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Vol. 56, Number 8

SEPTEMBER 2019

24 | Framework for designing the intelligent building

Intelligent buildings are no turnkey matter

30 | Evaluating power quality for mission critical facilities

Mission critical facilities that use sensitive power electronics have small tolerances for power source deviations

ON THE COVER: The recently opened Baptist M.D. Anderson Cancer Center in Jacksonville, Florida, incorporates condensing boilers for heating hot water. These are very high efficiency; the ones shown are gas-fired boilers. Courtesy: TLC Engineering Solutions

36 | Designing for power quality

NEWS &BUSINESS

42 | Determining which boiler system to design

5 | Viewpoint

Communicating with fellow engineers

7 | Research

Lighting in government, military buildings

9 | Career Smart

Three ways to retain engineering talent

11 | Future of Engineering

Four engineering industry trends to watch

BUILDING SOLUTIONS 12 | Pipe systems and materials: Design considerations

Choosing the right pipe system and design is essential

18 | Outcome-driven system integration in smart buildings

Digitalization is evolving the design and operation of the built environment

Engineers should follow four steps during the project life cycle to reduce harmonic distortion

There are many different configurations of boilers; learn about the three primary types

44 | Introduction to boilers for the entry-level engineer

Entry-level consulting engineers should understand the definition and applications of a commercial hydronic boiler

ENGINEERING INSIGHTS 50 | Enhancing efficiency in industrial and manufacturing facilities

There is more than meets the eye when it comes to warehouses and factories

55 | 2019 Product of the Year winners

Winners of the 15th annual Consulting-Specifying Engineer Product of the Year awards are featured

2019 WINNERS

CONSULTING-SPECIFYING ENGINEER (ISSN 0892-5046, Vol. 56, No. 8, 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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September 2019

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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.

Communicating with fellow engineers What’s the best way to connect? Like many other responses to questions about engineering, the answer is “it depends”

lack, Tumblr, Twitter, WeChat, Engineers study managed by CFE video chat, Pinterest, TikTok, Media, the parent company of this Instagram, messaging — the brand, had a different take. The 2018 list goes on and on. How many report showed that 33% of respondents of these tools are you using never used social media for work. The today to connect to clients, colleagues next biggest number, 16%, use social and family? media two to three times per week. The worldwide data about When respondents did social media and smartphone use social platforms, the preoptions is a bit overwhelmferred channel is LinkedIn, ing. The number of different with 79% of survey particiapps available to the planet’s pants indicating they use it 5.1 billion smartphone users for work-related informagrows by the day. According tion. The primary reasons to We Are Social, the numengineers don’t use other ber of unique mobile users social networking tools is Amara Rozgus, grew 2.6% from April 2018 because the information is Editor-in-Chief to April 2019. Jumping dounot credibly sourced by other ble-digit numbers over that engineers or just isn’t technisame time period, mobile social media cal enough. While engineers might be users grew 11%. using Facebook to connect socially to Your ageing uncle most likely isn’t family and friends, they’re not finding using Hootsuite to manage his social it a useful tool to obtain information feeds, or posting to YouTube, but as about products or specifications. these tools continue to grow worldIn an ongoing research study being wide, more people will move toward conducted by Consulting-Specifying using these options for communication. Engineer, respondents have indicated The Center for Generational Kinetics thus far that about half of Generation Z reported in fall 2018 that 35% of Gener- are lacking communication skills, both ation Z — loosely defined as those born internal and external, as they enter the 1995 to 2015 — use their smartphones workforce. That’s rather ironic, as these one to four hours per day, and anoth- junior team members spend so many er 35% use them five to nine hours per hours per day communicating on their day. They’re completely immersed in smartphones. a mobile world, something that older Back to the original question: What’s generations might not be able to say. the best way to communicate? The Engineers are a bit different. While answer appears to be a moving target, certainly tech-savvy, engineers who and individuals will need to keep up-toparticipated in a 2018 Marketing to date on the options. 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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consulting-specifying engineer

September 2019

•

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Value of fire, life safety systems

NEWS&BUSINESS

RESEARCH

Less than $500,000

Don't know

16%

22%

More than $5.0 million

20%

25% 17%

$1.1 million to $5.0 million

$500,000 to $1.0 million

Figure 1: Engineering firms specified an average of $2.6 million in fire and life safety systems for new and existing buildings in 2018. Source: Consulting-Specifying Engineer 2019 Fire & Life Safety Study

37%

of engineers expect to specify demand-controlled ventilation systems and energy recovery systems in the next 12 to 24 months. Source: Consulting-Specifying Engineer 2019 HVAC & Building Automation Systems Study

7 in 10

engineering firms obtained design revenue in 2017 for projects involving electrical distribution systems and circuit breakers, fuses, etc. Source: ConsultingSpecifying Engineer 2018 Electrical & Power Study

24%:

Average amount of billable hours/time at work that engineers spend researching and/or specifying lighting and lighting controls. Source: Consulting-Specifying Engineer 2019 Lighting & Lighting Controls Study

More research Consulting-Specifying Engineer covers several research topics each year. All reports are available at www.csemag.com/research.

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LIGHTING & LIGHTING CONTROLS STUDY

Lighting in government, military buildings

orty percent of engineers specify, design or make product selections for government or military buildings, according to the Consulting-Specifying Engineer 2019 Lighting & Lighting Controls Study — and 88% 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 government or military building projects: 1. Technologies specified: LEDs (92%), occupancy sensors (88%), multilevel lighting or dimming (69%) and daylight harvesting (68%) are the most common types of lights, lighting systems or controls currently being specified into government or military buildings. 2. Design value: Engineering firms are specifying $787,500 annually, on average, in lighting and lighting control products for new and existing government or military buildings, with 40% specifying more than $1 million.

3. Specifications: For government or military buildings, prescriptive lighting specifications are written 74% of the time, followed by performance (71%) and open: alternate or substitute (69%). 4. Challenges: Inadequate budgets (64%), the speed of project delivery (49%) and designing for compliance with LEED, ASHRAE 90.1, California Title 24 and/or sustainability (48%) are the top challenges engineers face when specifying lighting for government or military buildings. 5. Design factors: When comparing lighting products for government or military buildings, engineers heavily weight product quality, energy efficiency, the manufacturer’s reputation and previous experience with the manufacturer. cse

M More RESEARCH

Access more lighting trends at www.csemag.com/research. Amanda Pelliccione is the research director at CFE Media.

Lighting design coordination in government, military buildings 92%

Architect

70%

Contractors (electrical, etc.)

