Key Construction Materials for a Streamlined Building Life Cycle Assessment: A Meta-Analysis of 100 G-SEED Projects

Abstract

As operational emissions decrease due to improved energy efficiency, reducing embodied carbon in buildings has become increasingly important. Life cycle assessment (LCA) is a widely used method to quantify these impacts. However, its implementation often remains data-intensive and time-consuming due to the need for detailed material inventories. This study analyzes 100 LCA reports submitted for G-SEED certification in South Korea to identify a core set of construction materials that accounts for most of the total material mass. Unlike previous approaches that relied on 99% cumulative mass thresholds, this study introduces a function-based classification framework considering both material roles and environmental impact intensity, offering a novel pathway for simplifying LCA. The findings reveal 12 key material categories, such as ready-mixed concrete, cement-based products, structural steel, wood, and interior finishes, that dominate embodied carbon contributions, with concrete alone composing over 85% of the total mass based on the analyzed G-SEED dataset. A material classification framework is then developed, organized by functional role and carbon impact. By focusing on these high-impact materials, future LCA efforts can be significantly streamlined without compromising accuracy. This approach offers data-driven guidance for LCA practitioners, designers, and green building certification bodies aiming for efficient and reliable carbon assessments.

1. Introduction

The building sector is responsible for almost 37% of global greenhouse gas (GHG) emissions, with a significant portion originating from the production, transportation, and installation of construction materials, commonly referred to as embodied carbon [1]. As operational carbon emissions decline due to high-performance insulation and energy-efficient systems, embodied carbon has become a critical focus in the pursuit of carbon-neutral buildings [2].

Life cycle assessment (LCA) is widely recognized as a robust methodology for evaluating the environmental performance of buildings across their entire life cycles. Numerous studies have shown that a small number of materials, such as concrete, steel, and insulation, account for the majority of embodied carbon from buildings [3,4,5]. Despite this, current LCA practices typically require exhaustive material inventories, many of which have minimal impact on the overall environmental footprint.

Recent studies have emphasized the importance of material mass and carbon intensity when assessing material contributions to building LCA, for example, high-impact yet lightweight materials such as insulation foams or aluminum finishes. This dual lens allows for a more accurate prioritization of materials that significantly influence embodied emissions. In parallel, bill of quantities (BoQ) analysis and digital approaches such as building information modeling (BIM)-based quantity take-offs are increasingly used to identify and cluster key material groups in early-stage design phases [6,7].

International certification systems, such as LEED, BREEAM, and DGNB, have incorporated LCA into their frameworks, and countries such as France and the Netherlands have mandated LCA submissions for new buildings [8,9]. However, the lack of practical guidance on which materials to prioritize in carbon assessments limits both the efficiency and applicability of LCA in design and policy contexts.

In South Korea, the G-SEED certification system currently includes LCA as part of its evaluation criteria. In 2016, LCA was initially allocated only 1–2 points out of a total of 100 points; however, the revised guidelines in 2024 allocated LCA up to 8 points in certain categories, reflecting the growing policy emphasis on embodied carbon in Korea [10,11]. Despite its growing importance, no studies have systematically analyzed LCA data submitted for G-SEED certification to identify material contribution patterns. This evidence gap limits efforts to streamline LCA practices and integrate embodied carbon considerations into routine design workflows and reflects the policy blind spots and potential optimization points in building sustainability regulations in Korea.

To address this evidence gap, this study analyzes 100 LCA reports submitted for G-SEED certification to identify the construction materials that collectively represent over 99% of the total material mass. Based on this analysis, this study develops a simplified classification framework comprising 12 core material categories, organized by functional role and carbon impact. The aim of this study is to support practical LCA simplification by focusing on essential components while preserving sufficient accuracy for carbon assessment and certification purposes.

2. Literature Review

2.1. Overview of LCA in Buildings

LCA has become a standardized methodology for evaluating the environmental impacts of buildings across their entire life cycle, from the extraction of raw materials to end-of-life disposal [12,13]. In highly energy-efficient buildings, embodied carbon, emissions resulting from the production and construction of materials, can account for 30–70% of total GHG emissions [2,3]. As such, emissions from the material phase have become increasingly central to achieving carbon neutrality in the built environment (Figure 1).

