traditional architecture.

This hybridization reflects the tension between modern construction efficiency and cultural authenticity.

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Figure 6. Traditional alang-alang thatched roof and exposed timber roof structure at the main lobby of the Oberoi Resort Bali, demonstrating climate-responsive vernacular architecture

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Figure 7. Exposed timber column and roof structure at the lobby of the Oberoi Resort Bali, illustrating the integration of local structural materials and traditional Balinese architectural expression

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Figure 8. Jimbaran coral-stone boundary wall at the Oberoi Resort Bali, representing the application of locally sourced natural stone in Balinese resort architecture

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Figure 9. Brick-paved amphitheater flooring at the Oberoi Resort Bali, illustrating the use of locally produced brick as a durable and culturally compatible landscape material

The observed material applications in the selected tourism buildings are documented in Figures 6–13. Figures 6–9 illustrate material applications at the Oberoi Resort Bali, including alang-alang thatched roofing, exposed timber roof and column structures, locally sourced coral-stone boundary walls, and brick-paved amphitheatre flooring. Figures 10 and 11 show the application of alang-alang roofing, timber columns, and timber flooring at Adiwana Resort Jembawan, Ubud.

Figures 12 and 13 illustrate the use of locally available volcanic stone and timber cladding at Pramana Zahill Kintamani. Collectively, these field observations demonstrate how locally sourced and culturally recognizable materials are incorporated into contemporary tourism architecture across coastal, cultural, and highland settings in Bali.

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Figure 10. Alang-alang grass roofing supported by teak timber columns and timber flooring at the lobby of Adiwana Resort Jembawan, Ubud

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Figure 11. Alang-alang grass roofing supported by timber columns and timber flooring at the Adiwana Resort Jembawan Ubud swimming pool pavilion

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Figure 12. Volcanic-stone wall finish at Pramana Zahill Kintamani, demonstrating the application of locally available highland materials in contemporary tourism architecture

The case-level analysis shows that reinforced concrete is mainly used in foundations, columns, beams, and floor structures because of structural safety and construction efficiency, but it has lower cultural expression and higher embodied carbon. Façade elements commonly use natural stone, brick, and timber, which provide stronger cultural identity and moderate ecological performance. Roof elements using thatch, tile, or timber structures contribute to climatic adaptation and Balinese visual identity, although maintenance and durability must be considered. Decorative elements such as stone carving, timber ornamentation, and traditional gates have high cultural value but should be evaluated in relation to material sourcing, durability, and maintenance needs.

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Figure 13. Timber cladding applied to the exterior façade of Pramana Zahill Kintamani, illustrating the integration of natural materials into contemporary eco-lodge architecture

Table 11. Material application in tourism buildings

Table 11 summarizes the application of major building materials in the observed tourism buildings and evaluates their ecological performance, cultural significance, and potential alternatives. The analysis demonstrates that different building components require different material selection strategies depending on their structural function, environmental performance, and cultural relevance. Natural materials such as alang-alang thatch, natural stone, timber, and brick exhibit strong compatibility with Balinese architectural traditions while providing favorable ecological characteristics, including climatic adaptability and lower environmental impacts. Conversely, reinforced concrete remains essential for structural systems because of its strength and durability, although its higher embodied carbon necessitates mitigation strategies such as reducing material consumption, incorporating recycled content, and combining structural elements with locally sourced natural materials. These findings highlight that sustainable tourism architecture in Bali should adopt a balanced approach that integrates technical performance with ecological responsibility and cultural preservation.

3.6 Integrative framework

When ecological and cultural criteria produce conflicting evaluations, the framework applies a trade-off rule rather than a single-dimension decision. Materials that score highly in durability but poorly in carbon footprint or cultural compatibility are not automatically rejected, particularly when they are required for structural safety. Instead, their use should be minimized, justified, and mitigated through design strategies such as reducing material volume, using recycled content, sourcing from closer suppliers, exposing fewer industrial surfaces, and combining them with local culturally meaningful materials. For example, reinforced concrete may remain necessary for foundations or structural frames, but its negative ecological and cultural scores can be reduced by limiting its visible expression, optimizing structural efficiency, using supplementary cementitious materials, and integrating natural stone, timber, brick, or thatch in culturally significant architectural elements.

This study has several limitations. First, the questionnaire used a purposively recruited panel of 45 practitioners and was not designed or powered for population-level hypothesis testing. The reported means and weights therefore represent the participating professional panel and may not generalize to all architecture and construction practitioners in Bali. The overlapping precision intervals also limit fine-grained distinctions between adjacent importance ratings.

Second, the operational sampling frame was based on targeted professional and stakeholder networks rather than a complete probability-based register. Any unavailable recruitment denominator or cross-phase participant overlap limits the assessment of non-response and sample representativeness.

Third, the ecological and cultural dimension weights were calibrated from questionnaire means, but the four cultural subcriteria were not quantitatively rated separately. Equal cultural subweights were consequently used as a neutral baseline and examined through sensitivity analysis. Future studies should obtain direct importance judgments for every subcriterion using a larger multidisciplinary panel or a formal elicitation procedure.

Fourth, the material-performance matrix was constructed as an illustrative author-consensus worked example. The material scores were not independent ratings from the 45 questionnaire respondents, were not derived from complete laboratory or life-cycle inventory datasets, and were not retained at the individual-rater level. Inter-rater reliability could therefore not be calculated. Although the rank order was stable under the tested weight perturbations, this robustness applies only to the illustrative matrix and does not constitute external validation.

Fifth, material suitability is component- and project-specific. The framework cannot override mandatory requirements concerning structural safety, fire safety, durability, code compliance, cost, availability, or maintenance. Future validation should use project-specific functional units, measured or verified life-cycle data, independent multidisciplinary raters, documented inter-rater reliability, larger stratified practitioner samples, and completed construction projects.

The authors would like to express gratitude to the Faculty of Engineering, Udayana University, and all interview participants, including architects, academics, government officials, and traditional craftsmen, who contributed valuable insights to this research.