Carol Brzozowski 2016-03-01 12:33:38
While a reliable and efficient HVAC system is a priority in any commercial setting, it is significantly more so for critical settings such as data centers, hospitals, and labs. Data centers must balance capacity, energy efficiency, and management resources. Downtime can be costly: the mean cost for a data center outage is $505,502—according to a 2011 national study on data center downtime, cited in an Emerson white paper. Facilities are expected to deliver more computing capacity while increasing efficiency, eliminating downtime, and adapting to ongoing change. Emerson promotes seven best practices designed to employ cooling, power, and management technologies in the quest to improve overall data center performance: • Maximize the return temperature at the cooling units to improve capacity and efficiency. • Match cooling capacity and airflow with IT loads. • Utilize cooling designs that reduce energy consumption. • Select a power system to optimize availability and efficiency needs. • Design for flexibility using scalable architectures that minimize footprint. • Enable data center infrastructure management and monitoring to improve capacity, efficiency, and availability. Utilize local design and service expertise to extend equipment life, reduce costs, and address a data center’s unique challenges. Officials of Chandler, AZ, population 240,100, had set aside funds for 20 years to pay for a new municipal complex, a mixed-use facility to cater to community needs and serve as an example of design and sustainability, notes Marian Norris, Chandler’s assistant city manager. The SmithGroupJJR of Phoenix designed a 137,000- square-foot, five-building civic center with city offices, council chambers, a television studio, a printing center, a community art gallery, a courtyard, and a parking facility. Smith’s Jon Silhol, P.E., LEED AP, BD+C, selected a failsafe HVAC system to protect 17 electrical rooms and nine data closets located throughout the five buildings, while providing reliable climate control; meeting the project’s energy reduction goals; and offering the flexibility of placing inconspicuous fan coils in stairwells, hallways, bathrooms, elevators, and the TV studio control room. Chandler’s electrical rooms are loaded with transformers, emergency power switchgears, lighting and breaker panels, low-voltage panels, lighting control panels, and energy management control boards. The nine data closets contain Cisco network equipment, database servers, IP phone connectivity, and security equipment. Ongoing heat from the centers required a constant temperature of 75°F. City officials wanted the cooling system for the centers to be separate from the large Variable Air Volume mechanical systems selected to cool and heat the city hall offices, conference chambers, TV studio, print shop, art gallery, and common areas. For security purposes, the nerve center controls had to be separate from the unitary control systems for the five buildings. Having seen the Variable Refrigerant Flow (VRF) zoning system from Mitsubishi Electric’s US Cooling & Heating Division work successfully in other projects, Silhol chose it for use in Chandler. He selected the Y-Series technology for the mission-critical spaces and the R2-Series—a two-pipe heat recovery system that simultaneously cools and heats multiple zones—for the public spaces. With the VRF zoning system separate from the HVAC system powering the rest of the buildings, stand-by generators can still power the Y-Series units and one of the R2-Series units in catastrophic power failure, enabling them to continue cooling the nerve centers without having to power HVAC for the rest of the campus complex due to the system’s low electrical load requirement. Kris Kircher, Chandler’s facilities maintenance manager, notes that the Mitsubishi system—installed in 2010—has provided energy savings, “trouble-free performance,” and design flexibility. The installed VRF zoning equipment includes a variety of outdoor units, ceiling-concealed indoor units, wall-mounted indoor units, and controllers, including remote controllers. Kevin Miskewicz, senior manager of commercial marketing for Mitsubishi Electric US Cooling & Heating, points out that uninterrupted cooling in critical environments is derived from “the ability to have a piece of equipment that will go for 24 hours at a time and not have to shut down for a defrost cycle or something won’t happen to the unit in a certain amount of power surge.” This can be accomplished through ductless products with VRF, Miskewicz says. Flexibility is another benefit. “As you add server rooms, data closets, or electrical closets, it’s easy to add additional HVAC without having to find space for ductwork within a plenum,” he adds. In northern climate data centers, the ability to provide cooling when the ambient temperature dips below 0°F is important, says Miskewicz. Mitsubishi’s equipment and accessories enable cooling down to -20°F outdoor ambient, he says, alleviating the concern of cooling cutting out if the outdoor temperature is too cold. The inverter compressor—the cornerstone of VRF technology—is not only designed to provide lower electrical bills through its efficiency, but to ramp up and down to modulate depending on the conditioning requirements, Miskewicz says. Personalized comfort is another factor. “When you’re putting this into places where you have a server room that has to run at a certain temperature and there are adjacent offices off of that same outdoor unit, you can control the indoor unit to different temperatures,” says Miskewicz. Greg