The Environmental Protection Agency defines sustainable construction as “the practice of creating structures and using processes that are environmentally responsible and resource-efficient throughout a building’s lifecycle, from siting to design, construction, operation, maintenance, renovation and deconstruction.” The concept of sustainability, at its core, considers the resilience of the natural environment and the practices that impact it.
But sustainability issues extend to community health, social equity, and wealth distribution—and the construction sector is in a position to make significant impacts on all of those areas. These objectives will grow only more intertwined as the world continues to urbanize.
To understand why sustainable construction is important, start thinking big—really big. “If you look at climate change, I think the construction industry and the resulting buildings that are produced are 60% of the problem,” says Charles Kibert, director of the Powell Center for Construction and Environment at the University of Florida. Kibert is co-founder of the Cross Creek Initiative, which seeks to implement sustainability principles into construction; board member of the Green Building Initiative; and author of Sustainable Construction: Green Building Design and Delivery, now in its fourth edition.
Kibert says a significant portion of climate-change gases are associated with the built environment: the resource extraction, the manufacturing of materials, the operation of buildings, and the transportation systems that serve the way buildings are laid out and planned.
The construction industry sits between a rock and a hard place. The earth’s urbanizing, growing population is placing enormous demands on the construction sector: Since 2007, more than half of the world’s population has lived in cities; that figure is projected to rise to 60% by 2030.
To meet this surging human demand, global construction output is projected to grow by a staggering 2.5 trillion square feet by 2060. (For perspective, that’s like building one New York City each month for the next four decades.)
At the same time, concerns about climate change and dwindling natural resources place increasing pressure on construction firms to build green and reduce their environmental impact.
By conservative estimates, the construction industry is responsible for more than 30% of the world’s natural-resource extraction and a quarter of the solid waste generated. (That number climbs past 50% when considering sand and aggregates used on building sites.) The built world is also one of the biggest contributors to global emissions: According to the World Green Building Council, the construction and operation of buildings accounts for 36% of global energy use and 39% of energy-related CO2 emissions.
This puts the construction industry in a difficult position: It will have to meet skyrocketing building needs as the world continues to deplete its resources and demand grows for high-performance (even net zero) green buildings.
Yet, there’s good news. Because the built environment plays such a major role in the health of earth’s environment, green-construction initiatives can significantly boost efforts to improve global sustainability.
For forward-thinking builders, these challenges become opportunities. It’s time to view sustainable construction practices as value enhancements rather than cost or time burdens—because when implemented in smart ways, those practices will benefit both the environment and the bottom line.
Implementing sustainable business practices starts with considering a builder’s true scope of responsibility. “Historically, when we think about science-based targets to make any business more sustainable, it’s thinking about, ‘What’s our footprint? What is our impact, positive or negative? And how do we manage that based on our share of the market, our share of the contributions to carbon emissions?’” says Michael Floyd, senior specialist of Worldwide Sustainability Solutions at Amazon Web Services. “But a different question would be, ‘What is the biggest positive impact we can have based on what we control?’”
When measuring their carbon footprint, for example, construction companies have been conditioned to focus on their own operations. But general contractors can often make their biggest carbon impact through procurement choices, according to Floyd. “It’s something the sector has really woken up to in recent years,” he says. “For example, general contractors often measure how much diesel fuel gets burned on the jobsite—and that’s important. But given the urgency of climate change, realizing they can reduce a project’s embodied carbon so much more simply by choosing better materials? It just changes the paradigm, especially when those lower-carbon options cost about the same as the alternative.”
Sustainable construction methods span a lot of Ps: products, practices, processes, and policies. Sustainable construction methods begin in a project’s design phase and carry through to operation. Here are six such methods and how they’re integrated into the construction phase.
Lean construction is a collaborative approach to project delivery in which all stakeholders work together to optimize the project, minimizing waste wherever possible.
In some ways, lean construction and sustainable construction are two sides of the same coin: Both sustainable and lean construction strive for efficient use of resources through the reduction of waste. Whereas the goals of lean construction are short-term reduction of waste in all of its forms (not just material) and the environmental concerns of sustainable construction are longer term, both disciplines aim for the efficient use of valuable resources; an integrated systems approachcan help realize hidden cost reductions while producing more sustainable outcomes.
Because lean construction has the net effect of reducing defects, it tends to reduce material waste. Resulting assets are assembled using fewer resources and have a lower environmental impact from construction. When engineering and construction company BAM Ireland was tasked with constructing seven new courthouses in Ireland, to complete the project on time, the team employed lean-construction principles: Rather than one person “pushing” construction schedules to stakeholders, BAM Ireland implemented a “pull” planning process with the general contractor, design team, and subcontractors. Each discipline participated in a planning session together, working backward from the delivery date and aligning activities to avert or resolve issues.