2.2. Embodied Carbon and Material Contributions

Embodied carbon refers to the GHG emissions associated with all life cycle stages of construction materials, including raw material extraction, manufacturing, transportation, and installation. International standards, such as EN 15978 (Figure 2), provide methodological frameworks for conducting building LCAs and defining system boundaries and modules [14].

According to EN 15978, the building life cycle is typically segmented into modules A (product and construction stages), B (use stage), C (end-of-life stage), and D (benefits beyond the system boundary) [15]. Within this framework, modules A1–A3 (product stage: raw material supply, transport, and manufacturing) are considered critical as they account for the majority of embodied carbon in buildings (Figure 3) [11,16,17]. Numerous studies have confirmed that emissions from these stages dominate the overall environmental impact of construction materials, particularly for structural components [2,3].

Furthermore, a persistent challenge in LCA implementation lies in the exhaustive material inventories traditionally required by standards. While typical BoQs may include hundreds of material entries, research indicates that a small subset of materials, such as concrete, steel, and insulation, often represents over 90–95% of the total mass and carbon impact [10,18]. To improve LCA efficiency without compromising accuracy, recent approaches have proposed a cumulative mass-based threshold, commonly set at 99%, to limit detailed assessments to high-impact materials [10,19]. This method aligns with the Pareto principle, ensuring that the most significant contributors are fully captured while omitting negligible components. Meta-analyses have further validated that materials with high production volumes or energy-intensive manufacturing processes, such as cement, rebar, and aluminum, are primary contributors to environmental impacts [20,21].

In practice, calculating cumulative mass contributions and excluding the bottom 1% of materials enables substantial reductions in data entry and modeling complexity while maintaining robust carbon estimates for modules A1–A3. This approach is increasingly recognized as a viable strategy for simplifying LCA processes in certification systems and early-stage design decision-making [18,22].

2.3. Material Classification and Prioritization

Despite growing awareness of the importance of embodied carbon at the material level, standardized frameworks for classifying and prioritizing construction materials remain underdeveloped [10,23]. Discrepancies in classification criteria, such as functional roles (e.g., structural vs. non-structural), spatial location (e.g., envelope vs. interior), or database conventions, undermine consistency and comparability across LCA studies.

In response, studies have proposed various data-driven classification models, including impact clustering and material ranking [19,24], or recommended using Environmental Product Declaration (EPD)-based weighting schemes to support more objective material selection [18,22]. Building upon these approaches, this study develops a standardized framework that simplified cumulative mass contribution to enhance comparability across projects and certification systems.

2.4. Role of LCA in Certification and Policy

Leading international green building certification systems, such as LEED, BREEAM, and DGNB, have formally incorporated LCA as an evaluation criterion and offer credits for reducing life cycle environmental impacts [25,26]. In Europe, countries such as Denmark, France, and the Netherlands have gone further by mandating LCA submissions as part of the permitting process for new buildings [9].

However, research shows that despite the institutionalization of LCA, the absence of practical tools for material prioritization continues to limit its effective integration into design and assessment workflows [27,28,29,30].

2.5. Practical Challenges in LCA Implementation

Although LCA is widely recognized as a robust and standardized methodology, its implementation in design workflows remains challenging. Studies have identified three key barriers that limit the broader adoption of LCA beyond specialized expert groups.

First, LCA is heavily dependent on expert knowledge and specialized tools, posing high entry barriers for general practitioners, particularly during the early design stage [10,23]. Expertise is required to define system boundaries, interpret results, and apply complex databases, leading to the concentration of LCA tasks within consultancy firms and reducing its accessibility to architects and engineers.

Second, uncertainty in input data and variability across databases (e.g., emission factors and EPDs) pose significant challenges [18,22]. Inconsistent data quality and the lack of region-specific values compromise both comparability and reliability, reducing confidence in LCA outputs for design decision-making. Databases have different levels of detail even for the same materials, as shown in Figure 4. The number of datasets indicates the precision of a database [31].

