Geothermal Moves From the Ground Up
– Part 3

Heat is being taken from the building and being transferred into the ground in summer. In winter, heat from the ground is transferred into the building.

peak-shaving

Good Fit for Commercial Uses
Though commercial ground source geothermal is not the largest percentage of their business, AAON Heating and Cooling Products is quite versatile in being able to adapt any of their many systems to ground source geothermal installations. They typically do units for retail establishments, commercial systems, and schools—a lot of rooftop units, less than 10 stories in height.

“The difference in what we sell and what some of the larger outfits do, is that we sell more of a serviceable product,” explains Eric Taylor, AAON Heating and Cooling Products marketing manager, who also has a degree in electrical engineering. “Ours typically have doors, color-coded wiring, and are more service-friendly for the life of the unit overall. The construction is excellent with foam insulation such as you would see in a refrigerator, instead of Fiberglas insulation that is common in conventional units.

“We don’t have belts in our units, meaning that those don’t need to be replaced all the time. In addition to standard features, our systems also have a lot more flexibility so that we can have options for specific applications such as ventilation, bringing in outside air, or others might want energy-recovery options using the exhaust from the building. Others might want humidity control for some applications.”

Some locations with data centers want year round cooling. AAON has features that do this, and all of their products can accommodate ground source geothermal heat pumps. These include split systems and self-contained ones; they can all be configured with geothermal heat pumps. Pipes in the ground typically contain water or sometimes glycol. Antifreeze is used to prevent freezing on such areas as rooftop units.

“With geothermal, heat is being taken from the building and being transferred into the ground in summer. In the winter, you are taking the heat from the ground and transferring it back into the building,” says Taylor. “If you have multiple systems on a building where part of the building may be cold and part of it hot, with these geothermal systems you can transfer heat through the water loop to a cold part of the building. In that case, you are not even heating up the ground, but simply transferring heat between the parts of the building.”

This makes for much greater efficiency, upwards of 40% depending on the size of the building. A geothermal system works well for schools as these typically are going to be around for decades—up to 50 years many times. They can invest more initially to get that payback on the serviceability and the additional features that AAON sells. Systems are often sold to places more concerned about total life-cycle costs, rather than simply buying a unit to replace what they’ve got now.

“The majority of the installations use vertical wells. We’ve done some schools, including a whole school down in Texas that was geothermal. They are basically one unit per classroom and then they use that concept of one room being cold and one warm and spread the heat around the building. Long lifespan and ease of serviceability make this a great fit for a school application. We’ve done a lot of different applications for geothermal, though it is a small part of our business. We see it mostly for LEED buildings, not simply a small retail store.

“Our geothermal heat pumps can have variable speeds, energy recovery and a lot of additional energy efficiency features. When you get geothermal with all these other features we offer, you can really maximize energy savings. Ours also have the option of switching over to gas heat in the colder climates if thing get really cold; this is good if you have some backup heat issues involved.

“The only thing that has slowed geothermal down is the price of natural gas being so low now. That’s the only thing holding geothermal back and pushing natural gas heating more. This makes it difficult to justify the additional cost of geothermal at the present time. In the short term gas prices are low, but they will eventually go up.”

 

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