Each year, some 250,000 patients and their families use the services of Beth Israel Deaconess Medical Center (BIDMC) in Boston, MA. This 550-bed adult medical-surgical teaching hospital, affiliated with Harvard Medical School, is known for its surgical and clinical expertise. In addition, BIDMC prides itself on a high level of patient safety and quality of care. BIDMC also prides itself on implementing cutting-edge green technology. In fact, its goal is to increase green purchasing 15 percent by fiscal year 2012.

Data Centers Going Green

Perhaps most important of all for conservation and data protection, BIDMC’s two data centers have reduced energy use by consolidating servers, replacing older, less energy-efficient devices, and reconfiguring equipment despite growing electronic demand. For protecting vital data, including patient records, against costly power outages, the center now relies on flywheel systems, UPS, batteries, and generators. The data centers are also improving thermal management by reducing under-floor cables, using perforated inserts, shutting down an unneeded air conditioning unit, and making other adjustments as needed.

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“Beth Israel Deaconess Medical Center is committed to conserving and protecting our natural resources,” said John Powers, vice president of information systems. “By providing guidance, setting expectations, sharing outcomes, and educating the BIDMC community, we aspire to make sustainability a cornerstone of the way we do business.”

Acting on Powers’ green-tech vision, Data Center Plant Manager for Information Systems Tyrone (Ty) Dell efficiently and creatively designed the main 7,000 square-foot Renaissance Data Center, (a former Registry of Motor Vehicles building), located 1.5 miles from BIDMC’s hospital campus. A separate 3,000 square-foot disaster recovery data center, officially called the Span Data Center, is housed at the medical center’s main campus. BIDMC’s two data centers support all of the vital clinical systems including medical records, pharmacy, laboratory, chemotherapy suite, and operating rooms.

The Renaissance Data Center has approximately 300 servers, nearly 40 switches/routers, and 15 data storage devices. “Approximately 60 percent of our servers are virtualized and all new application/server requests go VMware unless they have requirements that VMware cannot handle,” explained Dell.

Power equipment for the main Renaissance Data Center includes a mixture of APC/MGE and KW Controls’ power distribution units (PDUs), remote power panels (RPPs) from APC/MGE, two 450-kVA uninterruptible power systems (UPS) from APC/MGE, and two flywheel systems from VYCON. GE Zenith provided the automatic transfer switches (ATSs), and the generator is a Caterpillar 1000-kW model number SR4 3508 series diesel engine.

The Renaissance Data Center receives its power from the utility vault through four ATSs that switch to a generator during a prolonged power event. The cooling system and computer load are supported by two sets of redundant ATSs. “Either the cooling system or the computer load can lose an ATS, and the data center will still remain operational,” said Dell.

Figure 3.1


Two power strips in each of the computer cabinets plug into the electrical circuits, and each server has two redundant power supplies that plug into these separate power strips. “Each electrical circuit is monitored to not exceed 40 percent of its rated capacity, so either power strip can carry the full load of the computer rack in the event of a UPS system failure,” explained Dell.

The rows of cabinets are in a cold aisle/hot aisle configuration. The electrical circuits are run in the cold aisles, and the data circuits are kept separate and run in the hot aisles.

The PDUs have sub-feed breakers that go to remote power panels at the end of each of the computer rows. Electrical circuits run from the RPPs to each of the computer cabinets in the row. There is a circuit from each of the two 450-kVA UPSs in the cabinets.

The smaller Span Data Center contains a standalone MGE Galaxy PW 225-kVA/20- kW UPS that is paired with two VYCON flywheels, each rated at 275 kVA for 11.7 seconds. At 200 kW of computer load, the flywheels provide 15 seconds of run time before the generator starts.

Dell and his staff are in the process of making the electrical and cooling systems in the Span Data Center as redundant as the main Renaissance Data Center. “It’s more of a ‘hot’ site that houses our most critical applications in the event our main data center were to become unavailable, and the hospital needed to maintain business operations,” he explained.

Danaher and Cyberex provided PDUs and RPPs in the smaller Span Data Center. The Intelligent Power Machines (IPM) are Model 80. The ATS are from Russelectric, and the generator is a Cummins 400-kW diesel engine. Both data centers have Cutler-Hammer switchboards for 480-V distribution.

The Renaissance Data Center includes ten Liebert downward flow FE240GUA00 computer room air conditioners (CRAC), with a 20-ton capacity. In addition, there are three DX Glycol Dry coolers on the roof. These CRACs pressurize an 18-in. computer room raised floor with 56 F degree air. “We place perforated tiles in front of the computer racks where we want cold air to travel,” said Dell. Each CRAC unit and dry cooler has a power selector switch that can get power from either ATS to maintain power to the cooling system. The computer power coming from both UPS systems is brought to the data center floor at 480 Vac and stepped down to 120/208 Vac by power PDUs.

