Where Data Centers Live: Above Ground, Underground, Modular, and More Good Neighbor Data Audio Briefing — Episode 3 Published July 2026 Duration: 9:56 This episode uses artificial-intelligence narration. The research, script, and source review were prepared for Good Neighbor Data. Educational content; not legal, engineering, utility, environmental, fiscal, or planning advice. CHAPTERS 00:00 Why “data center type” can mean several things 01:06 Conventional above-ground facilities 02:15 Underground data centers 04:08 Prefabricated and modular facilities 05:13 Edge and micro data centers 06:18 Experimental underwater data centers 07:05 Enterprise, colocation, cloud, and hyperscale models 08:03 Questions communities should ask TRANSCRIPT This is Good Neighbor Data, where we explain the physical infrastructure behind the digital economy—and the choices that determine whether it fits responsibly into a community. This episode uses artificial-intelligence narration. The research, script, and source review were prepared for Good Neighbor Data. When people discuss “types of data centers,” they often mix together different ideas. Underground and above-ground describe where a facility is built. Modular describes how it is assembled. Edge describes its role in a network. Enterprise, colocation, cloud, and hyperscale describe who uses it and how capacity is operated. One facility can belong to several categories. An underground mine can operate as a colocation center. An above-ground campus can serve a hyperscale cloud company. A modular building can support edge computing. The useful questions are: what is the physical form, operating model, network role, and workload? Start with the most common form: the conventional above-ground data center. This may be a converted building, one purpose-built facility, or a campus with several data halls. Above-ground construction is common because equipment, workers, utilities, and replacement parts can reach it more easily. Developers can also phase construction as demand grows. But the building is only part of the system. Supporting infrastructure can include substations, backup generators or other energy systems, cooling equipment, water infrastructure, fuel storage, fiber routes, security fencing, loading areas, and stormwater controls. For local reviewers, the important details are projected power demand, cooling method, water use, noise, emergency operations, equipment height, landscape treatment, traffic, and expansion timing—not simply the label “above ground.” The second form is the underground data center. These facilities can occupy former mines, military bunkers, purpose-built caverns, or other subterranean spaces. Underground sites may offer stable surrounding temperatures, limited access points, physical protection, and a lower visible profile. Lefdal Mine Data Centers in Norway places computing space hundreds of meters inside a former mine and uses nearby cold fjord water through heat exchangers. Iron Mountain operates a colocation facility about 220 feet underground in a former Pennsylvania limestone mine and uses an underground reservoir as part of its cooling system. These examples show the appeal: existing excavated space can be reused, the geology can add security, and local conditions may support efficient heat removal. But underground does not automatically mean low-impact. Heat still has to leave the servers. Power and fiber still have to reach the site. Engineers must address fire safety, evacuation, ventilation, humidity, water intrusion, structural stability, equipment access, and emergency response. Excavating a new cavern can create very different impacts from reusing an existing mine. Communities should ask whether the space already exists, how heat is rejected, what happens during a fire or flood, and whether geology and access routes have been independently reviewed. A third form is the prefabricated or modular data center. “Modular” can describe a self-contained facility, an IT pod, a power module, a cooling module, or factory-built components installed beside a conventional building. Vertiv defines these systems as pre-engineered, assembled, integrated, and tested in a factory to make deployment schedules and costs more predictable. Modularity can help an operator add capacity in stages, reduce some on-site construction, and repeat a proven design. Yet modular does not mean temporary or impact-free. Factory-built modules can still require a large utility connection, cooling, backup power, and permanent land. Local approvals should evaluate the full buildout—not only the first modules shown in an early phase. Next are edge and micro data centers. These are smaller facilities placed closer to the people, devices, networks, or industrial systems they serve. The Telecommunications Industry Association says an edge data center can range from a few servers in an outdoor enclosure to dozens of racks in a regional facility. Uses can include content delivery, telecom networks, industrial controls, retail systems, and applications that cannot tolerate sending every request to a distant cloud region. Edge facilities may reduce latency and long-distance data transport. But many are small, remote, and lightly staffed or unmanned. Designers must still plan for security, maintenance, weather exposure, backup power, cooling, and remote monitoring. Then there are underwater data centers—but this category needs a warning label. Microsoft’s Project Natick placed a sealed data center on the seafloor off Scotland for two years. The research suggested the concept was feasible and that a sealed, people-free environment could improve hardware reliability. It also explored seawater heat exchange and operation without freshwater cooling. That makes underwater computing an important experiment, not a normal commercial project type. Marine ecosystems, permitting, cable routes, retrieval, repair, ownership, and end-of-life responsibility would need careful answers before broad deployment. Finally, separate physical form from operating model. An enterprise data center supports one organization. A colocation center rents secure racks, cages, or suites to many tenants. A cloud data center provides virtualized computing services through a network. A hyperscale facility is built for very large, standardized workloads. Any can be above ground. Some can be underground. Many can use modular construction. Edge facilities can be enterprise-owned, carrier-operated, cloud-connected, or colocated. Cooling is another layer. Air cooling, evaporative systems, chilled water, direct-to-chip liquid cooling, and immersion cooling can appear in different facility forms. The choice affects electricity, water, noise, maintenance, equipment density, and heat-reuse opportunities. So what should communities ask? First: what physical form is being built, and is it reusing an existing structure or disturbing new land? Second: who will operate it, who will use it, and how much capacity is committed? Third: what is the full buildout—not only the first phase? Fourth: how will power, water, cooling, backup systems, fiber, noise, traffic, fire safety, and emergency access work? And fifth: what performance will be measured and publicly reported after opening? The best form depends on the site, workload, network, and community. Underground construction can reduce visibility and reuse caverns, but adds specialized safety and access challenges. Above-ground construction is accessible, but external infrastructure can be extensive. Modular systems can speed deployment, but do not erase resource demand. Edge facilities reduce latency, but distribute infrastructure across more locations. Underwater systems remain experimental. No label proves that a data center is sustainable or community-compatible. The evidence is in the design, operating commitments, and measured results. For practical evaluation guides, facility case studies, and the U.S. Data Center Map, visit goodneighbordata.com. This has been Good Neighbor Data. Sustainable data centers. Built to belong. SOURCES TIA-942-C Data Center Infrastructure Standard overview — data center design categories and edge/micro facility range. https://tiaonline.org/wp-content/uploads/2024/05/TIA-942-C-DC-infrastructure-stadard_TIA-white-paper.pdf Lefdal Mine Data Centers — underground mine design, fjord-water heat exchange, security, and modular expansion. https://www.lefdalmine.com/data-center Iron Mountain Western Pennsylvania Data Center — operating underground colocation example and reservoir-assisted cooling. https://www.ironmountain.com/data-centers/locations/pennsylvania-data-center Vertiv: Prefabricated Modular Data Centers — modular construction definition, deployment, and scalability. https://www.vertiv.com/4900ac/globalassets/shared/vertiv-prefabricated-modular-data-centers-white-paper-sl-70441.pdf Microsoft Project Natick — underwater data center experiment and findings. https://news.microsoft.com/source/features/sustainability/project-natick-underwater-datacenter/ IBM: What Is a Data Center? — enterprise, cloud, managed, and colocation operating models. https://www.ibm.com/think/topics/data-centers