Iron Mountain finds limestone a natural fit for data center efficiency

Iron Mountain

 Twenty-two stories below ground, deep within the secure confines of a former limestone mine in Pennsylvania, resides Room 48, Iron Mountain's state-of-the-art underground data center. Designed by Iron Mountain vice president of engineering Chuck Doughty, the facility takes advantage of the natural properties of the subterranean location to help the data storage and security company put a dent in its significant energy costs.

"A major challenge was helping our engineers and equipment suppliers understand the basic physics, thermodynamics, and electrical transformation and distribution of this unique location and how they could be leveraged -- and not just apply typical data center designs that have been used for the last 25 years," said Doughty.
The location's geothermal and subterranean conditions open up opportunities for energy reduction that you wouldn't find in a traditional data center. For starters, the natural temperature of the facility is between 55 and 65 degrees, so Room 48 benefits from free cooling. Ducting above the servers pushes air down naturally, using far less power than would be necessary to blow air upward, as a traditional data center would.
Iron Mountain also employs a cold-air containment strategy, which uses the limestone walls and ceiling vents to cool wires and cables hanging above the server racks to increase cool-air distribution by up to 20 percent. At the same time, air pressure differentials force warm air from the servers up and out through perforated ceiling tiles. Room 48 (which gets its name from its location on the underground facility map) has no need for raised floors found in traditional data centers, thanks to the natural limestone walls' ability to absorb 1.5 BTUs per square foot per hour.
Geothermal and subterranean conditions of former limestone mine yield significant savings on cooling
Mother Nature alone isn't responsible for the efficiency gains of the facility. As part of the design, Iron Mountain located the power distribution and air conditioning equipment outside of the facility, resulting in a further reduction in heat while freeing up 30 percent more space for racks.
Room 48 uses motion-sensor, low-power, low-heat lighting to further reduce temperature and costs. Additionally, Iron Mountain opted to purchase run-of-the-mill K-rated transformers and electrical load centers in the data center, the kind you'd find in an everyday electric supply store, rather than pricey electrical equipment typically used in data centers. The company also incorporated readily available, energy-efficient T8 fluorescent bulbs into its lighting scheme.

Iron Mountain's efforts paid off in spades. The company estimates that Room 48 cost about 30 percent less to build than a traditional data center because of its energy-efficient design and use of standard equipment instead of specialty gear. The various efforts to slash cooling save the company hundreds of thousands of dollars annually. Moreover, the natural cooling allows Iron Mountain to boost power in the room to 200 watts per square foot, 50 percent above the 125 watts per square foot used in data centers located in the same underground facility.
"Room 48's design and construction provided a powerful lesson in discarding prior data center design templates and leveraging the natural advantages this unique location provided," said Doughty. "Future Iron Mountain data centers will use the lessons of Room 48 to help design, construct, and operate the most cost-effective data centers, utilizing the geothermal cooling of the underground."