Tips and tricks for mission critical facilities

Reliability is important on any project an engineer is charged with, but especially when it comes to mission critical facilities, failure is not an option.

By Consulting-Specifying Engineer July 19, 2012


John Collins
Global Segment Director, Data Centers
Eaton Corp.

Ronald Johanning, CME, DCEP-G, DCEP-HVAC, LEED AP, PE
Lead Engineer, Mission Critical Systems
Affiliated Engineers Inc.
Madison, Wis.

Gary Olson
Technical Counsel

Usman Tariq
Electrical Section Manager
HDR Architecture
Alexandria, Va.


What sorts of challenges do mission critical facilities pose that you don’t encounter on other projects?

John Collins: Mission critical facilities differ mainly in the aspect that most standard commercial projects are constructed and designed to purely meet the requirements of applicable building codes. Mission critical facilities, on the other hand, can have much more extensive customer expectations. In many cases, the expectations of mission critical facilities far exceed what building codes require due to desired levels of reliability or efficiency. The density of the electrical and mechanical systems is a great example of this. Due to reliability requirements, one mission critical building could have a utility feed equivalent to that of a small city. Being able to coordinate the electrical conduits and mechanical pipes and ducting in a small space is a challenge for any engineer.

Ronald Johanning: Reliability and failure mode operation are primary challenges that many other projects don’t typically require. An additional challenge is energy reduction without reducing reliability. Also, what do you do with all the waste heat produced by the IT systems? What opportunities does that create?

Gary Olson: The time pressures always seem to be an issue in mission critical facilities. Whether it’s completing the design, commissioning, or routine testing of a system, there’s always a pressure to get things done more quickly than is comfortable. The only thing worse for time pressure is trying to resolve an issue that has been uncovered. Because of time pressures, many times optimum solutions can’t be considered or tried.

Usman Tariq: One of the main challenges is the need for enhanced system reliability that spans across the entire system down to each component. This has interdisciplinary design implications. One of the challenges is to design a facility by anticipating all possible scenarios that can affect system performance. The cost of system downtime is potentially huge compared to the cost of preventing a failure. This introduces redundancy and complexity that is not usually encountered on other projects.

CSE: How have the needs and characteristics of mission critical facilities changed in recent years?

Johanning: Many smaller facilities that never considered their computers to be “mission critical” are finding they are developing a higher dependence on their own IT infrastructure. With more corporate websites and Web-based catalogs, server rooms are becoming full-scale data centers. They’re seeing more equipment being installed in the same spaces, so even though the equipment is more efficient, the electrical power and cooling needs are increasing beyond the capabilities of traditional power and cooling distribution systems. The other trend is to create more modular systems that can be installed more rapidly as the load grows. This approach has the potential to be less capital intensive and more energy efficient, but may require larger footprints.

Tariq: Data centers are the mainstay of mission critical facilities, and in recent years, there has been a great deal of attention given to the total cost of ownership (TCO) where the capital expenditure (CAPEX) and operational expenditure (OPEX) are scrutinized to optimize the TCO. This approach has been emphasized strongly during the recent economic downturn, and there is increasing demand on the engineering design aspect of the mission critical facility to reduce both CAPEX and OPEX by employing integrated design principles that lead to a more efficient and sustainable mission critical facility.

Collins: Customers simply weren’t as interested in efficiency 5 years ago as they are today. In the past, the primary priority for mission critical facilities was reliability, and the industry developed a science of studying and refining reliability techniques. Today, the needs of these facilities have evolved into making these reliable facilities more efficient and sustainable, and proof of this is available by taking a look at the number of highly efficient products the industry is focused on developing. You can also look at the focus of industry conferences today; it’s all about making these reliable data centers more efficient or sustainable.

Olson: There seems to be a lot more third-party “supervisors” than there were in the past, and I am not certain that they drive better reliability or lower cost. Modern systems are all complex no matter how simple they look on the surface, and many supposed experts are out there that simply don’t know enough about the hardware they’re evaluating to understand what performance parameters are critical to achieve in order to assure a cost-effective and reliable operating facility. For example, I have seen engineers who insist on running a 48-hour full load test on data center generator sets. Experts on the engine in particular will tell you that a “test” of that nature is actually detrimental to the life of the engine and has no proven ability to make the system as installed more reliable. So, the test is extremely expensive and provides no value. Look at it from this perspective: If you were selling drag race cars, would you test the car by running down the strip a dozen times before you decided it was good enough to use?

