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Vol. 56, Number 11
DECEMBER 2019
20 | Transformer selection and sizing Selecting and sizing electrical distribution transformers is fundamental for electrical designers and engineers
26 | How to correctly size a transformer
8
ON THE COVER: Froedtert & Medical College of Wisconsin Center for Advanced Care maximizes efficiency and expandability while simultaneously supporting cutting-edge medicine. Courtesy: Steinkamp Photography
NEWS &BUSINESS 5 | Viewpoint
Codes and standards keep the wheels turning
7 | Research
Lighting in office buildings
BUILDING SOLUTIONS 8 | Advances in building automation
Building automation has seen a tremendous amount of advancement and is changing not only how buildings are managed and operated, but also how they interact with the grid
14 | Commissioning lighting occupancy sensors
Installing lighting occupancy sensors and commissioning the devices have many benefits, including reducing operational and maintenance costs
Engineers must make informed decisions regarding the proper transformer sizing selection, electrical and mechanical requirements and impacts to the electrical system under different operating and loading conditions
36 | Analyzing NEC 2017 changes
Several changes to the 2017 edition of NFPA 70: National Electrical Code should be noted
42 | Case study: Energy-efficient clean rooms
Designers formulated several energy-saving strategies that can be implemented into the HVAC system design of a pharmaceutical-grade clean room suite
ENGINEERING INSIGHTS 51 | New Products for Engineers 52 | Lab, research facility design
Learn tips on how to design labs and research facilities — some of the most high-tech buildings around
CONSULTING-SPECIFYING ENGINEER (ISSN 0892-5046, Vol. 56, No. 11, GST #123397457) is published 11x per year, monthly except in February, by CFE Media, LLC, 3010 Highland Parkway, Suite #325 Downers Grove, IL 60515. Jim Langhenry, Group Publisher/Co-Founder; Steve Rourke CEO/COO/Co-Founder. CONSULTING-SPECIFYING ENGINEER copyright 2019 by CFE Media, LLC. All rights reserved. CONSULTING-SPECIFYING ENGINEER is a registered trademark of CFE Media, LLC used under license. Periodicals postage paid at Downers Grove, IL 60515 and additional mailing offices. Circulation records are maintained at CFE Media, LLC, 3010 Highland Parkway, Suite #325 Downers Grove, IL 60515. Telephone: 630-571-4070. E-mail: customerservice@cfemedia.com. Postmaster: send address changes to CONSULTING-SPECIFYING ENGINEER, 3010 Highland Parkway, Suite #325 Downers Grove, IL 60515. Publications Mail Agreement No. 40685520. Return undeliverable Canadian addresses to: 3010 Highland Parkway, Suite #325 Downers Grove, IL 60515. Email: customerservice@cfemedia.com. Rates for nonqualified subscriptions, including all issues: USA, $165/yr; Canada, $200/yr (includes 7% GST, GST#123397457); Mexico, $200/yr; International air delivery $350/yr. Except for special issues where price changes are indicated, single copies are available for $30 US and $35 foreign. Please address all subscription mail to CONSULTING-SPECIFYING ENGINEER, 3010 Highland Parkway, Suite #325 Downers Grove, IL 60515. Printed in the USA. CFE Media, LLC does not assume and hereby disclaims any liability to any person for any loss or damage caused by errors or omissions in the material contained herein, regardless of whether such errors result from negligence, accident or any other cause whatsoever.
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NEWS&BUSINESS VIEWPOINT
CONTENT SPECIALISTS/EDITORIAL AMARA ROZGUS, Editor-in-Chief/Content Strategy Leader 630-571-4070 x2211, ARozgus@CFEMedia.com AMANDA PELLICCIONE, Director of Research APelliccione@CFEMedia.com MICHAEL SMITH, Creative Director MSmith@CFEmedia.com McKENZIE BURNS, Production & Marketing Coordinator 630-571-4070 x2231, MBurns@CFEMedia.com
EDITORIAL ADVISORY BOARD JERRY BAUERS, PE, Vice President, NV5, Kansas City, Mo. MICHAEL CHOW, PE, CEM, CxA, LEED AP BD+C, Principal, Metro CD Engineering LLC, Columbus, Ohio TOM DIVINE, PE, Senior Electrical Engineer, Johnston, LLC, Houston CORY DUGGIN, PE, LEED AP BD+C, BEMP, Energy Modeling Wizard, TLC Engineering Solutions, Brentwood, Tenn. ROBERT J. GARRA JR., PE, CDT, Vice President, Electrical Engineer, CannonDesign, Grand Island, N.Y. JASON GERKE, PE, LEED AP BD+C, Cx A, Mechanical Engineer, GRAEF, Milwaukee JOSHUA D. GREENE, PE, Associate Principal, Simpson Gumpertz & Heger, Waltham, Mass. RAYMOND GRILL, PE, FSFPE, Principal, Arup, Washington, D.C. DANNA JENSEN, PE, LEED AP BD+C, Principal, Certus, Carrollton, Texas WILLIAM KOFFEL, PE, FSFPE, President, Koffel Associates Inc., Columbia, Md. WILLIAM KOSIK, PE, CEM, LEED AP BD+C, BEMP, Senior Energy Engineer, Oak Park Ill. KENNETH KUTSMEDA, PE, LEED AP, Engineering Manager, Jacobs, Philadelphia SARA LAPPANO, PE, LC, LEED AP, Managing Principal, Integral Group, Washington, D.C. JULIANNE LAUE, PE, LEED AP BD+C, BEMP, Director of Building Performance, Mortenson, Minneapolis DAVID LOWREY, Chief Fire Marshal, Boulder (Colo.) Fire Rescue JASON MAJERUS, PE, CEM, LEED AP, Principal, DLR Group, Cleveland BRIAN MARTIN, PE, Senior Electrical Technologist, Jacobs, Portland, Ore. DWAYNE G. MILLER, PE, RCDD, AEE CPQ, CEO and Co-Founder, UNIFI Labs Inc., Las Vegas FREDDY PADILLA, PE, ATD, Principal/Senior Electrical Engineer, Page, Austin, Texas GREGORY QUINN, PE, NCEES, LEED AP, Principal, Health Care Market Leader, Affiliated Engineers Inc., Madison, Wis. BRIAN A. RENER, PE, LEED AP, Principal, Electrical Discipline Leader, SmithGroup, Chicago SUNONDO ROY, PE, LEED AP BD+C, Vice President, CCJM Engineers Ltd., Chicago RANDY SCHRECENGOST, PE, CEM, Austin Operations Group Manager/Senior Mechanical Engineer, Stanley Consultants, Austin, Texas MATT SHORT, PE, Project Manager/Mechanical Engineer, Smith Seckman Reid, Houston SAAHIL TUMBER, PE, HBDP, LEED AP, Senior Associate, Environmental Systems Design, Chicago MARIO VECCHIARELLO, PE, CEM, GBE, Senior Vice President, CDM Smith Inc., Boston RICHARD VEDVIK, PE, Senior Electrical Engineer and Acoustics Engineer, IMEG Corp., Rock Island, Ill.
Codes and standards keep the wheels turning Unlike a hamster wheel, on which the rodent goes nowhere, codes and standards can take engineers anywhere and everywhere
T
he most complex part about reaching the Consulting-Specifying Engineer audience is that the brand has to be all things to all people. Some audience members want only fire and life safety topics. Others need all things energy efficiency. Some managers want a broad swath of topics to help educate their younger team members. And much like any other medium, anything goes. Print magazines are in high demand. Webcasts and education are a necessity for most professionals. Bite-sized lists of topical articles and resources, like in a newsletter, are easily digested. What, then, is really the “best” content? What’s most important for a professional with 35 years of experience? What does someone with 10 years in the consulting engineering world need to know? The answer is, “It depends.” The No. 1 topic requested in all Consulting-Specifying Engineer research studies is codes and standards. Whether we’ve surveyed lighting designers, automation and controls experts or mechanical engineers, the answer never changes. Codes, standards, guidelines and regulations truly keep the wheels of engineering running. Without these playbooks for how to design or
specify a system, the building market would be flooded with haphazard designs, inefficient systems and unsafe products. And the top articles that have been published by Consulting-Specifying Engineer this year include mostly
‘
Codes, standards, guidelines and regulations truly keep the
Amara Rozgus, Editor-in-Chief
codes- or standards-related articles. Best practices, insights on new code versions or “how to specify” with a particular code or standard flooded the top 10 articles of 2019. The associations that function as code-governing bodies have their work cut out for them. Codes typically are on a three-year cycle, with several revisions, comment periods and committee discussions held during that time. These organizations should be lauded for keeping up-to-date versions available to engineers, authorities having jurisdiction and others allied with the building and engineering field. If you’ve been trying to figure out how to jump-start your career for 2020, get off the hamster wheel. Consider gaining a deeper understanding of codes and standards, and how they affect building design and construction. cse
MIKE WALTERS, PE, LEED AP, Campus Energy Market Leader, MEP Associates, Verona, Wis. APRIL WOODS, PE, LEED AP BD+C, Vice President, WSP USA, Orlando, Fla. JOHN YOON, PE, LEED AP ID+C, Lead Electrical Engineer, McGuire Engineers Inc., Chicago
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wheels of engineering running.
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2020 You drive your accomplishments and dictate your career success, and those achievements deserve to be recognized. Stand among the past 480 Consulting-Specifying Engineer 40 Under 40 winners who have made their accomplishments known. To qualify to be a 40 Under 40 winner, nominees must work in the building community, be 40 years of age or younger (as of May 1, 2020) and be nominated by a supervisor, academic advisor, peer, mentor, public relations professional, project leader or other person directly involved in their career progress. Note: Individuals whose work is related exclusively to single-family housing, structural engineering or civil engineering are NOT eligible. 40 UNDER 40 PROGRAM AWARDEES WILL: • Be highlighted in major media arenas as a Consulting-Specifying Engineer 40 Under 40 winner. • Be offered networking opportunities with other 40 Under 40 awardees. • Increase the exposure of their company by highlighting projects the young engineer has worked on. • Improve the company’s recruitment efforts by showcasing young employees.
NOMINATIONS DUE JANUARY 24, 2020 SUPPORTING MATERIALS DUE FEBRUARY 7, 2020
Nominate a colleague who is 40 years of age or younger by going to:
www.csemag.com/40under40
Performance HVAC, controls specifications Never
Don't know
1%
5%
NEWS&BUSINESS
RESEARCH
Always
11% 39%
44% Rarely
Frequently
Figure 1: Eighty-three percent of firms always or frequently write performance HVAC and controls specifications, which restricts text to stating the performance achievement required. Source: ConsultingSpecifying Engineer 2019 HVAC & Building Automation Systems Study
$131,000:
Average total dollar amount of building automation systems specified annually for new and existing buildings. Source: Consulting-Specifying Engineer 2019 Lighting & Lighting Controls Study
64%
of engineers report building owners and contractors (electrical, HVAC, etc.) as having significant impact on fire and life safety design projects. Source: ConsultingSpecifying Engineer 2019 Fire & Life Safety Study
42%
of engineers are responsible for selecting the brand of electrical or power systems included in specifications. Source: Consulting-Specifying Engineer 2019 Electrical & Power Study
More research Consulting-Specifying Engineer covers several research topics each year. All reports are available at www.csemag.com/research.
www.csemag.com
LIGHTING & LIGHTING CONTROLS STUDY
Lighting in office buildings
T
wo-thirds of engineers specify, design or make product selections for office buildings, according to the Consulting-Specifying Engineer 2019 Lighting & Lighting Controls Study — and 82% of these engineers are responsible for determining the requirements/ writing the lighting specifications for these projects. Below are five lighting and lighting controls findings as they relate to office building projects: 1. Design value: Engineering firms are specifying $708,900 annually, on average, in lighting and lighting control products for new and existing office buildings, with 31% specifying more than $1 million. 2. Specifications: For office buildings, performance lighting specifications are written 73% of the time, followed by prescriptive (70%) and open: alternate or substitute (67%).
3. Design coordination: When specifying lighting for office buildings, the architect has the most impact on design (91%), followed by contractors (63%) and the electrical engineer (58%). 4. Challenges: Inadequate budgets (62%), the speed of project delivery (49%) and frequent changes to codes, regulations and standards (43%) are the top challenges engineers face when specifying lighting for office buildings. 5. Design factors: When comparing lighting products for office buildings, engineers heavily weigh product quality, energy efficiency, the manufacturer’s reputation and service support offerings. cse
M More RESEARCH
Access the full 2019 Lighting & Lighting Controls Study at www.csemag.com/ research. Amanda Pelliccione is the research director at CFE Media.
Top 10 lighting technologies specified in office buildings LED
92%
Occupancy sensor
92% 71%
Multilevel lighting or dimming
65%
Daylight harvesting
52%
Building automation systems (BAS) Scheduling
46% 45%
Addressable lighting Plug-load controls
38%
T5, T8 or T12 (any size)
35%
Demand-response lighting
34%
Figure 2: LEDs, occupancy sensors, multilevel lighting or dimming and daylight harvesting are the most common types of lights, lighting systems or controls currently being specified into office buildings. Source: Consulting-Specifying Engineer consulting-specifying engineer
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By Julianne Laue, PE, LEED AP BD+C, BEMP, BEAP, Mortenson, Minneapolis
Advances in building automation Building automation has seen a tremendous amount of advancement and is changing not only how buildings are managed and operated, but also how they interact with the grid
T
he original functionality of a building automation system was to keep a building climate within a specified range. With advances in technology, the BAS can now control temperature, control building pressurization, regulate humidity, optimize lighting, monitor performance, indicate device failures, provide access control, control shading devices and provide alarms in the event of malfunction. As technology advances, the BAS of old is now more agile and intelligent and capable of managing business success factors beyond energy consumption and • Understand the core function and basics of building comfort. automation systems. Buildings built in 2020 and • Be able to discuss advanced beyond will be built to building automation for energy efficiency codes that are up to 50% more effiand occupant health and cient than when ASHRAE 90.1: wellness. Energy Standard for Buildings • Appreciate how modern BAS are Except Low-Rise Residential Buildbusiness integrators. ings was first issued in 1975; they • Recognize the relationship will operate with computing perbetween smart buildings and formance that has increased 1 trilsmart grids. lionfold since 1956 and they will have technology that can virtually ensure the No. 1 complaint of building occupants (comfort) will be nonexistent. New buildings will be smart, connected, healthy and secure. Smart buildings are the way of the future and without modern BAS, this would not be feasible. Modern advances in building automation, digital technology and the “internet of things” have made it easy for new and remodeled buildings to be smart, energy efficient and healthy. It can be difficult for new and existing buildings to capitalize on these opportunities as BAS technology is changing rapidly and requires today’s engineers to understand the basic capabilities and functions of a BAS,
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OBJECTIVES
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consulting-specifying engineer
become technically savvy and incorporate data analytics into BAS designs and think beyond buildings to harness possibilities from utility providers.