Third, there is a lack of clear, actionable guidance for material selection based on environmental impact, particularly in early design phases. While standards such as EN 15978 provide methodological structures, they do not specify how to prioritize materials within practical time and budget constraints [19,30].

Finally, while cumulative mass-based thresholds (e.g., 99%) offer conceptual simplicity, their application in practice can be a burden. Calculating and verifying cumulative contributions requires detailed quantity take-offs and reliable inventory data, information often unavailable during early design stages [10]. As a result, the intended simplification may become impractical without digital integration (e.g., BIM-LCA automation) or standardized material grouping.

These limitations highlight the need for user-friendly, streamlined frameworks that enable practitioners to focus on high-impact materials without requiring exhaustive analysis or exclusive reliance on expert workflows.

Although the 99% cumulative mass threshold is conceptually straightforward, its application can be overly resource-intensive. This study therefore explores a simplified protocol in which predefined material categories replace exhaustive cumulative calculations.

2.6. Summary of Literature Review

Internationally, the importance of building LCAs is gradually increasing, and LCAs are being conducted based on common international standards. In addition, with the recent radical developments in technology and systems related to the operation of buildings, reviewing building material selection has become a significant issue. Currently, a method based on the BoQ is used to derive 99% of building materials, but the remaining 1% also holds environmental significance. As a result, analyses are being conducted to classify materials and identify priority review targets for environmentally significant materials, which are being utilized in national permitting and certification systems.

Nevertheless, the LCA field remains limited to specific expert groups due to issues such as data inaccuracy and lack of transparency, as well as the complexity of calculations, making it difficult to reflect LCA in the development of related industries and initial design stages.

In the Republic of Korea, the G-SEED certification system incorporates LCA reporting and is set to strengthen these requirements after 2025. However, limited efforts have been made to synthesize accumulated LCA data to identify consistent material contribution patterns. This lack of analysis limits the development of a context-specific framework for classifying materials by environmental impact and the practical use of LCA in Korean design practice.

To address this evidence gap, this study analyzes 100 LCA reports submitted for G-SEED certification to identify 12 key materials that account for most of the total material mass. Based on their functional roles, this study proposes a systematic classification framework with the aim of improving embodied carbon management in both domestic and international contexts.

3. Data Collection and Analysis of Results

The primary dataset comprised 100 LCA reports submitted for G-SEED certification in the Republic of Korea between 2017 and 2024. The dataset analyzed in this study was sourced through direct collaboration with the G-SEED operation body. While G-SEED certification outcomes are publicly accessible, the full LCA reports are not routinely disclosed and were obtained under institutional agreements for academic research purposes. The LCA reports covered diverse building typologies (residential, office, school, and retail) and structural systems (reinforced concrete, composite, and steel-reinforced concrete).

The analysis proceeded as follows:

• BoQ review: The BoQ of each report was examined to determine the total number of materials listed.
• Mass contribution calculation: For each material group, the percentage contribution to the total mass was computed.
• Material ranking: Materials were ranked based on their frequency of occurrence across projects, cumulative mass contribution, and relative carbon impact potential.
• Classification framework: Materials were grouped into 12 categories based on their functional roles and potential integration into certification systems.

3.1. Status of Green Building Certification and LCA Reports in Korea

Similar to international green building certification systems, such as LEED, BREEAM, and DGNB, South Korea has implemented its own G-SEED green building certification program that has been in operation since 2002. G-SEED certification is mandatory for public buildings and is promoted in the private sector through incentives such as acquisition tax reductions and building regulation relaxations. As a result, the system has been widely adopted, with approximately 25,000 buildings certified as of 2024.

A major revision of the G-SEED framework took place in 2016, during which LCA was introduced as a formal evaluation criterion. Since then, the use of LCA in certification has gradually expanded.

Table 1. G-SEED certification and LCA reporting status.

