Energy Efficient Net-Zero Schools
- By Sarat Pratapchandran
- August 1st, 2011
With net-zero energy schools starting up in different parts of the country, there is an increasing demand to see their return on investment (ROI). Communities in Texas, New Mexico and Las Vegas are fast embracing net-zero energy schools or grid neutral buildings, and as they focus on zero energy bills, they are also investing time and effort in finding out returns on initial investment.
The success of net-zero energy schools is largely driven by location and availability of renewable energy sources. “For instance, some areas of the country are not eligible for geothermal because the ground temperature is too hot,” says Molly Smith, president of thinkSMART planning Inc.
The ROI in net-zero energy schools is based on different factors, including highly efficient light fixtures, fully upgraded and maintained HVAC systems, use of energy management systems, security systems that (when set) shut off all electric-using equipment, motion operated lights and proper daylighting techniques.
Net-zero energy schools share similar traits of high-performance schools, like improved learning environment through thermal and visual comfort, optimum air quality and material and resource efficiencies. “The big difference is that a net-zero energy school has a measurable performance goal — i.e. to reduce energy consumption to 25 kBtus per square foot per year, or less. With that goal realized, in its broadest terms, any building can achieve net-zero energy by simply adding enough alternate energy sources to offset its energy consumption,” says Kenny Stanfield, AIA, LEED-AP, principal at Sherman Carter Barnhart Architects. However, “that is not rational and can’t be sold to a public school board. It has to make financial sense, and above all else, it has to be achieved within the same budget constraints of a conventional school.”
An example is Richardsville Elementary School in Warren County, Ky., the nation’s first net-zero energy public school, designed by Stanfield’s firm. Since opening in October 2010, Richardsville Elementary has shown consistent energy performance at consumption slightly less than the energy model of 17.5 kBtus per square foot.
“Last month, the utility bill was in the form of a refund; the school produced more energy than it used,” Stanfield says. This facility is a replacement school built on the same site as the old school, and “comparisons are currently being evaluated for test scores, attendance, etc.”
Focus Is on Reducing Energy Demands
Reducing energy demands is critical in planning a net-zero design for schools. The use of photovoltaics (PV) and wind-sourced energy can initially be costly. “At Richardsville, our goal was two-fold: 1) reduce energy 75 percent; and 2) manage construction costs so the photovoltaic package could be included and the total budget be less than or equal to that of a conventional school,” says Stanfield. At the time of bidding, the state-mandated school construction budget was set at $203 per square foot. The actual construction cost of
Richardsville was $197 per square foot, including the photovoltaic package.
Similar results are being observed at The Putney School, a progressive, college-preparatory school in rural southern Vermont. Putney recently became the first private Platinum LEED-certified, net-zero energy school in the country. The school has a two-story field house with an onsite 36.8-kW solar PV system, energy-efficient lighting with daylight and occupancy sensors, composting toilets, natural lighting and uses earth- and human-friendly materials. The first floor has a gym, a rock climbing wall, ski waxing room, mechanical room and storage, while the second has bleachers that overlook the gym, offices, locker rooms and flex space for wellness and strength/conditioning activities.
According to Danielle Petter, LEED-AP, research director at Maclay Architects, and involved in the design of this facility, “Real time data for a complete year of operation does show that the field house has produced more energy than it has consumed, and is in fact a net-zero building.”
The field house consumed 162,152 kBtu and produced 175,278 kBtu between Dec. 1, 2009 and Nov. 30, 2010. Data also shows that actual energy intensity of the building was lower than what was predicted by energy modeling during the design of the project. Energy modeling predicted that the energy intensity for the building would be 11 kBtus per square foot per year (kBtu/sf/yr), while the actual energy intensity for the building throughout this first year of occupancy was 9.6 kBtu/sf/yr.