Functionality upgrades
In the early 1900s, a BAS was simple. If you scour the internet looking for the beginning of BAS, you’ll find some great stories of the potential first BAS installations. All in all, the basics are as simple as a lightbulb connected to a thermostat. The lightbulb would turn on when the temperature registered below a setpoint, signaling workers to shovel more coal into a boiler. The original intent was to make life easier for the person operating the building. Around the 1960s, engineers progressed to pneumatic controls and in the 21st century to direct digital and wireless controls. Energy codes, sustainability rating systems and sustainability commitments have increased the demand for better BAS. Even with need for better systems, the items a BAS controls have largely remained unchanged. The core function of the BAS has typically been to control heating, ventilation and air conditioning equipment to maintain temperature control in buildings. These traditional systems control heating and cooling plants, air side systems for fresh air delivery and space temperature and humidity. Many BAS also can integrate with lighting controls, security and fire alarm systems, but many times these systems remain separate. What is controlled and how it is controlled can largely depend on when the systems were installed. Older buildings are limited by the technology and design drivers of the age they were built. Depending on when they were built, the building may have had control only at the equipment level. In these buildings, there are controls available that only control individual pieces of equipment and they may not be able to be seen by a centralized www.csemag.com
Figure 1: Froedtert & Medical College of Wisconsin Center for Advanced Care maximizes efficiency and expandability while simultaneously supporting cutting-edge medicine. Having integrated and energy-efficient buildings are a priority. Building automation advancements and integrations were extensively studied and incorporated within the facilities to provide healthy and energy-efficient spaces. Courtesy: Steinkamp Photography
control system or BAS. Additionally, these buildings may have pneumatic or analog controls, which lack the ability to provide tight control of comfort conditions. As older buildings continue to age, their functionality may be unable to meet the needs of a tenant and they can develop problems that are difficult to solve due to difficulty in acquiring parts. If an older building does have some level of automation, it may still have a significant problem in the fact that an older BAS operates off proprietary protocols making modifications, expansion or integration into a newer system difficult. In buildings built during the late 1980s and beyond, the improvements in central computing gave way to distributed digital computers (essentially process controllers) located on equipment (equipment controllers), allowing communication back to a central system. By 1995, the central controller began to communicate with the internet, allowing for remote or web-based control of systems. Also during this period, proprietary protocols evolved to open protocols such as BACnet. The incorporation of BACnet into BAS allows for the open communication between multiple pieces of equipment on a centralized or head end system. By allowing all the communication between individual pieces of equipment, temperature control is improved, energy efficiency is increased, operating and maintenance costs are lowered and indoor air quality is improved. At a minimum, the controls are
web-based, have graphics that are easy for the user to understand and allow for data analytics and fault detection.
Current BAS options With the increase in computing performance, advancements in technology and increased demand for energy-efficient and healthy buildings, most new buildings now employ state-of-the-art BAS technologies and leverage analytics platforms that ride on top of the equipment and BAS. These systems can perform complex analytics by integrating multiple automation systems, metering systems,
Figure 2: This shows the business case for integrated, smart solutions. Smart grids connected to smart buildings to increase sales, reduce costs and meet sustainability goals. Courtesy: Mortenson www.csemag.com
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BUILDING SOLUTIONS
AUTOMATION AND CONTROLS
lighting controls, process controls, security, access control and other app-based smart devices. The biggest challenge in designing new buildings is being educated about new advancements and being able to scrutinize the different systems available for clients. New buildings should be designed as future thinking, with flexibility built in. This allows for future adoption of new technology and expandability of systems.
Future of buildings 50%
Reduction in energy consumption since 1975 Figure 3: Expectations of building performance for the future of buildings includes the integration of smart building automation system technologies and internet of things integrators. Courtesy: Mortenson
1 trillion
Increase in computing performance since 1956
Zero
Occupant complaints about comfort
Energy/cost conservation along with occupant comfort and productivity are two of the largest drivers of advancement in modern BAS. By providing improved equipment control, real-time monitoring, trend logging and fault detection building operators are better equipped to control how the buildings are operated, which decreases energy use and increases occupant satisfaction. These systems, coupled with strategic metering and data analytics, can further generate success stories around energy, carbon or climate goals, as well as wellness goals (such as air quality or quality of daylighting) that a company may have.
Climate and comfort
Reducing cost or saving money via energy conservation is a benefit of an optimized BAS. It is typically used to help justify the increased costs associated with a more complex system. However, there are other reasons for a company to track energy usage and reduce consumption. Many companies have strategic goals around energy conservation, carbon reduction and/or climate impacts. To track and validate consumption and conservation it is helpful to have automated systems to perform and track complex calculations. Further, the analytics provided by an analytics platform can identify potential areas for improvement that otherwise may not have been found. While wellness and human comfort can be difficult to track
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and monetize, standards like ASHRAE 55: Thermal Environmental Conditions for Human Occupancy and ASHRAE 62.1: Ventilation for Acceptable Indoor Air Quality set a baseline. With the increase in wellness standards that companies use to attract and retain employees, it is increasingly important to be able to verify that occupied buildings are healthy buildings. Using a BAS to maintain a healthy building and trend and verify wellness metrics is common for new buildings. This is most important in hospital designs. In an article on BAS in hospitals, Neil Lorenzi writes “With patient satisfaction and healthy outcomes more closely tied to reimbursement, hospitals are seeking ways to improve the overall patient experience and building performance is critical to that mission.” High patient satisfaction doesn’t happen without a state-of-the-art BAS.
Equipment control
By integrating equipment controllers into a centralized BAS building, operators can optimize HVAC efficiency and improve control. Examples of this include using economizers for free cooling, resetting boiler temperature setpoints based on outdoor air temperature and optimizing building start/stop times, which allows for night and weekend setbacks. Occupancy sensors can be integrated into ventilation systems to optimized ventilation rates, further reducing energy and improving IAQ, as well as control lighting. Carbon dioxide and volatile organic compound sensors can further optimize ventilation rates and occupant health. By providing improved equipment control and visualization into system operations, facilities can see lower maintenance costs and potentially lengthen equipment life. Alarms and trend logs can signal facility operators before they cause discomfort to building occupants and escalate into bigger, more costly problems that could result in equipment failure.
Metering and submetering
Metering and submetering equipment that uses energy and integrating the data into a BAS can provide additional insight into
Figure 4: There are limitations of pneumatic control systems. On this 1980s thermostat, the setpoint temperature is 80°F. The actual room temperature is 70°F. The current systems cannot meet the desired setpoints. Courtesy: Mortenson www.csemag.com
optimizing a building. To really get into energy conservation, the old saying “you can’t manage what you don’t measure” applies. Typically, metering is done in two ways — whole building and/or end use. Whole building metering is helpful when utilities haven’t provided smart meters. They can measure whole building use in real-time and in user specified intervals (each second, minute, 15 minutes, etc.). End-use meters get into real-time use of energy on a break-out level such as lighting, fans, water heaters and plug loads. Many buildings that have employed end-use meters have used the data to impact tenant behavior through energy conservation competitions. At Mortenson, the competition was on a floorby-floor level in the headquarters campus. Every electrical panel on every floor was analyzed and submetered to most accurately calculate the energy consumption on each floor of the building. Each floor was then provided with educational materials similar to the Energy Star Bring Your Green to Work program. The end result was a 12.9% reduction in energy use over a three-month period. All savings were attributed to the behavioral changed made by the occupants. An important part of metering and submetering is to understand the purpose of the data collection before you start to collect it. This avoids installing equipment and gathering data that you can’t or won’t use. Information that is accurate and useful will improve operations, cut costs and provide the best experience for occupants. One of the things that happens when data are gathered and analyzed is that additional data are generated and one can end up with “paralysis by analysis.” Harnessing data and generating meaningful analytics is complicated. Data can be expensive to acquire and use, and data have little value on their own. It is only as good as the insight it delivers. There are companies that specialize in providing data analytics platforms for buildings. These companies design easy-to-use automation software that can visualize and analyze real-time information for multiple applications and can provide metrics on energy, maintenance, productivity and even product quality. These systems are intended to integrate beyond the BAS and can tie into manufacturing, product quality, financial tracking, etc. Successful analytics uncover new business insights capable of driving real value and greater business performance. Equipment controls and a BAS are just two things that an analytics platform can use.
Smart buildings
Smart buildings are those buildings that have leveraged data and real-time information to optimize energy consumption. They have leveraged IoT connectivity, sensors and the cloud to monitor and
www.csemag.com
Figure 5: This shows the various building automation control levels. At the base are individual equipment controllers. These can be stand alone, smart or may need to be connected and controlled by a building automation system. The equipment controllers can be integrated into a functional head end or BAS for building level control. With strong equipment controls and BAS, an analytics platform can be used to perform complex data analytics to further optimize building performance. Courtesy: Mortenson
Figure 6: The example data provided by an analytics platform indicates the baseline load of the building as well as how the building is performing on weekends versus weekdays. Courtesy: Mortenson
control multiple building systems (HVAC, lights, plug loads, elevators, etc.). They use that connectivity to communicate and automate to generate greater efficiency, security and comfort while saving money. Smart buildings have a modern BAS. Many smart buildings are designed around the phenomena of “electrification of everything” and transition to 100% renewable energy. These buildings are better positioned for the future of the electrical grid. Incorporation of technologies such as heat pumps, electric vehicles and other electric consulting-specifying engineer
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BUILDING SOLUTIONS
AUTOMATION AND CONTROLS
Figure 7: The use of submetered data can influence human behavior to reduce energy consumption, as shown in this example of the company headquarters floor-by-floor competition. Courtesy: Mortenson
technologies are on the rise and their increased incorporation could increase U.S. electricity consumption by nearly 40% by midcentury, according to a National Renewable Energy Laboratory report. This need to electrify everything has complications for the electric grid and creates an increased demand for a smart grid. In a traditional grid scenario energy flows from the utility to the end user. It is a one-way transmission. A smart grid allows for many great improvements, but at a baseline one of those things is the ability to have two-way transmission. A smart grid is on the utility side of the meter. It involves the transmission lines, substations and transformers required to deliver power from the plant to the users. Smart grids allow for real-time energy usage and real-time energy pricing and can help building operators further manage usage cost, and manage when to use energy and when to generate on their own through renewable energy. Smart grids are continually evolving and smart buildings and BAS need to evolve with it to optimize performance on both sides of the meter. The smart grid will need smart buildings to talk to for ultimate success. Utilities have committed to being more connected to their customers, but to be truly successful, they need their customers to connect to them in a different way. Most of today’s smart grid integrations end with the utility providing a smart meter. It is a start, but only a start and it needs building designs to advance. When a smart building is connected to a smart grid, there is mutual benefit for both the building owner and power provider.
What’s next
The Jetsons — the 1960s TV cartoon — family lived in the future and they had amazing contraptions (smartwatches, video phones, drones, robots,
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autonomous vehicles) that aided in everyday living. They lived in perfectly climate controlled, healthy buildings in the sky. We are on the cusp of being in “the future” portrayed in that cartoon, but The Jetsons had robots and artificial intelligence. The automation systems used today continue to rely on human interaction and interpretation. As an example, fault detections and alarms still rely on humans to take action and much of our data still needs human interpretation. The technology that limits or eliminates the need for human interpretation is machine learning and artificial intelligence. These technologies are rapidly evolving and some aspects are being integrated in BAS algorithms, but it is happening gradually. In today’s increasingly connected world, the IoT communicates but is not independently intelligent. Current systems typically rely on “after the fact” reporting: analyze the past, make a change and hope the test works in the future. If the results of the change don’t meet expectations a different change is made and the process is repeated. In ML and AI, a machine collects the building management system and analytics platform data and combines them into increasingly robust data sets. These data sets are large and contain more information than a human brain can process. Current ML protocols for BMS use the robust data sets and combine them in a way that allows operators to schedule equipment based on better data. This is what is known as a supervised ML system, and while it is not a fully automated system, it is more vigorous than the current “after the fact” reporting. Additional benefits of the ML/AI integration include: the ability to use multiple data sets to forecast and operate the building off weather predictions, establishing better coordination of complex systems (combining HVAC, lighting, ventilation and occupancy) and improved fault detection (optimized continuous commissioning). In the most succinct terms, the core function and intent for BAS is to keep humans comfortable, healthy and safe. The business purpose of the BAS is to save money and improve productivity. Using advancements at an equipment level, an automation level and at an integration level, the BAS is a business tool in addition to an energy and comfort tool. When smart technology is applied to BAS and those advancements are in sync with smart technology from power providers, new business insights can be uncovered. These insights can drive real business and environmental value and greater business performance. cse Julianne Laue is director of building performance at Mortenson. She is a member of the ConsultingSpecifying Engineer editorial advisory board and was a 2012 40 Under 40 winner. www.csemag.com
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BUILDING SOLUTIONS
AUTOMATION AND CONTROLS
By Michael Chow, PE, CEM, CxA, LEED AP BD+C, Metro CD Engineering, Columbus, Ohio
Commissioning lighting occupancy sensors Installing lighting occupancy sensors and commissioning the devices have many benefits, including reducing operational and maintenance costs
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any of us have seen or personally experienced a person frantically waving their arms in circular motions when the lighting turns off in a space controlled by an occupancy sensor. While this may seem comical at first, users in these spaces tend to get frustrated at the occupancy sensor and override it to avoid being left in the dark. Occupancy sensors then get a bad rap. Why did the occupancy sensor fail to keep the lights on? Lighting uses approximately 20% of the total energy consumed in commercial buildings, according to the U.S. Department of Energy. There is great potential for energy savings by reducing the lighting levels or turning the lighting off when not needed. Occupancy and vacancy sensors are devices that use sensors to detect when a space is unoccupied and accordingly automatically turn off (or dim) the lighting fixtures. This saves energy by turning • Learn energy codes and the lighting off in a space or room if it standards related to lighting and is not occupied. The device can turn occupancy sensors. the lighting fixtures on automatically • Understand the commissioning upon detecting the presence of occuprocess for lighting and lighting pants and thus is referred to as an controls. occupancy sensor. • Know the role of the Vacancy sensors are like occucommissioning authority in the pancy sensors and use similar sendesign of lighting systems. sor technology. However, vacancy sensors require the occupant to turn the lighting fixtures on in a room or space by pressing a manual switch, which typically is integral to the motion sensor. See Figure 1 for an example of a wall-mounted vacancy sensor with dual technology (passive infrared and ultrasonic). The button with the light bulb is pressed as a manual on to turn on the lighting fixtures manually.
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Figure 1: An occupancy sensor with dual technology (passive infrared and ultrasonic) is shown. The button with the light bulb image is pressed as a manual on or off to control the lighting fixtures manually. Courtesy: Metro CD Engineering
Vacancy sensors should provide greater energy savings than occupancy sensors because they give the occupant a choice of whether to turn on the lighting fixtures. For example, if there is enough ambient light in an office with windows for daylight entering through the windows, the occupant may choose not to turn on the lights at all. Conversely, with an occupancy sensor, the lighting fixtures will turn on automatically regardless of how much daylight is in the room. This article will use the term “occupancy sensors,” which can be either occupancy or vacancy sensors depending upon the owner’s project requirements. Studies have shown that adding occupancy lighting controls can reduce lighting energy use 10% to 90% or more, depending on the use of the space in which the sensors are installed, according to the U.S. Department of Energy (see Table 1). One study conducted by the U.S. Department of Energy on a university campus found that installing wired occupancy sensors to control lighting in more than 200 rooms in 10 buildings provided an annual cost savings of about $14,000 with a simple payback of 4.2 years. Occupancy sensors are also mandated by energy codes. ASHRAE Standard 90.1-2010 and 2013: Energy Standard for Buildings Except Low-Rise Residential Buildings requires that lighting automatically turn off or be reduced in output in spaces/ areas such as conference rooms, classrooms, breakwww.csemag.com
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Lighting uses approximately 20% of the total energy consumed in commercial buildings, according to the U.S. Department of Energy.
rooms, storage rooms, private offices, etc., with a 30-minute maximum timeout setting, both for new construction and for major retrofits. Occupancy sensors help achieve this requirement. It is important to understand occupancy sensors need to be commissioned to realize these savings in practice.
