Back to the Earth

Nov. 1, 1999
A school district could do a lot with $8.8 million: Hire more teachers. Buy better textbooks and computers. Upgrade facilities and programs to enhance

A school district could do a lot with $8.8 million: Hire more teachers. Buy better textbooks and computers. Upgrade facilities and programs to enhance student learning.

With the $8.8 million it expects to save over the next 10 years, the Middletown Township School District in New Jersey could redirect some money for those improvements. The district is slashing its energy costs by using geothermal heat-pump technology, known as GeoExchange, to renovate heating and cooling systems at three middle schools and two high schools.

Middletown's schools are among more than 500 across the United States that use GeoExchange. Proponents contend that GeoExchange can help schools balance the costs of education with the need for maintenance, upkeep and new construction.

The U.S. Environmental Protection Agency (EPA) and the Department of Energy (DOE) call GeoExchange the most energy-efficient and cost-effective space conditioning available today.

"Original plans called for only partial replacement of our aging HVAC systems using conventional solutions," says Joe Grabowski, Middletown's director of facilities and planning. "With GeoExchange, the significant energy savings not only helped fund the complete replacement of all five HVAC systems, but it also provided air conditioning for our schools."

U.S. schools spend more than $6 billion a year on energy, mostly for heating and cooling. GeoExchange technology can save schools 25 to 40 percent in annual energy costs over traditional heating, ventilating and air-conditioning (HVAC) systems.

A 25 percent reduction could save schools about $1.5 billion a year. That translates into enough money to buy 40 million new textbooks or hire 30,000 new teachers.

How it works Below the frost line (a depth of about five feet), the temperature of the earth is relatively constant, ranging from 45 degrees F to 75 degrees F throughout the United States. GeoExchange relies primarily on this natural thermal energy for heating and cooling. The only additional energy these systems require is a relatively small amount of electricity to pump warm or cool air throughout the building. The result is a climate-control system that is regulated easily on a zone-by-zone basis.

The technology works on a different principle than an ordinary furnace or air-conditioning system. Furnaces must create heat by burning a fuel-typically natural gas, propane or fuel oil. With GeoExchange, there is no need to create heat, and no need for chemical combustion. Instead, the earth's natural heat is tapped by employing a series of below-ground pipes, called a loop.

A "closed" loop is installed in the soil either horizontally in trenches, or vertically in holes dug with well-drilling equipment.

An "open" loop is submerged in a pond or lake. Fluid circulating in the loop absorbs the earth's heat in winter and carries it to the building. The GeoExchange system then concentrates the heat and releases it at a higher temperature inside the building.

In the summer, the process is reversed. Excess heat is drawn from the building, expelled to the loop and absorbed by the earth.

In many school installations, one heat pump is used for every one or two classrooms. The heat pumps are compact and can be placed in the classroom as consoles, in closets or above hallway ceilings. Larger heat pumps are used for areas such as cafeterias and gymnasiums. Other heat pumps may be used to provide hot water for kitchens and locker rooms.

Steady growth In the early 1980s, a few U.S. schools pioneered the use of geothermal heat-pump technology. By the end of the decade, GeoExchange schools numbered 40. Then, in 1993, the EPA published a report, "Space Conditioning: The Next Frontier." The report encouraged schools to consider GeoExchange.

Two years later, about 200 schools had chosen GeoExchange in new construction and retrofit projects. As a result of advancing technologies, refinements in installation methods and increased demand for energy-smart alternatives, growth has risen sharply. Today, about 560 schools in 40 states are using GeoExchange technology.

According to American School & University's 1999 school construction survey, U.S. schools will spend $70.8 billion over the next three years in construction, renovations and additions. This much spending mandates greater accountability. Taxpayers are willing to foot the bill to equip schools for the 21st century, but they want their dollars invested in cost-effective systems and materials.

As a result, many districts are looking more closely at GeoExchange. The DOE encourages the use of GeoExchange through its Energy $mart Schools program.

Quick payback A perception exists that GeoExchange costs more to install than conventional systems. In many cases, architects, engineers and contractors are finding that the perception is false.

"Generally speaking, we have found that a geothermal system, properly designed, can be installed for about the same cost as a conventional HVAC system," says David Samokar, a principal at Clotfelter-Samokar, a Lexington, Ky., architectural firm that specializes in educational facilities.

Although GeoExchange does involve added costs because of drilling and underground loop installation, these expenses can be offset by reduced mechanical space. Many utilities, looking to offer consumers cost-efficient and environmentally sound options, also are backing GeoExchange projects with incentives and rebates that make upfront costs more palatable.