Year	Number of Certifications	Number of LCA Reports	LCA Reporting Ratio
2016	1639	-	-
2017	1765	6	0.34%
2018	2000	38	1.90%
2019	2169	118	5.44%
2020	2324	241	10.37%
2021	2383	377	15.82%
2022	2319	448	19.32%
2023	2509	565	22.52%
2024	2381	576	24.19%
Total	19,489	2369	12.16%

and Figure 5 present the number of LCA reports submitted annually since the introduction of the criterion.

In the first three years since its inception, LCA adoption was limited to approximately 2% of certified buildings. However, this uptake has steadily increased, reaching 24% by 2024. Initially, the concept of LCA was unfamiliar in the Korean building industry, and few professionals had the expertise to conduct such assessments. Over time, more experts have entered the field, and successful case studies have accumulated as submitting an LCA report is increasingly seen as manageable, contributing to its wider adoption in G-SEED projects. The increase in LCA report submissions appears to reflect a growing perception that LCA is no longer a burden.

As LCA reporting becomes more prevalent, a foundation for comprehensive life cycle carbon management in buildings is being established. However, G-SEED still has several limitations inherent to LCA, including the complexity of conducting a 99% cumulative mass analysis, limited integration with life cycle inventory (LCI) databases and EPDs, and insufficient verification of data completeness and consistency.

To address a critical limitation, this study proposes an alternative approach by identifying key construction materials using existing LCA reports. The objective is to provide a practical basis for material selection that could be a substitute for full cumulative mass analysis during LCA implementation. The analysis dataset consists of 100 LCA reports submitted for G-SEED certification (Appendix A). As shown in

Table 2. Analysis building cases.

		Number of Buildings (Total 100)
Building type	Residential	20
	Non-residential (all public, commercial, and institutional buildings, except below)	38
	Office	33
	School	6
	Hotel	2
	Retail	1
Structural type	RC	76
	RC + S	10
	SRC	14

, the building typologies included residential, office, school, hotel, retail, and other non-residential types such as research centers, warehouses, and data centers. The structural systems are categorized as reinforced concrete (RC), RC + steel composites (RC + S), and steel-reinforced concrete (SRC).

3.2. LCA Data Analysis

A review of the BoQs was conducted for the 100 buildings in the dataset. The number of BoQ items ranged from 110 to 6259, while the number of materials used in the LCA reports varied from 38 to 2473. On average, each BoQ contained 990 items, whereas the average number of materials included in the LCA was 319, representing 35.24% of the total BoQ items (Figure 6).

However, the correlation between the total number of BoQ items and the number of LCA-selected materials was relatively weak (R² = 0.4673), indicating that variations are largely influenced by BoQ composition and the level of detail applied by LCA practitioners during material selection (Figure 7).

Preparing an LCA report typically involves (1) an initial quantity analysis of approximately 990 BoQ items, (2) selection of approximately 319 materials that cumulatively account for 99% of the total material mass, and (3) collection of environmental data for each selected material.

This cumulative mass analysis presents a significant initial hurdle, which likely contributes to the limited practical adoption of LCA in design and certification workflows.

To address this challenge, this study aims to classify essential materials from the BoQs that should be prioritized in LCAs, providing a more practical alternative to full cumulative mass calculations. Figure 8 illustrates the proposed simplified process.

3.3. Quantity Breakdown in LCAs

All 100 LCA reports performed a 99% cumulative mass analysis to identify which materials were assessed (Appendix B). The number of selected materials ranged from 38 to 2473, with an average of 319 items. Collecting and linking environmental data for each material, potentially over 2473 data points per project, is impractical. Therefore, it is common practice to group similar materials into representative categories and assign shared environmental data.

In the analyzed reports, materials were typically grouped into 5 to 12 categories, with an average of eight material groups. These groupings are listed in

Table 3. Categorization of major construction materials.