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Commissioning guidelines
How does an engineer or commissioning agent commission occupancy sensors lighting controls? Fortunately, there are guidelines and processes: ASHRAE Guideline 0-2019: The Commissioning Process and ASHRAE Standard 202-2018: Commissioning Process for Buildings and Systems; the ACG (AABC Commissioning Group) Commissioning Guideline; and IES DG-29-11: The Commissioning Process Applied to Lighting and Control Systems. The IES Lighting Handbook defines commissioning of lighting systems as “a systematic process that ensures that all elements of the lighting control system perform interactively and continuously according to documented design intent and the needs of the building owner.” Energy codes and U.S. Green Building Council LEED certification have made commissioning of lighting controls a requirement. Standard 90.1 requires functional testing of lighting controls and systems. IES DG-29-11 breaks down the commissioning of lighting control systems into the following phases: • Pre-design. • Design. • Construction. • Occupancy and operations. The pre-design phase is when the commissioning team is formed and is led by the commissioning authority. The commissioning team, consisting of the construction manager, subcontractors and lighting engineer/designer, creates the commissioning plan, develops the owner’s project requirements and provides procedures to identify and track issues during the commissioning process. The OPR should include performance requirements for lighting control systems. For example, a section of the OPR for occupancy sensors may state:
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Figure 2: Ohio Northern University’s James Lehr Kennedy Engineering Building has increased laboratory space and an abundance of natural daylight in the building. Courtesy: Tara Grove, Metro CD Engineering
Table 1: Occupancy sensor savings Room type
Occupancy sensory lighting energy savings
Breakroom
29%
Classroom
40% to 46%
Conference room
45%
Corridor
30% to 80%
Office, open
10%
Office, private
13% to 50%
Restroom
30% to 90%
Storage area
45% to 80%
Warehouse
35% to 54%
Table 1: The table shows typical savings by room type when using occupancy sensors. Courtesy: U.S. Department of Energy
• Occupancy sensors shall be used to turn off lighting when a space/area is unoccupied. The sensors should be set for a maximum 30-minute timeout to shut off lighting. consulting-specifying engineer
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• Occupancy sensors shall use vacancy mode to turn lighting on in enclosed private offices with automatic off. • Occupancy sensors shall integrate with the heating, ventilation and air conditioning system and the building automation system in private offices to turn off lighting when unoccupied and provide code minimum ventilation levels. • Daylighting harvest sensors shall be installed in all open office areas. Daylighting controls shall dim the lighting automatically to maintain a minimum of 30 foot-candles measured at the desktop height above finished floor. In the design phase, the design engineer should complete the basis of design that explains the concepts that the engineer will employ to achieve the performance requirements of the OPR. For example, suppose the OPR states: “Vacancy sensors shall be used in all enclosed private offices.”
A BOD to achieve this OPR may state: “Vacancy sensors using passive infrared and ultrasonic, self-adaptive technologies shall be used in all private enclosed office. Sensors shall turn the lighting off within five minutes after an office is unoccupied.” Typically, the contractual design phases of a project consist of schematic design, design development, construction documentation, construction administration and final punch list. The schematic design contains an outline of the lighting control system to fulfill the OPR. The design development phase includes detailed drawings and specifications. The construction documentation incorporates commissioning in the specifications. It is highly recommended that the commissioning specifications be incorporated no later than the design development phase. The specifications would be updated in the construction documents phase. The specifications include lighting controls to be tested and roles and responsibilities of the commissioning authority and the contractor(s). Including these items helps reduce or even eliminate conflicts and issues during commissioning tasks such as functional testing. For example, a commissioning specification may state, “The contractor shall notify the commissioning agent in writing at least 14 days in advance of all pre-functional testing.” The commissioning authority reviews the lighting control design documents to check compliance with the OPR and the commissioning plan. For example, the commissioning authority may check that occupancy sensors are located correctly in each space/area. Another example includes verification that occupancy sensors are located more than 6 to 8 feet from HVAC diffusers (especially for sensors that use microphonics). Here are some typical occupancy sensor design items that should be reviewed by the commissioning authority: • Occupancy sensors are not allowed to control lighting fixtures in electrical rooms as stated in the NFPA 70: National Electrical Code.\
Figure 3: The 105,000-square-foot, $30 million, three-story James Lehr Kennedy Engineering Building at Ohio Northern University, Ada, Ohio, was completed in fall 2019. The new facility in allows more engineering student enrollment, increases laboratory space and encourages student-faculty collaboration. Courtesy: Tara Grove, Metro CD Engineering
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• Time delay setting of occupancy sensors stated in the specifications shall match the OPR. How long should the lighting fixtures stay on once no motion is detected? The less time the lighting fixtures stay on, the higher the savings will be. The commissioning authority should discuss this with the owner and the design team. With LED lighting now the standard and with frequent switching of LED lighting fixtures having little effect on the longevity of LED light sources, time delay settings should www.csemag.com
CASE STUDY: University lighting system commissioned
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hio Northern University’s 105,000-square-foot, to the door and can result in the lighting in her office $30 million, three-story James Lehr Kenne- to turn on when people walk past the door, but do not dy Engineering Building was completed in fall enter the office. The incorrect location of the occupancy sensor has 2019. The new facility in Ada, Ohio, allows more engineering student enrollment, increases laboratory space resulted in the lighting in the room to turn off while the and encourages student-faculty collaboration. Student occupant is completing tasks at her desk. The occupant input resulted in an abundance of natural daylight in the has tried waving her arms, but the lighting remained off. new building. The facility has daylighting harvest sensors, The sensor’s self-adapting technology usually recalibrates the sensitivity of the sensor when vacancy sensors and high-efficait detects someone waving their cy LED lighting. The building arms, but in this case, since her is seeking U.S. Green Building The commissioning seated position was not withCouncil LEED-NC v3 certification. authority needs to in the sensor’s minor movement The commissioning of the coverage, the sensor could not occupancy sensors was done ensure the design keep the lights on. post-occupancy to allow the The occupancy sensor is being occupancy sensors with selfintent of the occupancy relocated where shown on Figadapting technology to adjust to sensors is met during ure 4 and this should fix the issue the use of the building. This usuof the lights turning off when the ally takes about a week for the the commissioning occupant is working at her desk. sensors to automatically adjust process. It is critical that the design to the use of the rooms and engineer show the occupancy spaces. sensors in the correct location. The commissioning authority found issues with some of the installed occupancy sen- Most sensor manufacturers will provide no-cost evaluasors. These ceiling-mounted sensors were not installed tions of an engineer’s design to ensure major and minor where there are shown on the construction drawings. coverage motions are correct. The installing contractor This led to sensors not performing as designed and should be instructed before construction to ensure the resulted in the room occupants “waving their arms” to sensors are installed where shown on the construction drawings to eliminate sensor issues. The commissioning keep the artificial lighting on. Figure 4 shows a private office, Room 109D, with authority needs to ensure the design intent of the occuthe ceiling-mounted occupancy sensor labeled “OS3” pancy sensors is met during the commissioning process. in the room. The sensor is placed too far away from the desk to detect minor motion such as the occupant using a computer while seated at her desk. The sensor also is placed too close
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Figure 4: A partial first-floor lighting plan showing the case study private office with design location of occupancy sensor and actual installed location of sensor. Courtesy: Metro CD Engineering www.csemag.com
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ARCHITECTU RAL
LED EDGE-LIT EXIT COMBO
BUILDING SOLUTIONS
AUTOMATION AND CONTROLS
be 15 minutes or less. National Electrical Manufacturers Association guidelines recommend a 15-minute time delay. However, you may want to start with a 10-minute delay for greater energy savings and adjust to a longer time delay if occupants request it (refer to the U.S. Department of Energy). 7 + 0%+* +" + 1, * 5 /!*/+./ – Sensors should not be installed within 5 feet of HVAC supply diffusers. – For enclosed spaces, locate a wall-mounted sensor where it will not be blocked when the door is open. – Do not install sensors on an angled or inclined ceiling as they typically do not perform well when positioned at an angle. – Verify that the type of sensor used will sense both minor and major movement. – Restrooms should typically use ceiling-mounted ultrasonic sensors to detect movements in the stalls. Many lighting engineers/designers may use just one wall sensor to detect movement when an occupant enters a restroom, but this sensor may not detect an occupant in a restroom stall. It is good practice to have adequate lighting in restrooms in an unoccupied mode should the lighting be turned off at inappropriate times. – Ceiling height should be considered when placing a sensor. Most sensors should not be installed with ceiling heights over 15 feet.
Fully adjustable 2.5W LED lamps Up to 54’ on-center spacing Architectural low-profile design Surface & recessed configurations Includes single- & double-face panels Optional remote capability
BAR R O N LTG.C O M input #5 at www.csemag.com/information
The commissioning authority always notifies the design team of issues discovered during the review of the documents. The design team should then reply formally to the commissioning authority’s comments and resolve all issues. The construction administration phase involves training of the facility personnel on the operation and maintenance of the lighting and control system. A good example of a training program includes explanation on how occupancy sensors can be modified (e.g., change from occupancy to vacancy mode). Also included in this phase is performance testing. For lighting control systems, the commissioning authority, electrical contractor, operators, manufacturer representatives and other stakeholders are typically present for the testing. A sample partial performance test for occupancy sensors may include verification that the lighting fixtures in a space turn on within 3 feet of entering a space in a private office. The commissioning authority maintains an issues log that begins at the pre-design phase. The log includes details of each issue and who is responsible to resolve each issue one. A systems manual, with specified sections provided by the construction manager, is handed by the commissioning team to the owner at the project turnover. The systems manual pro2% !/ !0 %(/ 3$% $ .! *+3 !/ .% ! 5 2 +* 0$! +,!.-
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ation and maintenance of the lighting controls. Also included are record drawings, submittals (shop drawings), the issues log, the OPR and BOD, as well as operations and maintenance manuals. Training should always include a review of the systems manual and its use in normal operation of the building. The occupancy and operations phase begin at substantial completion. This includes providing completion of any deferred testing and training as well as maintaining the systems manual. The commissioning requirements of Standard 90.1-2010 require that the construction documents identify who will conduct and certify the testing. All specified lighting controls and associated software must be calibrated, adjusted, programmed and assured to operate in accordance with construction documents and manufacturer installation instructions. Specific requirements are identified for occupancy sensors, programmable schedule controls and photosensors. For example, at a minimum, the party conducting the testing must confirm that the placement, sensitivity and timeout settings for any installed occupancy sensors provide acceptable performance — for example, the lights must turn off only after the space is vacated and must turn on only when the space is occupied. Time switches and programmable sched-
ule controls must be programmed to turn the lights off. And photocontrol systems must reduce light levels produced by the electric lighting based on the amount of usable daylight in the space as specified. Standard 90.1-2010 requires a commissioning authority be engaged that is not involved in the design or construction team. The commissioning authority verifies that the lighting controls are adjusted, programmed and functioning in accordance with the design and the manufacturer’s installation instructions. The commissioning authority then submits documentation certifying that the lighting systems are in compliance with or exceed the performance requirements outlined for the project in the OPR. Installing occupancy sensors and commissioning the devices have many benefits, including reducing operational and maintenance costs. And with properly designed and commissioned occupancy sensors, it’s time to say goodbye to days of people frantically waving their arms when the lights turn off. cse Michael Chow is the founder and president of Metro CD Engineering. He holds a BSEE from Ohio Northern University and is the current chair of the university’s engineering advisory board. He is a member of the Consulting-Specifying Engineer editorial advisory board and is a 2009 40 Under 40 winner.
Installation in a Snap Belimo offers a complete range of sensors designed with a snap-on cover, enabling easy installation while providing NEMA 4X/IP65 protection.
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By Robert Sander and Mario Caraveo, NV5, Las Vegas
Transformer selection and sizing Selecting and sizing electrical distribution transformers is fundamental for electrical designers and engineers
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n the United States, transformers are governed by the NFPA 70: National Electrical Code; in this case, the latest version of the code published in 2017 will be used. Transformers are fundamental components in many different commercial, industrial and residential electrical systems. They allow for the working voltage to either be “stepped” up or down. Transformers are able “step” voltage up or down by using the magnetic field produced passively by the current carrying windings. • Learn design concepts for The most basic version this conselecting and sizing electrical cept can be illustrated by two coptransformers. per loops of different size, one inside • Review the codes and of the other with no contact. If one considerations associated with of these loops has current passing transformer design. through, it then an induced voltage • Evaluate a case study profile to is seen at the terminals of the other highlight best practices. loop. The voltage and current in the second loop is proportional to the voltage and current associated with the first loop. The amount of loops or windings can be changed to create a variety of voltages to work with. Transformer windings are made of aluminum or copper. Aluminum is the common selection because it is less expensive while offering similar electrical characteristics to copper. Aluminum is lighter in weight than copper, but is typically larger in physical size. Power distribution transformer power rating sizes are standardized throughout the industry. The most common type of application within a commercial facility are three-
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phase delta primary to wye secondary step-down type transformers. Industry standard sizes for 480- to 120/208-volt wye transformers are commonly 15, 30, 45, 75, 112.5, 225, 300 and 500 kilovolt-amperes. There are also single-phase 277-or 480-volt transformer sizes available at 5, 7.5, 10, 15, 25, 37.5, 50, 75 and 100 kilovolt-amperes. This is not a comprehensive list, but illustrates the variety and range that is commercially available. In general, three-phase transformers are the most commonly used for electrical designer application and selection. Single-phase transformers tend to be used for special applications or voltages. An example may be unit equipment that specifically requires 240 volts single-phase where the service voltage is 120/208 volts wye three-phase. For a special case like this, it is common to only provide a single-phase transformer for the equipment because there won’t be a multitude of loads served by it. When a single-phase transformer is used for general distribution, it can cause phase imbalances when using a three-phase utility. Otherwise, if a property is served by single-phase and a transformer is used (e.g., for isolation) then a single-phase transformer would be appropriate. All transformers are required to have a nameplate with the Figure 1: This harmonic mitigating transformer does not have vibration-isolation pads. Typically, these are noted during inspection by authorities having jurisdiction or field observations by engineer. Courtesy: NV5 www.csemag.com
information described in NEC 450.11(A)(1-8). This information includes the name of manufacturer, rated kilovolt-amperes, frequency, primary and secondary voltages, impedance of transformers 25 kilovolt-amperes or larger, required clearances for transformers with ventilating openings, amount and kind of insulating liquid where used. For dry-type transformers, temperature class for the insulat ion system.
Transformer sizing
The first step to sizing a transformer is to determine the load that will be served, either at the branch circuit, feeder or service level. This starts with estimating or calculating the demand load using NEC Article 220 and then applying and applicable demand factors. Based on the types of loads served, demand factors will reduce the calculated load to determine appropriate sizing of the transformer. ‘ This calculated design load represents the base load or starting point for transformer sizing. Once you have determined the base load, depending on the type of project, a few considerations will need to be made when determining the final size of the transformer. These considerations include the future flexibility, available physical space, cost and project type. Future capacity or expansion for a property is one of the most crucial considerations for sizing. This is important because both an undersized and an oversized transformer operate at lower efficiencies and could cause degrading damage to equipment over time. It is crucial to understand the owner’s intended use for the facility. There are instances where the property is not likely to expand and as such, owners may not require capacity for future loads or equipment. However, some owners may not use their space to full capacity at project completion (e.g., a pharmaceutical lab filled to half occupancy) and it would be prudent to allow capacity for future expansion at the transformer. Such considerations for expandability should be discussed and coordinated by the design consultant with ownership to suit their needs. Additionally, depending on the project type (e.g., new construction, tenant improvement, remodel) there may not be physical space for expansion. The addition of a transformer to an existing property can be costly dependent on location and size. The location of an added transformer requires coordination for ventilation, spacing for code-required clearances and may require structural bracing. Furthermore, transformers produce excess heat that the mechanical engineer must evaluate existing systems to determine if they will support sufficient cooling. Another consideration is the weight; some smaller transformers weigh less than 1,000 pounds
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Figure 2: A sample nameplate from a 1,500 kilovolt-amperes drytype transformer lists all parameters related to the transformer construction and capabilities. Courtesy: NV5 Figure 3: This is a sample K-factor transformer nameplate. Note that the K-factor is clearly identified. Courtesy: NV5
and can be incorporated with minimal structural coordination. These considerations should be evaluated before the addition of a transformer to an existing electrical system. Typically, it is easier, in terms of cost and coordination, to accommodate a larger-sized transformer in a new construction structure, but a remodeling project may prove to be more costly and require more coordination. Lastly and important for an owner to consider, is the transformer’s cost. Usually, the larger the size of the transformer, the higher the equipment and installation cost. Often, for larger transformer sizes, they can also incur additional design and structural costs. For example, a 225 kilovolt-amperes dry-type transformer placed at an upper floor and typically weighs 2,000 to 4,000 pounds and would require structural engineers and architects to consider the weight and additional bracing needed to support the equipment load. In general, as with most other aspects of electrical engineering, it is best to be conservative and oversize at the early stages of a project until further design development and final determination is made considering all the preceding items. It is worth noting that it is easier to downsize a transformer later in design, for coordination purposes, consulting-specifying engineer
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rather than upsize the transformer after the preliminary stages of design. Information regarding transformer installation is found in the NEC, Article 450. Article 450.3(A) and (B) provide tables for maximum rating or setting of overcurrent protection for transformers with voltages for both, equal to/less than and larger than 1,000 volts. The numbers given in the tables are percentages of the transformer-rated current which is derived by taking the transformer’s kilovolt-ampere rating and dividing it by the voltage of the feeder. Needless to say, the primary and secondary feeders of a transformer will have different current requirements corresponding to their voltage with one exception — transformers used for power isolation. Primary protection allows an engineer to make a simpler design, but using a combination of single and secondary protection allows for greater flexibility in the use of a transformer’s current rating. One could use the full rating of a transformer as long as the feeders are still adequately protected according to these tables.
