Lady Bird Johnson Middle School
In August 2011, Lady Bird Johnson Middle School in Irving,Texas, opened the first net-zero middle school and the largest net-zero public school in the United States. A net-zero building produces as much energy as it consumes, so its overall energy consumption over a year is net zero, which helps to reverse negative trends associated with climate change. The Irving Independent School District hired Corgan Associates to design a net-zero school building that also functioned as a learning tool for students throughout the school district. The architecture firm worked with general contractor Charter Builders on construction of the building.
Designing a net-zero school is somewhat easier than designing a net-zero commercial building because schools use little energy during the summer and the energy they save can be returned to the grid. So the architecture firm’s objectives were first to incorporate elements to reduce energy consumption as much as possible, and then determined how much energy had to be produced to meet the building’s needs. In addition, because budget was a primary concern for the public school, Corgan planned to use materials that would not be cost prohibitive and that would require low-cost maintenance. Lady Bird Johnson Middle School sits on a very long and narrow tract of land that is surrounded by apartments and commercial buildings, including laundromats and strip malls. Corgan designed the building so that all of the classrooms faced west to make use of the best possible views offered by the urban location of the site. A two-story classroom block is on the west side, and the fine arts areas, administration space and gymnasium are on the east. The library, which is considered the school’s jewel, has an elliptical shape and is in the southwest corner near the front entrance. A light interior color scheme with a few dark accents helps to make the spaces look bright and airy.
Three primary goals
To make the building as energy efficient as possible on an ongoing basis, Corgan’s three primary goals were to:
Minimizing Energy Loss and Reducing Heat Gain
To help achieve the first goal, insulation in the walls and roof was increased to an R value of 30, and double-glazed windows were installed. In addition, first-floor classroom windows on the west side are shaded by the second floor, which projects over the first level. The windows on the second floor are shaded by an overhang, which is supported by concrete columns. Floor-to-ceiling windows in the library bring natural light into the space. To reduce glare and heat gain inside the library, Corgan primarily used frosted panels in the curtain wall system on the west facade of the library.
Reducing Energy Use
To achieve the net-zero goal, Corgan had to incorporate numerous energy-efficient design features, including a geothermal heating and cooling system, which significantly more efficient than typical HVAC systems. Daylight harvesting, an Energy Star–rated kitchen and CONVIA energy-monitoring system that tracks plug loads and lighting loads also reduce energy use. In addition, the building incorporates high-efficiency lighting, including high-efficiency fluorescent fixtures and—in cases where it wasn’t cost prohibitive—some LED fixtures. Most classrooms get natural light, including interior classrooms. Clerestory windows in the tall main corridor bring light to the interior hallway and interior classrooms. Daylight sensors harvest light by turning off artificial lighting when there is sufficient natural light.
Producing Energy On Site
The majority of the energy that is used by the school is produced on site from highly efficient rooftop Solyndra 191 solar panels that cover almost two-thirds of the roof. Twelve wind turbines, which were installed adjacent to the building, produce a very small percentage of the school’s energy and serve primarily a learning feature for the students.