"We don't have to devote space for boilers, furnaces and other equipment," says Samokar. "That saves space or allows space to be utilized for other purposes, such as storage. And there's no outdoor or rooftop equipment to deal with. It's a good situation for the building team and for the schools."

Even when upfront costs are slightly higher than a conventional HVAC system, districts can quickly recoup their costs in energy savings and reduced operating expenses.

At Daniel Boone High School in Gray, Tenn., a GeoExchange system cost the school system about $197,000 more than a conventional boiler-cooling tower design. Combining the savings in energy costs and operations and maintenance, school officials expect a payback period of as little as three years.

Weighing the higher initial costs against the life expectancy of a GeoExchange system (some institutional-grade systems date back 20 years or more), an increasing number of schools are choosing this type of system.

When construction began eight years ago at Paint Lick Elementary School in Garrard County, Ky., school officials were initially skeptical about using the GeoExchange heating and cooling technology.

"The theory is great, but we wanted proof that the equipment was adequate to meet the theory," says Michael Luscher, who was director of facilities management. But a joint effort by the school's architect, the local electric utility and the geothermal heat-pump manufacturer persuaded the district to take the leap to GeoExchange. The school was completed in June 1992.

The building, nearly 40,000 square feet, is conditioned by a 120-ton GeoExchange system. It consists of 32 separate pumps, allowing 20 classrooms and other special areas to have individually controlled thermostats. The pipes for the system were installed vertically underground behind the school.

During its seven years of operation, the system has run smoothly. Paint Lick teachers and staff like the system's comfort and flexibility. District superintendent William Wesley stresses its high efficiency and low costs. For example, energy usage at Paint Lick during 1998 was 11.60-kilowatt hours (kWh) per square foot. At a nearby natural-gas-fueled elementary school, the equivalent usage was 16.49 (kWh) per square foot -about 30 percent higher than GeoExchange.

Paint Lick's energy efficiency has earned the school an Engineering Excellence Award from the National Society of Professional Engineers.

School officials also like the lessons in environmental stewardship that GeoExchange provides. The school's heating and cooling system emits no harmful substances into the air-indoors or out.

Schools considering GeoExchange should decide early in a project. In fact, several of the advantages of a GeoExchange system can be realized only when the technology is factored into the design phase.

In addition to the cost savings and environmental benefits, GeoExchange can help cut construction costs. For instance, because individual geothermal heat pumps can be placed in closets, ceilings or other small spaces throughout the building, the amount of space dedicated to mechanical equipment can be reduced significantly. That space can be used instead for extra classrooms or common areas, such as a band room, auditorium or cafeteria. Since GeoExchange systems require no rooftop equipment, flat roofs are not a design criterion-architects can design a more interesting and aesthetically pleasing building. Structural costs can be reduced because the roof girders do not have to support heavy chillers or other equipment.

Finally, because individual classroom thermostats can be adjusted for specific conditions, architects have more latitude in the number and design of windows, and the orientation of exterior walls. For instance, rooms with windows on a sunny exterior wall can be cooled even as rooms facing a shady interior courtyard are being heated.

When Middletown Township School District (NJ) passed a $78.4 million bond referendum for renovations and additions to two high schools and three middle schools, original plans did not include air conditioning or complete mechanical-system upgrades.

But Joseph Grabowski, director of facilities and planning, became convinced that energy-efficient systems could provide better long-term solutions. The district developed a proposal to completely redesign the mechanical systems using GeoExchange technology.

The plan showed that the savings would provide the funds needed to complete mechanical upgrades and provide air conditioning at the schools.

The project is expected to save the school district $8.8 million in energy costs over the next 10 years. The closed-loop system is among the largest GeoExchange projects in the Northeast.

What Grabowski finds most exciting about the project is the opportunity to bring the technology into the classroom.

"We all want our children to learn and excel in technology, mathematics and science, and we also want to teach them energy conservation and respect for the environment," he says. "Using a GeoExchange system saves tons of fossil fuels. Combining our GeoExchange technology with our state-of-the-art computer systems gives us a chance to bring these important lessons into the classroom."

The district is phasing in LonWorks, a computerized HVAC-control system that enables the district to monitor, control and increase the efficiency of the HVAC system using the same technology infrastructure used for the school computers.

Through this technology, Middletown students can use computers in the classroom to study the performance of the GeoExchange system.

"Teachers can demonstrate simple principles such as heat exchange and how GeoExchange uses the earth's natural stored energy to save fossils fuels," Grabowski says.

The system also can be used to demonstrate more sophisticated principles, including thermodynamics.

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