REDUCING CARBON EMISSIONS IN CONSTRUCTION THROUGH LEAN PRACTICES AND SUSTAINABLE MATERIALS

209 | P a g e 10.5281/zenodo.17874874 “REDUCING CARBON EMISSIONS IN CONSTRUCTION THROUGH LEAN PRACTICES AND SUSTAINABLE MATERIALS” Mahadeva M1*, Venkatesh Shivalingappa dulari2 1Assistant Professor, 2Undergraduate Students, Department of Civil Engineering, RNS Institute of Technology, Channasandra, Bengaluru, India *Corresponding author: [email protected] Abstract: This article discusses ways to reduce carbon emissions in construction. It examines the sources and factors contributing to greenhouse gas emissions, particularly in the construction sector. This sector creates a significant carbon footprint during both product manufacturing and onsite construction activities. The study uses the dEMAtEl method to analyze these factors during a project's lifecycle. Key influences include building information modeling (BIM), choosing appropriate materials, and having regulatory and financial support. The findings highlight the importance of sustainable practices to decrease emissions. It also notes that traditional materials still dominate the market, despite the availability of eco-friendly options. By analyzing commonly used materials in India, the research showcases a physical model that reduces carbon footprints through greener substitutes. Recommendations to minimize emissions focus on lean construction methods, optimizing processes, and using renewable energy sources. Ultimately, these insights aim to guide the construction industry towards lower carbon impacts. Keywords: Carbon Emissions, Sustainable Construction Cement and Concrete Supplementary Cementitious Materials (SCMs), Carbonation Curing, Life Cycle Assessment (LCA), Carbon Capture, Utilization, and Storage (CCUS), Low-Carbon Building Materials. Introduction The increasing concentration of greenhouse gases in the Earth’s atmosphere has led to 210 | P a g e 10.5281/zenodo.17874874 intensifying discussions on climate change and its wide-reaching consequences. While emissions from transportation, agriculture, and industry are well recognized, the role of the construction sector is often underestimated despite its substantial contribution to global carbon emissions. The growing demand for infrastructure, housing, and urban development has significantly increased the consumption of raw materials and energy, placing a heavy environmental burden on the planet. This situation underscores the need to reassess how buildings are designed, constructed, and maintained throughout their life cycles. A key concern within the construction industry is the carbon footprint, which includes both operational and embodied emissions. Operational carbon refers to the energy required to run a building such as for heating, cooling, and lighting whereas embodied carbon stems from the materials and construction processes themselves. Although advancements in building energy efficiency have helped reduce operational emissions, the embodied carbon associated with cement, steel, and other common materials remains high. These emissions are further amplified by extensive resource extraction, waste generation, and transportation activities. As a result, even energy-efficient buildings can carry a significant environmental cost before they are ever occupied. In recent years, efforts have been made to reduce emissions at every stage of the building process, from material production to demolition. Researchers have explored alternatives to conventional materials by incorporating industrial and agricultural waste, promoting prefabricated construction, and optimizing building design for sustainability. Policy interventions, such as Environmental Product Declarations (EPDs) and Life Cycle Assessment (LCA) frameworks, have also played a growing role in encouraging transparency and accountability within the sector. These strategies, along with the application of Lean Construction principles, point toward a more resource-efficient and climate-conscious construction industry—one that can meaningfully contribute to global carbon reduction goals. In parallel with academic and technological advancements, governmental and institutional policies have begun to reflect the urgency of addressing carbon emissions in the construction sector. International frameworks, such as the Paris Agreement, and national initiatives, including the Inflation Reduction Act in the United States and carbon reduction mandates in the European Union and parts of Asia, emphasize the need for change. 211 | P a g e 10.5281/zenodo.17874874 Source: (Milena Senjak Pejić reseach paper) Figure 1: Carbon emission in different project stages Source:(Salim Barbhuiya research paper 2025) Figure 2: Top countries with the highest CO2 emission annually from the cement industry (2005–2019) 1. Literature Review The production of traditional cement and concrete is a significant contributor to global greenhouse gas emissions, accounting for a substantial percentage of CO₂ released worldwide. 212 | P a g e 10.5281/zenodo.17874874 The primary source of emissions in cement manufacturing is the calcination process, where limestone (CaCO₃) is heated to produce lime (CaO), releasing CO₂ directly into the atmosphere Andrew (2018) [1]. Additionally, the high-temperature firing of cement kilns consumes large amounts of fossil fuels, further increasing the carbon footprint of cement production. Studies have shown that key factors influencing these emissions include the clinker-to-cement ratio, type of fuel used, and kiln energy efficiency Gartner and Sui (2018) [2]. The extraction, processing, and transportation of aggregates and binders for concrete also add to its overall environmental impact, highlighting the need for more sustainable practices in material sourcing and production. In response to these challenges, significant research has focused on the development and application of supplementary cementitious materials (SCMs) such as fly ash, slag, silica fume, and natural pozzolans. These materials replace a portion of Portland cement in concrete mixes, thereby reducing the clinker content and associated CO₂ emissions Gartner & Sui (2018) [2]. Moreover, SCMs often improve concrete’s durability and reduce permeability, extending the