59%

Electrical engineer

56%

Owner

53%

Facility manager Local authority having jurisdiction or local fire officials Mechanical engineer Commissioning agent or provider Fire protection engineer

37% 31% 25% 23%

Figure 2: When specifying lighting for government or military buildings, the architect has the most impact on design, followed by contractors and the electrical engineer. Source: Consulting-Specifying Engineer consulting-specifying engineer

September 2019

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input #6 at www.csemag.com/information

NEWS&BUSINESS

CAREER SMART

By Angie Keller, Randstad Engineering, Atlanta

Three ways to retain engineering talent Use these tips to keep engineers employed at your firm

here are a lot of challenges STEM sectors will need to overcome in the next decade. From upgrading the U.S.’s ageing infrastructure, to reducing manufacturing’s carbon footprint and guarding ourselves against the increased threat of cyberattacks — there’s a lot on our plates. To solve all these problems, we’ll need smart, dedicated engineering talent to lead the way. Unfortunately, they happen to be in short supply. By 2025, 3.5 million engineering jobs will need to be filled in just the manufacturing sector alone, but only 2 million of them are projected to be staffed, given the current shortage of talent. With so much competition, you need to make sure you can retain the engineers you do have to give your business the best chance of succeeding until the tight hiring market subsides. Here are three things you can do to improve retention levels on your engineering teams.

1. Up your upskilling efforts

With more job opportunities available to engineers, you may start seeing employees leave to take on new challenges that could broaden their skill sets and advance their careers. But if you take the initiative to provide training and development opportunities in-house, you may be able to anchor the gaze of a few of those wandering eyes and keep top performers on your premises for longer. Sixty-nine percent of employee respondents to a recent Gallup poll said that “professional and career growth opportunities” were important to them in a job — and that number jumps to 87% if we look at just millennials. Providing employees with the ability to learn new skills and hone their strengths helps

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improve retention by engendering loyalty: You’re demonstrating your commitment to their success and making it a priority to expose them to new skills that may make them more well-rounded candidates in the future.

‘

Forty-two percent of employees said they’re currently on the fence about leaving their jobs because of inadequate benefits packages, so the threat to engineering employers with subpar offerings is real.

’

2. Boost your benefits

Naturally, benefits and compensation packages are top of mind with employees when evaluating potential employers, so if you miss out on offering even just one or two highly prized perks — that may be all it takes to lose talent. Forty-two percent of employees said they’re currently on the fence about leaving their jobs because of inadequate benefits packages, so the threat to engineering employers with subpar offerings is real. Make a few adjustments to the range of perks you offer and monitor employee sentiment periodically to identify new trends in benefits expectations to keep your offerings up to date. In addition to upskilling, a recent Randstad survey revealed other popular incentives to consider to improve retention, like: • Early Friday release.

• On-site amenities like gyms, dry cleaning and childcare. • Flexible, remote work options. • Unlimited vacation time. • Benefits for different life stages (e.g., student loan support for younger workers, or more comprehensive health insurance for workers older than 50).

3. Keep your pay competitive

It’s a race to the top as far as salaries go in today’s war for engineering talent, so it’s important to make sure your wages are competitive. While a strong benefits and perks package is important — 61% of respondents to Randstad’s survey said they’d be willing to accept a lower salary if a company had a great benefits package — providing a decent wage is still one of the most effective ways to retain your best and brightest engineering contributors. Settling on that figure, however, can sometimes be difficult. To help you know where to start when establishing your pay rates, use an online salary calculator to see what the market averages are for the positions you’re looking to safeguard. While you can’t change the reality of the talent shortage across the market, you can take steps to improve retention levels on your own teams. Provide upskilling opportunities, align benefits with worker expectations and pay competitively to give yourself the best chance of retaining engineering talent. cse

Angie Keller is the senior vice president at Randstad Engineering, which specializes in the sourcing and placement of temporary and direct hire professionals in engineering, energy, utilities, petrochemical, manufacturing, information technology and other technologies industries.

consulting-specifying engineer

September 2019

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NEWS&BUSINESS

FUTURE OF ENGINEERING

By Neil Churman, 7 Mile Advisors, Houston

Four engineering industry trends to watch Are you ready for these technologies to change the way you work?

s with many industries, technology presents increasing opportunities for the engineering sector. While digital transformation is not a new phenomenon, several trends have come to the forefront recently as ones expected to continue driving change across industry firms. Drones, cloud computing, robotics and 3D printing are technologies that engineering firms are increasingly embracing to help streamline operations and run more efficient processes. Drones: Use of unmanned aerial vehicles, commonly known as drones, has been rapidly gaining traction in the construction and engineering industries. Minimizing risk, disruption and man hours, while still providing high-quality imagery and detailed information, presents an attractive opportunity for engineering firms. Outfitting drones with a variety of equipment and sensors allows for deployment in the service of a diverse set of goals — think LIDAR in the surveying process, developing topographic or hydrographic maps or aerial monitoring for project management purposes. As a recent report by Accenture outlines, incorporating drones should revolve around reinventing business processes rather than trying to force their integration into existing operations. Furthermore, firms must recognize drones represent a tool and the actual value to an engineering firm comes from the data produced, which can be analyzed and transformed into actionable information. Cloud computing: Cloud computing presents a transformative opportunity for engineering firms. Being able to harness advanced computing capabilities remotely means firms no longer have to rely on powerful in-house machines for comput-

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er-aided design or detailed simulations. This could present an advantage for smaller firms who no longer have to be limited on engagements by the amount of computing power readily available. For firms of any size, cloud storage can lessen the investment needed to store and manage large data sets, such as the output of LIDAR surveys undertaken via drones. Additionally, having plans and files in the cloud makes them readily shareable so that parties can work and collaborate in real time. With accessibility via mobile technology and the cloud, engineers can make changes in the field or on the jobsite. This eliminates the need to be the office to log changes, as well as the lag in notifying other stakeholders of updates. Robotics and robotic process automation: The less complex tasks of an engineering engagement represent opportunities to apply robotic process automation, a software tool that enables computers to automatically perform repetitive functions. These tasks could encompass some project-related functions, as well as back office processes. Additionally, as physical robotics gain traction in the construction industry itself, there is an argument that robotcentric construction can allow for later-stage changes by engineers and other design professionals without as much of a chance of incurring construction delays and cost overruns linked to the gap between the design and implementation phases. One could imagine an iterative improvement cycle wherein robotics applied to both the engineering and construction processes creates synergies that build upon one another throughout the design and build process. 3D printing: The applications of 3D printing to engineering are becoming

