The new Orange County Sanitation District Headquarters is designed to illustrate OC San’s core values of “honesty, integrity and respect for interactions between employees, the greater public and community.” As a civic building that serves all of Orange County, OC San is designed to be beautiful without being ostentatious and efficient while also being welcoming—a tangible symbol for a visionary sanitation district that is nationally recognized as one of the most sustainable in the country.

Working closely with the client, our design team developed a solution that:

• engages the public through educational experiences
• prioritizes employee well-being
• returns value for public investment
• advances precedent-setting—but cost-conscious—sustainability goals

Exterior materials (silicon-glazed curtain wall and terracotta rain screen) will perform well in the high-pollution/high-salt environment. The mass timber with steel-braced framed structure not only helps sequester carbon but also reduces the overall weight of the building (critical for soil conditions) and creates an inviting interior work environment. In fact, embodied carbon is reduced by approximately 60% using hybrid mass timber and green concrete specification. The concrete is sourced locally, and the performance specification mandated a minimum 30% reduction compared to the industry's Global Warming Potential baseline, which the Carbon Leadership Forum established. Like the honesty of the plant’s industrial facilities, the structural expression of the biophilic mass timber combined with expressed steel braces became the architectural language of honest biophilic beauty.

Office wings framing a landscaped courtyard address employee wellness with daylight equity and views of nature. Day-lit stairs, healthy materials and building systems that enhance indoor air quality improve employee and visitor health. Ergonomic workplace environments offer flexibility for different work styles, opportunities for connection and collaboration, and seamless technology integration.

Net-zero energy (operational carbon) starts with passive strategies, including orientation to deliver optimal daylighting and a high-performance building envelope. Then, active strategies were carefully tuned to the specific usage of the spaces with high-performance active chilled beams serving the office wings, radiant heating and cooling serving the high-volume lobby and VAV system serving the Board/Community room. Despite some heavy equipment loads, all of these strategies reduced the EUI from 91 down to 37.7.

This project is particularly notable for its innovative use of its infrastructural processes as an energy source. Sixty per cent of the on-site renewable energy needs will be met using biofuel captured as a waste product from the sewage treatment on-site that is then run through a CoGen with scrubbers that reduce the GHG emissions by 90%. On-site PV will supply the remaining 40%. This unique strategy meets ILFI standards for the use of biofuel.

The site previously had 97% impervious surfaces; now, it provides 300% more landscape area to reduce urban heat island effects, support pollinators, and provide beauty. With 100% drought-tolerant, native planting and water-conserving fixtures, the project will reduce potable water consumption by over 50% and will achieve 85th percentile rainwater retention on-site through low impact development (LID) standards.

OC San currently hosts nearly 3,000 visitors annually and expects to host many more in the new facility. A board room will welcome public meetings. Immersive indoor/outdoor exhibits will educate groups ranging from young children to public health students and operators worldwide. As a net zero energy project, the building itself will also showcase many features (mass timber, exposed MEP elements, PV, etc.) that will educate visitors about OC San’s commitments to a sustainable future. A new pedestrian bridge spans from the headquarters building over a heavy traffic road to the inside of the secured perimeter of the treatment plant, providing safe access for employees, utilities, and visiting tour groups.

In awarding the project an AIA LA COTE Next award, the jury commented: “We appreciated how this team was really looking at innovation and new models that can impact future development within the region and have a bigger impact beyond just a single project.”