Down a road that winds through the rolling hills of western Pennsylvania, just across from a cow pasture, the bucolic scenery of Butler County is interrupted by a high chain-link fence topped with razor wire.

Cars entering the compound are channeled into gated lanes before being searched by a guard. A short distance beyond the security point, the road disappears into a gaping hole in a cliff face. The hole is sealed off by the thick, steel bars of a tall sliding gate controlled by guards carrying semiautomatic pistols. They are protecting a 25-foot-high passage that leads 22 stories down to Iron Mountain's main archive facility, which takes up 145 acres of a 1,000-acre abandoned limestone mine.

Behind steel doors

Among dozens of red steel doors inserted in the rock face along corridors that create an elaborate subterranean honeycomb, you'll find Room 48, an experiment in data center energy efficiency. Open for just six months, the room is used by Iron Mountain to discover the best way to use geothermal conditions and engineering designs to establish the perfect environment for electronic documents.

Room 48 is also being used to devise a geothermal-based environment that can be tapped to create efficient, low-cost data centers. (For information on more companies using geothermal conditions to improve data center efficiency, see "Riding the geothermal wave.")

There is no raised floor in Room 48. Instead, networking wires are suspended above rows of server racks and cooled both by the limestone walls and vents attached to ceiling-mounted red spiral ducts 36 inches in diameter. The HVAC system uses the cool water of an underground lake hundreds of acres in size.

Outside light is beamed into the main aisle of the room through a long ceiling tube to reduce heat. Rows of server racks are encased in rectangular metal containers that trap electrical heat and force it up through perforated ceiling tiles, allowing the 55-degree limestone roof to absorb heat that otherwise would build up in the 4,100-square-foot room.

"Limestone can absorb 1.5 BTUs per square foot," Charles Doughty, the vice president of engineering at Iron Mountain, said during a recent tour of the facility by Computerworld. Facts on molecular chemistry and mineral properties roll off 61-year-old Doughty's tongue. He has worked as a technologist and archivist in the tunnels of the one-time mine for 37 years, studying thermodynamics in an ever-evolving effort to create the perfect environment for storing paper and electronic records.

An underground office

Doughty's underground office is adorned with dark wood furniture that's upholstered in the type of rich leather befitting his executive status. The furniture and carpeted floors contrast sharply with a rough-hewn wall of prehistoric rock. The office sits just off a larger room filled with cubicles that also butt up against rock walls, which are painted white to better reflect light and suppress any limestone dust.

The Underground, as the mine is called by employees, has its own cafe and a fire department with three engines. Like the other 2,700 workers here, Doughty traverses miles of roadways and tunnels in golf carts. Iron Mountain employs just 155 people in The Underground, the rest work for companies renting space in the facility.

An endurance kayaker who owns a working 30-acre farm and is training for an iron-man competition, Doughty is an idea man in a subterranean environment. He calls it "the best job in the world. I only get to create ideas. Other people do the work to make it happen. "