more tangible as companies source parts of the built environment via 3D printing. A 3D printed pedestrian bridge of microreinforced concrete was opened in late 2017 in Spain, and Dutch company MX3D is 3D printing a stainless steel bridge to span a canal as part of its proof-of-concept for its method of 3D printing most weldable alloys. While these may seem modest projects, large players in the engineering industry are taking notice of the promise of 3D printing. Ramboll Group, a Danish engineering and consultancy firm, noted how 3D modeling helps bridge the gap between the spatial thinking of architects and the engineers who make the design a reality. The ability to print directly from digital design files familiar to workers in the engineering industry, such as those produced using Autodesk and Bentley software, creates a streamlined process that has benefits both during a pitch process and once work is won. As the pace of digital transformation continues to build, the implications for the engineering industry grow in lockstep. Successfully incorporating technological change will continue to be a differentiator among firms. Whether to realize back office efficiencies, perform projects with greater precision or produce better outcomes on the jobsite, the trends outlined above can be gamechangers for the engineering firms that recognize the potential of using technology to the industry’s advantage. cse Neil Churman is a director at 7 Mile Advisors, where he leads the firm’s practice in advising architecture, engineering and construction industry firms on strategy, mergers and acquisitions and raising capital.

consulting-specifying engineer

September 2019

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BUILDING SOLUTIONS

PIPE AND PIPING MATERIALS

By Saahil Tumber, PE, HBDP, LEED AP, ESD, Chicago

Pipe systems and materials: Design considerations Choosing the right pipe system and design is essential to ensure excellence in mechanical, plumbing, fire protection and beyond

t’s easy to forget about pipe systems. Once installed, they are rarely seen or thought about. But that belies their importance, especially when it comes to choosing the right pipe system and design to ensure excellence in mechanical, plumbing, fire protection and beyond. Simply defined, pipes are pathways through which fluids are contained and flow in a system. The fluids may be water, glycol solution, fuel oil and refrigerant liquid. A network of pipes, fittings, joints, valves and supports is defined as a pipe system. There can be multiple pipe sys• Summarize commonly used tems on a typical project and they piping materials. can be segregated by disciplines such • Know the pipe sizing as civil (domestic water, stormwater, recommendations for sanitary, industrial water, wastewamechanical hydronic ter, etc.); mechanical or heating, venapplications. tilation and air conditioning (chilled • Learn about pipe supports water, condenser water, hot water, and thermal expansion steam, condensate, natural gas, fuel considerations. oil etc.); plumbing (domestic cold water, hot water, waste, vent, etc.); and fire protection (sprinkler water, compressed air, etc.). Pipe system design is dependent on the requirements and design criteria that are specific of each discipline. The design of pipe systems is also governed by codes such as those published by ICC and standards and guidelines published by trade associations such as ASME, ASTM, NFPA, MSS, AWWA and ASHRAE. An optimum pipe system design is critical to the operation and longevity of the overall infrastructure and requires a multipronged approach. With appropriate maintenance, piping is typical-

Learning

OBJECTIVES

•

September 2019

consulting-specifying engineer

ly expected to last the age of the building, while other equipment is replaced at the end of its service life. As pipe systems span multiple disciplines with varying requirements, developing an allencompassing design guideline would be a monumental task. There are numerous factors that need to be considered when selecting a pipe system, such as: • Type of fluid. • Fluid pressure. • Fluid temperature. • Fluid flow rate. • Code and authority having jurisdiction requirements. • Service life. • Project cost. • Project schedule. • Local labor expertise.

Piping materials

Pipes can be broadly classified as metallic type and nonmetallic type. Commonly used metallic pipes are carbon steel, copper and ductile iron. Metallic pipes and fittings have been used for ages and continue to be used extensively. Steel pipes manufactured in accordance with ASTM A53 standard specification are typically www.csemag.com

Table 1: Piping system maximum flow (ASHRAE 90.1 - 2016) Operating hours/year

<=2,000 hours/year

>2,000 and <=4,000 hours/year

>4,000 hours/year

NPS (inches)

Other (gpm)

Var flow/var speed (gpm)

Other (gpm)

Var flow/var speed (gpm)

Other (gpm)

Var flow/var speed (gpm)

2.5

120

180

130

110

180

270

140

210

110

170

350

530

260

400

210

320

410

620

310

470

250

370

740

1,100

570

860

440

680

1,200

1,800

900

1,400

700

1,100

1,800

2,700

1,300

2,000

1,000

1,600

2,500

3,800

1,900

2,900

1,500

2,300

14 to 24 (max vel.)

8.5 feet/second

13 feet/second

6.5 feet/second

9.5 feet/second

5 feet/second

7.5 feet/second

Table 1: ASHRAE 90.1-2016 piping system maximum flow is shown. Based on the flow configuration and annual hours of operation, maximum flow for different pipe sizes is indicated for chilled water and condenser water application. Courtesy: ESD

used in the mechanical industry. ASTM A53 covers nominal pipe size from 1/8 inch through 26 inches. Based on the manufacturing process and size, steel pipe can be classified as Type S (seamless), Type F (furnace butt weld) or Type E (electric resistance weld). Type F is available in Grade A while Type E and Type S are available in Grade A and B. The two grades have slightly different chemical composition of steel such as maximum percentage of carbon. Grade B is widely used due to its higher tensile strength. The wall thickness of steel pipe is identified by schedule or weight class. Depending on size, steel pipe is typically available from schedule 5 through schedule 160 and wall thickness increases with schedule number. For example, 8-inch steel pipe has an outside diameter of 8.625 inches. However, the wall thickness varies from 0.109 inch (schedule 5) to 0.906 inch (schedule 160). The working pressure of steel pipe increases with its schedule. ASME B31 identifies the criteria for calculating the working pressure of steel pipe systems. Calculations should include allowance for mill tolerance on wall thickness, corrosion allowance and cutting allowance if using threaded or cut-grooved joints. The ASHRAE Fundamentals Handbook is an excellent reference and it provides working pressure of commonly used steel pipe schedules from nominal pipe size 1/4 inch to 20 inches. www.csemag.com

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The working pressure of steel pipe increases with its schedule. ASME B31 identifies the criteria for calculating the working pressure of steel pipe systems.

