In India's rapidly expanding building sector, the focus on operational emissions often overshadows the critical issue of embodied carbon emissions. Despite this, the impact of Embodied Carbon emissions is profound, stemming majorly from the heavy reliance on energy-intensive materials such as cement and steel, which significantly contribute to the nation's carbon footprint. Addressing Embodied Carbon is paramount for India's resilience and sustainability, especially considering the country's vulnerability to climate risks.
Unlike operational emissions, which occur during a building's occupancy and can be mitigated over time, Embodied Carbon emissions arise at the outset of a building's life cycle and remain locked in it. These emissions encompass the indirect carbon emissions associated with extraction, processing, manufacturing, transportation, construction use, and end-of-life disposal of building materials. Alarmingly, current Embodied Carbon emissions in India's built environment amount to nearly 500 million metric tons of CO 2 annually, a figure projected to double with the expected growth in India's building stock over the next two decades.
India now stands committed to reduce Emissions Intensity of its GDP by 45 percent by 2030, as it moves on its long-term goal of reaching net-zero by 2070. However, achieving net-zero emissions poses challenges amid the building sector's projected expansion and increasing demand for emission-intensive materials. While current policies primarily target operational carbon, there's a pressing need to comprehensively address embodied carbon to truly mitigate the environmental impact of the building and construction sector.
The cement sector specifically is a significant contributor to global carbon emissions. According to data from the International Energy Agency (IEA), the cement industry is responsible for approximately 7% of global carbon dioxide (CO 2 ) emissions, making it one of the largest industrial sources of greenhouse gas emissions. The high carbon footprint of the cement sector is primarily attributed to the energy-intensive nature of cement production processes. These processes involve the calcination of limestone, which releases CO 2 , as well as the use of fossil fuels to heat kilns to very high temperatures.
One promising solution in this regard is Ground Granulated Blast Furnace Slag (GGBS), a by-product of iron manufacturing in blast furnaces. GGBS, widely used as a Supplementary Cementitious Material (SCM) in concrete production, offers a compelling opportunity to reduce the carbon footprint associated with concrete. Despite extensive research highlighting its potential benefits, market confidence in the widespread adoption of GGBS remains limited.
In our consistent pursuit of sustainable construction practices, Lodha has reached yet another significant milestone, bringing us closer to our ambitious net-zero targets. It comes in the form of a ground-breaking project—a G+23-storey building constructed using a triple blend mix of Ordinary Portland Cement (OPC), Fly Ash, and Ground Granulated Blast Furnace Slag (GGBS), a low-carbon alternative that exemplifies our commitment to environmental stewardship.
The utilization of this innovative triple blend mix has significantly reduced the embodied carbon emissions in the select buildings. With up to 47% of traditional cement replaced with GGBS across both substructures and superstructures, the embodied carbon of the building has reduced by 14% from the earlier baseline. The incorporation of GGBS has resulted in a myriad benefit, including enhanced durability, lower permeability, and most notably, a remarkable 36.75% reduction in embodied carbon content compared to conventional OPC and Fly Ash mixes.
By embracing alternative materials and pioneering eco-friendly construction techniques, we are not only reducing our environmental footprint but also setting new standards for the industry.
*Reference: Embodied Carbon baselining study conducted by the Lodha Net Zero Urban Accelerator
The shift from conventional construction to integrating Ground Granulated Blast Furnace Slag (GGBS) in concrete signifies a journey of overcoming hesitations and embracing sustainable building practices. While GGBS adoption offers benefits like reduced emissions and improved durability, it presents challenges. Firstly, GGBS prolongs concrete curing, especially in slab cycles, requiring careful scheduling and formwork selection. Secondly, in superstructures, high SCM content affects concrete pumpability, demanding precise mix design for optimal performance. Lastly, rising material costs may diminish GGBS's cost-effectiveness, urging exploration of usage optimization, negotiation with suppliers, and leveraging incentives for budget-conscious projects.
In the construction industry, we can make each project serve as a platform for innovation and advancement, particularly in the realm of concrete mix design, where the pursuit of sustainability and performance is constant. We had our journey towards adopting this triple blend mix while we challenged conventional practices and embraced this eco-friendly solution.
Phase 1: The Seeds of Change: Our venture commenced in December 2018 with the introduction of the triple blend mix during the substructure phase of our project. Departing from the conventional mix of 75% OPC and 25% fly ash, we crafted a new blend comprising 45% Ground Granulated Blast Furnace Slag (GGBS), 10% fly ash, and 45% Ordinary Portland Cement (OPC). This initial step laid the groundwork for a more sustainable approach to concrete construction, sparking further innovation.
Phase 2: Momentum Building: As confidence in the triple blend mix grew, we expanded its use to the superstructure phase of our project in August 2019. Tailoring the mix to suit superstructure requirements, we refined its composition to include 29% GGBS, 19% fly ash, and 52% OPC. This adjustment not only enhanced the sustainability of our concrete but also bolstered its structural integrity and durability, bringing us closer to our vision of a greener future for construction.
Phase 3: Maturation and Optimization: As our journey progressed, so did our understanding of concrete mix intricacies. In October 2022, we achieved crossed a new milestone by refining our triple blend mix for superstructure construction. Increasing the GGBS content to 45% while maintaining 10% fly ash and 45% OPC, this final iteration also represents the culture of learning, experimentation and refinement. With this optimized blend, we struck a harmonious balance between sustainability, performance, and practicality, setting a new standard in concrete construction.
In our exploration of Ground Granulated Blast Furnace Slag (GGBS) in concrete construction, we have uncovered several crucial insights that highlight the efficacy and benefits of incorporating this sustainable material into our building practices. These insights offer valuable guidance for future projects and underscore the significant role that GGBS can play in advancing environmentally responsible construction methods.
Reflecting on our journey toward implementing a triple blend mix, we are pleased to have made this sustainable transition. What began as a modest experiment has evolved into a milestone in our journey towards sustainability and net zero in construction. As we continue, we remain steadfast in our belief that sustainable innovation isn't just a goal but a responsibility we embrace in every project. While integrating GGBS into construction has posed challenges, the potential environmental benefits and long-term performance advantages outweigh initial hurdles. Through collaboration and dedication to sustainability, we can navigate these challenges and create resilient, eco-conscious built environments paving way for widespread adoption of sustainable practices. In summary, our experience with GGBS in concrete construction has been positive, highlighting its potential as a key component in sustainable building. Moving forward, we're committed to maximizing the benefits of GGBS as we strive for environmentally responsible construction practices.
We express our gratitude to the entire project team, and structural design team, who have demonstrated openness to trying and evaluating alternative and inventive solutions.
Driven by our mission to "Build a Better Life", and a sustainability strategy that rest on the key pillars of resilience and decarbonisation, we are also the first real estate developer in India to have our long-term and net-zero targets validated by Science Based Targets initiative (SBTi). Teaming up with RMI, we’ve also launched the "Lodha Net Zero Urban Accelerator". This pioneering initiative has an overarching goal to make net-zero the new normal for the built environment, thereby accelerating and maximising the building sector's contribution to India's 2070 net-zero emissions target. If you have innovative solutions to reshape India's future, contact us at sustainability@lodhagroup.com. Let's lead the change together.