CSE: Describe any special software or tools you use in designing mission critical facilities.

Tariq: For electrical systems, calculations that validate the reliability of the equipment and system operation are very important throughout the design process of mission critical facilities. Power system analysis software such as SKM Power Tools and ETAP are crucial in this regard. They offer a suite of analysis tools that are widely employed to determine electrical power quality, load profiles of linear and nonlinear loads and their contributions to harmonics in the power system, overcurrent device coordination studies to isolate equipment damaging fault current incidents, and arc flash hazard analysis to ensure personnel safety.

Collins: We use building information modeling (BIM) tools increasingly often on projects to maximize efficiency of planning and construction phases. BIM allows us to offer models not only for standard designed products like panelboards and UPS systems, but also for custom engineered hardware, such as switchgear lineups. The 3-D modeling BIM provides is very useful for the placement of the equipment within a facility. For example, when designing conduit piping for electrical equipment in the ductwork, the software allows us to assign attributes to the equipment and its design, and automatically finds intersections and collisions, allowing us to work with the contractor to find solutions while working within building codes. We also use software that allows us to conduct circuit breaker coordination studies to maximize the reliability of the facility. The software allows us to simulate short circuits in order to properly time our breakers to prevent system failures and preventable outages.

Johanning: In addition to the traditional computational fluid dynamic (CFD) analysis software for modeling airflow on the data center floor, we do energy modeling of the entire facility. We run energy modeling software such as E-Quest to help optimize the cooling systems solutions for that particular climate. We’re designing rack layouts, rooms, and infrastructure systems in 3-D modeling software. We’re working with the contractors to import those models into the fabrication process. Then the models are used post-construction to conduct some of the commissioning and training exercises.

CSE: Please describe a recent project you’ve worked on—share problems and solutions.

Johanning: On a recent project we needed to relocate an existing data center while minimizing downtime, reusing electrical and mechanical cooling systems. As part of the project we installed as much of the supporting infrastructure as possible prior to the move. This allowed for the existing equipment to function as “plug-and-play” once it was available to be moved. We worked with the owner and contractors to establish a move sequence and used daily meetings leading up to the move to make sure no detail was missed. At project completion we were able to reduce the downtime to 6 hours.

Collins: A customer in an older building in a large metropolitan area came to us with a problem concerning available space. The wall where the low-voltage (LV) switchgear was to be located contained an I-beam that could not be moved and there were no other approved locations for the gear. Eaton Corp. proposed using a combination of front- and rear-access LV switchgear to satisfy the customer’s needs. Combining front- and rear-access is possible because the horizontal cross bus is located in the same position on both types of gear. The customer was satisfied because cable was not required to connect two separate pieces of gear together. This type of solution highlights where engineering ingenuity and package solutions can make the difference.

CSE: What factors do you need to take into account when designing building automation systems (BAS) for mission critical facilities?

Olson: This all boils down to understanding and implementing solutions that answer the questions: What do the operators/technicians at the facility need to know? What do they need to do in response to the knowledge? Where do you want them to be able to work from? Nearly every operating system in a facility today can supply endless volumes of data, but the key issue is how to make that data into useful, timely information. Vendors are often so busy trying to sell their own system that they forget the goals of the facility design and just provide the data.

Johanning: Data centers are becoming much more complex in their control strategies. There are multiple control algorithms that have to be integrated and managed. At the server level, the airflow quantity and temperatures need to match the needs of the servers to keep the internal fans at their optimal speeds. At the room level, using air-side economizers may require different control systems working together to mix outside air with conditioned air to stay within the temperature and humidity parameters. There are control loops of optimizing the operation of the fans, drycoolers, cooling towers, pumps, and chillers all depending on the outside environmental parameters and even time-of-day energy costs. Reliability and failure mode operation, and control loop speed also are important.

CSE: How does implementing BAS in an existing structure differ from designing controls for a new one?

Johanning: An existing structure is typically under operation while trying to either expand or upgrade the facility and infrastructure. Whether upgrading or expanding, modifying, testing, and commissioning of the control sequences are being done while still keeping the computer equipment operating within the required space conditions and parameters.

