Architectural and engineering firm RTKL and Associates came up with some real outside-the-box thinking for Pennsylvania-based health insurance provider Highmark Blue Cross/Blue Shield.

The result is a two-story, 90,000 square foot data center, cut into a sloping ridge of a commercial park outside Harrisburg (PA) that is highly secure, makes use of roof top rainwater and has a focused and efficient computer cooling system. It also boasts impressive layers of redundancy for key infrastructure systems and a layout design that maintains its mission-critical servers running high and dry.

Completed in 2005, the Highmark Data Center handles up to 500,000 claims a day, connects more than 100 hospitals and 15,000 healthcare providers – and it’s geared for growth.

The project has earned two prestigious sustainability certifications: the Silver Leadership in Energy and Environmental Design (LEED) from the United States Green Building Council (USGBC), and the Uptime Institute’s Tier Three recognition. It is believed to be the only facility of its kind in the country that has achieved such a dual honor, officials said.

“It’s part of our social mission and being a good neighbor,” said Lowell Starling, Highmark’s Vice President of Infrastructure Management on the company’s commitment to sustainability. With a huge appetite for electricity and a demand for large amounts of chilled water to cool the constantly running computer servers, “an environmentally-friendly data center is kind of an oxymoron,” he said, which adds to the significance of the LEED and Uptime certifications.

When the company made the decision to replace its old data center, which was located in a 20-year old building and susceptible to failure, it put into gear four driving principles. It needed to improve reliability, increase security, demonstrate its good-neighbor and environmentally responsible beliefs and create a state-of-the-art facility that would provide a competitive edge in the industry.

“We believe that this positions us to be not only a viable player, but a highly competitive player because it gives us the ability to generate economies of scale,” Starling said. “It also demonstrates that technology is a differentiator – that we can do things that our competition
doesn’t.”

During an extensive site selection process, the company visited a number of data centers around the country to get some ideas on design. Most were single story facilities, but a few were two level affairs that grabbed their attention.

“We liked the idea of a two story primarily because that allowed us to put the infrastructure and all the chilled water below the data center so we have very little water on the actual data center floor,” Starling said.

Typically data centers are sprawling single story facilities. If they need to expand, the simplest way is horizontally, according to Doug McCoach, RTKL vice president in charge of the facilities design. By having the mechanical infrastructure below the computer center, you go up rather than out and realize significant economies on distribution.

“The distance vertically is perhaps 15 foot for both chilled water and electrical,” he said. “If I have a single-story solution, I have my chilled-water plant and electrical transformers next to the data center. All that power and all that water are potentially traveling hundreds of feet.”

A key area of efficiency is in the use of Tower of Cool technology in the server room. The chilled water is used as the circulating coolant in the air conditioners that are located with the servers on a three-foot raised floor, which serves as a plenum for the cooling system. Instead of venting to cool the entire room, small holes shoot the air into the cabinets themselves. “We move a lot less air, and realize some real savings in fans and fan energy,” McCoach said.

The method also calls for adjusting the temperature settings on the commercially supplied air conditioning units to decrease the supply air-temperature, resulting in the engineering solution known as High Delta T.  “We are supplying much cooler air through the cabinets and actually returning much hotter air,” McCoach said. “The greater that delta, the more efficiently they operate.”

That translates into fewer units on the floor. Fewer units on the floor translates into smaller requirement for chilled water. “Across the board, from the power to push the air, the electrical power to run the fans, to the requirement for chilled water, the High Delta T solution is a much more efficient approach,” McCoach said.

The computer cabinets are aligned in a configuration to concentrate the heat given off by the servers. By pushing the cooled air up into the front of the cabinets, which are designed with their own interior plenums to route the airflow, the chilled air blows across the equipment and out the back. “What you want to do is orient your computers so the fronts face each other and the backs face each other. That creates a cold row/hot row staggered layout,” McCoach said. “Heat rises, so as the hot air comes out you have hot air return ducts to take it back to the air conditioning units.”