Day, applications engineer for LG Electronics, points out that in addition to the need for energy efficiency, critical facilities don’t have the “luxury” of time to fix broken equipment. “The unit may possibly have a couple of circuits, so you need to be able to work on the unit so that if one circuit goes down, you could still continue to operate on the other circuits while they are repairing the one that went down,” he adds. LG Electronics’ controls are designed to be a “plug-and-play-type system” with ease of maintenance, says Day. The company’s diagnostics tool for smart phones enables users to check the equipment for proper operation and identify potential problems. LG Electronics’ system is used at Trinity Medical Center in Pasco County, FL. The four-story, 90,000-square-foot Trinity Medical Office Building, located on the Medical Center of Trinity’s campus, houses a women’s diagnostic center, an outpatient surgery center, physician offices, and a pharmacy. It had been constructed on spec with only the shell and individual floors and space not yet determined or sized. That left room for incoming medical tenants to design their own space. It also required developers to provide an HVAC system that would not disrupt existing tenants when adding new air conditioning to newly configured spaces. Developer Mark Gerenger recommended an HVAC system with VRF technology from LG’s Multi V line to fulfill the installation goals of a quiet, energy-efficient system that could heat or cool across separate zones. An LG VRF Multi V system was considered ideal for developing a commercial office building, as it provides heating and cooling to just the leased spaces, using only the amount of energy needed for the occupied building. With the system only cooling and heating occupied-leased spaces, energy costs decreased from $14,000 to $5,000 monthly. Additionally, there was minimal disruption to existing tenants as the additional spaces were completed. “Over several years, this system does pay back, and pays money going forward,” says Gerenger. “It’s all about economics and protecting doctors with the least amount of expenses on the building.” Although critical facilities require reliable HVAC equipment, even the most reliable break down from lack of maintenance or during weather events such as lightning strikes, necessitating support and service, points out Jackson Willis, P.E., Mid-Atlantic sales engineer for Fujitsu General America. Informed system design is “majorly important,” says Willis. “Facilities can greatly benefit from equipment redundancy in highly critical spaces. By installing a number of smaller distributed VRF systems instead of a large central plant, businesses can be assured that the heating and cooling of their facility does not rely on any single points of failure.” VRF provides the flexibility to install multiple systems in the same space for redundancy while maintaining efficiency as they operate at variable capacity or in a lead/lag arrangement, notes Willis. Fujitsu Airstage VRF equipment is designed to provide high-energy efficiency for critical facilities, especially when the facility has a variable heating or cooling load, notes Willis. “The key is to design systems that take advantage of the variable-speed inverter compressor and the ability to transfer heat between different spaces using heat recovery,” he adds. “For example, critical spaces can be combined onto a system with comfort-cooling spaces for improved efficiency while still providing redundancy in the critical areas.” One example is the Grifols Manufacturing Facility in Clayton, NC. Grifols is a Spanish pharmaceutical and chemical company known for its plasma-derived medicine. Its newest 155,000-square-foot manufacturing facility opened in June 2014. An operations center monitors the entire campus’ processes and safety and encompasses a master control room, server room, small office, and break room. The entire facility is on backup generators to ensure product quality, equipment operation, and employee safety as the center must remain operational at all times. The most important requirement of the HVAC system was to provide complete redundancy in the control room and the server room. Additionally, the high internal load necessitates year-round cooling. Ductwork was not possible because piping had to be run through the manufacturing facility to the nearest outside area and the control room had low ceilings. They chose Fujitsu Airstage V-II outdoor units, which cool down to 5°F ambient, for the ability to provide the required year-round cooling in the control room and server room. The equipment can be placed onto existing generators. Additionally, the units’ inverter compressor and variable capacity ensure the system can meet the server room’s cooling demand without overcooling other spaces. Raleigh Heating & Air designed and installed the Airstage system, splitting the cooling load onto two 6-ton systems. The control room and server room both have two indoor units, with each indoor unit connected to a different outdoor unit, ensuring system redundancy in critical spaces. Wall-mounted units were installed throughout due to the lack of available ceiling space. John Peter Valiulis, vice president of Emerson Network Power, notes that today’s technology enables critical facilities to achieve a higher level of reliability and efficiency, “so there’s no trade-off like there used to be.” The SmartDesign from Emerson Network Power uses a perimeter/room-based approach to deliver efficiency, availability, capacity, and control. For example, in a 1,100-kW Tier 4-E with 