service life and potentially lowering the total life cycle emissions of concrete structures. Alternative binder systems, including alkali-activated and geopolymer concretes, have also gained attention as viable low-carbon options. Reviews indicate that these binders can reduce carbon emissions by 30–50% compared to traditional Portland cement, provided that raw material sourcing and processing are carefully managed Provis and Van Deventer (2014) [7]. Beyond reducing emissions during production, recent innovations have aimed to enhance the CO₂ absorption capacity of concrete after placement. Natural carbonation, a slow reaction between atmospheric CO₂ and calcium hydroxide in concrete, results in the formation of stable calcium carbonate, effectively sequestering CO₂ over time Kharbanda et al. (2021) [4]. To accelerate this process, techniques such as accelerated carbonation curing have been developed, in which concrete is exposed to CO₂ in controlled environments during manufacturing. This not only increases CO₂ sequestration but also improves the mechanical properties of concrete, such as strength and durability Guleria et al. (2023) [6]. Modifying the pore structure and using reactive aggregates further promote carbonation rates, although the overall potential for CO₂ absorption remains limited unless applied on a large scale. 213 | P a g e 10.5281/zenodo.17874874 Despite these technological advances, the widespread adoption of sustainable cement and concrete solutions faces economic, regulatory, and logistical barriers. Policy-oriented studies reveal that while fuel switching, energy efficiency improvements, carbon capture, utilization, and storage (CCUS), and clinker content limits are well recognized strategies, challenges such as high implementation costs, limited raw material availability, and lack of standardized regulations hinder progress Zhang et al. (2021) [6]. Countries like India and China are making strides in SCM substitution and energy efficiency; however, large-scale deployment of CCUS and alternative binders remains constrained by economic and policy factors. Future research priorities include comprehensive lifecycle assessments across diverse climates, long-term durability studies of alternative materials, and the development of standardized metrics to evaluate carbon reduction technologies effectively. 2. Advantages And Disadvantages 1. Direct CO₂ reductions from process waste elimination fewer deliveries, less idling and rework reduce fuel and electricity use on site. 2. Lower embodied carbon via material substitution SCMs, geopolymers and recycled aggregates can cut cement-related emissions substantially. 3. Improved schedule and productivity lean methods shorten construction durations, reducing temporary energy consumption and site emissions. 4. Better decision support through LCA+BIM integrating LCA at design stage helps select low-carbon systems and quantify trade-offs. 5. Potential long-term cost savings and market advantage although upfront costs may rise, lifecycle savings, durability benefits and green market premiums can offset them. 6. Standards and regulatory gaps lack of uniform codes for many low-carbon materials slows adoption and approval. 7. Quality control at scale ensures consistent mixed performance for alternative binders and recycled aggregates is technically demanding. 8. Upfront costs and supply chain constraints precast/prefab and some low-carbon options can have higher initial cost and limited local availability. 9. Data and LCA variability differing LCI databases, system boundaries and assumptions cause uncertainty in embodied carbon estimates. 214 | P a g e 10.5281/zenodo.17874874 10. Organizational inertia and skills gap implementing lean + LCA requires training, crossdiscipline coordination and cultural change across supply chains. 3. Implementation: To effectively reduce the carbon footprint of cement and concrete, several implementation strategies can be adopted across the production and construction lifecycle. One of the most direct approaches involves replacing a portion of traditional Portland cement with supplementary cementitious materials (SCMs) such as fly ash, ground granulated blast furnace slag (GGBS), and natural pozzolans. This substitution can reduce CO₂ emissions by up to 50%, while also promoting the circular economy by repurposing industrial by-products. In addition, emerging technologies such as geopolymer concrete and alkali-activated binders provide a viable alternative to conventional cement, offering a potential reduction in emissions of 40– 80%. Accelerated carbonation curing (ACC) represents another innovative solution, whereby CO₂ is injected into precast concrete during curing, converting it into stable calcium carbonates and thus sequestering it within the concrete matrix. This process not only reduces net emissions but also improves the mechanical properties and durability of the material. Furthermore, the adoption of Lean Construction principles—such as just-in-time delivery, offsite prefabrication, and value stream mapping—has demonstrated significant potential in minimizing construction waste, reducing idle machinery use, and optimizing logistics, all of which contribute to lower carbon emissions during the construction phase. Life Cycle Assessment (LCA) tools should also be integrated during the design phase to evaluate material choices and construction methods based on their environmental impact. Moreover, incorporating recycled aggregates from construction and demolition waste can reduce the demand for virgin materials, thereby decreasing the environmental burden of raw material extraction and transport. Finally, industry-wide adoption of low-carbon practices can be accelerated through green procurement policies, government incentives, and demonstration projects that validate the performance and cost-effectiveness of sustainable materials and methods. Together, these strategies offer a comprehensive and practical pathway for decarbonizing the cement and concrete sectors while supporting broader climate change mitigation goals. In addition to material innovations, effective implementation requires strong collaboration between policymakers, industry stakeholders, and researchers to establish regulatory 215 | P a g e 10.5281/zenodo.17874874 CO₂ Capture & Collection CO₂ Source (Industrial Production) Utilization (Factory) Onshore storage Offshore storage Carbonated drinks Injection underground (1km deep ) Injection Under seabed geological formation Enhanced Oil Recovery Oil Production frameworks and standards that promote low-carbon construction. Training programs for engineers and contractors can help ensure the correct application of sustainable techniques onsite. Public awareness campaigns can also drive demand for greener infrastructure. Ultimately, success depends on aligning economic incentives with environmental goals. Figure 3: Flow chart for implementations of reducing carbon emission in construction. 