About

CO- is intentionally hybrid. Some projects we design, some we develop, and for some, we do both. Making quality affordable housing is one of our primary missions. Our team maintains a unique blend of architects, urban designers, and developers.

Architecture and Urban Design

View Architecture Projects
View Urban Design Projects

CO- designs places and offers architecture, planning, and urban design services across various scales and types. We are a design-led studio focused on sustainable implementation in the built environment. When conceiving buildings or master plans, we always consider design within its context, including its architecture, landscape, and cultural influences.

Our mission is to collaborate with clients—both organizations and individuals—to envision and deliver projects that exceed the initial brief. As both architects and developers, we create efficiency by offering integrated design and development services. Whether working on interior renovations, feasibility studies, standalone buildings, or large-scale master plans, CO- approaches every project with a commitment to design excellence and creativity. CO- is fully licensed to provide architectural services in California.

Real Estate Development

View Development Projects

CO- is a comprehensive real estate and development services firm with a proven track record of navigating complex affordable housing development processes. Our primary mission is to create quality, accessible housing, particularly in California’s most unaffordable markets.

We are committed to delivering exceptional projects by coordinating the permitting and approval process, securing financing, managing budgets, overseeing loan closings, supervising bidding and construction, and engaging with government and local community organizations. CO- offers a wide range of real estate development services and has expertise in managing projects from acquisition to occupancy.

Our expertise spans acquisitions, land transactions, new construction and rehabilitation projects, securing planning approvals and building permits, managing design and engineering consultants, obtaining financing from private and public lenders, closing construction and permanent financing, negotiating construction contracts, overseeing construction, and managing the lease-up and marketing process. This breadth of experience enables us to engage in a variety of project types and sizes. We work closely with our partners and clients to realize their vision. Through design and development, CO- is passionate about making a positive impact in the communities we serve.

Mission

By grasping both sides of the building process, we can more thoughtfully engage in design and development – separately or simultaneously.

Our collective process draws on our design experience and pedigree to imagine and iterate and on our development and project management expertise to qualify those design options for implementation.

As a single studio that engages in both design and real estate development, CO- balances concern for the character of our design investigation with handling the critical externalities that enable our ideas to become reality. Making housing, particularly quality affordable housing, is CO-‘s immediate and long-term focus.

CO- is a registered Minority-Owned San Francisco Local Business Enterprise (LBE) and a Micro Local Business Enterprise.

Team

  • Danny Kolosta

    Senior Real Estate Development Manager

    Danny Kolosta is a housing development project manager. An East Bay native, Danny received a Bachelor of Arts in Geography with a GIS emphasis from UC Santa Barbara before returning to the Bay Area to work in municipal infrastructure mapping and asset management for local government. With a desire to engage with issues at a more granular urban scale, Danny pursued a Master in Urban Planning degree from Harvard University Graduate School of Design, which he received in 2022.

     

    Danny has been project managing new construction and rehabilitation affordable housing developments across the Sacramento and Bay Area regions for more than three and a half years. He has experience in all stages of the development process from submitting responses to competitive RFPs, site acquisition, financing applications, construction closings, construction administration and closeout, lease up, permanent conversions and beyond. Danny has collaborated with local grassroots community organizations, private developers, investors, lenders, political leaders, and local, regional, and state government agencies.

  • Weijia Song, RA

    Co-Founder and Development Director

    Weijia Song is an Architect and Real Estate Developer hailing from Auckland, New Zealand. She is a founding Principal of Collective Operations (CO-), a real estate development and contemporary architecture firm based in San Francisco, CA. CO- has a portfolio of work that includes residential, commercial office, and urban infrastructure design and construction in the United States and New Zealand. CO- has secured over $500M in funding from public and private financing sources and supported the development and construction of over 800 multifamily units in the greater Bay Area.

     

    Prior to founding CO-, Weijia Song practiced as an Associate Architect and Designer at SHoP Architects in New York and Ricardo Bofill Taller de Arquitectura in Barcelona, after which she worked as a Senior Project Manager for Eden Housing, an affordable housing developer in California. Weijia Song holds a Master of Science in Real Estate Development from MIT and a Bachelor of Architecture from Rice University. She is a Registered Architect in California and New Zealand.

  • Courtney Stephen

    Project Designer

    Courtney Stephen brings an interdisciplinary background as an architect and structural engineer to CO-. Originally from Texas, Courtney completed a Bachelor of Science in Civil Engineering, graduating Summa Cum Laude from Texas A&M University, where she also minored in Art and Architectural History. Driven by a passion for innovative and holistic structural solutions, Courtney pursued a Master of Science in Civil Engineering with a Structural Engineering concentration from MIT, where she joined the FEMA Post-Disaster Housing Response Research Team under the Digital Structures research group. She most recently graduated with an M.Arch I degree from Harvard GSD, focusing on adaptive reuse and resilience design.

     

    Courtney’s work has spanned engineering, design, and project management, establishing her cross-disciplinary skillset and collaborative approach to project realization. Courtney has worked on diverse architectural and structural projects, including foundational systems for high-profile buildings like the LA County Museum of Art at Skidmore, Owings & Merrill, and architectural concept development for Tesla’s Gigafactory in Texas. Her experiences include architectural internships with JK-AR in Seoul, where she helped design a timber clinic complex, and HOK in San Francisco, where she contributed to architectural design in sustainable airport construction. She now contributes to the mission of CO- to provide quality housing to California.

  • Alex Yuen, RA

    Co-Founder and Design Director

    Alex Yuen is an architect and urban designer. Hailing from Hong Kong and San Francisco, Yuen received a Bachelor of Architecture from Rice University and a Master of Architecture in Urban Design, with Distinction, from the Harvard University Graduate School of Design. His individual design work and involvement in larger urban research projects have been published and exhibited globally. Yuen has received numerous awards, including the Odebrecht Award for Sustainable Development, the William Ward Watkin Fellowship from the Rice School of Architecture, the Award for Excellence in Urban Design, and the Urban Design Thesis Award from the GSD.

     

    Yuen is currently a faculty member at the Harvard University Graduate School of Design and has previously taught at the California College of Arts and the University of Virginia while also having lectured on architecture and urbanism and serving on juries at institutions around the world. Prior to CO-, he worked at a number of Architectural and Urban Design firms around the US and Asia, including Diller Scofidio + Renfro and the Office for Metropolitan Architecture (OMA). Yuen is a registered architect in California and a LEED Green Associate.