And The Sustainable Practices That Will Get Us There
As structural engineers, we’re constantly thinking about the bones of a building – that skeleton that holds together the work and vision of those involved in the facility design and construction process. As our industry continues to evolve, the adoption of sustainable building practices have become top of mind – and it’s a focus that is here to stay.
Globally, the construction industry accounts for nearly 39% of greenhouse gas emissions. The need for sustainable practices in construction cannot be overstated, as the consequences of inaction could lead to catastrophic global temperature increases. Current projections indicate that without substantial intervention, global temperatures could rise by as much as 7 degrees by 2100.
“The drive we are seeing towards sustainability in construction isn’t just a fleeting trend,” says Kate MacDougall, Associate Principal and Massachusetts Studio Leader at e2engineers. “It’s a fundamental shift in how we approach building. It’s about preserving our planet’s finite resources for future generations.”
Sustainable construction is grounded in core principles that prioritize environmental responsibility and resource efficiency. It involves designing and building structures that minimize their ecological footprint by reducing waste, conserving energy and water, and utilizing sustainable materials.
“We all know that sustainability is important,” says Trey Zaharek, Senior Structural Engineer at e2engineers. “We hear about it all the time in our work, and it’s the topic of countless webinars, conferences, and workshops. A lot of it has to do with climate change, which has become an undeniable reality, and the construction industry has played a significant role in exacerbating what’s becoming a crisis.”
Sustainable construction is not just about the here and now – it’s about longevity. True sustainability means designing buildings that minimize their environmental impact throughout their entire lifecycle, from conception to demolition.
Embodied Carbon and the Life Cycle Assessment
Embodied carbon refers to the total greenhouse gas emissions produced throughout all phases of a building’s life cycle, from material extraction, manufacturing, and transportation to construction and eventual demolition or recycling of construction materials. It is a crucial metric for assessing a project’s sustainability. The structural systems of a building – particularly those made of concrete and steel – are the most significant contributors to embodied carbon.
“What’s unique, and unfortunate, about embodied carbon is that it’s fixed (or locked in) once a building is constructed,” says Kate. “That makes it quite a bit different from operational carbon emissions which can be reduced over time through energy efficiency upgrades and the adoption of renewable energy sources.”
In order to evaluate the impact of a building throughout its entire lifespan, architects, designers, and structural engineers will use a Life Cycle Assessment (LCA), which is also a vital tool for measuring embodied carbon.
“The goal of a life cycle assessment is not only to assess the carbon footprint impact but also to facilitate decisions,” says Trey. “It is designed with a specific goal in mind: to analyze, disclose, and improve the environmental footprint in response to customer demand and compliance with building codes, standards, and rating systems.”
“The LCA process can consider the raw materials used, the transportation and construction methods, the operational energy and water usage, and the eventual demolition of the building,” says Kate. “Using these tools allows designers to compare different materials and systems, helping them to make informed decisions that align with their sustainability goals and meet customer demands for environmentally responsible buildings.”
The Role of Environmental Product Declarations in Life Cycle Assessment
Environmental Product Declarations (EPDs) are critical tools within the LCA framework, providing transparent and standardized information about the environmental performance of construction materials.
“Think of it like a nutrition label on food,” says Trey. “EPDs state the environmental impact/performance of the product over its lifetime.”
By comparing EPDs for different materials within the LCA, structural engineers and designers can make more sustainable choices that contribute to a building’s overall environmental footprint. EPDs also play a role in achieving credits in green building certification.
Innovative Solutions: Concrete
“Globally, concrete is one of the most widely used building materials, and its production poses significant environmental challenges due to the high embodied carbon content, primarily from the cement component,” says Kate. “Cement production contributes to global carbon emissions, largely because of the energy-intensive process of heating limestone to create clinker, which releases a significant amount of carbon dioxide as a byproduct.”
To mitigate this impact, sustainable alternatives like Ground Granulated Blast Furnace Slag (GGBS) and fly ash can be used as partial replacements for traditional Portland cement. GGBS, a byproduct of the iron and steel industries, can replace 20-70% of cement in concrete mixes, significantly lowering the embodied carbon while often improving the material’s workability. There are also new technologies up and coming, such as a recycled glass pozzolan, that can pave the way for lowering the embodied carbon in concrete mixes.