Olson: The most problematic issue is probably integrating existing systems and operating practices with the new equipment that is coming online.

CSE: What are some common problems you encounter when working on such systems?

Olson: The most frustrating thing is that there is so much potential achieving operational improvement, and so little will to use all the information available to achieve this goal. The overall system goals don’t seem to be thought through from a global perspective in most cases.

Johanning: Just installing another pump on a chilled water loop due to increased load requires a study of the impact on staging the existing pumps. At what point of the pump curves do you start the pumps? How do you ramp the existing pumps down to match and equalize the flow through each pump? Or what changes need to be made when a pump fails or a strainer gets plugged, etc.

CSE: Which codes/standards area proves to be most challenging in mission critical facilities?

Johanning: ASHRAE Standard 90.1 and U.S. Green Building Council’s LEED are causing a challenge in the ability to design redundant and maintainable cooling systems while meeting the requirements as mandated.

Collins: NFPA 70E: Electrical Safety in the Workplace is probably less well understood in the data center than in other power-intensive applications, such as oil refineries or paper mills. This standard becomes increasingly important as data centers move to 400 V electrical systems in order to increase electrical chain efficiency. Engineers working in racks supplied by 400 V must be aware of the increased hazards from arc flash compared to 120 V or even 208 V fed equipment. 70E introduces very specific OSHA-enforced requirements. Data center engineers and operators must be aware of these laws and standards. Further complicating the issue, updated versions of the codes are adding new safety requirements for data center installations, because their dense battery systems are significant arc flash hazards. In order to mitigate these hazards, you must first recognize the hazard in the first place, and OSHA holds the employer responsible for knowing the law and for training and certifying its employees. NEC Article 708.4 requires that a risk assessment of the electrical system be performed above and beyond the typical arc flash study required by NFPA 70E. This need for a written risk assessment that goes beyond just an arc flash study might be new for those responsible for mission critical facilities, but cannot be overlooked.

CSE: Describe a recent HVAC challenge you encountered, and how you worked to overcome it.

Johanning: We had a project in which the owner wanted to optimize all the available electrical power for the IT equipment, leaving very little to support the mechanical equipment to cool the space. Because this was on a campus setting, there was a large chilled water loop connected to a campus chiller plant reasonably close by. Understanding the parameters of the IT equipment, we were able to use closed containment in-row cooling equipment connected to an internal loop in the data center. The internal loop was connected to a heat exchanger that connected to the campus chilled water system and our own secondary pumps, which we put on a dedicated “mechanical” UPS system. We were able to calculate the volume of water in the loop. Upon failure of the chiller plant, we determined how long we could maintain the data center adjusting for the temperature rise of the water in the piping systems, eliminating the need for a separate chiller plant for the building.

CSE: What’s the most important factor to keep in mind when wrestling with codes/standards issues on mission critical facilities?

Tariq: Public and personnel safety is the most important factor when it comes to this question. Most of the codes and standards are written with the premise of public safety. This has profound implications in design of mission critical facilities where the very function of the building itself can have a great impact on public safety and well being.

Collins: NEC and NFPA 70E are both very important safety standards. Mission critical facilities place high levels of importance on reliability and energy efficiency, but safety should always be top of mind, too. For this reason, designers must be fully versed with the safety standards in order to intelligently incorporate them into the design or risk a heavy-handed retrofit to meet compliance. For example, a data center might require operators wearing PPE “moon suits” to work in an IT rack, while technologies such as arc flash reduction switching or zone selective interlocking could have been installed to possibly eliminate that need.

Johanning: The codes and standards are for the protection of the firefighters who need to respond to an incident and/or the individuals working in the space and the surrounding building areas. The requirements in the codes need to take precedence over the desires of the owner when their direction is in conflict with the codes.

CSE: What’s the one factor most commonly overlooked in electrical systems at mission critical facilities?

Tariq: I think that reliability is often confused with complexity. The most reliable system is often the simplest yet redundant. The use of a modular and scalable design approach often facilitates more reliability and mitigates human error. Sadly this approach is often overlooked when it comes to electrical systems, and systems that are complex to operate often lead to human errors.

