San Francisco faces a daunting shortage of housing. The City’s 2023-2031 Housing Element identifies a need for 82,000 new homes in the next eight years. Rather than an incremental parcel-by-parcel building approach, The Green Line addresses this housing need with an urban system deployed at scale across the length of the City. The prototypical block spans from 20th to 21st Avenues with a narrow 20-foot by 240-foot footprint that maximizes natural light and ventilation with six stories of housing over one story of community-serving uses.
A proposal developed for the AIASF Housing+ San Francisco 2050 Design Competition, “The Green Line” offers a radical solution to address the housing and climate crises: infrastructure that integrates housing, community solar, and transit in a new street type. By marrying these elements, a healthier and more equitable San Francisco emerges, connecting downtown, through the diverse west side neighborhoods, to the ocean.
Instead of transit-oriented development (TOD), The Green Line flips the approach and makes a case for development-oriented transit. Geary Boulevard, like many American city thoroughfares, has developed over the years with a single user in mind: the automobile. Now its car-scale right-of-way contains a banked reserve of street width (public land) that can be equitably distributed to new users and activities. The vision for this transit-integrated development (“TID”) is to integrate transit, housing, energy generation, and social space into a single linear gesture along Geary Boulevard.
The Green Line building footprint divides the existing street into two parts: a bike and pedestrian-friendly promenade, running parallel to yet separated from a right-sized car and bus-rapid transit lanes on the other side of the new buildings. These new buildings provide covered access to MUNI stations below, above-grade bike storage for residents, and shared electric bicycles for the community.
ConnectSF heat map most requested transit routes via socketsite.com (2)
The ground floor of the building serves a variety of functions, adapting itself to the needs of different neighborhoods as the project traverses the city. At each block, a modest but active residential lobby provides elevator and stair access to the housing above and services below. A mid-block opening activates the center of the building, where a community pop-up and residential entrance are located. The remainder of the ground floor serves the community through uses such as retail, restaurants and cafes, food markets, and other neighborhood services.
The Green Line prioritizes walking, cycling, and public transit. It assumes the ongoing electrification of the transportation sector, including electric bicycles, private and shared electric vehicles, delivery vehicles, electric buses, and transit. No personal vehicle parking is provided as part of the proposed project. A 15-minute walking or biking “radius” from the new Geary housing and transit spine covers a significant portion of the west side of the City. This singular linear gesture has the potential to transform large areas of San Francisco into more sustainable, equitable, and healthy communities.
The Green Line passes through neighborhoods impacted by decades of discrimination, urban renewal projects, and neglect. Despite these challenges, the district has a rich history of neighborhood organizing and community advocacy. The Green Line attempts to stitch together the torn urban fabric by creating neighborhood connections and providing a linear hub of resources and resiliency.
San Francisco Redevelopment Agency via foundsf.org (1, 3)
San Francisco History Center, SF Public Library via foundsf.org (2)
Throughout the history of Geary Boulevard, numerous proposals for a subway have emerged, including a BART-proposed line that would extend all the way to the Golden Gate Bridge. However, despite the significant need and demand for additional public transportation on the west side, plans have failed to materialize. Today, Geary Boulevard remains an important transit corridor, serving as a vital link between downtown San Francisco and the western neighborhoods. It is consistently ranked one of the most highly requested subway lines by San Franciscans.
Running along the Green Line under Geary Street, the new B-GEARY-OCEAN Muni Metro line addresses the long-standing need for improved transit infrastructure along Geary Street. Stations will be accessed from the base of new buildings, introducing more accessible and functional transit to the west side.
San Francisco Call, 1909 via foundsf.org (1)
Market Street Rail Archive (2, 4)
Technical Committee of the Mayor’s Transportation Council via wikipedia.org (3)
The roof is both a functional space and a social space interweaving building technology and creative occupancy. A photovoltaic (PV) canopy generates power and provides shade and dappled light. To serve the building, there is space for rainwater capture, heat pumps, and other building systems. For residents, the rooftop is an active open space, programmed with community gardens, communal cooking and dining areas, and spaces for outdoor play and exercise. Benefits of the rooftop include heat island reduction, biodiversity in plant life, and habitat for birds and pollinators.
The building structure minimizes embodied carbon through the use of a timber frame, cross-laminated timber (CLT) floors, CLT lateral systems, and carbon-sequestering concrete technology. The building’s façade is designed to limit operating carbon by allowing for natural ventilation and solar shading. The balconies and shutters allow for access to the outdoors and interaction between neighbors and the street life below. The modular system is intended to deploy in a variety of ways in response to adjoining neighborhood conditions.
The Green Line aspires to move beyond net-zero energy (NZE) building toward “Real Zero.” NZE calculations consider annual energy accounting, while 24/7 carbon-free energy (CFE) aims to match production with consumption, every hour of every day of the year. There are three approaches to smoothing out the fluctuation in solar energy production: demand management (load reduction, load shaping, and load shifting), energy storage (batteries), and eventually, clean-firm generation on the grid (hydro, advanced geothermal, and long-duration storage, etc.).
The proposed community microgrid supports the project’s energy resilience by integrating several distributed energy technologies into a single controllable solution. It can operate by supplementing the municipal utility grid in grid-parallel mode and function completely autonomously in island mode. For residents, this means cleaner, cheaper, and more stable energy.
Extending five miles along Geary from Gough Street to 40th Avenue, the project has the capacity to provide more than 2,900 units of housing, adding up to approximately 7,800 residents. A total of 40 units are included at each block, offering a wide range of floor plans to accommodate the diverse households across adjoining neighborhoods. Circulation spaces are designed for community wellness and connection. Open-air exterior stairs and single-loaded exterior corridors minimize enclosed conditioned space while offering balanced daylight, ventilation, and a shared ‘front porch’ at each level.