Integrated Approach Is Necessary
Meanwhile, according to Franklin Brown, AIA, LEED-AP, REFP, planning director of the Ohio School Facilities Commission (OSFC), who prefers using the term “grid-neutral” rather than net-zero, “Getting to grid-neutral is more of a journey than a destination. While one can set out to design a grid-neutral school, it is more realistic to see it as a goal to be realized over a series of projects. It requires working as a true integrated design team as no single, disciplined approach can get you there.”
At OSFC, success in grid neutrality is measured in the reduction of energy use intensity (EUI). “Before the OSFC adopted LEED for all state-funded K-12 schools in Ohio, we were routinely seeing designs that had an EUI of somewhere around 50 kBtu/sf/yr. After adopting the LEED commitment, we saw that drop to 30 to 35 kBtu/sf/yr. On projects that incorporated Ground Water Source Heat Pumps, we are seeing 24 to 28 kBtu/sf/yr.”
Architects in Ohio are now designing more LEED Gold buildings than LEED Silver and have 19 new buildings registered as LEED Platinum.
OSFC uses energy simulation modeling to measure success and to keep teams adequately informed about progress from the eco-charrette to the end of the first year of operations. “It is used iteratively to ‘what if’ suggested design strategies during the design phases and to verify that each consumption bin is performing as predicted during the first year of occupancy. It is critical that the team follows the building and updates the model during at least the first year. This helps them to understand the design and builds confidence in their modeling skills,” says Brown.
In terms of assessing ROI among net-zero schools, several factors are examined including impact on educational outcomes, policy outcomes, the use of the building as a teaching tool, technology, use of alternate forms of energy, energy-saving techniques and operations and maintenance strategies.
For instance, at the Richardsville Elementary, a few techniques that have been incorporated to improve human comfort include using daylighting strategies that have had a dramatic impact on occupants’ visual comfort in classrooms, gym, cafeteria and even the hallways. Nowhere do you go from well-lit to dark spaces. Sunlight penetrates hallways and interior spaces, such as the gym, with tubular daylighting devices as well as clerestory lighting.
Adaptability Is Needed
The use of sustainable techniques also brings forth their share of challenges. For example, kitchen staff at Richardsville had initial challenges adapting to a kitchen without deep fryers or tilting skillets. “But now the students report that the french fries baked in the combo-ovens are ‘better than McDonald’s,’” Stanfield says.
Recently, the food service director initiated a district-wide “green day” lunch, in which no cooking equipment is turned on, and the students fill a sack with healthy fruits and vegetables, sandwiches and salad “shakers.”
Interestingly, all aspects of the net-zero design are integrated into the curriculum at Richardsville. Members of the energy team, comprised of 4th and 5th graders, make their own presentations about the net-zero design strategies, having established laptop “tour stops” throughout the building where the students show and describe the energy saving features to guests.
This has also led to environmental stewardship with students teaching what they learned at school to their parents. “Students absorb these principles and literally teach them to their parents,” says Stanfield.
At The Putney School, a “Sustainablity Squad” meets on their own time, every Wednesday lunch, that engineers ways to make the campus even more eco-friendly, says Don Cuerdon, director of Communications for the district.
Recognition and Inspiration
Successful net-zero schools have also started inspiring the community to endorse other projects. For instance, the Warren County Public School District has one
“net-zero ready” school — Bristow Elementary— in operation, and another — Elrod Road Elementary — is scheduled to open in August.
“Each of these facilities will operate with the same energy performance as Richardsville Elementary, with the infrastructure in place and ready to add a photovoltaic’s package in the near future,” Stanfield adds.
Policymakers have also started taking notice, and Kentucky’s state legislators have introduced a bill to set green standards for schools and recognized Warren County Public Schools for the district’s energy saving strategies. The Kentucky Department of Education has endorsed the net-zero and net-zero ready schools designed and built in Warren County, and are now required to encourage all Kentucky public school districts to pursue net-zero design concepts.
Sarat Pratapchandran is a writer specializing in education, environment and healthcare. His website is www.lettersnatcher.com.