165-kW high-efficiency refrigerant economization, the approach is designed to generate a PUE of 1.19, reduce rack count by 43%, lower energy bills by $170,000 a year, save 52% in OPEX and 14% in CAPEX, leverage a density of 12 kW a rack, improve TCO while maintaining availability, obtain more than 97% UPS efficiency while using Eco-Mode, and improve flexibility and scalability. Economization technology is a driving factor. Instead of bringing in outside air or using water to economize, Emerson’s technology pumps refrigerant around to the outside air where it is cooled and brought back in to cool the interior space. “An end user can economize and set the compressor off up to 95% of the year, get enormous energy savings, and not have to use any water at all,” says Valiulis. “There are no worries of having to filter outside air or maintain dampers.” Emerson’s technology is saving a billion gallons of water a year, he adds. As drought conditions intensify over longer periods of time, states such as California have approved the use of cooling technology using chemical refrigerant instead of water. Controls augment redundancy and reliability, says Valiulis. “There is control at the unit level and supervisory level controls, which are controlling a site or multiple units. With the unit level control, most downtime or problems in a data center are due to human error. New controls are easier to use and significantly reduce human error.” The supervisory level coordinates the unit activity and also provides a high level of efficiency so all of the units can move up and down together to preserve energy, says Valiulis. Emerson offers data centers the Liebert CRV, self-contained, row-based data center cooling of 19.6 to 40 kW. The unit is designed for cooling server rack cabinets in small and medium data centers and feature iCOM controls and a digital scroll compressor for high reliability and optimized data center heat management. Some trends Valiulis notes going forward is the use of systems that will run even more efficiently and be self-correcting with minimal human interaction or troubleshooting that can be done remotely through electronic devices, he says. Mick Schwedler, applications engineering manager for Trane, notes that a reliable HVAC system begins with “simple and reliable pieces that have been designed to be able to respond to changing conditions, that have robust means to adapt to those changing conditions, and have a wide operating map that can operate under many different conditions.” In order for data centers and other mission-critical facilities to be kept up-and-running, the equipment has to be put together in systems that are properly designed and properly sequenced as well as able to respond to issues that occur during its operation, Schwedler points out. One factor to consider when there are system changes, is the control logic for that piece of equipment designed to quickly adapt to those changes and how adaptable is it to significant changes, says Schwedler. Trane offers chiller control systems that control the entire chilled water plant and the air handling system can be used to keep the system operating and up for data centers and other critical operations, he says. Of note is Trane’s EarthWise CenTraVac chiller, which uses a direct drive compressor—the motor is directly coupled to the centrifugal compressor, says Schwedler. It has one moving part with two bearings. Trane’s compressor uses multiple stages designed to operate through a broader temperature difference for a data center installation, he adds. Part of the driving factor of the compressor’s efficiency is its economizer stage, which utilizes a low-pressure refrigerant with a documented refrigerant emissions rate of 0.5% annually. “Rather than refrigerant leaking out of the system, that air can be sensed if it leaks into the system by a purge unit,” says Schwedler. “The purge unit operates automatically to get rid of the air from the system to keep [it] operating efficiently.” The CenTraVac auto-regeneration cycle reclaims lost refrigerant and returns it to the chiller. The Trane CenTraVac has Environmental Product Declaration (EPD) registration, following the requirements of ISO 14025. Trane offers chillers that use bearings with or without oil. When oil is used in the bearings, it enables an analysis to help forecast potential problems with the system, Schwedler points out. Using refrigerant for lubricant on the bearings and the bearing types Trane uses is designed for a longer equipment lifespan compared to electronic bearings. That eliminates down time and aligns with the company’s design choices to “keep it simple, efficient, reliable, and robust,” says Schwedler. The CenTraVac chiller operates at a 0.45-kW-per-ton efficiency at full-load conditions and Integrated Part Load Value as low as 0.305 kW per ton at Air-Conditioning, Heating & Refrigeration Institute ratings. The chiller sustains operating temperatures of down to 34°F without the use of anti-freeze. The Simplex operates at 120 to 1,300 tons at 50 Hz and 120 to 2,000 tons at 60 Hz. For larger cooling capacity, there is the Duplex, which operates at 1,200 to 2,500 tons at 50 Hz and 1,400 to 3,950 tons at 60 Hz. Uninterruptible power can be fed to the controller and the purge to enable continuance of critical monitoring functions despite main power loss. Options include Adaptive Frequency drives, heat recovery, free cooling, thermal energy/ice storage, and high-efficiency tubing. BE Carol Brzozowski specializes in topics related to energy and technology.
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