Johanning: We see proper coordination between the mechanical and electrical systems in the UPS and battery rooms overlooked. The electrical systems may be designed for redundancy to allow for maintenance, but the cooling systems supporting the UPS equipment may not have the same level of redundancy. Another example may be that when upgrading the UPS systems, the mechanical systems might not get upgraded due to space constraints, thereby reducing the redundancy on the cooling systems, or the ventilation and exhaust airflows may not get increased to support the additional batteries installed.

Collins: As the industry strives to improve mission critical facility efficiency, it becomes even more important to fully understand the relationship between electrical safety, risk, and efficiency. For example, while removing transformers from PDUs in a 400 V system can increase efficiency by 1% to 3%, transformers limit the amount of energy that can be fed downstream. When you eliminate transformers, there is no more block for that energy, which could increase the potential for electrical fault at the IT load. When transformers are removed from the power path, the voltage available at the load is increased while simultaneously decreasing the source impedance. This can produce an exponential increase of arc flash energy. In the past, accidental shorts caused a semi-harmless spark and a pop, but now such a fault in a transformer-less system has the potential to cause an explosion capable of causing significant damage to equipment and injuries to employees. Therefore, it is of the highest importance that engineers fully understand associated risks and vendor-recommended grounding methods before implementing techniques to increase efficiency.

CSE: How has NEC Article 708 critical operations power systems (COPS) affected your work? Provide an example.

Olson: I work primarily on emergency power systems, so in my world every project is a COPS in the eyes of the designer/owner.

Johanning: We have not seen NEC Article 708 be a factor in our work to date. A data center in a major health or critical care facility, for example, is no more or less critical than the systems used to support the patients.

Collins: 708.5(B) requires that electrical equipment only be accessible to qualified personnel, but 70E describes the requirement of a “qualified” person being one who has attend arc flash training courses, and that his or her employer certifies that the person has received the training. As an example: Have the IT employees operating on the raised floor attended arc flash training? OSHA holds the employer responsible for providing the training and certifying that a particular employee is cleared to work on certain equipment. If those employees are plugging in electrical devices, especially 3-phase, or worse, 400 V 3-phase, 70E will require advanced arc flash mitigation techniques.

Tariq: NEC Article 708 presents a real challenge in trying to determine its applicability for a given mission critical facility. The term “mission critical” is open-ended in its meaning, whereby the mission could be important to the organization but not necessarily impact public safety. When the intended operation of the facility is clearly outlined and impacts public or national safety for facilities such as 911 call centers or emergency response control centers, etc., the applicability is obvious as outlined by Article 708. But often in the case of a data center, the added requirements of 708 can be onerous to the owner and present a conflict that must be resolved prior to the start of design. Some of the additional requirements pertaining to NEC 708 include:

  • Performance of risk assessment
  • Supply of an alternate power source for a continuous 72 hours at full load
  • Grounding compliance for all sources and circuits
  • Equipment protection against physical damage and accessibility for qualified persons only
  • Site consideration related to 100-year flood plain
  • Selective coordination of all overcurrent protective devices. 

CSE: Describe some recent challenges you encountered when commissioning the electrical system in a mission critical facility.

Collins: Ten 875 kVA modules were installed at a facility. Although the modules were fully tested at the factory and all tests were passed, when the UPS modules were going through site integration and commissioning, a loud, high-pitched noise was emanating from the battery disconnect while recharging the batteries. After several days of troubleshooting at the project site, the problem turned out to be an impedance issue between the battery string and UPS modules. This was a unique situation where site-specific variables such as length of wire between the battery disconnect and the module, the resistance of the battery string, and other factors played a role. This issue was not noted in the factory because when the UPS modules went through system test, they were tested with a string of sealed batteries and the site was a flooded cell application. The UPS control logic had the capability of being adjusted, which resolved the problem. This highlights the need for experienced service techs from the OEM vendor to be available during the commissioning process.

Johanning: We were commissioning the changes to the control schemes for switching between two utility sources and the standby generators. We had to develop flow charts for every possible scenario and include sequences to handle a “switch fails to operate” situation, or if a relay fails to pick up. We created failure mode tests that required us to create the failures in order to verify that the system would recognize the problem and automatically correct for it. All of the testing needed to be done while the data center was live, so we were constantly monitoring the operation of the mechanical systems that were being impacted when power was transferred between sources. We also had to have plans to back out of the test if something unforeseen occurred that could not be recovered from quickly by manual intervention.

