Net-zero energy Lady Bird Johnson Middle School is a crown jewel in Dallas
The LBJ Middle School exemplifies give and take with net-zero.
When engineering veteran Don Penn came to the Lady Bird Johnson Middle School project in Dallas, he did not foresee the opportunity to carve out a new career.
“We’ve helped them write the school’s curriculum regarding the facilities’ geothermal and solar element,” he says. “They would write it up and pass it across to us to make sure everything was correct.”
The 152,000-sq.-ft. LBJ Middle School — named after the former First Lady and wife of the United States’ 36th President, Lyndon B. Johnson — is a net-zero energy facility that also serves as a living library for its students. Penn, a professional engineer since 1985 and the owner of Dallas-based Image Engineering Group since 1991, has helped the school’s faculty develop lesson plans for students on topics such as the above-mentioned geothermal and solar, and other energy efficiency, sustainability and recycling best practices.
LBJ’s net-zero systems are consistently checked by students and studied in the classroom where math classes can be structured around the calculation of each system’s energy usage. Art projects explore green living, while students are given homework where they chart how their family uses water.
LBJ Middle School has a group of student ambassadors that assist on visitor tours of the facility. They explain the special features that are installed and what impact the renewable elements and the curriculum have made on them as students.
“It definitely creates a higher level of thinking and responsibility on the part of our students,” says Angie Gaylord, the school district’s director of professional and digital development. “We’ve heard from high-school administrators who now have our students in their classrooms and they tell us a Lady Bird Johnson graduate is a different kind of student.”
Penn says that he’s witnessed first-hand LBJ students and teachers showcasing the school and its benefits to the young third- and fourth-graders that may end up learning at the facility in future years.
“This campus is a living, learning lab where students are immersed in renewable, sustainable and recycling process,” he says. “The school thrusts the next generation into these concepts that are going to be paramount to future generations.”
Stepping up to the plate
In 1991, Penn went into business for himself and opened Image Engineering Group. Eight months into his venture a school district he worked with during his time at his previous employeer laid a challenge on Penn’s desk.
“They called me in and said they want to do geothermal heat pumps in their school,” Penn recalls. “I said, ‘No, you don’t.’
“They said, ‘Oh yes, we do and we want you to figure out how to do it.’”
Penn hit the road and learned everything he could and 20-plus years later the results speak for themselves. Penn, licensed in every state expect Alaska, and IEG have consulted on about 250 geothermal school projects, spanning more than 30 million sq. ft., he estimates.
As for a net-zero project, this was a first for Penn and IEG.
“We have designed solar PV systems, we’ve designed wind turbines and we’ve done a ton of geothermal,” Penn says. “We’ve talked about doing one and I’ve done presentations all across the country on bundling all the elements together, but this was the first project where we actually got to do it.”
The beginnings of the LBJ project start with Scott Layne, Irving Independent School District’s assistant superintendent for support services. Layne had made it his goal to build a school that would lower the average annual energy utility cost of $200,000 down to the $60,000-$70,000 range.
Since opening in time to start the 2011 school year, LBJ continues to hit that money-saving benchmark. Other significant savings the school has reached include reducing the energy use to 17 KBtu per sq.-ft. compared to the 54 KBtu average of a Texas middle school.
“(Everything has been) operating right on the mark,” Layne says. “It’s been a win-win situation, especially for our students. That’s what it’s all about – the kids and making a better world for all of us.”
The facility is the first net-zero school in the state of Texas, the only middle school and the largest net-zero school in the United States. In 2013, LBJ Middle School was honored as the best K-12 school in the country by the U.S. Green Building Council in the group’s annual “Best of Green Schools” list, which identifies the best schools in sustainability and environmental efforts.
Earth, wind and sun
There also are 107 Bosch/Florida Heat Pump high-efficiency EC and EV Series water-source heat pumps. The heat pumps vary in size, ranging from 1 to 20 tons. Each classroom is connected with dedicated heat pump building automation software. Penn also had Venmar energy recovery ventilators which work on demand and serve classrooms, the cafeteria and the gyms. These units provide the occupants proper ventilation by transferring both latent and sensible heat between the fresh air brought into the building and the air exhausted.
Penn installed nearly 3,000 photovoltaic solar panels from Solyndra that sprawl over 65,000 sq. ft. on LBJ Middle School’s roof.
“Payback on the geothermal system compared to the district’s standard four-pipe systems was less than one year,” he states. “By minimizing the consumption with geothermal, the solar PV cost was minimized. The economics on the bundled solution were attractive. The net result of the design is a 40% total energy reduction for the facility, thus minimizing the extents and cost of the solar PV plant. That makes the system cost effective.
“Before any incentives or rebates, the payback for the bundled renewables was 11 to 12 years. But with those incentives and rebates actually awarded, the payback was eight to nine years.”
The 10 geothermal bore fields Penn designed are stationed under the football field’s parking lot. More than 500 holes were drilled and the water table was reached at a depth of 250 ft. To complete the job, 50 miles of 1-in. HDPE pipe was laid and connected so the geothermal system could accommodate almost 600 tons of air-conditioning.
“This is IEG’s signature modular design utilizing demand pumping,” he says. “It is the most effective, efficient and proven design that we have developed and continue to optimize with changing geothermal heat pump, pumping and ERV technologies.”
High-efficient Zurn bathroom fixtures were used through the school alongside Bradley modular lavatories. Penn also installed 12 Skystream 3.7 wind turbines that generate 2.4kW of electrical capacity, daylight harvesting, high-efficient window glazing, wall and roof installation and an EnergyStar-rated kitchen to serve the more than 1,000 students.
The net-zero system also features a graywater collection and repurposing element. There are three 10,000-gal. cisterns buried into the ground that capture water runoff from the athletic area showers, lavatories and all the condensate from the air-conditioning units as well as rainwater. Penn adds the graywater is used to irrigate the school’s athletic fields.
Making the honor roll
Considering this was Penn and IEG’s first swing at a net-zero facility, and an intricate one considering the harsh elements Texas can throw at its residents, the system has passed with flying colors.
“The school is performing on the money even with the extreme weather we’ve been having down here in Dallas,” Penn says. “We had the second-hottest summer on record and the system still performed at 99.7% of design expectations. We also built in some safety factors and the design has proven true. Our estimations and projections have been accurate. We’re very happy with it.”
In addition to earning LEED GOLD status, Dallas-based Corgan Associates, the school’s architectural firm, triumphed over 94 other prospects to win the 2012 Caudill Award for best in show.
“From the engineering side it was a very rewarding experience,” Penn says. “But see how it has been put to use, that’s another level. This is one of those cherries you get in your career. This will always be one of those projects that will stand in the forefront. I hope it gets replicated somewhere else.”