For the mechanical industry, commonly used steel piping is schedule 40 and schedule 80 for sizes 10 inches and below. Schedule 40, STD (standard weight) and schedule 80 are commonly used for pipe sizes 12 inches and above. Steel pipes are typically joined by using welded, flanged, threaded or grooved-end fittings. A hybrid solution is common, such as using threaded fittings for pipes 2 inches and below and flanged fittings for sizes 2.5 inches and above. Copper tubes manufactured in accordance with ASTM B88 standard specification for water service; ASTM B306 for drain, waste and vent service; and ASTM B280 for air conditioning and refrigeration service are typically used in the mechanical industry. A minimum of 99.9% pure copper is used for their production. Copper tubes are classified as Types K, L, M and DWV depending on the wall thickness per ASTM standard B88 and B306. Wall thickness and working pressure reduces from consulting-specifying engineer

September 2019

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BUILDING SOLUTIONS

PIPE AND PIPING MATERIALS

Type K through DWV. For example, a 2-inch copper tube has an outside diameter of 2.125 inches. However, the wall thickness is 0.083 inch (Type K), 0.070 inch (Type L), 0.058 inch (Type M) and 0.042 inch (Type DWV). Similar to steel piping, ASME B31 identifies the criteria for calculating the working pressure of copper tube systems. Copper tubes are available as hard-drawn (rigid) or annealed (bendable). Hard-drawn tubing has a higher working pressure compared to annealed tubing. Copper tubes are typically joined by using brazed, soldered, groovedend or press-connect fittings. When brazing is used for joining hard-drawn copper tubing, the high temperatures associated with the joining process anneals copper at the joint and therefore the pres-

sure ratings of annealed tubing are used. Ductile iron pipe is used sparingly in the mechanical industry, though it is extensively used in plumbing and civil applications. AWWA C150 deals with DI pipe. Common nonmetallic pipe systems used in the mechanical industry are polyvinyl chloride, chlorinated polyvinyl chloride, cross-link polyethylene (PEX), high-density polyethylene, polypropylene, acrylonitrile butadiene styrene and others. Nonmetallic systems continue to gain popularity in the mechanical industry and proprietary plastic blends continue to be developed. Nonmetallic pipes offer several advantages such as low cost, light weight, inherent corrosion protection, immunity from galvanic effects, chemical

CASE STUDY: Data center piping

data center located in the Midwest was undergoing expansion. The project involved a new data hall with an initial load of 1,300 kilowatts and capability to scale up to an ultimate load of 2,600 kilowatts. An air-cooled chilled water plant was designed to serve the expansion space. The plant comprised of three 225-ton chillers piped in parallel to provide N+1 redundancy with the capability to add two additional 225-ton chillers in the future. The heat transfer fluid was 40% ethylene glycol for freeze protection; each chiller featured a design flow of 380 gallons per minute and the chilled water pumping configuration was variable flow. The day one design flow was 760 gallons per minute and the ultimate design flow

Figure 1: Chilled water pipe serving the data center is shown. Branch piping to computer room air handling units and condensate piping is also visible. Courtesy: ESD

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was 1,520 gallons per minute. Design chilled water temperature was 60 F supply and 76 F return. The system design pressure was 150 pounds per square inch gauge. It was critical that the piping system serving the data center be robust. A piping system comprised of 8-inch schedule 40 steel pipe (ASTM A53, Grade B, Type E) with welded joints and fittings was used to create chilled water supply and return pipe loops beneath the raised access floor. The 8-inch pipe loops incorporated lugged butterfly valves at strategic locations to ensure that the piping system was concurrently maintainable â&#x20AC;&#x201D; i.e., pipe segments could be isolated for maintenance activities without impacting the critical loads. Flanges were limited to valve and equipment connections. Figure 1 indicates the 8-inch chilled water supply and return loops. Also visible is 3-inch chilled water branch piping and Âž-inch condensate piping from the computer room air handling units. The piping system above the suspended ceiling was supported from the roof structure by using clevis hangers and metal framing system was used to support the piping system on slab beneath the raised access floor. Pipe supports were provided every 10 to 12 feet in compliance with the applicable code. Additional supports were provided at heavy pipe accessories such as air separators per manufacturer requirements. Figure 2 indicates the lugged butterfly valves at the 8-inch chilled water loops and the supports for the piping system beneath the raised access floor. Based on day one design flow of 760 gallons per minute, the maximum flow through an 8-inch pipe segment was 380 gallons per minute during normal operation, which corresponded to a pressure drop of 0.3 www.csemag.com

inertness, low thermal conductivity, low friction losses and ease of installation. However, the application needs to consider the disadvantages, such as low baseline strength and severe degradation at elevated temperatures, high coefficient of expansion and limited ultraviolet resistance if installed outdoors. Nonmetallic pipes are typically joined by solvent, threaded and flanged connections.

Identifying the right pipe

The various pipe materials have inherent advantages and disadvantages. During design, it is critical that the attributes of pipe systems be reviewed in detail to ensure that the system that best satisfies the project requirements is selected.

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Nonmetallic systems continue to gain popularity in the mechanical industry and proprietary plastic blends continue to be developed.

feet water column per 100 feet of pipe and a velocity of 2.4 feet per second. Based on ultimate design flow of 1,520 gallons per minute, the maximum flow through a pipe segment was 760 gallons per minute during normal operation, which corresponded to a pressure drop of 1 feet water column per 100 feet and a velocity of 4.9 feet per second. In the event a pipe segment had to be isolated for maintenance during an ultimate design condition, the maximum flow through the active pipe segment was 1,520 gallons per minute, which corresponded to a pressure drop of 3.9 feet water column per 100 feet and a velocity of 9.8 feet per second. In all scenarios, the pressure drop and velocity were within the recommended limits. Thermal expansion of the pipe system was reviewed. During normal operation, the minimum chilled water temperature was 60 F. In the event the data center was offline for an extended period and the chilled water system was disabled, the maximum water temperature was anticipated to be 95 F — i.e., the maximum temperature differential was only 35 F and the pipe loops had adequate capability to accommodate thermal stresses. There were multiple locations where dissimilar pipe connections were necessary. For example, the CRAH units serving the data center had copper pipe connections. To reduce the potential of galvanic corrosion, dielectric flanges were used to connect steel pipe to copper. Chlorinated polyvinyl chloride was initially considered for condensate drain piping from the CRAH units. However, few CRAH units were equipped with an integral humidifier and the units also used the condensate piping www.csemag.com

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Sizing • For hydronic applications, velocity and pressure drop (due to friction losses) are the two primary factors that are considered for sizing pipes. The intent is to select the smallest possible pipe size while ensuring that velocity and pressure drop are within limits.