CSE: How do you balance the need for reliable power in mission critical facilities with desire for efficiency and sustainability?

Collins: You should never rely on unproven technologies in mission critical facilities, but in order to find a balance between reliability, efficiency, and sustainability, it is important to have an open mind for new, innovative technologies. Implementing new efficiency techniques requires research and dialog with vendors and facility owners, but as seen in applications such as transformer-less UPSs, 400 V distribution in data halls and recent economizer designs, new efficiency methods can have a very positive impact on the efficiency and sustainability of mission critical facilities without threatening reliability.

Data center engineers tend to be very risk-adverse. But before defining the project balance of reliability and efficiency, it is important to really understand your client’s business objectives and risk tolerance. Companies are now weighing the relationship between electrical efficiency and the level of reliability their facility actually needs. If your customer is operating high-speed financial trading, a fraction of a second of downtime could cost millions. Conversely, if you’re hosting e-mail or social media Web pages, your data may not be as critical and you may not necessarily need the same level of reliability. Overall, it’s best to balance gains in efficiency against perceived risk; you must understand your facility’s tolerance for alternate approaches by balancing potential risk with reward.

Tariq: Reliable power is a nonnegotiable aspect of any mission critical facility. The need for redundancy to achieve higher levels of system availability and reliability can quickly turn into a less than efficient on-site power generation system with standby diesel generators. A blended approach of employing distributed power generation technologies such as fuel cells, micro turbines, and/or cogeneration systems can supplement the alternate power system requirements. Data centers are especially good candidates for co-generation because of a near constant load profile.

Johanning: We work with our clients to help them recognize that by segmenting their operation into different classes of resiliency and/or separate infrastructure systems, we can operate higher on the efficiency curves of, say, the UPS equipment. Some are seeing that allowing the systems to go to bypass instead of a redundant system can save them capital construction costs, reduce energy costs, and still keep the IT equipment in operation, which is the ultimate goal.

CSE: Describe a recent project in which you specified standby or emergency power in a mission critical facility. What challenges did you face, and how did you overcome them?

Johanning: We added two 1250 kW diesel generators to a campus facility that already had four units installed that were more than 10 years old. The control schemes on the generators’ units had changed over the years. The algorithms were significantly different—even the PLCs had different manufacturers. The output breakers going into the paralleling switchgear had different overcurrent trip units that reacted to the changing voltage and current flow differently. It certainly wasn’t just a “plug-and-play” addition.

Collins: Recently, while working on a newly constructed enterprise-class data center for a Fortune 100 company, we ran into an issue based around the installation of a transformer-less UPS system within a redundant electrical architecture. Following the data center’s commissioning, an investigation of reported problems showed a higher than desirable ground current circulating between the UPS system and the data hall. Our first assumption was that the transformer-less UPS was causing the problem.

So we first inspected the input wiring to the UPS, which was done correctly, three-wire to UPS and four-wire to bypass circuit. This design distributed 400 V to each IT rack so the incoming neutral came from the bypass source. We then ran through more testing and diagnostics until we put the UPS on bypass and turned it off. When we turned off the unit, we found that the ground currents were still present, meaning the problem was not resulting from the UPS. The issue was then determined to be caused by a combination of two circumstances. First, each conduit was grounded both at the UPS output and the RPP input, which created multiple ground loops. Compounding this problem, at the point where the magnetic fields from one phase induced currents on the conduits of the other phases, the conduits were installed too close together. The problem was solved by removing the conduits and re-running the system with more spacing. When installing transformerless systems, it is important to understand there should be no grounding issue. Installation manuals provide preferred methods, but the best resource to consult is always a vendor’s engineers.

Tariq: One of the big challenges is determining the size of the standby/emergency generators. Often that requires carefully profiling the intended load to achieve the optimum starting kVA requirements for the generator. Another challenge encountered in recent projects was the amount of required on-site fuel for the generators. Owners want to safeguard that their facilities will continue to operate in a natural disaster for a prolonged period of time. Instead of scaling the on-site fuel requirements beyond code requirements which have cost and environmental impact, the bi-fuel option of natural gas/diesel has been successfully implemented where the standby generators run on a mixture of diesel and natural gas, thereby extending the maximum run time for these generators in the event of a disaster.

