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A new geothermal system to more efficiently heat the Oregon Zoo‘s new elephant habitat will also eventually help keep neighboring polar bears cool.

While PAE engineers developed the system, they realized it could be even more efficient by taking advantage of the proximity of two bond-funded projects for animals with opposing temperature preferences, Portland-based PAE mechanical engineer Tim Elley said. They recommended burying a series of coiled plastic water tubes in an approximately 1.5-acre geo-exchange field between the elephant habitat being constructed and a planned polar bear habitat. The 1-inch diameter tubes will absorb heat from the ground and eventually transport warmth expelled by cooling equipment for the future polar bear exhibit to Forest Hall, the 32,000-square-foot indoor portion of the zoo’s $57 million Elephant Lands habitat.

鈥淲e knew that one of the first big bond projects was elephants, and one of the next ones in the pipeline was polar bears,鈥� Elley said. 鈥淲e knew that was going to happen, so we identified that as the best place to put this geo-exchange field.鈥�

Once the system is fully operational, heat pumps attached to both exhibits will use less energy to maintain comfortable temperatures for elephants and polar bears, Elley said. This will help the zoo meet sustainability targets, he said.

鈥淭he idea for geo-exchange fit well with the zoo’s goals,鈥� he said. 鈥淲e had the idea for geo-exchange before it became clear there was this great opportunity for the elephants and the polar bears.鈥�

The project team anticipates construction starting in two years for a new polar bear exhibit close to Elephant Lands, said Wayne Starkey, Elephant Lands’ project engineer. Eventually, the two habitats will exchange opposing heat and cooling needs, he said.

鈥淗aving those (habitats) right next to each other was a huge advantage,鈥� he said. 鈥淧olar bears will be injecting hot water into the loop while elephants will be injecting cold water into the loop.鈥�

When Forest Hall is completed next year, the geo-exchange field buried up to 12 feet deep at the north end of the outdoor habitat will pull warmth from the ground, which averages around 55 degrees, to more efficiently heat the barn via a heat pump.

It will work even better once heat expelled from the polar bear habitat is added to the system, Elley said. Polar bears will in turn benefit from cooler temperatures created when the elephant habitat pulls heat out of the system.

鈥淲hat you’d rather be doing is pulling heat out of the ground and putting heat into the ground sometimes,鈥� he said. 鈥淪o what you really want is a balance. Once polar bears come on line you get this real synergy where the polar bears are going to want cooling.鈥�

Lease Crutcher Lewis crews installed the pipes that make up the geo-exchange field this past spring while performing excavation work already needed for the Elephant Lands project. This greatly reduced the cost of installing the pipes, which will connect to the larger geothermal system still under construction, Elly said.

鈥淎ll they had to do is lay this plastic pipe on the ground so the cost becomes more competitive,鈥� he said.

Zoo officials hope to expand the geothermal system to help heat and cool other habitats, and it’s designed to accommodate those plans, zoo construction manager Jim Mitchell said.

鈥淲e’re always looking for ways to save energy,鈥� he said. 鈥淭his actually goes beyond polar bears and elephants.鈥