Types of transformers
Once a transformer size is determined, consider the application of and types of loads that will be served by the transformer. In commercial design, there are a few commonly used types of transformers with characteristics as described below: Dry-type transformers use ambient air to cool the core and windings. These transformers tend to be larger than liquid-filled transformers, but are generally less expensive in materials and installation costs. The two commonly used dry-type transformers are encapsulated and ventilated. Nonventilated or encapsulated are sealed completely with surface area cooling, suited for wash-down areas and corrosive, combustible or other harmful conditions. Ventilated dry-type transformers are made with openings that allow air to move through the inside, are larger in dimension, use different insulation materials and contain an enclosure for the windings providing physical protection for the equipment and for personnel. Liquid-insulated transformers use liquid for cooling and to act as an insulator for the cores.
CASE STUDY: Manufacturing facility electrical design
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n equipment manufacturing company has procured an existing building with 277/480volt wye service to open a new office for its business. The company manufactures and tests specialized, sensitive electronic equipment for the health care industry. It is opening a new location for its operations and plans to use 80% of the space and power capacity with a requirement to allow for at least 20% growth in the next few years. Project scope consists of standard commercial office space as well as a portion of laboratory and manufacturing. The owner’s required power allowances are: 10 volt-amperes per square feet for office, 25 volt-amperes per square feet for lab and 20 volt-amperes per square feet for manufacturing areas. Upon receiving floor plans, the areas are 14,000 square feet of office, 8,000 square feet of lab and 120,000 square feet of manufacturing. Lastly, all office and lab spaces will need 120 and 208 volts single-phase distribution, manufacturing requires
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a 70/30 split of 277/480 volts (singleand three-phase) and 120/208 volts (single- and three-phase), respectively. From this information and criteria, the connected load power allowances are determined: • Offices Of (120/208 volts): 10 voltamperes/square feet x 14,000 square feet = 70 kilovolt-amperes • Laboratory (120/208 volts): 25 volt-amperes/square feet x 8,000 square feet = 96 kilovolt-amperes • Manufacturing (277/480 volts): 20 volt-amperes/square feet x 120,000 square feet x 0.7 = 1,680 kilovoltamperes • Manufacturing (120/208 volts): 20 volt-amperes/square feet x 120,000 square feet x 0.3 = 720 kilovoltamperes The next stage is to select transformer capacity sizes. Office spaces can
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be served from a 75 kilovolt-amperes transformer based on the next standard size of transformer and the calculated connected load. However, the owner’s requirements are to account for at least 20% growth for future. Once the growth amount of 1.2 for the office space is factored in, we arrive at 84 kilovolt-amperes. This connected load will need to be serviced by the next standard size, 112.5 kilovolt-amperes. The laboratory space requires 115.2 kilovolt-amperes (with the 20% growth included) and will require a 225 kilovolt-amperes transformer. Manufacturing will similarly require a 1,000 kilovolt-amperes transformer to service its 864 kilovolt-amperes (with growth accounted) connected load at 120/208 volt distribution. Now that loads are accounted for, general locations in the building can be considered. There are many means and methods to determine appropriate transformer locations and distribution, so one design philosophy described here. The building layout is rectangular. www.csemag.com
Mineral oil and bio-based oils are the most commonly used liquids. Liquid-insulated transformers allow better cooling that translates to a more compact transformer than a dry type. However, these transformers require periodic oil analysis, but are considered less costly for repairs. Bio-based oils are less flammable and are environmentally friendly in the case of a leak. Less flammable is considered for liquids with a fire point of not less than 300°C. Exterior padmounted utility transformers are typically used with mineral oil and are considered combustible. For transformers less than 35 kilovolts, indoor installations may require minimal requirements such as an automatic sprinkler system or liquid containment area with no combustibles stored inside the room. NEC 450.23 covers the requirements for indoor and outdoor installations for these liquid-insulated types. Additionally, nonflammable fluid-insulated transformers that use a dielectric fluid that is nonflammable require a transformer vault to be installed indoors per NEC 450.24.
Overall dimensions are 200 feet wide by 655 feet long, with a second story at the building front that will house offices and laboratory spaces. Because the labs and offices reside in the same area, consolidation of the lab and office loads to one transformer are considered. This will give a combined connected load of 166 kilovoltamperes that can be serviced by a 225 kilovolt-amperes transformer. One larger combined transformer allows for space and cost savings. Instead of two rooms at either side of the building with associated feeders, the single larger transformer can be centrally located. In this scenario, with the labs and offices on two floors that are relatively small, the transformer is placed at grade level to avoid potential structural impacts. Distribution for the manufacturing floor requires additional consideration. With the 120/208 volt demand spread throughout the floor space, transformers must be arranged to avoid excessive voltage drop. With a 600-foot-long www.csemag.com
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Once a transformer size is determined, consider the application of and types of loads that will be served by the transformer. In commercial design, there are a few commonly used types of transformers.
Oil-insulated transformers must be installed in a transformer vault per NEC 450.26 when indoors.
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Special applications
K-rated and harmonic mitigating transformers typically are used for harmonic, nonlinear loads such as computer/servers with switch-mode power supplies, gaming slot machines, LED lighting, motors or variable frequency drives. HMTs can be used to correct the harmonic issues generated by the nonlinear loads.
Figure 4: In contrast to harmonic mitigating transformer without vibrationisolation pads, dry-type transformers are shown with pads. Courtesy: NV5
run and assuming somewhat uniform distribution, two locations are planned — one at 200 feet down and another at 400 feet. This will cover the manufac-
turing floor and will allow the load to be split for the manufacturing area to 360 kilovolt-amperes, allowing two 500 kilovolt-amperes transformers to service either end of the manufacturing area. These loads are only rough estimates, but allow the design team to prepare and allocate floor space. Once demand factors (if any) are applied, the sizes may be revisited and sized accordingly. Lastly, the specification of the transformers is considered. Because this is an indoor and controlled environment, dry-type ventilated transformers will be used. To reduce cost, the windings for the transformers will be aluminum instead of copper. At the office and labs, harmonic mitigating transformers are considered due to the sensitive nature of the equipment in the facility. This selection also will help increase power quality and reduce inefficiencies, in the form of harmonics, introduced from the multitude of AC/DC power supply transformers common to modern computers and electronics.
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Dry-type transformers installed indoors require at least 12 inches of separation from combustible material for transformers rated less than 112.5 kilovolt-amperes, per NEC 450.21(A).
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K-rated transformers, on the other hand, do not mitigate harmonics, but rather allow for a more robust system to tolerate the harmonics. Transformer failure from harmonics are caused by excessive and/or constant overheating of the coils leading to a faster degradation of the coils’ insulation. Electrical systems with excessive harmonics can cause electronic components to fail due to a distorted sinusoidal wave. The major difference between K-rated transformers and HMTs is that K-rated transformers are built to handle the stresses and strain of nonlinear loads depending on the level. Meanwhile, HMTs are physically constructed in such a way to reduce or mitigate harmonic currents from downstream devices to keep disruptive currents from traveling electrically upstream of the transformer. Most electronic equipment nowadays is powered by switch mode power supplies. SMSPs convert sinusoidal alternating current to constant direct current using rectifiers and capacitors that draw short and sharp bursts of current, which alter the original AC sinusoidal wave. This altered wave is now a nonlinear load and has odd harmonics that can become harmful to the transformer by increasing the current in the windings resulting in excess
Table 1: Transformer efficiency Single-phase
Three-phase
Kilovolt-amperes
%
Kilovolt-amperes
%
15
97.70
15
97.89
25
98.00
30
98.23
37.5
98.20
45
98.40
50
98.30
75
98.60
75
98.50
112.5
98.74
100
98.60
150
98.83
167
98.70
225
98.94
250
98.80
300
99.02
333
98.90
500
99.14
750
99.23
1,000
99.28
Table 1: The efficiency of a low-voltage dry-type distribution transformers is governed by the Department of Energy. Courtesy: NV5
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consulting-specifying engineer
heat in the transformer coils. HMTs suppress or reduce the effects of these odd harmonics, in particular the third harmonic that is additive on the neutral conductor.
Transformer design considerations
Location: An important factor to consider is physical location of the transformer. The type of environment/building material where the transformer is located and the surrounding occupancies or rooms adjacent to the transformer should be considered. For example, an oil-insulated transformer installed indoors requires spill containment areas that are typically more costly. Specifically, for oilinsulated transformers, a vault room would be required by NEC Article 450.26, unless at least one of six exceptions are met. There are advantages and disadvantages for using a transformer vault depending on any number of variables, however they require special attention and tend to add significant cost, which should be taken into consideration. Although they are not governed by the same building construction regulations mandated by the NEC, utility companies commonly use oil-insulated transformers. Additionally, when locating a transformer, consider its physical location in the building and the area it is intended to serve and distribute power to. A 277/480 volt-delta transformer is better suited for longer runs on medium-sized buildings due to voltage drop. To avoid sizing larger feeders for longer runs, it’s better to use a higher voltage to distribute power as needed. A 120/208 volt-wye is common for nonindustrial applications at the branch circuit level, but the lower voltage makes it subprime for longdistance distribution. Medium-voltage properties, where the voltage-to-ground is 1,000 volts or more, carry power from clusters of buildings throughout the site. Noise: Noise also should be considered, depending on the type of building occupancy. The constant vibrations from the transformer may cause an undesirable audible hum for the client or occupants. In a hotel tower occupancy, for example, transformer rooms in the upper floors where guestrooms are located may need sound-proofing or acoustical treatment to mitigate noise from the electrical space. This room treatment may be avoidable if the transformers are placed at grade level or on the roof in a location that gives adequate separation from the transformers and guests. Another solution could be to provide vibration-isolation pads that reduce the noise to a level acceptable to the client. An acoustical engineer or consultant may be involved to assist with this noise mitigation. www.csemag.com
Not all projects will follow the exact methodology as described here, but may expand to make further considerations. No two properties are the same and as such, no two projects will be the same. It is the responsibility of the design engineer to make the appropriate decisions and consult with their client to suit their needs. cse
Robert Sander is an electrical engineer at NV5. He has experience in electrical design of high-rise hospitality and PV. Mario Caraveo is an electrical designer at NV5. Experience includes electrical design for commercial offices, retail, hospitality, industrial, mixed-use, residential and health care.
Figure 5: An example of a pad-mounted oil-insulated 300 kilovolt-amperes transformer is installed outdoors on a dedicated equipment pad. Courtesy: NV5
There room construction is required to meet requirements as outlined in NEC Article 450 Part II. Specifically, dry-type transformers installed indoors require at least 12 inches of separation from combustible material for transformers rated less than 112.5 kilovolt-amperes, per NEC 450.21(A). For dry-type transformers larger than 112.5 kilovolt-amperes, the room requires a fire-resistant construction of at least one hour per NEC 250.21(B). However, there is an exception that commonly applies: those with Class 155 or higher and completely encapsulated except ventilation openings do not need to be located in one-hour rated rooms. Figure 1 represents one of these transformers; as such, the room it resides in does not require a one-hour fire-resistant rating.
Energy-efficiency requirements Energy efficiency for dry-type distribution transformers is governed by the U.S. Department of Energy. As such, compliant transformers are labeled with DOE-2016 to mark their compliance since Jan. 1, 2017. Dependent on the capacity of the transformer and its quantity of phases, the efficiencies range from 97.0% to 98.9% using 35% of the nameplate-rated load. In addition to the DOE requiring their label for commercially available transformers, many authorities having jurisdiction require transformers specified to meet these requirements. December 2019
25
input #7 at www.csemag.com/information
By Zia Salami, Ph.D., CDM Smith, Charlotte, N.C.; Lilly Vang, CDM Smith, Raleigh, N.C.; and Adrian Hendels, CDM Smith, Boca Raton, Fla.
How to correctly size a transformer Engineers must make informed decisions regarding the proper transformer sizing selection, electrical and mechanical requirements and impacts to the electrical system under different operating and loading conditions
A
transformer is a major component of an electrical distribution system with the most impact on system performance during steady-state (normal) operation and during system disturbances, such as a fault. Therefore, engineers must ensure that the transformer is appropriately sized for the specific application and can supply adequate power to the loads under designed conditions and standard guidelines. Typical applications for such major equipment are industrial plants, commercial buildings, hospitals, office buildings, shopping centers, schools, apartment buildings, etc. The article is focused on dry-type • Learn major transformer transformer such as ventilated selfcharacteristics, application and cooled, forced air-cooled, nonventilatparameters. ed self-cooled and sealed self-cooled • Understand the major criteria power transformers less than 30 megaand approaches to determining volt amperes and 34.5 kilovolts. proper transformer size. In general, dry-type transformers • Learn how to use electrical are less flammable (i.e., containing no power system software to liquids or oil) and carry less of a fire perform simulations. hazard, making them better suited for use in and near buildings. This type of transformer has a higher operating temperature and typically requires a larger footprint. Because dry-type transformers require air for cooling, it is necessary to provide an adequately sized ventilation system for the heat generated by the transformer. The overall approach for sizing transformers and related system impact are similar for all types of transformer with different cooling classes.
Learning
L
OBJECTIVES
Site location
Careful consideration must be taken when selecting the proper location for a transformer. Several details, including transformer type, size, ventilation, atmospheric pressure, altitude, voltage level and clearance will have a determining factor in selecting
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consulting-specifying engineer
the ideal location for the transformer required for a given installation. An engineer must be aware of the limitations due to the selected location of a transformer. In general, the kilovolt-ampere ratings are based on temperature not to exceed 40°C ambient temperature (or ambient temperature of 30°C averaged over a 24-hour period, otherwise some decrease in life expectancy will occur) and also installed below 3,300 feet at sea level. If any of these conditions are not met, transformer should be de-rated. In such case, transformer kilovolt-ampere should be de-rated by 8% for each 10°C above 40°C (when air-cooled for dry-type transformer) and also by 0.3% for every 330 feet over 3,300 feet altitude). More details for site consideration are discussed in NFPA 70: National Electrical Code Articles 450.8, 450.21 and 450.22.
Voltage class
The voltage class typically is selected based on available source voltage (e.g., utility source) and the required load voltage, if the load is designed to operate on a single- or three-phase system. The standard rated high-voltage transformers are: 2,400, 4,160, 4,800, 6,900, 7,200, 12,000, 13,200, 13,800, 23,000 and 34,500 volts. The low-voltage side includes 208, 480, 2,400 and 4,160.
Winding connection and impedance
Standard connection arrangements and terminal marking are included in the standards for particular types of transformers in accordance with IEEE Standard C57.12.70. The most typical winding (phase) connections for power transformers, including angular displacement between high- and lowvoltage, is shown in Figure 1. Based on this standard, the angular displacement of three-phase transformers with delta-delta or wye-wye connections shall be 0 degrees and wye-delta or delta-wye connections shall be 30 degrees. www.csemag.com
Figure 1: The most typical winding (phase) connections for power transformers, including angular displacement between highand low-voltage are shown. Courtesy: CDM Smith
‘
The grounding configuration and scheme depends on the overall neutral grounding system in the facility.
