Orange County Sanitation District Headquarters

The hybrid, Type III-B structure combines a mass timber gravity system with a steel brace frame lateral system. Wood’s light weight decreased the weight of the building, easing foundation requirements for the site’s poor soils, mitigating seismic forces, and reducing overall costs. Except for the 1-hour fire-rated stair areas, all connections are unrated, bolted, and exposed to view, allowing for future disassembly. Designers left mechanical systems deliberately visible to reflect OC SAN’s engineering culture; their exposure also eases maintenance.

Ambitious sustainability goals were achieved through smart design. Optimized building orientation, a high-performance envelope, and highly efficient building systems helped the project reach its net zero energy goals. OC SAN even leverages its own waste recovery processes to capture biofuel, which provides 60 percent of the building’s energy. The remaining demand is met by solar arrays on the roof and over parking.

Because OC SAN is a publicly-funded utility, it was particularly important to balance their sustainability objectives with fiscal prudence; the project had to meet the construction budget for a standard Class B office. This beautiful design hit the utility’s targets, and the project team proved it is possible to successfully meet public sector design/bid/build requirements using mass timber.

This building is a powerful demonstration of how mass timber can be used to create a high-performing building that meets cost, design, energy, and other parameters. This beautiful facility is elevating community engagement, supporting workforce collaboration, and promoting occupant health—and doing it all sustainably.