Project Overview
Located in the heart of Sacramento’s government center, 1021 O Street is serving as the temporary home for 1250 elected officials and staff from the California legislature and executive branch while the 67-year-old Capitol annex is being rebuilt. When the annex is reopened, 1021 O Street will be used as offices for legislative and executive employees. The 472,600 ft² building also has space for committee hearings, caucus meetings, and meeting rooms, as well as integrated parking.
The design for the 10-story structure reimagines the traditional solid central core and splits the building facade from north to south, creating a vibrant and verdant central opening. The pedestrian-scaled, transparent base of the building features two levels of publicly oriented space, a double-height main lobby, sun-lit waiting areas, and a suite of public hearing rooms. At the center of the building, interconnecting stairs serve as zones for social interaction and roof terraces provide views of the surrounding city and the State Capitol. The building’s precast concrete and glass facade emphasizes its civic presence, showcasing a timeless aesthetic that befits the stature of a state office building and reflects its urban context.
Informed by a life-cycle cost analysis, the project team selected precast concrete as a cost-effective, modular building system. A total of 274 precast concrete panels were installed, encompassing 52,200 ft². The precast concrete panels are white with a medium-sandblasted finish. Most of the panels are 13 ft wide and 30 ft long and span from floor to floor. The metal tracks used to attach the vertical sunshades are a unique part of the precast concrete facade. These vertical fins serve as a functional framework for the entire building, creating visual continuity while providing necessary shade in Sacramento’s sunny climate. Almost no direct solar load reaches the glazing, resulting in greater clarity of views and deeper daylight penetration, which supports a pleasant and healthy workplace environment.
The building’s sleek profile belies the many challenges that the project team overcame to complete the project on time and within budget. After breaking ground in 2019, the team had to cope with recurring air-quality issues from nearby wildfires, labor and supply shortages, and the impact of COVID-19 pandemic.
The precast concrete panels were installed quickly as part of a progressive design-build model, reducing the overall project delivery schedule by 18 months. “Having the precast concrete producer as part of the progressive design-build team allowed the structural engineer to closely coordinate all the precast concrete attachments with the BIM [building information modeling] model. This lead to a more-defined coordination process and few embed location errors,” says Patrick Crosby, SE, principal, Crosby Group Structural Engineering and Design. “Having all the key players—designers, contractor, subcontractors and precast concrete producer—involved from the early development of the BIM model made for seamless construction with minimal errors,” he adds.
Net-Zero
The building at 1021 O Street is one of California’s first net-zero, all-electric state office buildings, and its high-performance, optimized facade plays an integral role in energy conservation. Conceived as a layered shell, the outer facade overlays a preglazed enclosure, which enhances the building’s insulation and improves its thermal performance.
The facade has light shelves and vertical fins, and its orientations adjust to changing environmental conditions, balancing solar gain, daylight, and views. A two-story portico with expressive structural columns invites people into the main lobby. The translucent glass facade at the base provides views into committee chambers clad in native California wood.
The building, situated on a 1-acre plot that was previously a parking lot, is designed to use about one-third of the energy typically required in a comparably sized structure. Substantial energy savings will be achieved because the building’s exterior mixture of precast concrete and multipaned insulated glass, as well as sunshades, minimizes lighting, heating and cooling loads. Additionally, the building systems have been fine-turned and there is a dedicated off-site solar array. As a result of these strategies, the building has achieved net-zero energy status (102% energy use reduction). One of the most sustainable state office buildings in the United States, the building features low-water-use fixtures, recycled materials, natural lighting, native vegetation on the surrounding site and terraces, and LED lighting. |