’
In general, the selection of winding connections is mainly based on the overall system design, required system parameter (e.g., equipment short-circuit current withstand capability) and especially the system neutral grounding scheme. In addition, wye-connection can configure as one of the grounding types such as open (ungrounded), solid (solidly grounded, no intentional impedance in the neutral grounding path), resistor (a resistor is used in the neutral grounding path), reactor (a reactor is used in the neutral grounding path) and few other less applicable options. The grounding configuration and scheme depends on the overall neutral grounding system in the facility. A wye solidly grounded transformer (secondary) is a typical application in facilities for a lowvoltage system (e.g., 4.16 kilovolt:0.480 kilovolt). In addition, Z (impedence, based on transformer self-cooled kilovolt-ampere ratings) is typically shown on nameplate information that is attached to front or inside transformer enclosure. This value has a high impact on electrical distribution system parameters such as voltage drop, available short circuit and incident energy. For example, choosing a higher impendence transformer (i.e., from 5.5% to 7.5%) can lower the available fault current allowing for equipment with lower amperes interrupting ratings, as long as there are no issues with system voltage within a facility. ANSI C57.12.10 specifies typical impedance values for transformers larger than 500 kilovolt-amperes. This value depends on kilovolt-ampere rating and also highwww.csemag.com
Figure 2: The three-phase electrical distribution system ETAP model for a typical industrial facility, such as a water treatment plant, is shown. Courtesy: CDM Smith
and low-side transformer voltage ratings. For instance, %Z for transformer with high-voltage side less than 34.5 kilovolts is between 5.5% and 7.5%. Note that the typical %Z for 13.8 kilovolts (or less) on the high side and 2.4 kilovolts (or less) on the low side is 5.75%. Most industry power transformers are included in this voltage level range. For a transformer less or equal to 500 kilovolt-amperes, a typical %Z impedconsulting-specifying engineer
December 2019
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ance may vary between 2.3% and 5.2% based on the voltage level. For instance, a 100 kilovolt-ampere transformer with 8.32 kilovolts (or less) on the high side has a typical value of 2.6% impedance.
Transformer sizing for new systems
Due to the critical role of transformers in elec-
trical distribution systems, it is essential that the transformer is sized correctly so that it can meet all applicable loading conditions. If it is undersized, it may create issues within electrical distribution systems, including loss of loads. In general, transformer sizing can be performed based on two methods:
Table 1: Three-phase 4.16:0.480 kilovolt sizing with load factor 1 Power factor
Efficiency
Load factor
Kilovoltampere ratings
Load descriptions
100
0.9
0.93
1
89.1
Motor, service factor (SF)=1
480
50
0.9
0.93
1
44.5
Motor, SF=1
Motor 3
480
10
0.9
0.93
1
8.9
Motor, SF=1
Load 3
480
20
1
1
1
20.0
Lighting/ computer
Load 4
480
40
Panel 1
480
Loads for LV XFMR
Voltage
Rated horsepower
Motor 1
480
Motor 2
Rated kilowatts
Rated amperes
1
1
1
40.0
Heater
1
1
1
166.3
Panel
Total kilovolt-ampere
369
All connected loads
20% reserve
443
Including load growth
Transformer kilovolt-ampere rating
500
Standard size available
200
Table 1: The individual loads with their corresponding system parameters such as rated horsepower, power factor, efficiency and a load factor of 1 are tabulated to determine the low-voltage transformer size. Courtesy: CDM Smith
Table 2: Three-phase 13.8:4.16 kilovolt sizing with load factor 1 Loads for service XFMR
Voltage
Rated horsepower
Rated kilowatts
Rated amperes
Power factor
Efficiency
VFD pf
VFD eff
Load factor
Kilovoltampere rating
Load descriptions
Pump No. 1
4,160
600
0.85
0.9
1
584.9
Motor, SF=1
Pump No. 2
4,160
250
0.85
0.95
1
230.9
Motor, SF=1
Pump No. 3
4,160
600
0.85
0.9
1
539.5
Motor with VFD 1
Load 1
4,160
1
1
1
200.0
Heater
1
100.0
Lighting/ computer
1
Load 2
4,160
LV XFMR
4,160
200 100
1
1
0.95
0.97
500.0
LV XFMR
Total kilovoltampere
2,155
All connected loads
20% reserve
2,486
Including load 2
Transformer kilovoltampere rating
2,500
Standard size available
Table 2: The individual loads with their corresponding system parameters such as rated horsepower, power factor, efficiency and a load factor of 1 are tabulated to determine the medium-voltage transformer size. Courtesy: CDM Smith Note 1: Motor kilovolt-ampere with variable frequency drive: Motor kilovolt-ampere rating x (motor power factor/variable frequency drive/VFD efficiency). Note that the difference kilovolt-ampere required ratings between two similar 600 horsepower motors (pumps No. 1 and 3), one with VFD (pump No. 3) and one direct connection. VFD improves system efficiency in the system and consequently less required motor kilovolt-ampere when it is installed. Note 2: 500 kilovolt-ampere LV XFMR has already included 20% margin. Courtesy: CDM Smith
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www.csemag.com
• Connected load. • Operating load. In both cases, load growth and future facility modification and de-rating factors such as ambient temperature and altitude should be considered. The growth factor is typically based on each system design and can vary; 110% to 130% is a reasonable range. In both methods, the sizing is performed from the downstream system to the main transformer (i.e., bottom up). The difference between these two methods is to determine a total connected kilovolt-ampere loads. There are several considerations that will determine which method to use, such as required design margin, project specification, cost, space availability and impact on voltage drop and available fault current. The electrical distribution system of a typical industrial facility, such as a water treatment plants, is shown in Figure 2. The task is to evaluate the size of the new ventilated self-cooled transformer (or evaluate the size for the existing), based on its required loads, using the two methods previously mentioned. For sizing based on all connected loads, the conservative method, all connected loads are considered regardless of their operating condition and system function. The sizing is performed from the downstream transformer toward the main. As shown in Figure 3, the downstream transformer (LV XFMR) is three-phase at 4.16 to 0.480 kilovolts, and the main transformer (service XFMR) is three-phase 13.8 to 4.16 kilovolts supply to different type loads (e.g., motor loads, variable frequency drives, static loads, distribution panel). The individual loads with their corresponding system parameters such as rated horsepower, power factor, efficiency and load factor are tabulated in Tables 1 and 2. Total kilovolt-ampere of the connected system is calculated including design margin and then the next available standard size will be selected. The typical standard size kilovolt-ampere for three-phase transformer based on ANSI C57.12.00 typically range between 15 and 100,000 kva which are based on the output of the transformer. The input kilovolt-ampere is expected to be higher by 1% to 5% (i.e., refers to transformer efficiency) due to transformer losses in its core and windings, dissipated as heat. These flows for each transformer are shown in Figures 3 and 4. In general, unless specified, transformers should not be overloaded and should be approved by the manufacturer for any short-time overloading operation due to the lower ambient temperature. The evaluation of data and kilovolt-ampere transformer selected size tableted in these tables are confirmed and analyzed by performing load flow analysis using ETAP electrical software. Power (kilovolt-ampere) flow for each branch including percent voltage (of nominal rating) and fault current for the www.csemag.com
Figure 3: Power (kilovolt-ampere) flow for each branch including percent voltage (of nominal rating) and fault current for the major switchgear and motor control center is shown. Courtesy: CDM Smith
Figure 4: Power flow and short-circuit results for a system based on actual system operations were calculated using ETAP. Courtesy: CDM Smith consulting-specifying engineer
December 2019
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29
major switchgear and motor control center is shown in Figure 3. For sizing based on actual system operations, all connected loads will be considered based on their operating conditions (i.e., load factors). As with connected loads, the sizing is performed from the downstream transformer toward the main with the same process. Total kilovolt-ampere including design margin, load factors and the selected transformer size are calculated and shown in Tables 3 and 4. The evaluation of the same system with different transformer sizes is shown in Figure 4. Power
flow for each branch including percent voltage and fault current are also shown for the major switchgear and MCC. In addition, there are a few results that should be noted when comparing Figures 3 and 4. First, the connected loads method is a more conservative approach when sizing the transformer and will provide better system voltage profile on the secondary side, but it generates and injects more fault current. This is mainly due to higher kilovolt-ampere transformer rating and consequently higher short-circuit injection to the system.
Table 3: Three-phase 4.16:0.480 kilovolt sizing with different load factor Loads for LV XFMR
Voltage
Rated horsepower
Rated kilowatts
Rated amperes
Power factor
Efficiency
Load factor
Kilovoltampere ratings
Load descriptions
Motor 1
480
100
0.9
0.93
0.85
75.7
Motor, SF=1
Motor 2
480
50
0.9
0.93
0.85
37.9
Motor, SF=1
Motor 3
480
10
0.9
0.93
0.85
7.6
Motor, SF=1
Load 3
480
20
1
1
0.6
12.0
Lighting/ computer
Load 4
480
40
1
1
0.7
28.0
Heater
Panel 1
480
1
1
0.5
83.1
panel
Total kilovolt-ampere
244
Operating loads
20% reserve
293
Including load growth
Transformer kilovolt-ampere rating
300
Standard size available
200
Table 3: The individual loads with their corresponding system parameters such as rated horsepower, power factor, efficiency with different load factors are tabulated to determine the low-voltage transformer size. Courtesy: CDM Smith
Table 4: Three-phase 13.8:4.16 kilovolt sizing with different load factor Load factor
Kilovoltampere ratings
Load descriptions
0.9
0.8
467.9
Motor, SF=1
0.95
0.75
173.2
Motor, SF=1
0.8
431.6
Motor with VFD
1
0.7
140.0
Heater
1
0.6
60.0
Lighting/ computer
1
244.0
LV XFMR operating loads
Total kilovoltampere
1,517
Operating loads
20% reserve
1,820
Including load growth
Transformer kilovoltampere rating
2,000
Standard size available
Loads for service XFMR
Voltage
Rated horsepower
Pump No. 1
4,160
600
0.85
Pump No. 2
4,160
250
0.85
Pump No. 3
4,160
600
0.85
0.9
Load 1
4,160
200
1
Load 2
4,160
100
1
LV XFMR
4,160
Rated kilowatts
Rated amperes
Power factor
Efficiency
VFD pf
0.95
VFD eff
0.97
Table 4: The individual loads with their corresponding system parameters such as rated horsepower, power factor, efficiency with different load factors are tabulated to determine the medium-voltage transformer size. Courtesy: CDM Smith
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www.csemag.com
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input #8 at www.csemag.com/information
Codes and standards for transformers The following technical codes and standards are applicable to and should be considered when selecting and evaluating the overall performance of a transformer, specifically dry-type power transformers: % Dry-Type Transformers for General Applications.
% $ " General Requirements for Dry-Type Distribution and Power Transformers, Including Those with Solid-Cast and/or Resin Encapsulated Windings.
% $ " IEEE Guide for Transformer Impulse Tests. % $ " IEEE Standard Terminology for Power and Distribution Transformers. % $ " IEEE Standard for Standard Terminal Markings and Connections for Distribution and Power Transformers. % $ " IEEE Guide for Dry-Type Transformer Through-Fault Current Duration. % $ " IEEE Guide for Loading Dry-Type Distribution and Power Transformers. % $ ! $" ! Article 450, Transformers and Transformer Vaults.
% $ " Requirements for Ventilated Dry-Type Power Transformers, 501 Kilovolt-Amperes and Larger, Three-Phase, with High-Voltage 601 to 34 500 Volts, Low-Voltage 208Y/120 to 4160 Volts. % $ " Transformers — Used in Unit Installations, Including Unit Substations — Conformance Standard. % $ " Standard Test Procedure for Thermal Evaluation off Insulation Systems for Ventilated Dry-Type Power and Distribution Transformers.
off a Dry-Type Transformer Coil. % $ " Guide for Test Procedures for Thermal Evaluation of Insulation Systems for Solid-Cast and Resin-Encapsulated Power and Distribution Transformers. % $ " IEEE Standard for General Requirements for LiquidImmersed Distribution, Power and Regulating Transformers. % $ " Standard Test Code for Dry-Type Distribution and Power Transformers. % $ " IEEE Recommended Practice for Establishing Liquid-Filled and Dry-Type Power and Distribution Transformer Capability When Supplying Nonsinusoidal Load Currents.
% $ " Guide for Conducting a Transient Voltage Analysis
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input #9 at www.csemag.com/information
Second, typical power transformers are equipped with fixed taps (i.e., two 2.5% taps above rated voltage and two 2.5% taps below rated voltage) that are designed to adjust the transformer voltage at the primary or secondary side. Therefore, it is recommended to use this capability to increase (or decrease) system voltage if needed. For instance, voltage at the MCC bus in Figure 4 can be increased by 2.5% or 5% if desired. However, a system designer should be careful not to solve one issue (i.e., system voltage profile) and simultaneously create another issue (i.e., injecting more fault current by increasing system voltage). In addition to fixed taps, transformer could be equipped with automatic load tap changer which provide wider range typically -10% to +10% of the winding kilovolt with smaller step (0.625%) to adjust and control the bus voltage based on desired voltage value. It is also important to point out that a K-factor rated transformer is recommended to size the transformer due to heat generation if the facility contains high harmonic generating sources, typically more than 15% total harmonic distortion. The K-factor will determine how much a transformer should be de-rated or oversized to handle such a system. Refer to ANSI/IEEE C57.110 for more details.
Transformers play a critical role in ensuring proper power system operation. They should be carefully sized and selected when designing and analyzing electrical distribution system to provide reliable and safe power system operation. The proper transformer sizing should consider applicable de-rating factors such as ambient temperature and altitude and, in addition, impacts on electrical distribution system voltage and fault current contribution. cse
Zia Salami is a subject matter expert in electrical power systems at CDM Smith. Salami has more than 20 years of industry and academic experience in electrical power systems and has served in several roles as an advisory engineer, consultant and academic professor. Lilly Vang is a junior electrical engineer at CDM Smith, where she focuses on electrical power system design and analysis. Adrian Hendels is a junior electrical engineer at CDM Smith, where he focuses on electrical power system design and analysis.
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By Vahik Davoudi, PE, LEED AP BD+C, Arup, Los Angeles
Analyzing NEC 2017 changes Several changes to the 2017 edition of NFPA 70: National Electrical Code should be noted
T
he 2017 edition of NFPA 70: National Electrical Code went through extensive changes as part of the three-year code cycle to incorporate revisions resulting from the public inputs and public comments. Every code cycle, the NFPA goes through rigorous efforts to update NFPA 70 — to keep up with new technologies and trends in the electrical industry — while maintaining the goal of facilitating the safe installation of electrical wiring and equipment. The 2017 NEC revision process itself was changed during this code cycle in an attempt to improve the overall process. In general, there are two public meetings held for the • Understand the revision process NEC revision process during each for NFPA 70. code cycle. The first public meeting • Review a general analysis of now known as “first draft,” replacchanges to the 2017 edition of NFPA 70. ing “report and proposals,” is held when all suggested changes to NEC • Learn about the implications of some revisions on the design of are discussed. The suggested changes electrical systems. now known as “public inputs,” replacing “proposals,” that were acted upon favorably resulted in first revisions to the “first draft” of the 2017 NEC. The second public meeting now known as “second draft,” replacing “report and comments,” is held when all comments are heard. The new comments now known as “public comments,” replacing “suggested comments” that were successful resulted in “second revisions” to the second draft. After the two meetings, appeals were heard and voting for acceptance of the 2017 NEC took place at the NFPA Annual Conference & Expo in June 2016, which then paved the way for NFPA Standards Council to issue the 2017 NEC by August 2016. According to NFPA, there were 4,012 public inputs submitted recommending changes to the 2017 edition of the NEC that resulted to 1,235 first revisions
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along with 666 editorial comments to the first draft. Subsequently, 1,513 public comments were submitted that resulted in 559 second revisions to the second draft of NEC.