Material Category	Examples	Functional Role
Concrete (ready-mixed)	Normal- and high-strength concrete	Primary structural component
Structural steel	Deformed bars, welded wire mesh, H-beams, columns, and steel framing	Structural reinforcement and system (steel buildings)
Metal finishes	Aluminum and steel plates	Non-structural finishes and façade
Cement and bricks	Mortar cement and solid bricks	Masonry walls and partitions
Wood	Structural timber and plywood	Structural timber, internal reinforcement, and finishes
Glass products	Single-pane, double-pane, and low-E glass	Windows and façades
Insulation materials	EPS, XPS, glass wool, and urethane foam	Thermal insulation
Gypsum board	Drywall panels	Interior wall finishes
Sand and gravel	Fine and coarse aggregates	Concrete mix and bedding material
Stone materials	Natural stone, marble, and granite	Exterior and interior finishes
Tiles	Ceramic and porcelain tiles	Flooring and wet area finishes
Paint and wall covering	Emulsion paints and wallpapers	Interior finishing

.

An analysis was conducted on the frequency of use of 12 major construction material categories across 100 LCA reports (

Table 4. Adoption ratios of major construction materials.

	Material Category	Number of LCA Reports Using the Material Category	Mass Balance Average Ratio
1	Concrete (ready-mixed)	100	85.6%
2	Structural steel	100	4.6%
3	Metal finishes	45	0.4%
4	Cement and bricks	98	5.5%
5	Wood	4	0.0%
6	Glass products	57	0.3%
7	Insulation materials	98	0.1%
8	Gypsum board	63	0.4%
9	Sand and gravel	95	2.4%
10	Stone materials	63	0.6%
11	Tiles	35	0.1%
12	Paint and wall coverings	5	0.0%

). The results indicated that concrete and structural steel were included in all 100 reports. Cement and insulation were used in 98 reports, whereas sand and gravel were used in 95 reports. Stone and gypsum boards were included in 63 reports, whereas glass products were included in 57 reports. Metal finishes were reported in 45 cases and tiles in 35 cases. Paints and wall coverings and wood were the least frequently included materials, appearing in five and four reports, respectively (Figure 9).

When analyzed by their quantity contributions, concrete accounted for 85.6% of the total mass, followed by cement and brick (5.5%), structural steel (4.6%), and sand and gravel (2.4%), whereas all other material categories represented less than 1% each (Figure 10).

4. Discussion

The findings of this study underscore the practical challenges and potential opportunities associated with implementing LCA within the building sector in South Korea under the G-SEED certification framework. Although LCA adoption has grown significantly, from just 2% of certifications in 2016 to 24% by 2024, its effective application remains constrained by complex data requirements and methodological hurdles.

4.1. Practical Barriers to LCA Implementation

The analysis highlighted major barriers to LCA adoption in Korean building projects. While a typical BoQ includes almost 990 items, the average LCA report includes only 319 items, accounting for approximately 35% of the BoQ. This illustrates the resource-intensive and time-consuming nature of conducting a comprehensive 99% cumulative mass analysis.

The weak correlation between BoQ size and LCA material count (R² = 0.4673) suggests a lack of standardization in material selection, often relying on practitioner discretion rather than objective criteria, echoing findings from the international literature [10,18]. This complexity, particularly during early design phases when detailed take-offs and environmental datasets are unavailable, discourages broader adoption of LCA. Similar limitations have been observed in LEED and BREEAM systems, where early-stage tools lack guidance for practical material prioritization [32,33].

4.2. Dominance of Key Material Categories

The frequency analysis confirmed a strong Pareto effect: a small number of materials accounts for most environmental impacts. Concrete alone contributes 85.6% of the total mass, followed by cement and bricks (5.5%), structural steel (4.6%), and aggregates (2.4%). Other materials, such as glass, insulation, and finishes, each contribute less than 1% by mass, although they may exhibit high environmental intensity per unit mass. For example, aluminum cladding or polyurethane foam insulation can have disproportionately high carbon footprints despite low quantities. These results are consistent with international studies on embodied carbon distributions [16,19].

