As sustainability initiatives and regulations increasingly focus on the embodied carbon emissions of construction materials, property owners are facing tough questions. What can we do? Will it cost more? Will it make a difference? Here’s what project teams can do today.
Reducing embodied carbon is the next big step in the building industry’s efforts to reduce its impact on climate change. And change is coming fast.
This year, California became the first state in the nation to impose sweeping embodied carbon restrictions on construction, which could be a bellwether for similar initiatives around the country. Starting July 1, any new construction or adaptive reuse of commercial buildings larger than 100,000 square feet and school projects over 50,000 square feet will need to meet new carbon emission restrictions for concrete and steel and provide a comprehensive assessment of the entire building’s life-cycle carbon impact.
More states are sure to follow. Embodied carbon — carbon emissions resulting from the manufacturing, supply and transport of building materials — represents more than 11% of global CO2 emissions and will need to be addressed for the industry to meet its goals and assist in international agreements to stay below 2-degree warming levels.
Embodied carbon is a much different challenge than operational carbon, the emissions typically associated with using fossil fuel–based energy sources to power buildings. The return-on-investment for reduced carbon materials is not always clear, and the benefits are harder to quantify.
“We are still in the beginning stages of understanding how to best analyze embodied carbon, to say nothing of using that analysis to influence design decisions,” says LPA Director of Sustainability and Applied Research Ellen Mitchell.
At this stage, many building owners don’t know what they can do to reduce embodied carbon — or what they should do. But there are clear strategies available that can significantly impact their projects today, while staying within budgets and helping to create healthier, more efficient buildings.
In many cases, reducing embodied carbon is simply good design.
“It starts with looking for opportunities to do more with less, such as repurposing assets and reducing the amount of materials,” Mitchell says. “A project that is judicious about the use of materials can benefit from saving embodied carbon and saving money.”
Each building owner needs to choose their own priorities. Taking a multidiscipline approach can develop options that impact the environment and find different ways to generate ROI, without increasing the capital budget.
Sites
Nature-based solutions can provide up to 37% of the emission reductions needed to meet global warming goals by 2030, according to research published by a group of agencies led by The Nature Conservancy. Landscape design is the one area of a project that can actually be made carbon positive by simple design choices and choosing plants that sequester carbon.
There are steps to any landscape carbon strategy, says LPA landscape architect and Project Designer Andrew Wickham. The first step is to preserve the existing site as much as possible. Reuse what’s already there. The second step is to minimize carbon-heavy materials, such as paving and walls. Designing with civil engineers can combine water treatment with carbon-reduction strategies to further reduce embodied carbon. And the third step is to maximize planting that can sequester and draw down the carbon emissions.
Smart carbon choices often have multiple benefits. Paving materials like decomposed granite are less carbon intensive and less expensive than concrete. Finding ways to reduce moving earth and reworking the site will cut carbon emissions and save money. “A lot of our clients’ goals have co-benefits with decarbonization,” Wickham says. “For example, adding more trees can increase shade, mitigate urban heat and sequester carbon.”
Structures
The bulk of a project’s early embodied carbon discussions will always focus on the structural choices, which initially contribute the largest share of a project’s embodied carbon. Low-carbon concrete and strategic use of mass timber can dramatically reduce the carbon impact.
But structural design must also consider safety, programming, budget and the client’s long-term goals. The choices are very different in a lab or education space than a commercial office building.
Structural systems play the largest role in a project’s life-cycle carbon footprint. (Pictured: Boys and Girls Club of Lake Tahoe.)
An integrated design approach, including structural engineers early in the process, helps blend the project’s different interests and priorities with the structural choice.
“A good structural design has the minimal amount of steel and concrete to meet the project’s requirements,” says LPA Director of Structural Engineering Bryan Seamer. “Of course, that’s the number one thing that reduces embodied carbon — less steel and less concrete.”
Location makes a big difference in the ability to source local materials, which can offer different options for carbon reduction. “Concrete is very local, and different batch plants and different regions have different capabilities for carbon reduction through different technologies,” Seamer says.
Interiors
A recent study by the Center for the Built Environment and the Carbon Leadership Forum found the inclusion of interior construction and finishes increased the embodied carbon in the studied buildings by 18% on average. “Even under our limited scope, this analysis suggests that the impacts of interior elements are significant … [and] modeling and reporting can be an important consideration for developing more comprehensive assessments and results,” the report concluded.
For interiors, embodied carbon strategies start by reducing the amount of materials that will be used over the life of the space. Designers can work with clients to develop flexible spaces that won’t need a redo every few years. Selecting reusable, reconfigurable and durable materials will reduce the project’s carbon impact for decades.
Interiors can impact embodied carbon through sensitive material choices. (Pictured: 550 South Hope Street.)
