If God is in the details, then NeoCity Academy, Florida’s first net-zero public high school, may be blessed with a touch of the divine.

The $13.2 million, 44,820-square-foot magnet school opened in the fall of 2019 to more than 400 of Osceola County’s top STEM students. Florida’s top academically ranked high school is a masterclass in the power of tilt-up construction and detailing.

Just ask the lead architect, Philip Donovan, AIA, and studio principal of Little Diversified Architectural Consulting’s community practice. Working closely with the project’s general contractor, Gilbane Building Company, Donovan and school officials now report:

  • 20 energy use intensity rating (versus a national average of 68 EUI)
  • $115,000 in annual energy savings
  • 76% less energy used than a typical Florida school
  • Generates 365 kWh and consumes only 346 kWh, a net energy surplus

The good news for school leadership and county taxpayers: The cost came in below the state’s tightly prescribed budget system.

“Best Air and Water Barrier Money Can Buy”

Donovan credits extreme detailing of the tilt-up concrete envelope for much of the school’s low energy use. Tilt-up concrete construction is popular with Florida school officials for its economy, durability, and installation speed. The mass of the concrete panels is also an effective barrier to central Florida’s notorious heat and humidity.

“Concrete is the best air and water barrier money can buy. It’s the most durable for the cost, time, and schedule,” Donovan says. But could a comparatively low-cost, tilt-up solution meet net-zero envelope requirements?

Proven Means and Methods

“We couldn’t come in with a bunch of new systems. We had to work with proven means and methods everyone understood,” Donovan explains. The architect had seen the effect of careful detailing on net-zero school projects in Virginia. Maybe even more rigorous sealing could yield similar or better results.

Redundant sealing was applied around all doors, windows, roof, and panel joints. “Building code requires that air leakage must not exceed 0.4 CFM. We specified 0.15 CFM. The testing equipment registered just 0.027 CFM. The testing guys thought their equipment was broken,” Donovan says. “They had never seen such a low CFM.”

The architect is quick to point out many other factors that contributed to the building’s miserly energy use, from the distributed arrangement of 38 heat pumps to a photovoltaic rooftop array that minimizes thermal bridging.

6-Year Payback

Marc Clinch, chief facilities officer for the Osceola School District, the building’s owner, is delighted. “NeoCity Academy proves there is a more cost- and energy-efficient way to build schools. This represents a less than six-year payback on our investment,” he says. “That’s phenomenal for a building that will serve the community for many decades.”

2x Expansion Underway

Now just four years after opening, the concrete tilt-up walls are up in a second phase expansion, doubling the school’s size. The new 52,000-square-foot, three story addition serves as emphatic validation of Florida’s first net-zero high school building system.

To learn more about designing with tilt-up concrete, visit BuildWithStrength.com.