Back in 2001, the winter heating bill for Grand Meadow School in Minnesota averaged about $28,000 a month. The following year, officials built a new type of green school that purportedly would save as much as 50 percent on heating and cooling costs.

The new school consisted of five Monolithic Dome buildings, steel-reinforced concrete structures that are known not only for energy efficiency, but their ability to withstand severe weather such as tornadoes and hurricanes. Seven years later, and at a time when energy costs have been rapidly on the rise, the results have been even better than predicted. Utility costs at this Minnesota school now average only about $11,000 a month, even in the coldest winter months.

While Monolithic Domes are still relatively unknown to the general public, school officials across the nation have become increasingly aware of this energy efficient option for new-school construction.

Although Grand Meadow was the first school district in Minnesota to build a Monolithic Dome, other states, like Oklahoma, Texas and Arizona, are home to several dome schools. Six Monolithic Dome schools have been built in Oklahoma alone, and two more are slated for construction there this year.

“Utility costs represent a substantial portion of a school’s operating budget,” said David South, who co-invented and patented the process for constructing Monolithic Domes and now heads the Monolithic Dome Institute in Texas. “We have found that these schools can pay for themselves in 20 years from the energy savings alone.”

That’s good news for cash-strapped school districts looking to stretch limited dollars.

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The domes’ energy efficiency is due in part to the concrete’s thermal mass, which keeps the temperatures inside the buildings stable. The domes also typically feature high-performing windows and doors. Another plus is their sustainability. Because of their shape, Monolithic Domes require the smallest surface area and employ the fewest materials to enclose space. They also have a life span measured in centuries.

“In order to match the long life and energy conservation of Monolithic Domes, conventional structures would be much more expensive to build and require significantly more materials and maintenance,” said Dr. Arnold Wilson, Professor Emeritus of Civil Engineering at Brigham Young University (BYU).

The process used to build Monolithic Domes is as unique as the structures themselves. It begins with the placement of a ringbeam footing and the pouring of a circular steel-reinforced concrete slab floor. Vertical steel bars embedded in the outer ring later attach to the steel reinforcing of the dome itself. An Airform, a tarp made of tough, single-ply roofing material, is attached to the ring base and inflated, creating the shape of the dome.

Crews then move to the interior of the dome, where they spray polyurethane foam on the Airform and reinforce it with a grid of steel rebar. They then spray the dome with two or three inches of Shotcrete. The result is a safe, permanent and energy efficient structure designed to last for centuries.

School officials can choose from a variety of pre-designed “modules” designed in various sizes and styles as school gyms, multipurpose buildings and classrooms, or they can commission an architect experienced in thin-shell structures to design the facility from scratch.

Because Monolithic Domes can cost less to build than conventional structures, they often appeal to smaller school districts that are short on money. Now school officials even have the option of building Monolithic Dome modules on a lease-to-own basis. Instead of having to pass a bond to pay for the new building, they can pay the lease out of their operating budget while offsetting that cost with the utility savings.

“Because of arrangements we’ve made with two government funding entities, school superintendents can now shop for a single module or group of modules as they would for a new school bus,” said South, who also operates a construction company called Monolithic Constructors.

Grand Meadow voters passed an $8 million bond to build their school, and the state legislature provided a $3 million grant. The result is a five-dome campus: one for elementary classrooms, another for secondary grades, and the other three for a cafeteria, gymnasium, computer lab and administrative offices.

Bruce Klaehn, who was the Grand Meadow superintendent when the dome schools were built, said there were challenges involved in convincing the community to take an unconventional approach. “I think our greatest challenge has been making folks understand that this is clearly a better way to build," Klaehn said in the school’s pre-construction days. "I think it's just a matter of letting them see how well they're built."

Today, the Grand Meadow school district’s website touts itself as providing “Education in Minnesota’s School of the Future.” It also ranks the dome buildings high on its “Top 10” list of reasons for choosing the Grand Meadow school district. Ranked second from the top is: “Energy efficient and environmentally safe learning environment.”