“Throughout the life of the building, the embodied carbon emissions associated with the typical 10- to 15-year renovation timeline can actually double the building’s embodied carbon because of constant furniture and finishes refresh,” Mitchell says. “Designing flexible and adaptable spaces with a timeless materials palette reduces the need for renovation and gives materials a longer life span.”
When renovations and updating must happen, designers can prioritize products that participate in the circular economy, where takebacks and reuse can minimize unnecessary waste. These days, it’s becoming easier to specify natural materials, as manufacturers increasingly share information and promote transparency around carbon. Discussions around carpet, paints, wall coverings and finishes can include quantifiable data on the attached carbon emissions. Furniture is more difficult to assess, but manufacturers are responding to calls for data and developing new product lines.
Mechanical, Electrical and Plumbing
The building’s mechanical and electrical systems, which play a large role in operational carbon emissions, are often overlooked in the embodied carbon discussion. While there is still no widespread data, MEP systems may contribute roughly 25% of a new building’s embodied carbon and could be 50% or more of the embodied carbon impact of a renovation.
As with other disciplines, reducing embodied carbon impacts of MEP systems starts with looking for opportunities to do more with less. “Can we design more efficient systems with less ductwork, less piping and smaller equipment?” says LPA Director of Engineering Erik Ring. “Wherever we have a more efficient building, with reductions in equipment, ductwork, piping and conduit, we know we’re conserving project budget and reducing embodied carbon.”
Natural ventilation can reduce the need for mechanical systems. (Pictured: Innovation Office Park.)
Refrigerants are another issue. All mechanical cooling systems contain refrigerants — although the type, quantity and associated environmental impact of refrigerants in different systems vary dramatically. Variable Refrigerant Flow (VRF) systems may improve operational efficiency, but these systems use high quantities of refrigerants, which are almost certain to leak into the atmosphere eventually. The EPA is phasing out widely used refrigerants with the highest GWP (Global Warming Potential), but the HVAC industry is struggling to develop suitable, safe and cost-effective alternatives.
The best response: constructing less space that needs conditioning reduces the need for HVAC systems and long pipe runs. As with other building materials, efficient systems that last longer also improve carbon performance over a building’s life cycle. Equipment won’t need to be replaced or repaired as often. Building and MEP designs that are more flexible and adaptable mean ductwork, piping and other materials will not need replacing every time a new tenant moves in.
Architecture
Aside from setting the tone for the rest of the disciplines, architects play two major roles in embodied carbon. The first is through the envelope design. In recent years, architects have grown more sophisticated in their understanding of how façade design affects energy performance. They are now expanding that understanding to include embodied carbon considerations in their wall assemblies. This undoubtedly adds a level of complexity, forcing tradeoffs when additional materials may make the envelope more efficient and save operational carbon, but require more materials, potentially increasing embodied carbon. Conversely, there are also opportunities where strategies can align. Designing the envelope to reduce peak heating or cooling can lead to a downsized mechanical system, which in turn can lead to a reduction in system size, saving both cost and embodied carbon.
But perhaps the greatest opportunity for an architect to affect embodied carbon happens before a single line is drawn. Architects are often the first point of contact with a client who has a project in mind but potentially has not identified a program or even a site. In these cases, architects are uniquely qualified to help their clients understand the benefits and the potential in reusing an existing building versus building anew. This single strategy will undoubtedly reduce a project’s embodied carbon emissions significantly more than even the most environmentally sensitive new building. As the saying goes, the greenest building is the one that is already built.
Sidebar: A Focus on Materials
After years of pressure, manufacturers are increasingly sharing information about the origins and production of materials, creating opportunities to make more informed choices about the embodied carbon impact.
“We’ve pushed for transparency, and the manufacturers have delivered,” says LPA sustainable materials specialist Jill Pedro. “Now it’s our turn to understand what the information is telling us and apply it to our projects.”
Pedro is LPA’s materials specialist charged with making information about materials more accessible to design teams and clients. She is helping to build the firm’s materials lab, which serves as an evolving resource, test site and meeting spot.
LPA’s sustainable materials specialist Jill Pedro in the Irvine studio’s materials library.
Pedro is uniquely positioned for the role. She worked as an architect for 10 years, which gives her an insider understanding of materials and their impact on design discussions. She also has a degree in environmental psychology, providing another layer to her study of the effects of materials choices on building occupants.
It’s an ongoing effort. The materials industry is still working to develop a common language to measure and discuss embodied carbon associated with building materials.
“We need a better understanding of the different aspects of the material life cycle,” she says. “Then we can start to focus more on content and not the nuances of the acronyms.”
Pedro is determined to close the gaps in the industry’s knowledge of both the environmental and human health impacts associated with materials.
“It gives me hope to be able to be involved in something that is so important to the sustainability of this planet,” she says.