New articles added to NEC
There were nine new articles proposed for this code cycle, but only five new articles were adapted and included in the 2017 NEC: • Article 425: Fixed Resistance and Electrode Industrial Process Heating Equipment: Presents needed regulations for industry. • Article 691: Large-Scale Photovoltaic Electric Supply Stations: Addresses the requirements for large-scale PV systems (5 megawatts or higher) generation capability that are solely connected to the utility grid.
Figure 1: A primary current injection testing wiring diagram is shown. Courtesy: Arup www.csemag.com
Figure 2: The addition of new subsection into 2017 edition of the National Electrical Code to clarify the requirements for a permanent switching means for emergency systems that rely on a single alternate source of power. Shown here is a generator quick-connect switchboard Courtesy: Schneider Electric
• Article 706: Energy Storage Systems: Addresses the requirements for ESS operating at more than 50 volts alternating current or 60 volts direct current that can operate independently or interactive with power production sources. • Article 710: Stand-Alone Systems: Addresses the requirements for power production sources operating in stand-alone mode that are not connected to the grid. • Article 712: Direct Current Microgrids: Addresses requirements for independent energy distribution networks that allow the use of power from DC sources to DC loads.
Top 10 code changes
Branch circuits — general provisions: Section 210.8(B) — Ground-Fault Circuit Interrupter Protection for Personnel, Other than Dwelling Units. The GFCI requirements for receptacles at commercial and industrial applications have been expanded to require ground fault protection for circuits beyond 15 and 20 amperes at 125volt applications. The code now mandates that at “other than dwelling units” all single-phase receptacles rated 150 volts to ground or less and up to 50 amperes shall be equipped with GFCI devices. Whereas three-phase receptacles rated 150 volts to ground or less and up to 100 amperes require GFCI protection devices. The Class “A” GFCI devices, which are designed to trip when the current to ground exceeds 4 to 6 milliamperes, have been critical safety features that have reduced the number of injuries and fatalities due to electrical shock since their inclusion into the 1968 NEC. Major equipment manufacturers provide single-phase GFCI circuit breakers through 50 to 60 amperes, but nothing higher and certainly they have no three-phase GFCI circuit breakers. There are some alternate UL listed products available in the market that could be considered to provide GFCI protection to people for higher ampere rating single-phase and three-phase circuit appli-
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cations. Generally, these devices are located between the circuit breaker and the load and are self-powered with a protective relay and a contactor to open the circuit when the ground fault exceeds 5 milliamperes. Branch-circuit, feeder and service load calculations: Section 220.12 — Lighting Loads for Specified Occupancies. Exception No. 1 of Section 220.12 was introduced in 2014 NEC, which allowed lighting loads to be calculated based on energy code adopted by local authorities while meeting three listed conditions. New exception No. 2 added to 2017 NEC expands this allowance where an energy code is adopted and that energy code specifies an overall lighting density of less than 1.2 voltamperes/square foot. It permits the unit lighting loads in Table 220.12 for office and bank areas within the building to be reduced by 1 volt-amperes/square foot.
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The 2017 National Electrical Code revision process itself was changed during this code cycle in an attempt to improve
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the overall process.
Article 220 provides specific requirements for calculating branch-circuit, feeder and service loads. The title and scope were revised somewhat to enhance clarity of what is covered by the article and to emphasis on calculating loads in this article and deferring the branch circuit and conductor sizes to Articles 210 and 215. The recent changes that allow lighting loads to be calculated using adopted energy codes are significant steps in the right direction to reduce the electrical service size and thereby cost of equipment. Hopefully, the type of occupancies listed in exception No. 2 will expand in the near future to avoid having many buildings or tenants with oversized service. Services — Service Equipment Overcurrent Protection: Section 230.95(C), Ground-Fault Protection of Equipment — Performance Testing. The performance testing requirement for ground-fault protection system has been modified to ensure the testing is conducted by a qualified person(s) using a test process of primary current injection and that a written record of this testing is available to the authority having jurisdiction. This requirement also affects feeders listed under Section 215-10. consulting-specifying engineer
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The addition of testing requirements was the result of many failures due to ground-fault protection systems that were improperly connected and did not function properly to provide the intended protection. The addition of testing by qualified persons and proper documentation of test results and making it readily available to AHJ for review should eliminate all the concerns related to GFPE. Overcurrent Protection — Fuses: Section 240.67 — Arc Energy Reduction. The code expands the requirement for arc energy reduction where fuses rated 1,200 amperes or higher are installed. This requirement will become effective Jan. 1, 2020. This is similar to Section 240.87 that was added to the 2011 NEC to reduce incident energy for circuit breakers rated 1,200 amperes and higher. This new requirement will reduce incident energy to which an electrical worker or maintenance personnel could be exposed when working on the load side of an overcurrent device — in this case, fusible switches. Unfortunately, no manufacturers have developed fusible switches with an energy-reducing maintenance switching feature with local status indicator, like what is available in the market for circuit breakers. This will impact the installation costs where in lieu of a low-cost fuse, a more expensive circuit breaker
with energy reduction maintenance switch has to be considered. Overcurrent Protection — Circuit Breakers: Section 240.87 — Arc Energy Reduction. The subsection (B), which covers requirements for reducing clearing time on breakers rated 1,200 amperes or more, describes three new permissible methods. Two of the three new means involve using an “instantaneous trip setting” or “instantaneous override” that is less than the available arcing current, while the third option allows “an approved equivalent means.” This section was originally added to 2011 NEC to reduce incident energy for circuit breakers rated 1,200 amperes and higher to limit the arc-flash energy. The new methods of reducing arc flash energy required under 2017 NEC at first glance offer substantial savings compared to the ones listed under 2014 NEC by using trip unit with arc flash reduction switch, which may not be the case for many situations. Now, instead of an expensive trip unit with arc flash reduction switch, a standard instantaneous adjustment dial could be used, if the breaker’s fixed instantaneous override or instantaneous trip setting can be set below the calculated available arcing current. However, unlike the four methods listed under 2014 NEC, the two new methods have performance
Overview of changes throughout NEC Some of the most notable changes impacting 2017 edition of NFPA 70: National Electrical Code are: • All definitions that appeared in two or more articles have been relocated to Article 100. • New requirements have been added for the use of calibrated tightening torque tools for electrical connections, where a torque value is indicated on equipment or listed in installation manual by the manufacturer. • New labeling requirements, such as detailed arc flash hazard warning on equipment to help assess electrical risks, have been added per Section 110.16(B). • New Section 110.21(A)(2) requires reconditioned equipment to be marked with the name, trademark or other descriptive marking, identifying the organization responsible for
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reconditioning the electrical equipment including the date of the reconditioning. • New Section 110.26(A)(4) addresses access and space clearances required for equipment that by installation instructions or function is located in a “limited access location.” • The migration from 600 volts to 1,000 volts that started with 2014 NEC continues, all relative to the current trends in the electrical industry. These changes have been primarily in response to renewable energy systems that operate over 600 volts and the NEC lacked requirements to safely cover these systems. • New and revised provisions for arcfault circuit interrupter and groundfault circuit interrupter protection to improve electrical and fire safety at homes have been addressed per Sections 210.12 (C) and (D).
consulting-specifying engineer
• New Section 210.11(C)(4) requires at least one 20-ampere rated branch circuit to supply dwelling unit garage 125-volt receptacle outlet(s). • New Section 210.71 requires a minimum number of receptacles to be installed in meeting rooms not exceeding 1,000 square feet. • Revisions made to the acceptable grounding electrode system for a separately derived system listed under Section 250.30(A)(4). The metal water piping and structural metal grounding electrodes are no longer mandatory and now any of the building or structure grounding electrodes described at Section 250.52(A) can be used as the grounding electrode for separately derived system. As a matter of fact, the water pipe and the structural metal frame per Section 250.68(C) are not considered grounding electrodes but rather are conductors extending www.csemag.com
requirements to demonstrate the effectiveness of this procedure. There has to be a short-circuit, coordination and arc-flash study prepared for verification that indeed the breaker settings can be set below the calculated available arcing current. The use of lower-cost breakers with standard instantaneous adjustment dial may be economical for some projects, however for larger complex buildings the additional cost for studies could easily wipe out any savings expected depending on the number of breakers involved. Health Care Facilities — Essential Electrical Systems, Sources of Power: Section 517.30(B)(2) — Types of Power Sources — Fuel Cell Systems. According to the new subsection, a battery system is no longer permitted as an alternate source of power, while the fuel cell systems will be permitted as the alternate source for a health care facility, provided that they: • Meet the requirements for fuel cell systems in Article 692. • Meet the redundancy requirement. • Meet the 10-second rule. • Meet the fuel supply requirements.
the grounding electrode connection. • Revisions made to Section 310.15(B) (3)(c) requires a minimum of 7/8 inch clearance from the roof surface for raceways and cables or else they will be subject to 60°F temperature adder. The old temperature adder table has been removed. • Revisions made to Section 406.12 expand the list of spaces requiring the use of tamper-resistant 125- and 250volt, nonlocking 15- and 20-ampere receptacles. • New Section 422.6 requires that all appliances operating at 50 volts or more to be listed. • All battery management equipment and batteries, except lead-acid, must be listed per Section 480.3. • Electrical metallic tubing is no longer allowed for installation in Class 1, Division 2 areas per Section 501.10(B)(1). www.csemag.com
Figure 3: Devices like this emergency lighting branch circuit transfer relay will now be evaluated to the performance and construction requirements that is applied to traditional emergency transfer switches for use on branch circuits rated up to 20 amperes. Courtesy: Ecoflex Solutions
• The surge protection device requirements have been expanded beyond emergency power systems to include protection for specific elevators, critical operations power systems and for industrial machinery per Sections 620.51(E), 645.18 and 670.6.
• The recent developments and growth in the renewable power systems generation and storage technologies have resulted to significant changes to the existing Article 690 along with addition of four new articles 691, 706, 710 and 712, all mentioned earlier.
• New requirements added throughout the NEC involving the documentation of the available short-circuit current at specific types of equipment (e.g., motor control centers, air conditioning equipment, elevators, industrial machinery and industrial control panels) and the date the short-circuit current calculation was performed. The documentation for the calculation required for the short-circuit current marking must be made available to the owner and to anyone maintaining or operating the facility and more importantly to the authority having jurisdiction.
• The short-circuit current rating of the transfer equipment, based on the specific overcurrent protective device type and settings protecting the transfer equipment, shall be field marked on the exterior of the transfer equipment per Sections 700.5(E), 701.5 (D) and 702.5. • New Section 725.144 has been added to address requirements for types of Class 2 and 3 cables for transmission of data and power to connected devices. This is commonly referred to as power over Ethernet and is becoming very popular for many applications such as circuiting for LED lighting.
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• Have a connection for a portable diesel generator. • Are listed for emergency system use. The fuel cell systems will now be permitted to serve all or part of an essential electrical system. The requirements for sources of power for essential electrical system of a health care facility was located at article 517.35 of NEC 2014, which as a minimum required two independent sources of power — a normal power source and one or more alternate power sources for use when the normal power source is interrupted. For the 2017 NEC, the requirements for two independent sources of power and an alternate source of power for the essential electrical system for health care facilities were revised and relocated to article 517.30. The most notable change was the addition of fuel cell systems to the list of acceptable sources of alternate power. Emergency Systems — Tests and Maintenance: Section 700.3(F) — Temporary Source of Power for Maintenance or Repair of the Alternate Source of Power. According to the new subsection (F), if the emergency system relies on a single alternate source of power, which will be disabled for maintenance or repair, the emergency system shall include permanent switching means to connect a portable or temporary alternate source of power, which shall
be available for the duration of the maintenance or repair. The permanent switching means to connect a portable or temporary alternate source of power shall comply with five provisions listed in the code. It shall be permissible to use manual switching to switch from the permanent source of power to the portable or temporary alternate source of power and to use the switching means for connection of a load bank. There was a statement at the end of section 700.4(B) of 2014 NEC that said, “A portable or temporary alternate source shall be available whenever the emergency generator is out of service for major maintenance or repair.” However, there were no prescriptive requirements provided for this requirement in 2014 NEC, causing confusion, which resulted in the addition of new subsection into 2017 NEC to clarify the requirements for a permanent switching means for emergency systems that rely on a single alternate source of power. Emergency System — Circuit Wiring: Section 700.10(D) — Fire Protection. According to modified subsection (D), emergency systems shall meet the additional requirements in (D)(1) through (D) (3) in the following occupancies: • Assembly occupancies for not less than 1,000 persons. • Buildings above 75 feet in height. • Health care occupancies where persons are not capable of self-preservation. • Educational occupancies with more than 300 occupants.
Figure 4: Part IV was added to Article 705 of the 2017 edition of the National Electrical Code to address all the issues related to microgrid systems as an interconnected electric power production source. This shows a microgrid distribution plan. Courtesy: Arup
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The subsection 700.10(D) in 2017 NEC was expanded by adding Health care and Educational occupancies to the requirements for fire protection of emergency system feeders in addition to high-rise buildings and buildings with high occupancy loads. All efforts shall be made at the engineering, designing, plan review and construction stages of a project for the protection of emergency circuits in Health care and other listed occupancies from damage due to a fire. The fire protection methods employed shall provide a minimum two-hour fire rating for the emergency cables or raceways and contain only emergency wiring circuits as required. Emergency Systems — Control of Emergency Lighting Circuits: Section 700.25 — Branch Circuit Emergency Lighting Transfer Switch. A new definition along with provisions and requirements have been added to the 2017 edition as part of the reason to introduce the new branch-circuit emergency lighting transfer switches into the code. Emergency lighting loads supplied by branch circuits rated www.csemag.com
at not greater than 20 amperes shall be permitted to be transferred from the normal branch circuit to an emergency branch circuit using a listed branch circuit emergency lighting transfer switch. The mechanically held requirement of 700.5(C) shall not apply to listed branch circuit emergency lighting transfer switches. Section 700.25, along with its definition described in section 700.2, were added to ensure code compliant devices under UL 1008 standards are used. These devices will now be evaluated to the performance and construction requirements that is applied to traditional emergency transfer switches for use on branch circuits rated up to 20 amperes. In the past there were no clear definition or requirements stated in the code and over the years automatic load control relays have been used to transfer emergency lighting loads from the normal supply to an emergency supply even though this is not in compliance with section 700.26. The addition of section 700.24 to 2011 NEC did not clearly address the issue, but now the addition of 700.26 in the 2017 NEC shall eliminate any misunderstanding of the code intent. Interconnected Electric Power Production Sources: Article 705, Part IV — Microgrid Systems. The microgrid systems also referred to as “inten-
tionally islanded systems” and “stand-alone systems” have been getting a lot of recognition in recent years as a way to reduce energy usage, lower cost and, more importantly, add resiliency against the loss of utility power. Microgrids are small wiring systems consisting of generation, energy storage and load(s) or any combination thereof that shall be permitted to disconnect from the primary source of power or other interconnected electric power production sources and operate as a separate microgrid system. The 2014 NEC did not clearly address the installation of microgrid systems and a new Part IV was added to Article 705 of 2017 NEC to address all the issues related to microgrid systems as an interconnected electric power production source. The code changes/additions are in response to the recent developments in microgrid systems industry to further develop a flexible and efficient electric grid, by enabling the integration of growing deployments of renewable sources of energy such as solar and wind and distributed energy resources such as combined heat and power, energy storage and demand response. cse Vahik Davoudi is an associate principal at Arup. He is an expert at codes and energy standards with more than 30 years of experience in the building industry.
