New City Hall

Designed to be an example of innovation, energy conservation, and sustainability for its community, the City of Johnston’s new 24,000-square-foot city hall is the centerpiece of an overall town center redevelopment project that brings new civic, retail, hospitality, office, and entertainment opportunities to the area.

The city hall is a showcase of civic engagement and sustainable responsibility with highly energy-efficient mechanical and electrical support systems and a rooftop solar array. The facility is targeting LEED Silver certification and net-zero energy consumption.
Both the building and site support community growth and expansion with flexibility to accommodate evolving needs. The large entryway and adjacent green space serve as an inviting “front porch” of the city hall with a plaza, amphitheater, farmers market, and events space. Surrounding amenities include a splash pad, skating rink, bicycle pump track, and large open green spaces. Inside, the building combines municipal office functions and community spaces with new offices, council chambers, conference and training rooms, and a centralized lobby.

Meeting some of the project goals required close teamwork and coordination. The design team provided quick responses to hanges during the design process. For example, a site support building was originally designed to house the support equipment for ice making and serve as a skate rental shop and public restroom. During construction, the city decided to eliminate the ice making equipment and the building was quickly redesigned as a concession stand with a public restroom.

Additionally, the roof-mounted mechanical systems needed to blend in with the overall building aesthetic. To do this, the architect and engineers worked together to conceal air-cooled VRV heat pumps in a louvered penthouse and created a recessed portion of the roof to hide the dedicated outside air ventilation units. This created the seamless look the city and architect desired.

The engineering team was challenged with designing an audio/video system that provided the functionality for the city to host a variety of events, both inside and outside. The design included A/V over IP control, a multi-camera video presentation system in the council chambers for recording and live broadcasting, a large outdoor projection system for city movie nights, and a skating rink sound system.

  • The team also implemented several innovative strategies, including:
    High-efficiency mechanical VRV equipment, demand-controlled ventilation, low-flow plumbing fixtures, LED lighting, daylighting, building massing and shading devices to reduce cooling loads, highly efficient exterior insulation system providing an R-25 value, and a roof-mounted photovoltaic (PV) array rated at 179kW. The PV panels were installed in an alternating east/west fashion to maximize the system power production.
  • Energy modeling of the chosen systems, which showed a 37 percent savings compared to ASHRAE 90.1-2010 before including the electricity generated by the roof-mounted PV array.
  • Additional power and site layout considerations to accommodate a weekly farmers market and outdoor performances and backup power so the building can
    be a haven in times of disaster and power loss in the community.
  • Room for growth. With city and staff needs expected
    to double in the next 50 years, the new city hall was designed with a flexible office module and open office space that can be reconfigured in the future to support more staff.

The city envisioned its new city hall being a place of community pride and safety, anchoring the town center and providing enhanced services and inviting spaces. The project team not only met these goals, but also provided a modernized and highly sustainable facility with updated technology. The result is a community-focused building that evokes a town square aesthetic and honors Johnston’s rich history.

City of Johnston - City Hall
Johnston, IA
24,000-sf New
Services Provided

Mechanical, Electrical, Plumbing, Fire Protection, Technology, Security, Construction Administration