Critical power: hospitals and data centers

Electrical engineers must consider many factors when designing backup, standby, and emergency power systems. Specific requirements for emergency power vary based on the mission critical facility, such as a hospital or data center.

03/19/2018


Learning objectives:

  • Learn about system availability and importance of redundancy for building reliable mission critical facilities.

  • Compare the electrical and power needs of hospitals and data centers.


Safety, maintainability, code compliance, and economics play crucial roles in determining the topology of an emergency system for a critical facility. Specific requirements for emergency power vary based on the mission critical facility. Hospitals and data centers have the one of the highest power availability requirements in the industry to ensure minimal to no interruption of service in critical areas.

Figure 1: A hospital served by an N+2 generator plant has two critical busway feeders to the hospital wing where the operating rooms are located. The design allows for maintenance while continuing to provide power. Courtesy: Casey Dunn Photography

Availably is the ability of an item—under combined aspects of its reliability, maintainability, and maintenance support—to perform its required function at a stated instant of time or over a stated period of time. Reliability is the ability of a component or system to perform required functions under stated conditions for a stated period of time.

As building typologies, hospitals and data centers are inherently distinct, one being largely unoccupied and the other providing life-safety services to inpatients. The electrical systems of hospitals appear to be trending more toward the robust designs found in data centers.

Data centers house computer equipment used to process, analyze, and store electronic data. Many businesses today rely on services performed within data centers to maintain their own functionality, including day-to-day IT/communication infrastructure. The need for electronic data is growing while the need to process or access this data at all times also is increasing. Keeping these buildings available 7x24 is a necessity, not a luxury.

Hospitals, on the other hand, are occupied, public buildings that provide critical care, and depending on the type provided, these facilities must be available 7x24. While code requirements compel hospitals to have emergency, standby generators primarily for life-safety and essential reasons, they are not as stringent as the standard practices for redundancy in data centers.

Maintaining demand for power

Demand for uninterruptable reliable power in data centers is now the norm. As most of these facilities are not regulated by the government, their electrical system topology is flexible and innovative. Guidelines, such as Uptime Institute and Telecommunications Industry Association (TIA), are used industrywide.

Hospitals are increasingly requiring redundancy in their electrical systems, especially as the use of computers and electronic equipment to save lives and improve the patient experience has become integrated into critical care. As technology evolves, the number and complexities of hospital systems requiring uninterruptable power steadily increases.

This diagram illustrates electrical system configuration at a data center for a 911-call center. Critical loads are connected to an uninterruptible power supply (UPS) and have flexible environmental requirements where generators didn’t have to start within

Many hospitals are growing their budgets to include support of electrical reliability and availability of their systems. Examples of hospital equipment requiring continuous power include operating room machinery, life support, nurse calls, blood storage, fire alarm, mass notification, etc.

Comparing hospitals, data centers

Hospitals and data centers have different type of requirements because they are serving distinct types of loads. The difference in their requirements influence their electrical topologies as described below:

  • Data centers predominately use dual-corded equipment for critical loads, while hospitals rely on single-corded systems.

  • Data centers use centralized uninterruptable power supply (UPS) systems for critical loads, while hospitals have preferred to use internal equipment UPS to allow equipment to be transferred from room to room. We are starting to see the uses of centralized UPS systems, especially for operating room lighting applications. Mini-data centers also are part of hospital medical record systems that employ centralized UPS systems.

  • Data centers are often required to operate 7x24 without critical load scheduled outages. Critical load is all electrical loads required to perform the intended task. Most hospitals occasionally can be shut down for repairs or maintenance, but this trend is changing because electrical system uptime is increasingly considered an expected level of service in hospitals.

  • Hospital start-up sequences for larger generator plants are usually faster due to critical and life-safety time requirements.

  • Hospital breaker coordination is required by code, while the data center industry considers it good practice. Data centers frequently have had better and more up-to-date documentation on breaker coordination, but more hospitals are now keeping track of this information, too.

  • Hospitals typically use automatic transfer switches to separate different branches; data centers tend to use electrically operated breakers in a “main-tie-tie-main” configuration.

Figure 3: In hospitals, power supply devices serving the same purpose are strategically connected to the electrical system to allow one system or device to be turned off for maintenance while the other system is in use. Courtesy: PageNext-generation electrical infrastructures

The 7x24 electrical distribution systems are becoming essential to the day-to-day operations of all types of buildings. The more solutions engineers design, the greater the demand—and need—grows for electrical systems to power these solutions, especially in data centers and hospitals. The current generation of electrical infrastructures has created a high level of expectations among owners and users, who have an increasingly harder time tolerating gaps in high-quality service for these types of buildings.

Reliability and availability for electrical distribution systems will remain on the front line for electrical designers, and these requirements are here to stay. These qualities not only determine the service that a building provides, but also have a great impact on the safety of those who operate these facilities. Additionally, increasing focus on environmental impact and energy consumption will continue to challenge designers during their innovation of new ways to provide a high level of reliability and availability. In the future, next-generation hospital electrical distribution systems will more closely resemble those of data centers.


Freddy Padilla is a principal and the MEP engineering director at Page. He is a member of the Consulting-Specifying Engineer editorial advisory board.



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