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CASE STUDY
By David B. Korzuch Jr., PE; and Christopher J. Barbieri, PE, CRB, Philadelphia
Energy-efficient clean rooms Designers formulated several energy-saving strategies that can be implemented into the HVAC system design of a pharmaceutical-grade clean room suite
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eating, ventilation and air conditioning systems account for a large percentage of the total energy use in a typical commercial building. Functionally intensive buildings, such as pharmaceutical and biotechnology manufacturing facilities, consume much more energy per square foot and often take exception to energy-efficient building codes that typically apply to the design of commercial buildings. The average commercial office building built after 2000 has an average energy use intensity of 81.4 Btu/square foot (257 kilowatt hours/square meter) The average pharmaceutical plant has an EUI of 1,210 Btu/square foot (3,819 kilowatt hours/ square meter). This is due to the fact that these types of facilities consume energy to maintain clean room environments, to power production equipment and to power large utility generation equipment. • Learn about the energy-efficient An increasing number of projdesign strategies that should be considered for a clean room ects have attention focused on enerHVAC system. gy reduction initiatives, such as • Understand the energy use of green building certification and clieach clean room design strategy ent-mandated energy benchmarks. and how each one compares to These are structured around corpoa traditional design approach. rate goals and strategies for sustain• Evaluate the most common ability and reduced carbon footprint. HVAC system design It’s no surprise that energy reduction approaches to consider for requirements similar to the design of maintaining a clean room environment. commercial buildings are unavoidable and must be accomplished using atypical strategies that take engineers, designers and clients out of their realm of comfort. Overdesigning and oversizing mechanical systems will directly result in higher capital and operating costs as well as facilities with higher carbon footprints. Increased emphasis on total building performance and energy code compliance, coupled
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with corporate sustainability goals, will be the mandate for the industry moving forward.
Energy codes
Energy codes are adopted at a local or state level. These codes establish minimum energy-efficiency requirements and other baseline requirements related to building construction. The International Energy Conservation Code is the most widely adopted energy code in the United States. The IECC establishes a baseline for energy efficiency by setting performance standards and requirements for the building envelope as well as the mechanical, electrical and plumbing systems (in both residential and commercial settings). ASHRAE Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings has been the benchmark for commercial building codes for the past few decades and is often adopted as code through the IECC. The IECC contains three basic options or approaches for commercial buildings: • Meet the requirements of ASHRAE 90.1. • Meet IECC prescriptive provisions. • Meet IECC total building performance provisions. In the past, there has been debate over the applicability of energy codes developed for commercial buildings as they relate to more industrial facilities. As states have adopted green building and energy codes, industrial facilities are generally directly included and fall under the jurisdiction of the code. There has been a rapid progression and development of energy codes and standards since 2010. Selective compliance and questions over code applicability will become a distant memory as energy codes are further refined. www.csemag.com
Figure 1: An open clean room design was programmed for flexibility to allow for future reconfiguration of low wall return chases and high-efficiency particulate air supply terminals. Courtesy: CRB
According to Pacific Northwest National Laboratory, the three most recent editions of the IECC and ASHRAE 90.1 have the potential to generate almost a 30% reduction in energy use compared to codes a decade ago. Their analysis, published in 2016, forecasts that energy codes will save U.S. homes and businesses $126 billion between 2012 and 2040. These savings correspond to 841 million tons of avoided carbon dioxide emissions, which equate to the annual emissions of 245 coal power plants. The new challenge for the design engineer is advocating for the application of cost-effective design practices and technologies that minimize energy consumption and carbon footprint without compromising the critical environmental parameters of industrial facilities.
HVAC design
The design of HVAC systems to serve pharmaceutical and biotechnology facilities is completely custom and is uniquely dependent upon the specific manufacturing process, raw materials and drug product as well as the project sponsor/client specific standards and requirements. Some clean rooms require very strict temperature and humidity control based on raw material or drug product requirements while other clean rooms require high levels of air containment or air filtration to protect the product from personnel or vice versa. Some clean rooms require all of the above as well as active pressurization controls. Therefore, not all clean room facilities are the same. Each project’s HVAC system requirements are unique and must be custom engineered in detail to
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Figure 2: A model clean room facility is used as the basis of this study (approximately 3,600 square feet).
implement energy-saving strategies that align with the scheme of the facility. The facility presented in this case study consists of approximately 3,600 square feet of clean room space consisting of ISO-7, ISO-8 and common circulation corridor. The study compares four different approaches, which are all common among engineers and designers for an HVAC system design of clean room spaces. The study assumes identically configured central plants serving the HVAC system for each model and provides the following central utilities for the purpose of this comparative analysis: consulting-specifying engineer
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• An air-cooled chiller with distribution pump to serve a chilled water-cooling coil. • Natural gas-fired steam boiler to serve steam heating and direct steam injection humidification requirements. • Natural-gas fired hot-water boiler to serve heating hot water requirements of the air systems. The four cases evaluated in this study each assume that the space will be maintained at 68°F plus or minus 2°F and relative humidity is controlled between 30% and 60%. Each air system of this study has its own purpose for supporting a clean room environment and is described in further detail.
CASE 1: 100% outside air unit
A once-through air system that provides 100% outside air to the clean room environment typically is required when the designer wants a system to serve suites where a biosafety level must be contained or where segregation is necessary to prevent cross-contamination between products or processes. A once-through system design is usually required as a result of suite pressurization relationships, dust extraction or fume containment needs or process equipment requirements. The design used in this case study consists of a central station air handling unit with cooling, heating, dehumidification and humidification capabilities that provides filtered, preconditioned outside air directly to the clean room environment. An exhaust system also has been provided in the analysis to remove air directly from the
Table 1: Fan sizing comparison by system type Air system type
Room(s) served
Supply fan data Room(s) area
Return/exhaust fan data
Outside air
Flow rates
Motor sizes
Flow rates
Motor sizes
Flow rates
3,575 square feet
13,800 cfm
30 hp
13,800 cfm
10 hp
13,800 cfm
CASE 1: 100% OUTSIDE AIR SYSTEM DESIGN 100% outside air unit
All
CASE 2: PRIMARY-SECONDARY SYSTEM DESIGN MUA-1 (primary unit)
-
-
600 cfm
1 hp
600 cfm
1 hp
600 cfm
AHU-1 (secondary unit)
Controlled nonclassified) corridor
1,070 square feet
2,150 cfm
3 hp
-
-
-
AHU-2 (secondary unit)
Grade C areas
575 square feet
4,250 cfm
10 hp
-
-
-
Grade D areas
1,930 square feet
8,950 cfm
20 hp
-
-
-
AHU-3 (secondary unit)
CASE 3: RECIRCULATION UNIT WITH ECONOMIZERS AHU-1 (unit with economizer)
CNC Corridor
1,070 square feet
2,200 cfm
3 hp
2,200 cfm
2 hp
100 to 2,200 cfm
AHU-2 (unit with economizer)
Grade C areas
575 square feet
3,450 cfm
7.5 hp
3,450 cfm
3 hp
150 to 3,450 cfm
AHU-3 (unit with economizer)
Grade D areas
1,930 square feet
8,200 cfm
20 hp
8,200 cfm
7.5 hp
400 to 8,200 cfm
CASE 4: FFU WITH MAU SYSTEM DESIGN MUA-1 (primary unit)
-
-
3,700 cfm
5 hp
3,700 cfm
5 hp
3,700 cfm
FFU room 1 (five fan-powered HEPAs)
CNC corridor
1,070 square feet
2,150 cfm
0.390 kW
-
-
-
FFU room 2 (two fan-powered HEPAs)
Grade C airlock
175 square feet
1,025 cfm
0.156 kW
-
-
-
FFU room 3 (five fan-powered HEPAs)
Grade C clean room
400 square feet
2,350 cfm
0.390 kW
-
-
-
FFU room 4 (two fan-powered HEPAs)
Grade D air lock
240 square feet
1,000 cfm
0.156 kW
-
-
-
FFU room 5 (14 fan-powered HEPAs)
Grade D Clean room
1,690 square feet
7,050 cfm
1.092 kW
-
-
-
Table 1: This evaluates a traditional HVAC system approach for the design of the clean room suite compared to several alternative designs that emphasize energy performance optimization and compliance with the latest energy-efficient building codes. Courtesy: CRB
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suite or from process equipment within the suite. The air handler is typically a custom unit with multirow heating and cooling coils using steam and chilled water, respectively, for temperature and humidity control. The fans require higher motor horsepower ratings to accommodate the necessary supply airflow rates of the clean room suite(s). This is due to higher air-change rates inside the clean rooms. The larger fans need to overcome higher static pressures from high-efficiency particulate air and ultralow particulate air filtration. These types of systems are extremely energy-intensive and are usually designed to include provisions for energy recovery to comply with international codes and ASHRAE standards.
CASE 2: Primary 100% outside air unit with secondary recirculation units
A primary/secondary air system is a traditional approach for clean room HVAC system design and consists of a 100% outside air primary unit for preconditioning makeup air to multiple recirculation-type secondary units. This design allows for a smaller 100% outside air unit, which provides only enough air to maintain the ventilation and pressurization requirements of the secondary units. Most facilities that have multiple clean room suites designed for multiproduct or campaign production use this approach for their HVAC system design. The secondary units contain smaller coils and fans that are designed to meet the specific temperature/humidity requirements and air-change rates of the individual clean room suites.
Figure 3: This schematic diagram of the air system design is associated with case 1 and case 2 of this study. Courtesy: David Korzuch, CRB
CASE 3: Recirculation units with enthalpy-based economizers
Dedicated, recirculation-type units with modulating (0% to 100%) enthalpy-based outdoor air economizers are being used for the clean room environment due to the advancement of direct digital control technology. HVAC systems for clean room environments operate best under constant conditions. Once the designer introduces modulating technologies for energy optimization, such as the dampers required of an economizer, the clean room suite risks controllability of pressurization and temperature/humidity excursions. However, due to the advancement of DDC technology for HVAC controls, systems are now programmed with complex algorithms capable of maintaining temperature, humidity and pressurization while compensating for modulating sequences related to fan speed, temperature reset strategy and outside air control. If the designer must meet more stringent energy conservation goals, such as U.S. Green Building Council LEED or more recent versions of ASHRAE 90.1, then economizers may be considered mandatory in the clean room’s HVAC system.
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Figure 4: A schematic diagram of the air system design is associated with case 3 and case 4 of this study. Courtesy: David Korzuch, CRB
CASE 4: Fan-filter modules with a makeup air system
Fan-powered HEPA filter modules are very popular in clean room environments and use energy-efficient electronically commutated motors to maintain the air-change requirements of the suites. The once-through air system for this configuration, which is more commonly referred to as a makeup air unit, would provide preconditioned outside air to the fan-powered HEPA modconsulting-specifying engineer
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ules. This design allows for a MAU that provides enough outdoor air to maintain the ventilation, pressurization and cooling air requirements of the clean room suite. Fan-powered HEPA modules would either be directly ducted or pull air from a common distribution plenum to serve the suites. The MAU would provide enough air to overcome any fan
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If the designer must meet more stringent energy conservation goals, then fan-powered HEPA modules with a MAU should be considered for the design of a clean room’s HVAC system.
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motor heat gain and other sensible heat gains within the space. If spaces have a larger latent heat gain (typically from a wet process), then this HVAC system design is not ideal considering dehumidification is provided by the MAU and is not directly controlled for each suite. If the designer must meet more stringent energy conservation goals, such as LEED or more recent versions of ASHRAE 90.1, then fan-powered HEPA modules with a MAU should be considered for the design of a clean room’s HVAC system.
Table 2: Annual cost analysis CASE 1
CASE 2
CASE 3
CASE 4
HVAC COMPONENT ANNUAL COSTS Air system fans
$26,483
$21,465
$24,729
$7,299
Cooling
$24,598
$8,477
$3,224
$10,733
Heating
$29,103
$1,818
$964
$10,246
HVAC subtotal
$80,184
$31,761
$28,917
$28,279
NON-HVAC COMPONENT ANNUAL COSTS Lights
$1,098
$1,098
$1,098
$1,098
Electric equipment
$4,814
$4,814
$4,814
$4,814
Non-HVAC subtotal
$5,912
$5,912
$5,912
$5,912
GRAND TOTAL
$86,096
$37,672
$34,829
$34,191
Table 2: The case study presents 12 months of estimated energy performance data and garnered energy use on a dollar-per-square-foot basis that can be used as a conceptual tool by designers and engineers to aid in the development of more energy-efficient clean room facilities. Courtesy: CRB
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It also should be noted that these types of systems are notorious for having balancing issues and it may be difficult to meet pressurization requirements if plenums are not properly sealed or balanced.
Study results, achieving energy efficiency
This study produced comparative energy modeling calculations of four different air-system design approaches and how they relate to a model clean room environment. Modeling was conducted using a third-party computer-based program to perform an 8,760-hour energy simulation to determine the energy consumption of each case. The study has concluded that airflow rates remain relatively constant among different design strategies due to the mandated air change requirements of the facility; however, fan motor efficiency and air delivery method for conditioning the clean room environment is very different in each model and proves to be where the majority of energy usage occurs within each design strategy. Fan energy and space conditioning typically account for about 47% of energy use in pharmaceutical manufacturing facilities. Therefore, even small reductions in the required air-change rates can garner large energy-saving opportunities over the annual energy usage profile of the facility. As shown in Table 1, each system’s total supply flow rate is relatively equivalent; however, varying the air delivery and conditioning methods across each case presents opportunities for energy-conscious design. The model shows that case No. 4 provides the greatest amount of energy savings due to the extremely efficient ECM fan motors that maintain the required air-change rates within the spaces. The MAU only requires two 5-horsepower fans to deliver the optimal amount of outside air to the clean room environment for space conditioning; the designer must be careful to properly size the MAU for conditioning the heat gains and heat losses in the spaces to ensure space temperature and relative humidity can be maintained. The designer must also account for pressurization air gains and losses into the clean room suites, as the MAU and associated exhaust fan will need to maintain the required pressurization of the facility, which hasn’t been factored into this analysis. It should be noted that this type of system design doesn’t work well for large clean room areas with lots of separate rooms at different pressurization levels. In addition, this type of design could require more maintenance due to a large quantity of fan filter units. The second alternative in pursuit of a more energy-conscious HVAC design is a traditional www.csemag.com
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BUILDING SOLUTIONS
CASE STUDY
Table 3: Annual cost analysis per square foot by case CASE 1
CASE 2
CASE 3
CASE 4
HVAC COMPONENT ANNUAL COSTS PER SQUARE FOOT Air system fans
$7.408
$6.004
$6.917
$2.042
Cooling
$6.881
$2.371
$0.902
$3.002
Heating
$8.141
$0.509
$0.270
$2.866
HVAC subtotal
$22.429
$8.884
$8.089
$7.910
NON-HVAC COMPONENT ANNUAL COSTS PER SQUARE FOOT Lights
$0.307
$0.307
$0.307
$0.307
Electric equipment
$1.347
$1.347
$1.347
$1.347
Non-HVAC subtotal
$1.654
$1.654
$1.654
$1.654
GRAND TOTAL
$24.083
$10.538
$9.742
$9.564
Table 3: This summarizes the component costs in an estimated dollar per square foot metric that can be extrapolated and used by designers looking to baseline the annual energy use of a clean room facility based on HVAC system type. Courtesy: CRB
‘
A methodical approach to the overall building design can have a significant impact on reducing the HVAC loads and the overall energy consumption.
’
primary and secondary air system strategy, which is identified as case No. 2. The designer using this system must ensure the design meets the latest version of energy code, which may now require alternative design methods, such as HVAC systems with 0% to 100% economizer controls, to be considered. If economizers are considered for a clean room facility, the designer would need to carefully identify a design method for managing the economizer system functionality and would need to provide a means to exhaust the necessary airflow from the clean room during that mode of operation. Therefore, the designer must be aware that this design strategy would likely result in more controls and equipment to achieve the economizer function. Case No. 3 shows the annual energy use of three air handling systems with integrated economizers. The cost of heating and cooling energy
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use reduces significantly when considering the use of economizers of case No. 3 compared with the primary/secondary system of case No. 2; however, the designer must be aware that the facility’s pressurization strategy could be jeopardized with the introduction of air-side economizers. Water-side economizers may be a better alternative to comply with energy code and are typically preferred over air-side economizers when designing clean room HVAC systems. Twelve months of energy data based on the simulated energy model were compiled and the estimated energy use of each HVAC system design are summarized in Tables 2 and 3. Table 2 shows component costs based on an average electric rate of $0.973 kilowatt hours and an average natural gas rate of $10.13/mille cubic feet. Table 3 summarizes the component costs in an estimated dollar per square foot metric that can be extrapolated and used by designers looking to baseline the annual energy use of a clean room facility based on HVAC system type.
