For decades, the U.S. Green Building Council’s (USGBC) LEED rating system has served as the primary yardstick for sustainable construction. But as the climate crisis evolves from a distant threat to a daily reality, the yardstick is changing.

The introduction of LEED v5 represents more than a simple iteration of previous standards.

• While v4 and v4.1 focused heavily on incremental efficiency improvements, v5 shifts the goalposts toward total decarbonization, climate resilience, social equity, and ecological restoration.
• At the East County Service Center project for Contra Costa County in Brentwood, California, Webcor is finding out what that shift looks like in the field.

The Decarbonization Mandate

The most significant departure from previous versions is a relentless focus on carbon.

• Under v4, projects could earn points by reducing energy use.
• Under v5, the requirement is to plan for a future that doesn't rely on carbon at all.

"LEED v5 is really pushing projects to decarbonize as much as possible," says Suzie Pedersen, Sustainable Design Advisor at project designer Perkins&Will. "It requires us to complete a carbon projection plan and figure out how to decarbonize the building over a 25-year timeline. It’s a much bigger emphasis in the overall rating system than we saw in v4."

This focus extends deep into the supply chain through a "multi-attribute optimization" of materials. Rather than merely collecting Environmental Product Declarations (EPDs), teams must now leverage a common materials framework that simultaneously assesses health, social equity, and climate impacts.

A Human-Centric Framework

Beyond the "green" metrics, v5 offers greater capacity to address the human element of construction. This includes strict prerequisites for accessibility and inclusion, as well as credits for hiring from the local labor force and for supporting apprenticeship programs.

"It includes more of a human aspect than before," Suzie notes. "We are focused on making this an inclusive site for both building occupants and the broader community it serves. This effort goes beyond a typical v4 project—we’ve carefully evaluated the climate risks and social conditions of the area and are designing a building that responds directly to those factors, ensuring it serves the community effectively over the long term.”

The East County Strategy: Chasing Platinum

For the team at the East County Service Center, the decision to pursue v5 wasn't just about meeting a standard — it was about testing the limits of what is feasible for a public-facing facility. The project is dialed in on 82 points, placing it within the threshold for a Platinum rating, which requires 80 points.

What they're saying: Project Director Alec Bangs attributes much of this potential success to a client — Contra Costa County — that views sustainability as a core priority.

"We originally assumed we’d hit Gold under v4 and perhaps stretch for Platinum," Alec says. "But with the way everything is shaking out, we are in a position to hit Platinum under v5. It’s a team effort, and it takes a client who values it.

• This is a priority for the County Board, which makes it a priority for our client.

The project boasts an impressive array of sustainable features that serve as the engine for these credits:

• Geothermal Systems: Utilizing the earth’s constant temperature for high-efficiency heating and cooling.
• Microgrid and Battery Backups: Ensuring the building is "off-grid survivable." In the event of a power outage during a heat wave, the building's two main assembly spaces will remain operational as emergency cooling centers.
• Mass Timber: Used specifically to reduce the embodied carbon of the structure while enhancing the occupant experience.

The Burden of Documentation

Yes, but: If there is a hurdle to the new standard, it is the rigor of the "integrated design process." LEED v5 requires significantly more upfront work, forcing contractors, architects, and consultants to align before the first shovel hits the dirt.

"The rubber will meet the road with documentation," Alec explains. "The requirements are changing and becoming more stringent.

• While it hasn't been a burden on the operations team yet, Suzie says our partners at Perkins&Will and our internal sustainability experts are muddling through the documentation and learning the differences.

She agrees that the learning curve is steep. "We are still finding small things — requirements we didn’t fully understand at first. It requires clarifications with the LEED coach at USGBC to make sure we are interpreting the credits correctly."

A Path Forward

The East County Service Center is already being viewed as a "first-in-class" case study across Perkins&Will’s studios, serving as a template for integrating geothermal and mass timber under the new v5 rigor.

For Webcor, the lesson is clear: the era of "checking the box" for sustainability is over. Achieving the highest levels of certification now requires integration and upfront assessment that were previously optional.

LEED v5 is designed to be difficult, Suzie notes.

• It is a response to a world that no longer has time for "languishing in a state of denial."
• By leaning into these requirements now, the East County Service Center team isn't just building a county facility; they are defining the methodology for the next generation of the built environment.

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On April 1, our East County Service Center (ECSC) team joined representatives from Contra Costa County (CCC), Perkins&Will, BKF, and MIG to celebrate breaking ground on the $150 million essential services facility in Brentwood—a major milestone representing the progressive design-build team’s tireless, exceptionally fast-paced efforts over the last few months.

