From Vision to Reality: Achieving Zero Carbon at 300 Kansas Street — A Conversation with Spear Street Capital

300 Kansas Street was recently awarded the first Zero Carbon Core & Shell certification from Living Futures. Atelier Ten’s Meghna Koushik sat down with Ethan McCall from Spear Street Capital to discuss the decision to pursue Zero Carbon certification from a developer’s perspective, its impacts and the lessons learned.

Deciding to pursue ILFI Zero Carbon Core & Shell:

The achievement of Zero Carbon Core & Shell certification at 300 Kansas Street demonstrates how ambitious sustainability goals can align with market success. By integrating performance-based strategies, securing 100% renewable energy, and engaging tenants through clear guidance and shared responsibility, the project sets a new benchmark for high-performance, low-carbon buildings. 300 Kansas illustrates how forward-thinking developers can lead the market, proving that sustainable design is not just an environmental imperative but a strategic advantage.

From the outset, Atelier Ten was keen to pursue Zero Carbon certification because it is a performance-based standard, requiring an ongoing commitment to verify the building is performing as intended, even after the initial design and construction phases. When Atelier Ten realized that Spear Street Capital shared this ambition, we immediately conducted a comprehensive feasibility study to ensure all consultants understood the certification’s specific requirements and expectations. Since the design process was already underway, our role involved making small, cost-effective adjustments to meet the new criteria, which required navigating complex discussions with the consultant team and reviewing already proposed design options.

MEGHNA: What made you want to pursue ILFI Zero Carbon – Core & Shell, a pilot program that nobody had pursued before?

ETHAN: When we decided to pursue to the Zero Carbon Core & Shell designation at 300 Kansas, we had recently completed a smaller project in Seattle (dubbed the “Watershed”) that had achieved the ILFI Living Building Petal Certification. During the lease up and sale of the Watershed, it was evident to us that the market had rewarded our forward-thinking sustainable design and unique environmental attributes via higher lease rates and asset value. We had already specified a LEED Gold and all electric building design, but the experience at the Watershed helped convince us to think bolder about our sustainability strategy at 300 Kansas.

MEGHNA: Did you face any initial hurdles when deciding to pursue certification and how did you overcome them?

ETHAN: Once the decision was made to pursue Zero Carbon Core & Shell, we immediately began due diligence with our architect, consultant and engineering teams to analyze the building’s qualifications. We wanted to make it happen, but we had just broken ground on the development and needed to move quickly. What was the most surprising, and key to the overall success, is that a lot of what was going to be required by Living Futures in terms of reporting, GWP reductions, etc. was already being done by our team as part of their own internal best practices. We just had to aggregate it all.

MEGHNA: Did the upfront costs associated with achieving Zero Carbon – Core & Shell significantly impact the project’s budget? How did you manage these costs, and what strategies would you recommend for future projects aiming for similar certifications?

ETHAN: Given all the work going on behind the scenes with our AEC team, the upfront costs were minimal. We worked with Atelier Ten to purchase the carbon credit, but did not have to implement significant design changes given that we had already specified low GWP materials (like recycled concrete mixes).

Finding Future-Thinking Tenants

Pursuing ILFI Zero Carbon Core & Shell certification has positioned 300 Kansas Street as a market leader in sustainable development, attracting tenants who value environmental performance and ESG alignment. The certification’s requirement for 100% renewable energy presented a key challenge: with no available roof space for on-site generation due to the building’s zero-lot line and green roof design, the team pursued an innovative off-site solution. Through collaboration with CleanPowerSF, the local community choice aggregator, Atelier Ten secured a 10-year renewable energy contract—with an option to extend another five years—after negotiating beyond the standard five-year term.

Meeting this commitment required full cooperation from Spear Street Capital and all tenants, who were onboarded to ensure the entire building operated on 100% renewable electricity. To facilitate this process, Atelier Ten developed a Tenant Sustainability Guide outlining the building’s key environmental features, renewable energy commitments, and guidance for maintaining sustainability goals throughout tenant buildout and operations. A companion “kit of parts” details equivalent sustainability measures for tenant improvements, ensuring alignment with the project’s overall certification framework.

MEGHNA: ILFI ZC C&S requires the project to power the building’s electricity with 100% renewable energy for the next 15 years. How have tenants (existing or prospective) responded to this requirement?

ETHAN: Most prospects have responded positively—especially as corporate sustainability goals have become more ambitious. By contracting with Clean Power SF and PG&E to bring 100% renewable energy to the project, we’ve made it easier for tenants to meet their own goals without extra effort. More and more businesses see sustainability commitments like this as a way to attract talent, customers, and investors.

MEGHNA: How has ILFI ZC C&S certification changed the process of finding a tenant for the building?

ETHAN: Pursuing the ZC Core & Shell certification has helped 300 Kansas stand out in a competitive leasing environment. We’re seeing more tenants—particularly in tech, life sciences, and venture-backed startups—prioritize environmental performance and ESG alignment. Sustainability is embedded in all our marketing materials, serving as a natural conversation starter with prospective tenants. For mission-driven companies or those with their own sustainability goals, the building’s zero-carbon designation provides them with a tangible way to align their space with their values.

MEGHNA: How are you educating tenants about the building’s sustainability features and encouraging them to share the commitment? 

ETHAN: The building’s sustainability features are highlighted on our website, reinforced through environmental graphics throughout the space, and integrated into all our conversations with prospects. We offer a Tenant Sustainability Guide that outlines key base building strategies—such as electrification, embodied carbon reductions, and renewable energy procurement— along with guidance to help tenants maintain their own sustainability goals during buildout and ongoing operations. We aim to foster a shared commitment to sustainability by demonstrating our dedication to integrating environmental strategies from day one.

Setting an example for other developers and marketability

As climate regulations tighten and market expectations evolve, developers are taking a more proactive role in sustainability—viewing high-performance, low-carbon buildings as both environmental and financial imperatives. Projects like 300 Kansas illustrate how sustainability is becoming the new market baseline. Beyond attracting mission-aligned tenants, achieving Zero Carbon certification enhances asset value, mitigates future regulatory risk, and demonstrates to investors that sustainability is integral to a project’s long-term performance and credibility.

MEGHNA: In a rapidly changing climate and regulatory landscape, how do you see the role of developers shifting towards more proactive sustainability initiatives?

ETHAN: The role of the developer is evolving quickly—and sustainability can no longer be a buzzword tacked onto marketing materials after the fact. With tightening regulations across the city and state, rising tenant expectations, and growing pressure from capital markets around ESG performance, forward-thinking developers are realizing that high-performance, low-carbon buildings aren’t just good for the environment—they’re better long-term investments. Projects like 300 Kansas are setting new baselines for what the market will come to expect.

MEGHNA: Has the Zero Carbon certification influenced the building’s valuation or marketability in ways beyond just attracting tenants?

ETHAN: Yes. Beyond attracting mission-aligned tenants, the Zero Carbon certification enhances long-term asset value and helps futureproof the project against regulatory and market risk. Investors are looking for assets that perform overtime, both financially and environmentally. The certification serves as third-party validation of the building’s sustainability performance, which builds credibility and signals to capital partners that sustainability is embedded from the outset, not added as an afterthought.