CSE: What unique fire suppression systems have you specified or designed in mission critical facilities?

Johanning: We have actually seen a shift in where fire suppression is being applied. We are seeing less suppression on the data center floor and more applied to the infrastructure. The electrical and mechanical spaces all have air sampling smoke detection systems to provide early warning of any events. They are being protected by double-interlocked pre-action sprinkler systems. The standby generators are being enclosed in individual fire-rated compartments. Each space has its own flame detection system and CO2 or fire foam suppression system.

CSE: How have the costs and complexity of fire protection systems changed in recent years?

Collins: The advent of hot and cold aisle containment has added complexity to applying fire/life safety systems within the data hall. Installation of horizontal ceiling containment systems require a fire-activated feature to allow fire suppression systems access into the contained aisles. This feature should be tied to the building’s pre-activation system or BMS in order to trigger the opening mechanism of the “fire-activated ceiling.”

Johanning: The costs and complexity have stayed relatively the same or perhaps dropped over the years. More of our clients are investing in early warning smoke detection systems and not installing clean agent suppression systems. This has also reduced the impacts on the costs of walls, ceilings, doors, and security hardware.

CSE: How has NFPA 99-2012 affected your work in mission critical facilities?

Johanning: The server and IT communication rooms housing or transporting the patient records, medical images, etc., need to be protected at a higher level than previously. With the volumes of air being needed, standard smoke detectors may not be enough, and air sampling systems may be needed.

CSE: What are some important factors to consider when designing a fire and life safety system? What things often get overlooked?

Johanning: With the use of closed containment around the servers, the volume between the racks is no longer protected by the smoke detection systems and/or the fire sprinkler systems. You need to add smoke detection such as air sampling heads inside the containment areas, and also either put suppression heads inside the containment zones or add fire links to the containment barriers to allow the ceiling-mounted suppression systems to protect all of the electronic equipment.

CSE: How often is sustainability a concern with mission critical facilities?

Olson: I think almost all owners would like to have facilities that are “green,” but decisions around this area are very complex and difficult. They really are difficult for a layman to make, and many experts (with their own product to sell) are available to push unrealistic environmental goals on these owners. For example, the current push to move diesel and gas generator sets to Tier 4 performance seems like a great idea from the perspective of protecting the environment and having greater operational flexibility; but if it hurts reliability, has negligible environmental benefits, and costs a lot more, is it really something that you should do?

Johanning: Many of our clients are making energy issues a major topic of discussion, even on mission critical facilities. For private clients, energy efficiency directly impacts expenses and the bottom line. Institutional clients are also trying to meet larger goals and targets (reduce emissions, AIA 2030 challenge targets, etc.). Energy efficiency and PUE are also increasingly being used as marketing tools to attract clients in the private sector. We are seeing water use reduction and renewable energy being part of the discussions as well.

Collins: Sustainability is becoming a greater concern within mission critical facilities as more and more organizations realize that being sustainable doesn’t mean decreasing reliability. In fact, sustainable methods are enticing because of their ability to increase efficiency and lower operating costs. For example, when utilizing 400V in the facility with transformer-less UPSs, you’re not only practicing sustainability by using fewer natural resources in the UPS, but you’re also saving physical footprint and using power more efficiently.

CSE: With changing awareness of sustainability issues and increased number of products, has working on green structures become easier, or more challenging?

Johanning: While new techniques and technologies exist, there is still a challenge in convincing operators that robustness and flexibility will not be impacted by their application. There are also challenges of scale; successful energy strategies deployed at a massive facility do not always scale down well to a small data center, and it can be difficult to explain these issues of scale to a client who has become enamored with those strategies.

Collins: Overall, I would say working on green structures has become easier. Not only are there more solutions at a designer’s disposal, but due to the balances between cost, performance, efficiency and reliability, the whole process encourages more conversation with the building owner, which always makes a project easier. Additionally, because sustainability has been such an area of focus lately, USGBC is updating its requirements to better define the differences between commercial and mission critical buildings. As USGBC continues to update its requirements, it becomes easier for designers and engineers to properly implement sustainable techniques into mission critical facility design.

Olson: I think more challenging, due to the complexity of the decisions that need to be made and all the emotion behind many of them.

CSE: Have the challenges of the tough economy affected your work in mission critical facilities?