Figure 2: Shown are metal struts for supporting piping systems on slab. Lugged butterfly valves at the chilled water supply and return loops are also visible. Courtesy: ESD

for humidifier blowdown. Due to the potential of elevated water temperature in the pipe, CPVC was deemed to be unsuitable for the application and 1-inch copper pipe (ASTM B306 Type DWV) was used per CRAH unit. The closed-loop system incorporated expansion tanks to accommodate fluid expansion, air separator to vent air from the system, glycol feeder to fill the system with glycol solution, side-stream filter to remove suspended solids from the system and chemical feeder for periodic injection of water treatment chemicals such as biocides, scale inhibitors and corrosion inhibitors. Pipe connections with isolation valves and blind flanges were provided to ensure that future chillers and CRAHs could be incorporated without disabling the system. Pipe dead-legs were limited to 2 feet in length. consulting-specifying engineer

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BUILDING SOLUTIONS

PIPE AND PIPING MATERIALS

• The general recommendation is to limit fluid velocity to 10 feet per second for metallic pipes and 5 feet per second for nonmetallic pipes to minimize the impact of noise, erosion, cavitation and water hammer, depending on the application. Water hammer and pressure surges need to be specifically reviewed for nonmetallic pipes — hence the general recommendation to limit velocity to 5 feet per second. A minimum velocity of 2 feet per second is recommended for closed-loop systems to ensure that entrained air can flow to the air-separation device and be vented from the system. • Another general recommendation is to limit pressure drop to 4 feet water column per 100 feet of pipe to ensure that pump head and power requirement are reasonable. Charts are available to help size pipes of various materials and they are typically used for most calculations. For complex applications requiring detailed analysis, pressure drop through piping can be calculated by using the fundamentals of hydraulics and equations such as Dar-

cy-Weisbach and Hazen-Williams. The impact of fittings and pipe accessories such as valves can be accounted as equivalent pipe length or pressure drop equations that use loss coefficients. In addition, standards such as ASHRAE Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings also dictate pipe sizing. See Table 1 for chilled water and condenser water pipe sizing requirements per ASHRAE 90.1-2016. Pipe supports • Pipe supports must be designed to support the static and dynamic loads anticipated during operation. Static loads include weight of pipe system (pipe, valves, fittings, insulation, etc.), weight of fluid and weight of supporting elements. Dynamic loads include wind loads (for piping installed outdoors), seismic loads and forces generated by thermal expansion and contraction. • The impact of these loads and means of support should be coordinated with the building

Piping details

crylonitrile butadiene styrene pipe is strong Type B (silane method) and Type C (electronic irraand impact-resistant. It is occasionally used for diation method) and properties such as flexibility, drain, waste and vent applications. ASTM stan- strength, thermal stability, repairability, etc. vary for dards D2661 and D3965 deal with ABS pipes. each type. PEX is commonly used for radiant heating Chlorinated polyvinyl chloride has similar prop- and cooling applications. ASTM standard F876, F877 erties to PVC and is rated for higher pressures and and F2023 deal with HDPE pipes. temperatures. CPVC pipes Polyethylene and highand fittings are available with density polyethylene pipes CPVC pipes are extensively flame/smoke index less than are flexible, lightweight and 25/50 and therefore can be durable. They are frequently used for industrial water used in air plenums. used for underground water applications associated with When using CPVC pipes and drain applications. ASTM and fittings, it is critical that standard D2239 deals with PE evaporative cooling systems manufacturer data sheets be and ASTM standard D3350 such as those serving data reviewed in detail, as not all deals with HDPE pipes. pipe sizes and fittings are listPolypropylene pipe is centers. ed to meet the flame/smoke lightweight and resistant to index threshold mandated by chemicals and can be used for building codes. CPVC pipes are extensively used for higher-temperature applications compared to PVC. industrial water applications associated with evapora- They are frequently used for corrosive and drainage tive cooling systems such as those serving data cen- applications. ASTM standards F2830 and F2389 deal ters. ASTM standards D1784 and D1785 deal with with polypropylene pipes. CPVC pipes. Polyvinyl chloride is a commonly used pipe mateCross-linked polyethylene (PEX) incorporates rial due to its low cost. One of the big disadvantages cross-link bonds in the structure of polyethylene. PEX of PVC is its inability to meet the flame/smoke index pipe is strong and durable and can be used for fluids threshold of 25/50 as mandated by building codes for up to 200 F. Depending on the manufacturing pro- use in air plenums. ASTM standards D1784, D1785 cess, PEX is classified as Type A (peroxide method), and D2665 deal with PVC pipes.

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Table 2: Maximum pipe support spacing (IMC 2018) Pipe material

Max horizontal spacing (feet)

Max vertical spacing (feet)

ABS pipe

Cast iron pipe

Copper or copper alloy pipe

Copper or copper alloy tubing

CPVC pipe or tubing (1 inch and smaller)

CPVC pipe or tubing (1.25 inches and larger)

2.66

PEX tubing (1 inch and smaller) PEX tubing (1.25 inches and larger) PP pipe or tubing (1 inch and smaller) PP pipe or tubing (1.25 inches and larger)

2.66

PVC pipe

Steel pipe

Table 2: This highlights the 2018 edition of the International Mechanical Code maximum support spacing for common pipe materials. Nonmetallic pipes require frequent supports compared to metallic pipes. Courtesy: ESD

Table 3: Coefficient of linear expansion (C) Pipe material

C (inches/10 F/100 feet)

Carbon steel

0.08

Copper

0.11

PVC

structure. Standards such as ASME B31.9 and MSS SP-58 provide pertinent information related to design and installation of pipe supports. In addition, building codes such as the International Mechanical Code also have requirements associated with supporting pipes. Table 2 indicates the maximum support spacing of common pipe materials as mandated in IMC 2018. Note that nonmetallic pipes require frequent supports compared to metallic pipes. Pipe expansion • Pipe length alters with changes in its temperature. For an unrestrained pipe, the magnitude of change depends on the pipe material (coefficient of thermal expansion), original pipe length and magnitude of temperature change. Table 3 indicates the coefficient of thermal expansion of common pipe materials. As is evident, nonmetallic pipes typically have significantly higher coefficients of thermal expansion compared to metallic pipes. • Significant movement is possible for piping systems operating at high temperatures or in long runs of piping. Failure to account for thermal expansion and associated stresses can lead to failure of pipe supports, equipment connections and pipe joints. It is imperative that the pipe system be adequately flexible to accommodate pipe movement throughout its operating temperature range while keeping the internal stresses and anchoring forces within reasonable limits. Expansion compensation can be incorporated by using L-bends, Z-bends or U-bends at strategic locations along the pipe to www.csemag.com

0.36 - 0.6

CPVC

0.41

0.5

ABS

0.62 - 0.72

HDPE

1.1

PEX

1.2

Table 3: Coefficient of linear expansion is shown for different pipe materials. Nonmetallic pipes typically have significantly higher coefficient of expansion compared to metallic pipes. Courtesy: ESD

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Standards such as ASME B31.9 and MSS SP-58 provide pertinent information related to design and installation of pipe supports.