In addition to material substitutions, performance-based specifications offer a pathway to more sustainable concrete. By allowing concrete suppliers greater flexibility in mix design, they can tailor their approaches to meet specific project goals while incorporating sustainable materials. Early collaboration with suppliers can lead to concrete mixes that align with both environmental goals and performance requirements.
“Structural engineers have the ability to explore strategies that can reduce the overall volume of concrete required,” says Trey. “Designing thinner slabs, designing more efficient foundation walls and footings, or employing post-tensioned systems are all approaches that reduce the carbon footprint and enhance the efficiency and functionality of the structure.”
Recycling and reusing materials is another key strategy for minimizing concrete’s environmental impact. Recycled concrete can be repurposed for new construction by breaking it down and crushing it to the desired specifications, thereby reducing the demand for new materials and the associated carbon emissions. Water from concrete truck washouts can be reclaimed and reused. These solutions may not always be possible on new buildings but could be employed on non-structural concrete applications (such as sidewalks or planters). Employing alternative foundation designs, such as shallow frost-protected foundations using rigid insulation, can also reduce the amount of concrete needed, contributing to the overall reduction of embodied carbon.
Evolving Practices: Steel
Steel is another material where innovative practices are driving sustainability. The steel industry has made significant progress by adopting Electric Arc Furnace (EAF) technology, which utilizes up to 90% recycled materials and has the potential to be powered by renewable energy. EAF technology can reduce CO2 emissions by roughly 50% compared to traditional steelmaking processes, which are still used in other parts of the world.
“To further decrease embodied carbon, engineers can prioritize the use of domestic steel, optimize structural designs to reduce excess material, and select higher-grade steels that offer increased strength without additional material use,” says Kate.
For structural applications, using braced frames instead of moment frames can significantly reduce material needs and improve a building’s ability to resist lateral loads, potentially decreasing a project’s carbon footprint by up to 12% (based on a typical three story building). Additionally, using lighter steel sections, selecting Hollow Structural Sections (HSS) or tube shapes for columns, and utilizing open-web steel joists, can lower the overall steel tonnage required for a project, further enhancing its sustainability.
Sustainable Choices: Wood
“Wood is often regarded as the most sustainable building material due to its lower carbon footprint and potential to lead to carbon-neutral buildings,” says Trey. “However, this is only true when wood is sourced from responsibly managed forests and used in a way that supports sustainable forest practices. Locally-sourced timber and reforestation are key factors in maintaining wood’s sustainability.”
Advancements in engineered wood products, such as Laminated Veneer Lumber (LVL), Glulam beams, and Cross-Laminated Timber (CLT), allow for stronger, more efficient use of wood resources, often requiring smaller trees. Prefabrication of wood components can also reduce waste and accelerate construction timelines, further reducing a project’s carbon footprint. Despite these benefits, careful consideration must be given to fire safety and building size limitations when using mass timber, especially in compliance with the latest building codes, such as the 2024 International Building Code (IBC), which includes updated fire rating assemblies for mass timber.
Collaborative Approaches to Sustainability & the Future
“Achieving sustainability in construction is a collaborative effort that requires the involvement of multiple disciplines and the early engagement of all stakeholders,” says Kate. “Cross-disciplinary collaboration is essential for integrating diverse expertise and perspectives, which can lead to more innovative and effective sustainable solutions. When design teams, construction teams, and clients are brought together early in the process, it allows for the integration of sustainability goals into the project’s planning and execution.”
As we look toward the future of sustainable construction, the path forward is clear: embracing innovation, setting ambitious sustainability targets, and fostering collaboration across disciplines. Innovation and new technologies are central to this vision.
“From advanced materials with lower embodied carbon to cutting-edge building techniques that enhance energy efficiency, the future of construction lies in our ability to harness these tools effectively,” says Trey. The long-term vision for sustainable construction is one of resilience and harmony with nature. By prioritizing environmental stewardship in every aspect of building, from design to building use, from demolition to material recycling, we can create structures that not only serve human needs but also contribute positively to the world around us. This vision challenges the construction industry to lead the way, demonstrating that it is possible to build a greener, more sustainable future that stands as a testament to human ingenuity, resilience, and care for the Earth.
Sources
https://www.climate.gov/news-features/understanding-climate/climate-change-global-temperature-projections
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https://carbonleadershipforum.org/
https://pozzotive.com/
https://steeltubeinstitute.org/resources/navigating-sustainability-in-structural-engineering/
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