Best approach and recommendations
As with all building design, energy efficiency needs to be evaluated at the beginning of the design process. The approach should be a collaborative one that involves the design and construction teams. Thoughtful consideration should be applied to developing key building attributes. This needs to be discussed early in the design process due to the major impact they can have on the overall building energy consumption and more specifically, the HVAC systems. A methodical approach to the overall building design can have a significant impact on reducing the HVAC loads and the overall energy consumption. Slight changes in key attributes, such as glazing types and amounts, can be easily be modeled in various design platforms showing real-time impact of the design decisions. Another key aspect for the design process is defining meaningful and measurable energy performance benchmarks and setting project-specific goals. With clearly defined goals, the design team can develop energy-saving strategies for the various building systems. When approaching HVAC design for a clean room application, the first step is documenting key performance parameters of the critical environment, such as cleanliness levels, temperature, humidity, pressurization and air changes per hour. The definition of these requirements is a vital initial step in the HVAC design process as it has the largest impact on system sizing and configuration and the overall complexity of the facility. Often, the owners of the facility have established ACH that are associated with their unit www.csemag.com
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BUILDING SOLUTIONS
CASE STUDY
operations and the required cleanliness level. Advocating for a risk-based approach and challenging established practices will be the required paradigm shift for the design team moving forward. Without designers advocating for lower airchange rates, many owners will remain averse to changing their guidelines despite energy and cost savings due to perceived risk. In addition, the design teams must challenge common misconceptions associated in the industry with respect to the zoning of HVAC systems and the effectiveness of proper filtration. Unless there is potential for free-floating viruses, pushing for increased unit segregation with HVAC systems should only be considered in extreme situations. Maintaining the status quo, using high ACH rates and increasing the complexity of HVAC systems to mitigate perceived risk directly correlates to increases in initial facility cost, ongoing operational costs and a carbon-intensive facility. Another key aspect for consideration when designing HVAC systems for clean rooms, although not the intent of this article, is understanding the impact of hazardous raw materials, such as flammable, combustible liquids and potent compounds. As a designer, it is vital to understand the quantities and types of materials used in the process, as they
have design and code implications related to personnel safety, building safety and environmental impact. Building codes, fire codes and adopted standards will dictate the design of facilities using such materials in their processes. In general, more stringent ventilation requirements will be the result of using these materials and will take precedence over some of the energy code requirements due to the impact on life safety. A risk-based approach combined with analytical and economical models can assist the design team in determining the appropriate HVAC system design that not only meets the critical design requirements of a facility, but also achieves an energy-efficient and code-compliant design. cse David B. Korzuch Jr. is a mechanical engineer at CRB, focused on HVAC and mechanical system design for current good manufacturing practice manufacturing facilities, laboratories and central utility plants for the biotech and pharmaceutical industries. Christopher J. Barbieri is a project manager and the mechanical discipline lead at CRB, focused on discipline specific and cross-functional strategic initiatives and tactical tasks for the company.
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ENGINEERING INSIGHTS
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consulting-specifying engineer
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ENGINEERING INSIGHTS
MEP ROUNDTABLE
Lab, research facility design Learn tips on how to design labs and research facilities — some of the most high-tech buildings around CSE: What’s the biggest trend in laboratory and research facility projects? Kelley Cramm: Probably the biggest trend we’re seeing is an increased move toward open, modular laboratories. Open, modular labs accommodate changing research over time and allow flexibility for new equipment, researchers and evolving technology. They also improve collaboration between researchers from multiple disciplines. To improve flexibility, many labs are using pre-wired and piped modular casework with “plug and play” capability. The utilities are supplied to a ceiling panel or overhead service carrier and connected to the casework from there. Utilities can be distributed to every module with services not initially needed valved and capped above the ceiling or in the overhead service carrier. This allows flexibility for changing needs with minimal disruption. Bryan Floth: The biggest trend we’re seeing within laboratory and research facility projects is designing for flexibility. Advances in scientific research are accelerating in all areas. This has created unprecedented demand for new and more sophisticated facilities that can accommodate state-of-the-art technology. The cost to remodel facilities at the same rate can be substantial. It’s forcing a lot of planning and designing to be more generic and flexible, to better react to shifts in the industry.
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George Isherwood: The biggest trend we are seeing is working through the balance of energy efficiency with equipment costs for the energy performance. Most, if not all, of our clients have “green” plans until they realize the increase in equipment costs. Adam Judge: Most new facilities we have seen in the past few years have included large, shared open lab areas that catalyze collaboration and conversations among researchers. This collaboration encouraging concept is even spreading outside the laboratory spaces and into the common area and circulation spaces, such as open stairways and atria creating visibility between different floors, areas or departments. Often the primary investigators are not all known at the time of design, so most laboratory spaces need to be designed to be flexible for adaptation to future needs. Iain Siery: Generally, I think advanced therapeutic medicinal products research and development are on the rise. This is particularly true in Philadelphia, where several key advancements have been made that are driving significant attention to this space within life sciences. These projects have different drivers and require specific expertise to create facilities that support clients in this field. David Wilson: Providing flexibility in the design of laboratory spaces and utilities to allow for modifications to the laboratory spaces on an individual basis as research changes or changes in research-
ers occur. The advancement in technology and funding availability is often driving changes in the type of research being performed at any given time and changes appear to be occurring more rapidly than in the past. CSE: What future trends should engineers expect? Isherwood: Integration of the controls throughout the projects are starting to gain momentum in the industry. We are starting to see multiple trades starting to work together to accomplish a more efficient system. Window shade controls are interfacing with lights that are interfacing with temperature controls. There have been several challenges with integrating these systems and allowing them to not only read into their system but adjust setpoints as well. Siery: I am expecting continued and increasing pressure on projects due to overall cost. Today, we explore numerous approaches to managing the cost of projects. This includes saving time by integrating the design and construction process, as well as design approaches that directly manage cost such a target value design/delivery. Finding the right balance of flexibility, speed of delivery and cost has been increasingly central to the success of research laboratory projects. These aspects can be at odds in many cases. In particular within the life sciences R&D industry, speed to market is becoming
Kelley Cramm, PE, LEED AP BD+C
Bryan Floth, LEED AP, AIA
George Isherwood, PE
Associate/Mechanical Technical Leader Henderson Engineers Kansas City
Senior Project Manager Burns & McDonnell Kansas City, Mo.
Vice President, Health Care/Laboratory Group Leader Peter Basso Associates Inc. Troy, Mich.
December 2019
consulting-specifying engineer
www.csemag.com
more critical, so solutions to these challenges must continue to evolve. Floth: Speed to market is critical for lab and research facility projects today and will continue to be critical in the future. There is a growing expectation for buildings to be designed and built faster. Schedule, productivity and innovation are always top of mind. Any scenario in which the research associated with a lot of these facilities is delayed can delay the ability of the research organization to meet market deadlines. We’re incorporating lean principles and management approaches into the process to help meet expectations, delivering a high-quality, on-schedule project. The purpose of the lean management approach has two central components: a fully integrated team approach to design and delivery from the early stages of a project, and the incorporation of lean principles, processes and tools to attack the sources of waste. Together these two concepts can translate to big advantages for an owner. Cramm: I think an increased demand for sustainability and reduced carbon footprint will be the overarching trend. Laboratories consume massive amounts of energy and water. This will drive changes to the way we design labs and to the way users operate in the lab. We will see an increase in the use of energy recovery, high-performance fume hoods, occupancy-based setbacks for lighting and ventilation, wind responsive exhaust fan modulation and improved ventilation effectiveness at lower air change rates. Users will be pushed to use more efficient lab equipment — especially freezers — and to shut down lab equipment when not in use. Judge: I expect future projects to continue the trend of flexibility. This may mean flexibility to adapt the design to different floor plan layouts, different equipment or other environmental requirements as researchers are recruited during the design phase, during the construction phase or post-occupancy.
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Figure 1: The University of South Florida Health Morsani College and Heart Institute is a new research and teaching facility designed to provide students with a high-tech learning environment, a with an advanced research facility to explore new heart disease treatments. Features include clinical teaching laboratories, large lecture halls, smaller classrooms and teaching labs and flexible space. Courtesy: TLC Engineering Solutions
CSE: What types of challenges do you encounter for these types of projects that you might not face on other types of structures? Cramm: Density of power is one key difference. We’re seeing an increased use of ultralow-temperature freezers and analytical instruments that come with computers and printers attached. This equipment demands more power than most other occupancies. Spare circuits to accommodate future growth and new instruments are critical. Another key difference is the hazards associated with laboratories and the resulting need for
Adam Judge, PE
Iain Siery, PE
Associate/Mechanical Project Engineer TLC Engineering Solutions Tampa, Fla.
Senior Mechanical Engineer CRB Philadelphia
containment to protect personnel. This drives us to fully exhausted laboratories with systems that need to run 24/7. Another difference is the increased use of gases that create a flammability or asphyxiant hazard. These require specialized systems to mitigate the risk to human life and health. Wilson: The challenge is designing utility and utility systems to be generic in nature but customized on a lab-by-lab basis to meet the current research needs of each individual space. Providing utility systems for future use in each laboratory may add additional upfront cost when initially constructing the building but allows
consulting-specifying engineer
David Wilson, PE, LEED AP Senior Engineer Dewberry Raleigh, N.C.
December 2019
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ENGINEERING INSIGHTS
MEP ROUNDTABLE
for modifications to each laboratory on an individual basis without affecting adjacent spaces and associated research occurring in each space. Long-term research can be lost if disruptions to utility systems occurs due to shutdowns required to modify utility systems. Floth: The biggest challenge is the complexity of these projects. Science facilities require design that integrates specialty building systems, utilities and equipment with the human element of a pleasant working environment. Each laboratory, clean room or research space has unique environmental requirements, but all have a focus on efficiency, flexibility and safety at their core. Layered on top of that, many facilities hope to attract grants and achieve other unique certifications, requiring additional guidelines beyond making the building code compliant. Judge: Building in sufficient flexibility for changes in laboratory spaces can be much more challenging than in other types of buildings. Because laboratory equipment can often vary widely in utility requirements, much more flexibility must be built in. In addition, with the governing energy efficiency codes become more stringent, laboratory facility design often requires thinking out of the box to not only meet energy code requirements, but often beat them to meet the sustainability goals of the project. Isherwood: Most buildings are built with the intent of keeping the occupants comfortable. People working in offices
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and students in classrooms are more productive when comfortable. Laboratories introduce harmful elements into that environment that can affect both the safety of occupants and the surrounding areas. The management of chemicals or other harmful elements is what makes laboratories unique. Siery: Specific design challenges include creating inspirational environments that balance scalable infrastructure, flexible casework and utility distribution, constructability and project cost and schedule drivers. CSE: What are engineers doing to ensure such projects meet challenges associated with emerging technologies? Cramm: Innovation and creativity are key to successful laboratory design. The understanding that what’s happening in the lab today will not be what’s happening in the future is critical. Engineers should never design a “purpose built” laboratory. All systems and utilities need to be designed to be flexible enough to adapt to future changes in laboratory equipment and evolving research. This means planning for systems to be expandable and designing services using a modular planning approach. It also means sizing ducts and chases to allow for additional airflow and providing plenty of spare electrical circuits in panelboards to accommodate the inevitable addition of laboratory equipment. Floth: Having an integrated team is a game changer when it comes to delivering facilities that meet challenges associated with rapidly evolving technologies. Long before design begins, our architects, engineers, planners, environmental specialists and construction professionals work with clients to establish requirements. This gets all stakeholders and involved parties on the same page from day one. By interviewing lab stakeholders — from director to technicians — our designers help shape facilities’ physical and aesthetic goals and objectives. We carefully analyze traffic flow, space needs, type and number of analyses, standard testing methods, lab safety and equipment and regulatory requirements — a crucial first step in turning the vision of a facility into steel, concrete and glass, utilities and systems. Judge: Engineers need to get as good of an understanding as possible of potential future plans for the laboratory spaces. Considerations must be taken regarding ventilation, cooling and exhaust, power requirements — including emergency generator or uninterruptible power supply standby power — water requirements, data requirements and chemical quantity limitations of potential future equipment and processes. The design team must inform the owner of the assumptions and limitations they must live with. Siery: I am seeing significant emphasis on integrated solutions that bring the design and construction experts together (design-build and design-assist) to improve overall project schedule. Then these teams can more effectively leverage budget management strategies such as target value delivery to ensure the project is successful. CSE: Tell us about a recent project you’ve worked on that’s innovative, large-scale or otherwise noteworthy.
54
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RedeďŹ ne
Floth: One recent project our team was selected for is the NextGen Precision Health Institute at the University of Missouri. We’re providing architectural, master planning and engineering design services for the $220.8 million research facility. The facility will aim to bring together industry partners; engineering, medicine and veterinary science students; and the federal government to pursue a collaborative approach to personalized health care, supported by advanced technology. Construction for the 275,000-square-foot facility is expected to be completed in October 2021. Judge: Construction is nearing completion of the new 395,000-square-foot, 13-story University of South Florida Morsani College of Medicine and Heart Institute in the newly designated Water Street district in downtown Tampa, Fla. TLC Engineering Solutions teamed with architects HOK and builder Skanska for this design-build project with an estimated construction cost of $173 million. The project includes four classroom floors, including a 400-seat auditorium; three research laboratory floors; two shelled floors for future laboratory space; three shelled floors for future classroom, office or clinical space; and approximately 6,200 square feet of ground floor space shelled for future tenants. The project includes run-around hydronic heat recovery loops to transfer heat from incoming outside air to exhaust airstreams and reduce cooling demand, purchased from a district chilled water plant. High-efficiency, low-flow fume hoods with automatic sash closers were specified to reduce outside air requirements. High-efficiency, natural gas fired condensing boilers are used to provide heating hot water and plate and frame heat exchanger skids are used to heat domestic hot water using heating hot water as a heat source. cse
M More ROUNDTABLE
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United Wire & Cable . . . . . . . . . . . .35 . . . . . . . . .11 . . . . . . .www .MaxiampUnderground .com
Marketing Consultant Brian Gross BGross@CFEMedia.com 3010 Highland Parkway, Suite #325 630-571-4070 x2217 Downers Grove, IL 60515
REQUEST MORE INFORMATION about products and advertisers in this issue by using
International Stuart Smith stuart.smith@globalmediasales.co.uk SSM Global Media Ltd. +44 208 464 5577
SENS . . . . . . . . . . . . . . . . . . . . . . . .25 . . . . . . . . . 7 . . . . . . . .www .sens-usa .com
the www.csemag.com/information link and reader service number located near each item. If you’re reading the digital edition, the link will be live. When you contact a company directly, please let them know you read about them in Consulting-Specifying Engineer.
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consulting-specifying engineer
www.csemag.com
Uncomplicate Your Day Control Your HVAC System With Yaskawa Drives
Expo R H A t a Visit us- Feb 3, 2020 J a n 3 0 L a s Ve g a s , N V 71 Booth #4
Controlling comfort throughout a facility presents unique challenges. Make your complicated day simple by using Yaskawa variable frequency drives for reliable, consistent performance. Whether you are looking at a new project or a retrofit, consider Yaskawa drives. Our Z1000 and Z1000U Matrix drives are designed specifically for your HVAC applications and deliver simplicity, efficiency, and low harmonics at all loads to meet your specific needs. Yaskawa. We make the complicated simple.
Yaskawa America, Inc.
Drives & Motion Division
1-800-YASKAWA
yaskawa.com
input #16 at www.csemag.com/information
http://go.yaskawa-america.com/yai1357
KOHLERPOWER.COM
OVERPOWER
POWER OUTAGES.
This is a KOHLER® power system. And it’s built to perform. How do we know? We engineered it ourselves. Generators, engines, transfer switches, switchgear, controllers – you name it, we make it. Every part is designed to work with the entire system. So when the grid goes down, you’ll be glad you spec’d Kohler. Visit KOHLERPOWER.com/Industrial and never lose power again. input #17 at www.csemag.com/information