This efficiency in communication also led to efficiency in construction: BAM Ireland says its pull-planning process (in conjunction with production planning and supply-chain management) made it possible to leverage just-in-time delivery of materials and assemblies, which reduced waste because supplies weren’t damaged while sitting on-site.
“From a delivery point of view, we wanted to better coordinate the information that was being issued by our designers and our supply chain to avoid clashes and other issues on-site,” says BAM Ireland’s digital construction manager, Michael O’Brien. “One of the outgrowths was in and around sustainability.”
In a study by Dodge Data & Analytics, more than two-thirds of contractors surveyed in the United States with moderate experience in lean construction practices said they expected to increase their use of weekly work planning and early stakeholder involvement over the next two years. The contractors also revealed that their top motivator for incorporating technology into lean practices is to avoid rework, which reduces waste.
Take it from the “Queen of Prefab,” Autodesk Head of Industrialized Construction Strategy and Evangelism Amy Marks: Approaching design and construction from a manufacturing mindset is critical to easing the pressure on the ecosystem. “Without a commitment to industrialized construction, including prefabrication and the enabling principles of design for manufacture and assembly, I don’t think we’ll be able to meet our world’s future infrastructure needs,” Marks says.
The environmental benefits of industrialized construction are significant. Prefabrication processes:
Use fewer natural resources
Reduce pollution
Optimize material usage
Sites offer safer working conditions and reduced operational energy, and off-site construction minimizes impact on communities.
Based in Windsor, CA, BamCore is working to industrialize the way residential and low-rise commercial buildings are built. The company uses sustainably harvested bamboo as the core element of its custom-engineered, hollow-wall structural lumber system, as well as data-driven digital construction tools to quickly and efficiently erect the wall panels at the jobsite.
For each project, BamCore designs and develops a set of custom-fabricated, engineered timber-bamboo hybrid panels in its factory. Each panel is cut to fit into its adjoining panels and is precut to accommodate every door, window, light switch, and outlet. Panels are marked with sequential numbers that allow for precise installation order. Color-coded lines can be added during fabrication to indicate where every electrical and plumbing line will be positioned. BamCore then delivers the complete set of panels to the jobsite.
At the jobsite, crew members can access a 3D animated model of the project on their mobile devices. BamCore worked with a developer to create an application that transforms digital building models into animations. Crew members can easily follow the animated build sequence and view the entire order of construction—from the first panel to the last. Prefabrication and the use of digital construction tools have resulted in faster build times, fewer errors, less waste, and lower cost for BamCore—proof that industrialized construction can have an impressive impact on sustainability.
DfMA, or design for manufacture and assembly, is a design methodology that enables and optimizes prefabrication through a set of design choices and principles. Adopting DfMA processes makes prefabrication easier. It also enables the shift from a “project” to a “product” mindset. This productization strategy drives waste reduction in both design and construction. Designers can spend more time focusing on the complex elements of projects while less construction waste is generated on-site, site logistics are improved, and fewer materials need to be transported to the site. With an estimated 25% of construction materials ending up in landfills, the ability to cut waste through DfMA enabling prefabrication has great green potential.
Sustainable construction materials can be thrilling to behold, from the warm, tactile beauty of mass timber—a near-perfect material for industrialized construction—to the sculptural curves of bamboo structures, to the striking use of whole trees as structural columns, to shapely sustainable concrete forms made stronger and lighter through generative design.
Behind the scenes, builders are looking upstream more in their search for sustainable solutions—starting with procurement. “Green-building project teams are putting pressure on the materials and product suppliers to prove their products are low impact,” Kibert says. “There are many standards being written around this stuff that tie into the green-building movement. If you’re a project team, you often have to demonstrate that your products are recyclable, have recycled content, have low impacts. More recently, the scrutiny of products has gone beyond environmental issues to include social issues that the companies affect.”
Kibert says two sets of materials standards are gaining momentum: Environmental Product Declarations (EPDs) and a second, newer set called multi-attribute standards, or MASs. EPDs are lifecycle assessments of products. “Within that EPD framework, there are five to six criteria, including climate change, that are provided in the spirit of transparency,” he says. “A good example of a criterion covered by an EPD is the carbon footprint of the product. For a carpet tile, as an example, this information is provided as kilograms of carbon per square meter of carpet for each of the brands being compared.”
MASs, on the other hand, are directed toward very specific classes of products and are approved by standards groups such as UL and FM. “It’s about producing a standard that declares this product meets specified requirements across the sustainability spectrum of environmental, economic, and social criteria, and at different levels within those criteria,” Kibert says.
“Very recently, there has been an enormous increase in the number of companies producing EPDs for their products,” he continues. “The reason is, the project teams are asking for them because green-building rating systems like Green Globes and LEED require EPDs to earn credit toward certification. There has been great progress in this arena, but a robust decision system that provides a roadmap on how to compare EPDs for specific products is still lacking.”