Once complete, ECSC will offer local residents a one-stop hub for a wide variety of essential services while keeping sustainability top of mind: The building will be powered by geothermal and solar energy systems, and the use of mass timber in lieu of typical building materials will significantly lower our carbon footprint.

• “ECSC is incredibly exciting for Webcor and the County because we're pushing the boundaries of sustainability goals,” says Project Manager Karen Turcios.  “We’re delivering the County’s first mass timber and geothermal-powered structure while staying mindful of owner costs.”

It’s a unique project rooted in community, both in purpose and delivery. The building was intentionally designed as a public cooling space to help residents and visitors combat Brentwood’s notorious summer heat, particularly in the event of a power outage or low air quality.  

• The center will also offer several public amenities, including a plaza, gazebo for events, gathering spaces, shared training and conference rooms, lobbies, and family-friendly resources such as lactation rooms and a children's play area connected to family services.

For CCC’s East County residents, this vital project has been a long time coming. ECSC’s Brentwood location means they’ll no longer have to travel 30+ miles to Martinez (where the CCC Admin Building, which we delivered in 2023, is located) to access essential services from Employment & Human Services, Contra Costa Health, Veterans’ Service Office, and more. It will also dramatically reduce CCC employees’ commute times, as many of them are East County residents who regularly battle rush hour traffic to and from Martinez.

In a feat believed to be among the first of its kind, Webcor and its project partners successfully developed and placed a low-carbon concrete mix for drilled-shaft auger-cast piles.

• This isn't just another incremental gain; it is a solution to one of the most stubborn challenges in the construction industry.

The Tremie-crete Problem

Deep-foundation concrete, often referred to as tremie-crete, is notoriously difficult to decarbonize.

• Most green baselines (measured by Global Warming Potential (GWP)) don’t easily apply to drilled shaft foundations because of the specific physical properties required during the "fresh state" of the pour.
• While standard concrete is often judged by its final strength, tremie-crete is driven by rheology, or how the mixture flows.

To work at these depths, the mix must have high fluidity and strong resistance to "bleeding" and segregation under high hydrostatic pressures.

• Historically, achieving this meant using mixtures with very high Portland cement contents to increase paste density. As Webcor Concrete Director Eric Peterson points out, "The use of high amounts of cement in tremie-crete is not determined by strength. It is driven by the rheological requirements of the mixture."

Breaking the Status Quo

The project team was initially on the verge of abandoning the low-carbon approach.

• Early attempts did not perform well in terms of strength or fresh-state properties, and a traditional "back-up" mix carried a heavy carbon cost of 430 kg CO2-eq/m3.
• However, Eric — who chairs the ACI Committee 237, Self-Consolidating Concrete (SCC) — saw an opportunity to apply SCC principles to the foundation piles.

For four months, the team Keller, CEMEX, and Webcor Concrete worked at CEMEX’s laboratory in Livermore to develop and test a new mixture.

• One major hurdle was a site-added "fluidizer" that lacked an Environmental Product Declaration (EPD) and had not yet been used in the Project’s previous strength tests.
• Without an EPD, the total carbon impact could not be quantified, which is required by SFO.
• Webcor assisted the manufacturer of the fluidizer in obtaining a verified product EPD through Climate Earth and ASTM, allowing the team to confirm a GWP of 270 kg CO2-eq/m3—well below SFO’s requirements.

From Lab to Labor

In the lab, the mixture performed like a champion, but as any seasoned practitioner knows, the lab is a controlled environment.

• When early field results for the test piles appeared to differ from the trial batching in the lab, Eric spent the better part of two weeks in the field observing the batching, curing, and testing processes.
• He identified several critical issues, including the addition of water in the field and the handling of specimens before transfer to the lab. He also documented issues occurring at the lab related to preparation and testing procedures.

"There is a significant difference between the capability of a concrete mixture and how it performs during high-paced production," Eric notes.

• By resolving these field-level and testing gaps, the mix began to behave as it had in Livermore.
• It developed significant strength between 28 and 56 days, consistently exceeding 6,000 psi and demonstrating that the Code's "over-design" requirements were satisfied.

The Bottom Line

The success at SFO demonstrates that:

• It is often possible to satisfy both performance requirements and low-embodied-carbon goals.
• We have moved beyond identifying the problem to offering a performance-based solution for the rest of the industry.
• By understanding the challenges and applying a proven strategy, we’ve created a roadmap to decarbonize one of the difficult elements of our structures.

The bottom line: If you think deep foundations are a "necessary evil" in terms of carbon cost, think again.

• We have proven that even 90 feet down, sustainability is achievable with the right mix of expertise, materials, and persistence.

The goal now is to apply the lessons from this success to other projects in our pipeline with similar or more complex challenges.