New leasing momentum, Kilroy Realty’s 100 First Street reshapes downtown San Francisco office space

Kilroy Realty’s 100 First Street in San Francisco stands out with LEED Platinum certification, flexible floor plates and a transit-first location as the landlord leans on this flagship tower to capture demand for high-quality West Coast offices.

Edited by ad hoc news New Releases & Launches Desk. Reviewed before publication on 06/15/2026 at 11:57 PM ET. Details in the imprint.

With leasing momentum slowly returning to select U.S. office cores, Kilroy Realty is leaning on a proven workhorse: the repositioned 100 First Street tower in downtown San Francisco, a 27-story Class A building that combines LEED Platinum sustainability credentials with highly flexible office layouts and direct access to regional transit hubs. The property, totaling roughly 524,000 square feet of rentable space, has become one of the company’s key showcases for the kind of energy-efficient, amenity-rich office product that still commands tenant interest despite broader market softness. Kilroy’s official property profile highlights the building’s LEED Platinum certification and full-block presence at First and Mission Streets.

What 100 First Street offers tenants in a challenged office market

100 First Street sits in the heart of San Francisco’s South Financial District, within a short walk of both the Transbay Transit Center and the Montgomery Street BART and Muni station, a location that reduces commuting friction for workers across the Bay Area and helps corporate occupiers meet their own sustainability and accessibility goals. The site spans an entire city block bounded by First, Mission, Fremont and Howard Streets, giving larger tenants the option of contiguous floors and efficient floor plates that can accommodate a range of workspace concepts from traditional perimeter offices to open, collaborative layouts. According to Kilroy, typical floor plates in the tower run roughly 20,000 square feet, allowing mid-size firms to secure full-floor identity without overcommitting on space, while larger enterprises can stack multiple levels to create branded vertical campuses within the high-rise.

The building’s LEED Platinum rating, based on the U.S. Green Building Council benchmark, reflects a combination of high-performance building systems, energy-efficient glazing and lighting, and water-saving fixtures that aim to cut operating costs and carbon footprint relative to older inventory in the downtown market. Kilroy emphasizes that 100 First Street’s retrofit program, completed prior to the pandemic, included upgrades to mechanical and control systems designed to improve indoor air quality and thermal comfort, a set of features that has taken on renewed importance for tenants focused on employee health and wellness in hybrid working models. In addition to traditional conference areas, the property offers on-site amenities such as secure bicycle storage, modernized lobby spaces and access to nearby food and retail, making it easier for employers to position the office as a destination rather than an obligation in their return-to-office planning.

From a leasing perspective, modern, sustainable buildings like 100 First Street have generally outperformed older, commodity offices during the post-2020 reset, with many occupiers using expirations or downsizing events as an opportunity to trade into higher-quality space while maintaining or even lowering total rent outlay. Market commentary from West Coast brokers has repeatedly stressed the emergence of a two-tier market in which Class A and trophy assets capture a disproportionate share of active tenant requirements, while less efficient, non-upgraded buildings struggle with elevated vacancy. Kilroy’s San Francisco portfolio strategy reflects this reality: the landlord has largely exited non-core, non-high-rise product in favor of energy-efficient towers and creative office campuses that can demonstrate concrete ESG performance metrics to corporate real estate teams. Industry reports point out that assets like 100 First Street, with strong transit connectivity and green certifications, tend to be better positioned to attract tech, professional services and financial tenants that are consolidating footprints but still want a central, high-amenity address. Recent coverage from CNBC describes how demand concentrates in newer, highly amenitized office buildings even as overall office vacancy remains elevated.

Although 100 First Street is not a newly constructed tower, its Class A profile and focus on environmental performance align it with the subset of “have” properties in the so-called flight-to-quality dynamic, in which tenants are willing to pay a premium for space that helps with recruitment, retention and corporate ESG reporting. For occupiers evaluating downtown San Francisco, the building’s combination of flexible floor plates, access to regional transit, on-site and nearby amenities, and LEED Platinum certification can make it a candidate for long-term headquarters or hub functions even as companies right-size their total footprint. For Kilroy Realty, 100 First Street plays a strategic role as a stabilizing asset within its West Coast office portfolio, complementing newer developments while demonstrating that repositioned legacy towers can still compete effectively when upgraded with modern systems and environmental credentials. Shares of Kilroy Realty (US49427R1086) traded on the NYSE at $39.15 on 06/14/2026.

100 First Street in brief: key details

• Product: 100 First Street (office tower)
• Manufacturer: Kilroy Realty Corp.
• Category: New Release / Launch (office leasing and repositioned Class A asset)
• Launch date: Originally completed in the 1970s; repositioned and held as a flagship stabilized asset in Kilroy’s San Francisco portfolio in the late 2010s
• MSRP / Price: Not applicable (multi-tenant office leasing product; rents negotiated by lease)
• Availability: Office space available for lease in downtown San Francisco through Kilroy and leasing brokers
• Target audience: Corporate tenants, including technology, professional services and financial firms seeking centrally located, transit-oriented Class A space
• Key differentiator / USP: LEED Platinum-certified, full-block high-rise with efficient floor plates and direct access to major transit connections in San Francisco’s South Financial District

This article was a.i.-assisted and editorially reviewed. Product information without warranty; prices and availability may change at short notice. Not investment advice and not a buy or sell recommendation. Trading involves risk up to and including the total loss of invested capital.