4.3. Implication for G-SEED and Global Certification Frameworks

The current G-SEED requirement for a 99% cumulative mass analysis could be effectively replaced by assessing 12 predefined material categories. This simplification would significantly reduce data demands, supporting wider adoption of LCA in both certification workflows and early design phases.

This approach is aligned with international trends promoting streamlined LCA protocols, as advocated by recent European initiatives and ISO-based guidelines. For example, EN 15978 permits scenario-based assessments when detailed data are unavailable, while LEED v5 emphasizes early-stage carbon considerations via predefined assemblies. By incorporating similar principles, G-SEED could improve comparability with global standards while maintaining methodological robustness.

While the 99% cumulative mass threshold offers a practical means to focus on dominant contributors, it does not capture carbon intensity. Lightweight but emission intensive materials may be overlooked. Moreover, this classification model could be integrated into BIM-based LCA automation workflows in Korea, paving the way for streamlined carbon assessments during early design stages. Future research may explore algorithmic mapping between predefined material categories and BIM object libraries [28,30].

5. Conclusions

This study analyzed 100 LCA reports submitted under the G-SEED certification system to identify patterns in material contributions and develop a simplified classification framework to support LCA implementation. The results revealed that 12 material categories, dominated by concrete, structural steel, and cement, consistently represented over 99% of the total material mass.

By predefining these categories, the proposed framework reduces the complexity of cumulative mass analysis and facilitates broader adoption of LCA across the industry. Beyond improving methodological efficiency, this framework enables more targeted applications of low-carbon materials across both structural and non-structural components, including building envelopes and finishes.

Such targeted material strategies are essential for achieving national and global carbon neutrality goals, particularly as embodied emissions increasingly dominate the life cycle impacts of high-performance buildings.

However, a key limitation remains. Current LCA practices in Korea are largely confined to building structures, excluding civil engineering works and mechanical, electrical, and plumbing (MEP) systems. While MEP systems were not included in the dataset in this study, their growing importance in total embodied carbon is recognized. The progressive integration of civil engineering works and MEP systems has become increasingly important in comprehensive carbon assessments. Recent initiatives in Europe have begun to require LCA for infrastructure and building service systems, highlighting the need for sector-wide harmonization [34,35]. Future studies should focus on integrating these components into a comprehensive sector-wide assessment. In particular, predefined MEP assemblies and environmental profiles could facilitate their inclusion. However, due to the relatively low mass yet high carbon intensity of many MEP components, traditional cumulative mass thresholds may be insufficient. Therefore, a carbon intensity first approach may be more appropriate for evaluating MEP elements in future LCA frameworks.

Beyond certification compliance, the LCA data collected through G-SEED can serve as a valuable resource for optimization at multiple levels. Accumulated datasets enable benchmarking of embodied carbon performance across different building types, structural systems, and material combinations. They can also inform targeted strategies for low-carbon material substitution, such as replacing conventional insulation with low-carbon alternatives or promoting recycled steel. Moreover, G-SEED submissions could form the foundation of a centralized national LCA database, which would provide policymakers with robust evidence for updating certification criteria and establishing embodied carbon regulations. By leveraging the full potential of these datasets, G-SEED can evolve from a compliance-oriented system into a driver of continuous improvement and innovation in Korea’s transition toward carbon-neutral buildings.

This study also highlights several avenues for future investigation. First, the simplification protocol proposed here could be further developed into an automated BIM-integrated workflow, reducing the burden of the 99% cumulative mass threshold and enabling real-time carbon feedback in early design stages. Second, the proposed standardized classification framework, which integrates mass contribution, frequency of occurrence, and carbon intensity, requires further testing across broader building typologies and international datasets to ensure generalizability. Third, future work should explore solutions to reduce reliance on specialized expertise, such as developing practitioner guidelines, open-source tools, and digital templates that embed simplified material categories into design workflows. Finally, the progressive integration of MEP systems and civil engineering works remains a critical frontier. Given their relatively low mass but high carbon intensity, future LCAs should adopt a carbon-intensity-first approach, incorporating predefined MEP assemblies and environmental profiles to ensure more comprehensive assessments across the entire built environment.