Now is a critical time to address the ways building materials contribute to carbon emissions. Thanks to collaborative industry efforts, open, free carbon-reduction and carbon-calculator tools are beginning to make that process more transparent.
But it takes some self-scrutiny on the part of the building-material manufacturer, Floyd says: “They have to basically commission an assessment of their products. And then that data has to be published in a way that’s easily consumed and easily browsed through. You want procurement teams to say, ‘I need concrete that has this compressive strength and this much slump and this much cure time. And I need it within 100 miles of this site.’ And they need to be able to quickly pull up all of the products that fit the bill and easily stack-rank them by embodied carbon.”
Building Transparency—supported by a consortium of partners including global construction company Skanska, Autodesk, and others—recently launched the Embodied Carbon in Construction Calculator (EC3) tool, a free, open-access platform for revealing the embodied carbon in building materials.
Pulling data from third party–verified EPDs, the EC3 tool compares the carbon intensity of available materials, letting even general practitioners make fast, carbon-smart procurement choices.
“As soon as industry professionals have that data at their fingertips, it unlocks a transformative process,” Floyd says. “That’s why EC3 is a game changer. It has done a great job of centralizing what’s out there, creating some momentum around low-carbon materials innovation and lifecycle assessment on the part of the manufacturers because they want their products to show up in the database.” For example, when building Microsoft’s new 500-acre campus in Redmond, WA, Skanska was able to reduce embodied carbon by 30% without raising costs.
The circular construction economy approaches design and building with the intention to reduce, reuse, and recycle as many resources as possible. While design is central to the model, builders can divert construction and demolition materials from disposal by practicing source reduction, salvaging, recycling and reusing existing materials, and buying used and recycled materials and products.
“Circularity relates to the general contractor’s role because it has to do with procurement and how you manage anything you might be demolishing or deconstructing onsite, where you direct those material flows,” Floyd says. “It also has to do with documenting what goes into the final result, making it easier and less expensive to recover those materials at an asset’s end of life—effectively raising the future value of those embedded materials.”
Although BIM (Building Information Modeling) is mostly associated with design and preconstruction, it benefits every phase of the project lifecycle. BIM processes introduce so many efficiencies that employing BIM almost always reduces a construction project’s environmental impact.
Sophisticated 4D and 5D BIM projects integrate scheduling and cost/material estimation, ensuring more efficient management of change orders, for example. (The focus of 6D BIM, which supports facilities management, is on sustainability through energy analysis and modeling.) BIM and lifecycle assessments can also be integrated to automate environmental impacts assessments of building elements.
Consider China Construction Eighth Engineering Division Corp., Ltd. (CCEED), which built the 1,740-foot Tianjin Chow Tai Fook Financial Center, a super-skyscraper complex in Tianjin, China. To meet LEED Gold certification for one hotel’s luxury interior, CCEED integrated 2,000 types of materials within a sustainable structure. Using BIM, the team was able to use prefab construction to manufacture components precisely according to drawings, preventing material waste and eliminating the need to cut materials on-site.
“When someone really invests in adopting BIM, the project’s going to run smoother, so they’re going to make fewer errors,” Floyd says. “They can generate less waste and reduce their carbon impact. And they’re going to come in more on budget; their jobsite’s going to be safer. All of these good things are going to happen.”
These truths are indisputable: The earth has finite resources, a growing population, and a critical need for sustainable construction. This need is so pressing that the United Nations is leading the charge for change with its Sustainable Development Goals (UNSDG), a call for action by all countries to achieve a more sustainable future through strategies that build economic growth and address a range of social needs, including education, health, social protection, and job opportunities—while tackling climate change and environmental protection.
Ultimately, adopting sustainable construction techniques prepares construction companies—and their clients—for the future. “You future-proof your client by removing the risk of penalties in the future,” Kibert says. “Then what’s going to happen is that when the full impacts of climate change are experienced, conditions on the planet will badly deteriorate. Hurricanes and other storms will become more frequent and more intense and cause enormous destruction. Food supplies will be affected, and most species of sea life will disappear. It is likely that at this point, governments around the world will institute draconian policies and slap enormous penalties on those who contribute to climate change. In comparison, companies who have learned to operate with low impacts and make low-impact products and buildings will thrive in this future.”
The learning curve will get easier, and outlying processes will become best practices as more stakeholders respond to the need for sustainable construction. “Communities around the world are starting to get it, so companies that are behaving responsibly have the advantage of more business,” Kibert says. “The younger people coming out of college—the people we want to hire to be leaders and managers of people—they want to be with a company they can be proud of because they are doing the right things, with sustainability and environmental protection as some of their core values.”
This article has been updated. It originally published in October 2020.
Design & Make AEC section editor Sarah Jones is a Bay Area–based writer, editor, musician, and content producer. Sarah’s articles have appeared in Mix, Audio Media International, Live Design, Electronic Musician, Keyboard, Berklee Today, The Henry Ford, and on Grammy.com.
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