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increase flexibility or by using fittings such as bellows expansion joints and braided hose assemblies. Pipe stress analysis software can be used for complex applications. Pipes are essential to civilized life. The idea that choosing the right system and design ensures all of us will be better off is a lead-pipe cinch. cse Saahil Tumber is technical authority at ESD. He is responsible for the overall design of mechanical systems for data centers, trading areas and other mission critical facilities requiring high availability. He is a member of the Consulting-Specifying Engineer editorial advisory board. consulting-specifying engineer

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BUILDING SOLUTIONS

SMART BUILDINGS

By Jay Wratten, IALD, LC, WSP USA, Boulder, Colorado

Outcome-driven system integration in smart buildings Digitalization is evolving the design and operation of the built environment and a smart building design approach can focus on outcomes that deliver results

he digitalization of the built environment is, if not already upon us, arriving in the next design and construction cycle. Looking at other industries for examples, in the last 50 years the music industry saw the generation, distribution and consumption of music evolve from magnetic tape recording and vinyl records to digital audio workstations and streaming platforms. Looking forward, it is easy to conceive that postmillennial consumers of music may never purchase a physical copy of the songs they love. While it may not be as evident on the surface, the technology that drives building systems today is going through a similar shift. Or perhaps it is evident • Develop an outcome-based — just ask any colleague who recentmethodology for designing smart ly attended a conference on the built buildings. environment. It is a good bet buzz• Identify key challenges in words words like “internet of things,” executing a smart building design. big data, analytics, machine learning • Outline how to define systems or cloud platform were sprinkled libintegration requirements based on erally across conference marketing desired outcomes. materials. Smart buildings, intelligent places or connected venues are all terms the industry is using to describe this new way of thinking about how users consume the built environment. While a definition of what makes a facility a smart building is not yet agreed upon, a broad statement of goals and outcomes could be the following:

Learning

OBJECTIVES

• A smart building aspires to be agile, responsive and adaptive to its users. Data generated by the building should continuously inform system operation, enabling the building to

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take proactive steps, anticipating user needs and optimizing target outcomes. • A smart building leverages technology to improve the quality of experience, and provides users contextually relevant information to inform their actions in real time. • A smart building provides solutions that bring added business value through data analytics informing organizational decision making. We have had smart features in buildings for quite some time. Let’s take, for example, the user experience of a modern sensor-based lighting control system as would be found in an open or private office setting. When a user walks into the space, an occupancy sensor notices their movement and communicates this change to the controller, which in turn triggers the lighting to turn on automatically to some preset value. If the space is at the perimeter of the building, a photosensor is measuring ambient light level and communicating back to the controller, which automatically dims lights up and down to maintain a programmed light level. When the user leaves, the sensor notices the space is empty and communicates this to the controller, which shuts off the lights. Referencing the definition of a smart building above, one could argue this lighting control system ticks most of the boxes for a smart building. So why is there so much press about smart buildings these days? Is it just manufacturing hype trying to sell what is essentially the same legacy product with a flashy new front end? Or can we design smart buildings that meaningfully bring www.csemag.com

Figure 2: The WSP open offices support sit/stand desks with docking stations to enable agile working. Courtesy: WSP USA

‘ Figure 1: The 6,000-square-foot WSP Boulder, Colorado, office includes a typical mix of commercial real estate program including open and private offices, collaboration and meeting space, café, restrooms and support areas. Courtesy: WSP USA

value to clients? Compared with legacy solutions, three key features differentiate the design and operation of smart building from a traditional one. • Data generation: Characterizing the operation of the building through data are the foundational building block of a smart building. These data are generated through sensors or through system operational reporting. www.csemag.com

So why is there so much press about smart buildings these days? Is it just manufacturing hype trying to sell what is essentially the same legacy product with a flashy new front end? • System integration: Connecting multiple building systems, enterprise applications and third-party platforms and enabling them to interact either automatically or manually creates the heart of a smart building.

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• Analysis and response: Creating successful outcomes from a smart building requires the ability to aggregate data from various systems and platforms, make sense of the story the data are telling and act based on that story. This is often referred to as “insights” or “business intelligence.”

Why have a smart building?

The features outlined above do not answer the question of why we should propose a smart building, how the architecture, engineering and construction community will design and implement smart buildings or what clients will do with them consulting-specifying engineer

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SMART BUILDINGS

They also are instrumental in defining requirements for the features noted above — what data are required, how must systems interact, how will the data be analyzed and presented and who will do something with it. Potential smart building use cases could include: • Using weather predictions to sub-cool a building ahead of a heat wave. • Advising employees if and when to travel to the office based on current traffic, air quality or colleague availability. • Adjusting temperature zone setpoints based on profile preferences of users currently in the space. • Dynamically adjusting white noise based on ambient sound levels or signaling users when ambient level exceeds threshold by flashing the lights.

Figure 3: In this “internet of things” diagram, data are shared natively at the edge between systems, without the need for an integration layer to share data between siloed systems. Courtesy: WSP USA

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In the context of smart buildings, use cases are a compelling mechanism to connect the design and construction of traditional building systems to a business need through the application of technology.

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once completed. What are we as designers of the built environment trying to accomplish by going smart in this approach? To identify and communicate value, use cases have become an important component of a smart building design. A use case outlines the desired outcome and the systems and users that interact to generate the outcome. In the context of smart buildings, use cases are a compelling mechanism to connect the design and construction of traditional building systems (mechanical, lighting, security, etc.) to a business need (Do I need to rent more space for new hires, or do I have enough?) through the application of technology. They are critical for defining the “why statement” for a client and for creating a cost model justifying the implementation of systems to enable the use case outcomes.

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CONSULTING-SPECIFYING ENGINEER

A common example of a smart building use case is space use. Within the corporate real estate realm, a way to state the use case value proposition might be to “improve workplace efficiency by maximizing the use of office assets (rooms and desks).” Designing an appropriate implementation of this use case requires a thoughtful approach, considering both the implementation and operational aspects of this solution.