The upper level layout separates the people from the computer area. “You don’t want people working in the data center. Let’s keep the people where people want to be and lets keep the equipment where it wants to be. They have two totally separate requirements for comfort,” he said. Office areas are located on two sides of the upper floor and are equipped with temperature and lighting controls and CO2 monitors all tie back to the central controls.

Reliability is built into the entire project. “We needed something in today’s world with the internet that is available 24/7/365,” Starling said. But with the critically high demand for water and electricity, the company did not want to put all its cards in the hands of local utilities that could suffer outages or interruptions. Back up systems – or an N Plus-1 level of preparedness – was also a requirement for the Uptime certification.

McCoach said the center’s design goes beyond that. “We want to maintain an N Plus-1 level of reliability even if we have to take one piece of the infrastructure down for maintenance,” he said of the heating, cooling, water and electrical systems. “Really every aspect of the building’s infrastructure has a reliability, redundancy strategy.”

For example, there are two electric lines from the local utility running connecting to the center and two back-up diesel generators on site, each one capable of powering the facility. “So we have four strikes before we’re out of power,” Starling said.

One of the most interesting aspects of the center’s redundancy design is its use of rainwater as a back up for AC coolant. Instead of running off the roof and down the sloping terrain, it is captured in a cistern, located below the lower level’s loading dock.

“We know that data centers are in a cooling mode constantly. The process causes a huge amount of evaporative loss,” McCoach said. “Basically the water carrying heat away is evaporated out of cooling towers. There is a constant need for make up water.”

It was estimated that 50,000 gallons would carry the facility for three days. They doubled that amount and created a cistern capable of containing 100,000 gallons. RTKL’s solution was a flexible lining, which is reinforced on the interior by a tray system, or “egg crates,” provided by Rain Store. “You dig a big hole, lay down this sheet of rubber and stack up the egg crates and fold the rubber back over itself and seal it up,” McCoach said. “It is as if you would stick something sturdy inside a balloon, you could step on the balloon. The great thing about the egg-crate structure is that they take up very little space, yet create a self-supporting bladder.”

To control the amount of water in this flexible cistern, a separate “gray water” system has been integrated into the building for sanitary use.

With it being benched into the slope it creates some built-in security features. There are two separate points of access via entrances and loading docks—one serving the top level computer center and office space and one to bring in supplies and equipment to the infrastructure level below.

“Because of the terrain, it is almost impossible for anyone to get a vehicle close to the building except for the driveways, all of which have gates,” Starling said.

The facility was built using precast concrete, another feature that helped in the LEED certification. “Because the concrete was fabricated and shipped within a 500 mile radius, we were able to reduce the impact on the environment by reducing the need to take local materials,” McCoach said. “The concrete was specified to have a certain amount of recycled material in it, fly ash, which helped us with our sustainability goals as well.”
Its design also lends itself to future growth. A back wall can be taken out, allowing for a 20-percent expansion. Today it is about 40-percent occupied, according to McCoach.

The building is designed and constructed to accommodate a 35-watt per square foot load with the ability to add infrastructure to go up to 75 watt per square foot. “The trend of late is that equipment gets smaller, more compact and generating more concentrated heating loads. We don’t think we will need more space, but more infrastructure capacity,” McCoach said. “One of the benefits of stacking the floor levels is that the infrastructure will grow on a one-to-one basis with the data center itself.”

Starling said that Highmark has been extremely pleased with the results. “The design and engineering of the building and its construction are world class,” he said. “Two of our subcontractors won awards for mechanical and electrical systems. The LEED and Uptime certifications speak for themselves.”

The project began with a corporate philosophy that Highmark Blue Cross/Blue Shield, Highmark Incorporated as a not-for-profit corporation had a mission to provide affordable health care to it’s subscribers, Starling said. “It also has a mission to basically be a good neighbor and to support the communities in which we have markets.” SLDT