School districts across the country are watching a new middle school in Irving, Texas, for results of extensive efforts to design and build the nation’s largest net-zero-energy public K–12 school. So far, says the architect, those efforts have been successful as Lady Bird Johnson Middle School is exceeding expectations for on-site electricity production and performance efficiencies during its first months. The real test, however, will come in the fall of 2012 when Johnson Middle School celebrates its first anniversary. That’s when the Irving Independent School District (ISD) plans to share data on the school’s first 12 months of operation.
Irving ISD made a commitment in 2008 that its next middle school, designed for 900 to 1,000 students, would produce more energy than it consumed on an annual basis. To achieve that net-zero-energy goal, officials decided to spend 12.5 percent of Johnson Middle School’s almost $30 million construction budget on high-performance design strategies and energy-efficient technologies. According to Corgan Associates, the Dallas-based firm that led the design team, those up-front costs totaled $3.7 million for the 152,000-square-foot facility.
Of that total, the bulk—$2,976,972—was used to purchase approximately 66,000 square feet of photovoltaic panels. Installed slightly above the building’s white roof, 2,988 Solyndra panels contain cylindrical tubes that capture sunlight from 360 degrees. The solar array is designed to generate 99 percent of the school’s electricity, approximately 850,000-kilowatt-hours each year for the system’s anticipated life span of 20 to 25 years. The remaining 1 percent is produced by 12 wind turbines atop 45-foot-tall towers erected along the west side of the building, each of which produces 2.4 kilowatts of energy at maximum capacity. Any surplus energy is redirected back to the regional electric grid for purchase by the local utility company.
To achieve net-zero energy use, the school needed a design that reduced energy use as well as one that has alternative electricity production. For the design of Johnson Middle School, 105 geothermal heat pumps are a critical factor, accounting for 30 percent of the overall energy-reduction strategy. In fact, Corgan’s presentation on the efficiency of geothermal HVAC systems resulted in Irving ISD considering a net-zero-energy school.
“The geothermal discussion got them thinking about how much energy they could save and took them to the next level on what else we could do here,” explains Susan Smith, AIA, the project manager and vice president at Corgan.
Once the decision was made, the design team set to work on planning a campus that combined several high-performance systems to reduce life-cycle costs and maintenance expenses. Among them are increased wall and roof insulation, high-efficiency glazing, exterior solar shading, and light shelves that bounce sunlight to interior spaces. In addition, sensors adjust artificial light levels in classrooms and corridors based on available daylight. All of these technologies are coordinated through an integrated energy-management platform that tracks how much electricity is used in different areas of the campus as well as how much is generated.
A Convia monitoring system also displays that energy data in real time, which offers multiple opportunities through the school day to teach students about energy. To maximize the learning potential, Corgan worked with the faculty to devise ways for the project to support the science curriculum. For example, an additional stairway was installed during the design phase for classes to access a rooftop observation deck for a close look at the photovoltaic array.
The lessons even extend to the school’s facilities personnel as they become familiar with the sophisticated and intertwined technologies on a campus at the forefront of a national trend toward extreme energy conservation. “It is a new challenge,” says Scott Layne, Irving ISD assistant superintendent for school support services, “but they recognize the need to move forward. This type of facility will be the future. Why not be the first group to learn and experience what others may have to wait 10 years to accomplish?”
Irving ISD is accumulating energy data to assess Johnson Middle School’s chances of achieving its goal of net-zero-energy by September 2012, and school officials expect to receive a LEED Gold rating for the project. “The direction of the project was first and foremost energy,” says Brittany Hodges, marketing coordinator at Corgan. “We did not use LEED as a checklist on the project, but rather used it as a tool for recognizing the decisions toward sustainable design that the district had made.” Smith concurs, explaining that while Irving ISD does not require LEED certification, “Corgan proposed that the district look at LEED as a recognition tool because they were putting a lot of effort, a lot of thought, and [a lot of] commitment into this building, and it seems only right that they be recognized for their effort.”
But there’s a more immediate way to gauge the relative success of Johnson Middle School—the monitors in the corridor that show daily energy production versus consumption. Recently, on an 84 F autumn afternoon, when informed that the campus was sending its surplus energy back to the grid, Irving ISD superintendent Dana T. Bedden noted with satisfaction that “the utilities are paying us for educating children.”
Stephen Sharpe is the editor of Texas Architect magazine in Austin, Texas.