A smart office building We will use this example as a case study through the remainder of this article based on the application of a smart building platform at WSP’s Boulder, Colorado, office location. For context, the office is approximately 6,000 square feet and includes a mix of open and private offices, focus and meeting rooms, a café and supporting spaces for 33 full-time employees (see Figure 1). Several smart building systems have been installed in the office as part of WSP’s ThinkBOLDR Innovation lab, including a variety of occupancy detection solutions, utility metering, indoor environmental quality sensing, meeting and desk management systems and platforms to ingest, aggregate, analyze and present data to stakeholders. The first step is to define its value and agree on the methods by which we will measure its success (often referred to key performance indicators). Why is this step critical? Because we are not just implementing smart building solutions because we can, we are delivering value to stakeholders. Whatever the desired outcomes are, the use case will almost certainly cost more to implement and run than if we maintained business as usual. Just like with any www.csemag.com

engineering solution where there are options, we designers need to show that the value justifies the implementation costs. Otherwise we are likely to face an uphill battle through value engineering, alternate system evaluations, integration and implementation challenges and operational change management. Technology continues to generally improve features in building systems and while there may be little to no capital expenditure impacts for a specific technology, there frequently are integration and commissioning costs that increase the installed cost, as well as operational expenditures to maintain platforms or for continued access to analytics, often referred to a software as a service model. These ongoing costs must also be considered in evaluating the value of any smart building design. Finally, the use case must also establish a baseline to identify opportunity for improvement. Using the case study, WSP had a stated goal to improving workplace efficiency. But what is the current space use for various types of program (open/private office, conference, etc.)? Accurately determining the potential improvement is certainly a challenge, as there are various ways to calculate a baseline. To assess this, we considered usage data from several sources using similar offices or the previous location of the existing office to establish a baseline workplace efficiency. Relevant data for workplace efficiency might include: • The number of full-time employees assigned to the offices (discounted to account for travel and time off). • Data from access control badge swipes. • Login information for employee’s workstations. • Booked meetings in conference spaces. • Site surveys manually counting employees. These are all data sources that a real estate group might already use to assess real estate portfolio needs and can be used to establish a baseline. There are opportunities for improved survey methods using occupancy sensors that can be temporarily installed to gather a richer dataset around use over a given time period. For the purposes of the case study, WSP established that the baseline workplace efficiency KPI is 50% during working hours. Using the baseline, we can then estimate the potential improvement in space use we believe we can achieve through the implementation of a workplace efficiency use case and thus the potential value it might bring. For the case study, it is worth noting that the ability to improve space use may be www.csemag.com

Figure 4: In this integrated automation diagram, edge system data are shown at the bottom (lighting, building management system, audio/visual, etc.) with data flowing through an integration bus and up to the cloud for analytics. Courtesy: WSP USA

limited in the short term, as reducing leased space or hiring more employees is not always an option. This is something that WSP has explored in assessing the implementation of the ThinkBOLDR Lab. The primary mechanism we have identified for space use value is through identifying ways to add more employees into the same office without impacting experience or through reducing program space that is poorly used for its intended purpose, such as large conference rooms.

How are data generated?

Following the definitions of the use cases, desired outcomes and value proposition, it is time to transition to design of the smart building infrastructure. Data generation, system integration and analysis and response form the three pillars of how to approach this design. The use case definitions are key drivers to identify what data are required to be generated to support the desired outcome. There are several types of data a smart building could use. Traditional building systems: • Presence detection (room or desk presence sensing, people counters). • System operation and status reporting (building management system equipment, elevators, audiovisual equipment, motorized shades). • Utility consumption metering (energy, water, gas). consulting-specifying engineer

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BUILDING SOLUTIONS

SMART BUILDINGS

• Enterprise systems or platforms (meeting room availability, user profiles, visitor management). • Building-generated data (parking spot availability, amenities). • Static data (square footage of building spaces, floorplans, locations of desks). • Utility rate schedules • Weather, traffic, public transportation, transportation network companies. Desired use case outcomes often require additional datasets beyond what can be generated by building systems alone to bring maximum value. Generating or accessing this data needs to be considered as part of the smart building design.

System integration

Figure 5: This diagram outlies the functional data connections that enable occupancy sensor information from the lighting control system to integrate with the room management system. Two types of integrations are happening here: one for direct connection between the systems for automated function and one to the server for analytics, visualization and reporting. Courtesy: WSP USA

• Location services (asset or user device mobile device location). • Indoor environmental quality sensing (carbon dioxide, total volatile organic compounds, particulate parts per million, ambient sound pressure level, light level). • Access control (badge swipes). Additional data sets: • User or device detection (video analytics, Wi-Fi access points, Bluetooth beacons).

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CONSULTING-SPECIFYING ENGINEER

Once the smart building design has identified the data that needs to be generated for all use cases and defined the governing values for resolution of data, system integration becomes the next task. While the aspiration of smart building advocates is that the industry will soon transition to a native internet of things environment where sensors, devices and actuators are connected and communicate with each other at what is referred to as “the edge” (see Figure 3), today’s reality is that most systems are siloed in their traditional design and installation, with a focus on individual system functionality. These individual systems provide a dedicated interface or server that can support integration with other systems (see Figure 4). The result is that well-defined system integrations become critical to the success of smart buildings. System integration should include the following aspects within a smart building design: • Functional diagram: The design must chart a path for the data, from where it is generated to its destination. This should include all systems through which data must pass, directions of data flow, hosted location of systems (on premises or cloud), storage, analytics platforms and user interfaces (see Figure 5). • Communication network: What is the physical networks over which data will be communicated, quality of service, resiliency and redundancy, performance and security? • System integrations: This is the connection points between systems, as identified in the functional diagram. Systems integration must define interoperability between systems. www.csemag.com

The systems integration requirements must be defined for each point of connection between two systems on the functional diagram. At each of these points, the integration and interoperability between each system must be defined very specifically. The following items are usually required for system integration: • Data shared by the system (occupancy data per space or individual occupancy sensor in open offices). • Control capability being given to other systems (i.e., can the building management system temperature setpoints be adjusted by other systems). • Communication protocols being used for integration. These would include open standard protocols, with common implementations including BACnet/IP (BACnet using transmission control protocol/internet protocol), representational state transfer application program interface (known as a RESTful API), message queueing telemetry transport, LonWorks and Modbus TCP/IP. • Semantic data model and data tagging. Both Brick and Project Haystack are commonly used here as metamodels. Use of semantic data models is important to provide context for the data being shared and should include naming conventions, tags, hierarchy and relationship. It is important to note that a system may require multiple integrations to the various systems with which it integrates. Taking the case study of space use, WSP implemented an approach for the office to generate data from the lighting control system. Referring to the functional diagram in Figure 5, the lighting control system needed to integrate with two systems — the analytics platform and the room booking system. The WSP team determined that different integrations would be required for these two systems, as the analytics platform would be located on premises and the room management system platform would be in the cloud. As a result, a BACnet/IP protocol was integrated with the analytics platform. The room management system, however, uses the lighting control system manufacturer’s cloud platform to connect via RESTful API to the room management system.