“We are trying to achieve a 1.6 PUE (power usage effectiveness) by upgrading older equipment,” explained Dell. “There is a project currently in the works that will replace our 16-year-old dry-cooler heat exchangers for our CRACs on the roof that will, hopefully, bring us to our goal.”

Redundant Power Protection

As with any medical facility, priority one is keeping the computer servers up and running no matter the state of the incoming utility power. “If our computers went down, we couldn’t schedule someone for surgery,” Dell said. “If a power outage occurred for a prolonged period of time, we might have to detour patients to other hospitals.”

Power outages are not the only calamity that data centers can experience. Batteries are notoriously prone to failure as Dell knows well. “A while ago, a UPS lead-acid battery failed in one of the battery strings. While no data were lost, computers and switches had to be brought back on-line in sequence. This took several hours and business operations at the hospital were brought to a crawl while we brought systems back on-line,” he recalled.

BIDMC is hardly alone in this dilemma. According to the Electrical Power Research Institute (EPRI), power disturbances cost U.S. industry as much as $188 billion per year in lost data, material, and productivity. In order to minimize these losses, annual spending on backup power systems exceeds $5 billion worldwide, according to industry analysts at the Darnell Group.

To assure the highest level of power protection, and to save on space, expensive cooling, weight and maintenance costs in the larger Renaissance Data Center, Dell chose two pair of VYCON’s highly efficient VDC flywheels to back up each of his two parallel 225-kVA UPSs.

These parallel units provide 400-kW capacity on each pair. “We had to do it this way because a single 400-kW UPS was too big to get to the 8th floor,” explained Dell. “So, we bought two smaller ones and tied them together. Each unit requires its own direct current source. So, a battery string or a pair of flywheels is used for each 200-kW module. We used a pair of flywheels instead of one for the additional runtime.”

Dell then added: “We found that at 400 kW of computer load, we get 30 seconds of flywheel runtime while waiting for the generator to start up during a power outage. This is plenty of time, as the generator must come on line within 10 seconds in order meet the NFPA 99 regulations for Emergency Power Systems.” The Joint Commission on Accreditation of Healthcare Organizations (JCAHO) requires that the generator must come on line within 12 seconds.


While the flywheel systems can completely replace the UPS’s batteries, Dell has chosen to use batteries and the flywheel systems together for now. “We are currently evaluating whether to eliminate the batteries altogether. The flywheels not only give us the ride-through to generator that we need, but with their very fast recharge time-under 150 seconds-they also tackle the momentary power fluctuations that can quickly reduce battery life,” he explained.

Spinning at up to 36,000 rpm, just one flywheel system can provide up to 300 kW of power. Electrical input spins the flywheel rotor up to speed, and a standby charge keeps it spinning 24/7 until called upon to release the stored energy (see the figure). The amount of energy available and its duration is proportional to its mass and the square of its revolution speed. For flywheels, doubling mass doubles energy capacity, but doubling rotational speed quadruples energy capacity:

E = kMv2

k – Depends on the shape of the rotating mass

M – Mass of the flywheel

v – Angular velocity

Increasing energy efficiency by not using special cooling for the flywheels was another bonus for Dell. Comfort cooling can adequately keep the UPSs and flywheels running at optimal temperature.

The flywheel systems not only offer improved efficiencies and reliability for the medical center, but they also take up very little space, require no bearing maintenance, and have a 20-year life with virtually no maintenance.

“Batteries are a mystery in a box,” Dell remarked. “The chemical electrolyte is only as good as its last discharge. They require vigilant monitoring and testing to ensure the chemistry inside of them is ready for the next discharge.” Dell’s staff performs monthly impedance tests on every battery, and the valve regulated lead-acid (VRLA) batteries are replaced every three to five years.

It’s interesting to note that over a 20-year design lifespan, cost savings from a hazmat-free flywheel versus a five-minute VRLA battery bank are in the range of $100,000 to $200,000 per flywheel deployed.

A Cleaner, Greener Future

Dell’s dedication to data protection as well as green technology is appreciated greatly by his boss, John Powers. “Since Ty joined the hospital, he has introduced many improvements to our IT infrastructure to harden our mechanical and electrical facilities,” Powers explained. “We thought we were doing well, but Ty showed us how a first-class data center is equipped.

“The flywheel technology is probably the project with the most pizzazz, as it is new in our medical center,” he continued. “It has worked well for us in reducing our reliance on environmentally unfriendly lead-acid batteries.”

While the data centers are still using batteries, Dell looks forward to completely eliminating them altogether in order to be more energy efficient, save costs and further decrease BIDMC’s carbon footprint.