Additional Photo Credit: American Hydrotech

Intensive Institutional

Project: Austin City Hall
Award Recipient: McKinney Kelley JV Landscape Architects
Client: City of Austin
Irrigation Consultant: SRI and Associates
Design Architect: Antoine Predock Architects
Record Architect: Cotera + Reed Architects
Structural Engineer: Datum Engineering
Structural Engineer: PE Structural
Civil Engineer: Urban Design Group
MEP Engineer: ACR Engineering
Supplier Green Roof System: American Hydrotech, Inc.
Horticultural Consultant: American Hydrotech, Inc.

The design process for the Austin City Hall and Public Plaza began on the banks of Bull Creek in northwestern Travis County, when Antoine Predock, Design Architect, sketched the exposed limestone bluffs of the Balcones Escarpment, as well as the waterfalls and creeks, and spreading live oaks and pasture on the lower plateau. McKinney Kelley Landscape Architects continued this theme by highlighting the diverse ecosystems of Travis County - the dry, rocky Edwards Plateau to the west and the deep clay Post Oak Savannah to the east. Lower lying
areas of the building design symbolized the creek canyons while the upper roof terraces signified the drier plant palette of the rocky hillsides. Native plant associations were grouped together for water efficiency, extreme heat tolerance, and unique geographical constraints.

Covering close to 12,000 sq. ft. at an approximate cost of $30 per sq. ft., the green roof of Austin City Hall used growing media in a proprietary blend based on the requirements of the supplied plants and project climate conditions and ranged from 30-60 inches in depth. The native plant palette responded to the different ecosystems in Travis County. The western side of the plaza and the upper roof terraces were highlighted by mountain laurel, agaves, yuccas, sotols, prickly pear, and feather grass with low ground cover of wooley stemodia and silver pony foot. The eastern side was dominated by yaupon holly, redbud, gulf muhly, and colorful prairie perennials such as bluebonnets, black-eyed susan and prairie coneflower. Bald cypress with horsetail fern, buttonbush, and inland sea oats reflected sunny creek settings, while dwarf palmettos and columbine revealed moist, shady overhangs.

As the self-proclaimed "Live Music Capital of the World", the cultural program called for a shaded outdoor amphitheatre and stage for ongoing live music performances. The program also required a variety of exterior spaces for different groups to gather and celebrate. The City of Austin Art in Public Places program provided a sitting area highlighted with different stone boulders from Central Texas. A seedling from Austin’s Treaty Oak carried the heritage of treaty-making on to the public plaza.

With the high profile nature of the City Hall, the City Council's goal was to create a sustainable public building that would serve as an educational model for green building. The green roof upper terraces and lower plaza level are the subject of weekly educational tours for citizens, visitors, and school groups.

Unique design features include the use of HVAC condensate for the waterfall, the use of groundwater to irrigate the green roofs, and solar panels for the amphitheatre canopy. Mature live oaks and other native shade trees were installed through the use of a federal grant to reduce the effect of Urban Heat Island. The project received the first LEED gold certification in Austin.

As a project Austin City Hall combines depth of vision with practicality of execution and so sets a superlative example for government and institutional building owners.

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