Inside Climate News recently reported on one of the largest geothermal heating and cooling networks in the world, located beneath the fantasy themed corporate campus of Epic Systems in Verona, Wisconsin. The medical records software company has installed more than 6,100 geothermal boreholes across its 410 acre site, creating a massive thermal network that significantly reduces energy use for heating and cooling.

The system circulates nearly 6 million gallons of water through underground pipes, drawing steady temperatures from the subsurface to heat and cool dozens of buildings. Electricity from on site solar panels and a nearby wind farm powers the network. Epic’s facilities engineers estimate that the company’s buildings use only one quarter of the energy consumed by typical office buildings, with more than half of those savings attributed to its geothermal system.

Epic is now expanding the network by drilling an additional 2,400 boreholes. The scale of the project exceeds most utility led geothermal pilots and has drawn attention from federal agencies and industry groups, who see it as a model for large campuses and district heating systems.

How the System Works

The boreholes extend 300 to 800 feet into the ground, where temperatures remain close to 50 degrees Fahrenheit year round. Water circulated through the pipes exchanges heat with the surrounding geology, providing a stable energy source that is warmed or cooled further by high efficiency heat pumps in centralized plants.

Epic’s system also functions as a thermal battery. Excess heat from buildings and from the company’s data center is stored underground during the summer and later recovered in the winter. Researchers from the University of Wisconsin–Madison have been monitoring the system since 2014 using a fiber optic network embedded in the borefield.

Case Study for Utilities

Epic’s geothermal network has attracted interest from utilities that are exploring alternatives to traditional natural gas systems. As states adopt climate goals and seek to reduce methane emissions, neighborhood scale geothermal networks are becoming a potential replacement for gas pipelines. Epic’s campus size, comparable to a small town, offers an example of how thermal networks may operate at scale.

Questions remain around cost and performance for future systems. Industry experts note that geothermal networks have higher upfront costs due to drilling, but long lifespans and lower operating costs can offer strong long term value. Epic reports a 15 to 20 year return on investment for its geothermal system, and its original borefield has already paid for itself.

Challenges and Growth

Epic’s early geothermal installations were not large enough to handle the heat loads of the rapidly expanding campus, which caused overheating in the first borefield. Over time, the company added thousands of additional boreholes and supplemental heat rejection systems in a stormwater pond and a flooded quarry. Engineers continue to model future campus growth to ensure the system remains balanced throughout the year.

Maintenance and operation also require advanced engineering expertise, and company officials note that geothermal networks are not yet a universal solution. However, the durability of the system’s underground piping, expected to last more than 80 years, and the efficiency gains across the campus demonstrate the technology’s potential.

Epic continues to expand its network as construction grows. Engineers working on the system describe their role as open ended, noting that the demand for geothermal buildout on the campus shows no signs of slowing.

You can read the original Inside Climate News report, One of the World’s Largest Geothermal Networks Is Buried Beneath a Corporate Campus in Rural Wisconsin, here.