4. Future Scope: The future of sustainable cement and concrete production depends on the ongoing use of new materials, digital technologies, and policy frameworks. As research into alternative binders like geopolymers and bio-based materials advances, the construction industry can significantly cut its carbon footprint. Innovations such as carbon capture, utilization, and storage (CCUS) systems designed for cement plants are likely to become more practical and affordable, helping the industry move toward near-zero emissions. Furthermore, improvements in machine 216 | P a g e 10.5281/zenodo.17874874 learning and data analysis can optimize mix designs, curing processes, and resource use, which will boost sustainability and efficiency in concrete production. On a larger scale, applying circular economy principles and lean construction methods will be vital for reducing waste and emissions throughout the building lifecycle. Future research should focus on large pilot projects that show the long-term durability and performance of green concrete in various climates. Teamwork among academic institutions, industry players, and policymakers will be key to overcoming regulatory and financial challenges. Additionally, educating and training the construction workforce in sustainable practices will ensure an easy shift to greener construction methods, helping the industry meet international climate goals. The use of smart technologies like sensors and Internet of Things (IoT) devices in concrete structures allows for real-time monitoring of carbonation levels, structural health, and environmental conditions. This improves the durability and performance of sustainable materials. It also creates opportunities for predictive maintenance and better lifecycle management, which can lower resource usage over time. As cities grow, adding these smart systems to green construction can provide environmental, economic, and safety benefits. These developments will play a key role in creating the next generation of strong, low-carbon infrastructure. As regulatory pressure grows worldwide to meet climate goals, future research and development will likely concentrate on standardizing low-carbon construction practices. Governments and industry groups are expected to set stricter emission standards and encourage the use of green materials. This will drive innovation in alternative binders like geopolymers and bio-based cement. Support from regulations will be vital for speeding up the large-scale use of carbon capture, utilization, and storage (CCUS) technologies in cement manufacturing plants. Another promising area of research is the development of carbon-negative materials. These materials not only cut emissions during production but also absorb more CO₂ throughout their life than they release. Investigating self-healing concretes and advanced nanomaterials could greatly improve the durability and lifespan of structures. This would lessen the need for repairs and reconstruction, both of which add to emissions. These materials could significantly influence the environment built of the future, making cities more sustainable and better equipped to handle climate change. Finally, with growing awareness of circular economic principles, there is increasing interest in 217 | P a g e 10.5281/zenodo.17874874 closed-loop systems where construction and demolition waste is recycled into new concrete products. This not only minimizes environmental impact but also reduces dependence on virgin raw materials. Future construction projects may be designed with end-of-life recycling in mind, enabling easy separation and reuse of components. Such systemic changes in construction practices will require interdisciplinary collaboration across materials science, architecture, policy, and engineering disciplines. Summary The construction industry is a major contributor to global carbon emissions due to energyintensive processes, material production, and inefficient project management. By integrating lean practices, such as eliminating waste, optimizing resource use, and improving workflow efficiency, construction projects can significantly reduce unnecessary energy consumption and emissions. Additionally, the adoption of sustainable materials—such as recycled aggregates, low-carbon concrete, bamboo, and other eco-friendly alternatives—further minimizes the environmental footprint. Together, these approaches not only support climate goals but also improve cost efficiency, project quality, and long-term sustainability in the built environment. Conclusion The construction sector holds a critical responsibility in addressing the challenge of carbon emissions. By implementing lean practices, projects can become more resource-efficient, reducing delays, excess use of materials, and unnecessary energy consumption. This not only contributes to lowering emissions but also improves overall project delivery, making construction more cost-effective and reliable. When efficiency becomes a guiding principle, environmental benefits naturally align with economic and operational gains. Equally important is the choice of materials used in construction. Sustainable alternatives such as recycled aggregates, bamboo, low-carbon concrete, and other eco-friendly products directly reduce the embodied carbon of buildings and infrastructure. The combination of efficient processes and sustainable materials represents a practical pathway for the industry to meet global climate commitments. Together, these approaches demonstrate that environmental