Johanning: The tough economy does not seem to have diminished client interest in energy efficiency. Energy efficiency impacts operating expenses after all, so facility owners are increasingly interested in what is available. PUE values have also become something of a marketing tool, and they allow mission critical facilities to set themselves apart.

Collins: Although capital lending was tight for some time, companies have been cautious about how their finances are spent since the Internet “bust” in the early 2000s. We have noticed that companies today have more options than ever before when it comes to re-engineering a mission critical facility to accommodate growth. There is a large drive to take advantage of new technologies such as virtualization and cloud computing to delay the need for a completely new facility. Today, due to economic restrictions and rising energy costs, when building new data centers, customers are more concerned with upfront costs, total cost of ownership, and maximizing the operating life of their facility than ever before. We are seeing a lot more customers build out their data centers with a modular approach, whether in prefabricated modules or simply by building out in phases as needed. When companies build out their data centers to keep pace with IT loads, they aren’t spending money upfront for unused equipment, and they aren’t wasting efficiency by running their data center at low loads, which in turn saves valuable capital.

CSE: How does the age of a structure affect your ability to retrofit or retro-commission features?

Collins: The older a structure is, the more likely the chance there could be significant constraints that need to be designed around. Constraints can be related to the building infrastructure and utility services or within the data center itself. External constraints could be no more available utility power for an expansion, or telecommunications bandwidth is limited. From a building infrastructure point of view there may be no space left on the roof or basement for additional generators or air handling equipment. There could also be constraints inside the data center, such as trying to rationalize a raised floor structure that was used as a cooling plenum and a cabling raceway. In some of these cases, the owner simply cannot achieve everything it hoped for. Building owners of sites that include anything that is sensitive to power anomalies—data centers, medical labs, industrial manufacturing—are finding that their problems relating to power quality are on the rise as the electrical infrastructure around them ages. If they are in a big city or even in a rural area, they have to recognize that their power-quality needs might be changing as the electrical infrastructure that they rely on continues to age. Older hospitals provide a great example: If these older buildings are being retrofitted with more modern CT-scan or MRI machines, hospital officials should order a site evaluation to make sure that their electrical systems are up to the task of supporting this newer equipment. You might have a data center moving into an old building that might have once been a warehouse or manufacturing facility. That can lead to potential or actual problems with an infrastructure not set up to handle the demands placed on it by a data center. A site audit will find those potential problems. The people doing the audit will also recommend any upgrades or procedural changes that can lessen these possible problems. There may be power-quality equipment needed to limit their exposure to power issues.

Olson: Speaking specifically of diesel emergency power systems, it is safe to say that if equipment is more than about 10 years old it will be nearly impossible to make it perform as well as more currently installed equipment (from an emissions perspective). Costs of the improved performance are also very high, making it a difficult decision for an owner in a world where retrofitting the equipment will not get the best performance, isn’t required, and is expensive.

CSE: What unique requirements do mission critical facilities’ HVAC systems have that you wouldn’t encounter on other structures?

Johanning: Mission critical facilities have a year-round cooling requirement that doesn’t allow for maintenance windows. The mechanical systems need to have modular subcomponents to allow for a wide range of load profiles. Typically when the systems are first commissioned, there may be very little load on the systems. Depending on the refrigerant, there may be a minimum level of load needed to keep the systems operational, or the mechanical systems could be cycling more often than desired. Then as the load grows or even cycles, you need to be able to add or modulate the pumps, drycoolers, chillers, etc., to match the load profiles.

CSE: How can automated features and remote system control benefit mission critical facilities clients?

Collins: Automated HVAC systems and remote system control primarily result in higher efficiencies. HVAC systems are the source of the most energy waste in a mission critical facility. Increasing automation allows for faster response times to stimulus in the system.

Johanning: Building automation systems benefit mission critical facilities by allowing the mechanical systems to react to changes within the system, maximizing energy efficiency, without human interaction. These systems also increase redundancy by automatically bringing on-line backup systems if primary systems fail.

CSE: What are the most important factors to consider when working on such a system?

Johanning: One of the most important considerations of a BAS is reliability. A BAS failure can result in a complete system shutdown. Control loop speed is also an important consideration, particularly when a system fails and a backup system needs to be started. Additionally, future flexibility and adaptability of building automated systems is an important consideration.