How to work with the data

A smart building has the potential to collect a much richer dataset about building operations than

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traditionally available. Additionally, combining data from multiple systems that have historically existed in silos brings opportunities to smart buildings that did not previously exist both in the types of analytics that can be implemented and in improving the confidence of decisions made from analytics. Finally, smart buildings enable real-time analytics that bring actionable information to users (such as quickly finding a focus room with nobody in it).

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It is critical that any smart building design includes a plan for how action will be taken based on the data and whether the actions need to be reactive, near real-time or predictive. This action is what will deliver the outcome.

As a result, the system integrations that smart buildings require to support desired use case outcomes can be both broader and deeper than contractors and building operators are familiar with deploying. To ensure smart buildings are prepared to deliver on their intended outcomes, careful consideration of the procurement of systems, installation and commissioning sequences and clearly defined scope of work for vendors, integrators and operators to eliminate scope gaps is required. Ultimately, the success of smart buildings depends on enabling decisions to be made based on the analysis of the data. It is critical that any smart building design includes a plan for how action will be taken based on the data and whether the actions need to be reactive, near real-time or predictive. This action is what will deliver the outcome. These decisions could be automated by enabling machine to machine interactions, such as precooling a conference room before a meeting. Alternately, they may require human review and action, such as deciding to hire another employee without leasing additional office space. Smart buildings likely will require change management for owners, and design teams should consider ways to provide a soft landing for stakeholders as they become familiar with operating systems, managing platforms and interpreting dashboards. cse

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Jay Wratten is a vice president at WSP USA. He is the national smart building leader for WSP and spearheaded the ThinkBOLDR Innovation Center, focusing on the impact of the built environment on the humanistic experience. consulting-specifying engineer

September 2019

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BUILDING SOLUTIONS

SMART BUILDINGS

By Brad Kult, PE, CTS, HGA, Minneapolis; and Neil Osten, PE, LEED AP, Mortenson, Minneapolis

Framework for designing the intelligent building Intelligent buildings are no turnkey matter. They take a deeper understanding of client’s goals and objectives for what is desired and discipline to implement through a collaborative design and construction process

truly intelligent building can mean many different things depending on the client’s needs. Designing building intelligence is about defining what success means, planning what will be allocated to make it happen and allowing for room to make it happen — especially because we don’t often have consistency of the same team or available technology. Building owners and operators recognize that buildings are becoming more intelligent and the way they manage facilities is changing. At the same time, occupants’ expectations of how they interact with built environment are changing. The way • Understand “building we collaborate, design, specify, buy intelligence,” which should be and construct buildings must change used consistently by the user as well. and team. There is no industry standard scale • Learn how to engage the for classifying a building as intelligent. owner, operator, design and Buildings that implement automation construction teams early to ensure team alignment and between building systems or that use successfully implement intent. data analytics for generating insights • Support the intelligent building and automating processes are comeffort, especially if the project monly accepted as operating at some becomes budget challenged; level of intelligence. Intelligent buildtrade-offs should not be made in ings can be dynamic, adaptive envia bubble. ronments that optimize occupant comfort and well-being, energy efficiency and operating efficiency. Owners and operators understand that buildings are capable of offering greater insight into how to they operate buildings to streamline the facilities management workflow, optimize energy efficiency and improve the occupant experience. They also recognize that they must take action to achieve results. But in the rapidly evolving marketplace, it can be a daunting task to determine what steps need to be taken to achieve desired goals in a fiscally responsible manner. In many cases, significant capital

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OBJECTIVES

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consulting-specifying engineer

investment has already been made in systems and equipment and there’s a desire to enhance the utility of the tools that are already in place. Clients look to their consultants as their trusted partners to provide guidance on what their expectations should be for their new construction or renovation projects. Many are seeking flexible and scalable solutions that will meet current needs and adapt to future demands that are often unknown at the time of design and construction. Many clients interested in adopting intelligent building technologies are aware that they can benefit from integrated automaton and intelligent data analytics, but they understand that there are capabilities they haven’t even considered and they are seeking a partner to help guide their education and decision-making process. It’s up to the architecture, engineering and construction community to familiarize owners with both the capabilities and limitations of new technologies to meet the needs of their business and avoid adapting “flavor of the day” short-term solutions or point to solutions that only solve a single problem.

Technology is pervasive

Technology can no longer be considered as an afterthought in the design process. Technology is so ubiquitous, it’s no longer a singular discipline tasked with determining where the outlets for computer or printer will be located. The use of high-tech tools drives daily processes and has enabled a shift in the way people work. Our clients understand the impact technology has on their businesses and often recognize there is untapped potential to use technology more effectively. As owners and operators progress in sophistication and as users begin to demand more from the place where they work, technology’s impact on daily life must be considered from the outset of any project. Owners are driven to adopt new practices www.csemag.com

Figure 1: More devices have the ability to communicate, interact with each other and provide meaningful data insights for facility and occupant enhancement. All of these specification sections, including owner operation technology/information technology systems, could contain devices that need to be coordinated and specified. It is important to address this early in design phases. Courtesy: HGA and Mortenson

because the rapid and accelerating pace of technology means it’s easy to fall behind if not proactively addressed and it’s hard to play catch-up if an organization falls behind.

How to implement the intelligent building

The good news for building owners and operators is that they can often leverage their capital investments in existing mechanical, electrical and plumbing systems and equipment to make their buildings more intelligent. Buildings with digital control and monitoring systems already are loaded with sensors connected to digital systems that are generating a great deal of data. We recognize our clients tend to work in siloed departments, but the technology tools they use cross over departments, so it’s important to align teams who may not be accustomed to working together so they can discuss common goals. To harness the potential value of building data, we must think differently about how traditionally siloed building systems share information and how that information is processed to generate insight to improve user experience, optimize energy and operating efficiency and enhance existing automation. For building systems to be able to exchange information, they must be able to communicate together. This requires communications network infrastructure to interconnect the disparate building systems and a common set of languages and protocols for systems to communicate. As more building systems turn to internet protocol technologies for communications, the trend is for building systems to converge onto a single network that uses commodity information technology networking infrastructure and equipment. This net-

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work may exist as a virtual segment on the IT network or it may manifest as a separate physical IT network for the operating technology equipment. The network provides the pathway for sharing signals and information between systems. With the connectivity strategy established, the communications language or protocol must be considered. Unfortunately, there is no single protocol for communicating with all of the systems that run a building. Legacy proprietary protocols are being replaced by standards-based protocols such as ASHRAE Standard 135: BACnet—A Data Communication Protocol for Building Automation and Control Networks for in-building communications. Many systems also are capable of using standards that have been developed for sharing information across the web, such as web services and application programming interfaces. After clearing the technical

Path to insight WISDOM

KNOWLEDGE

Action (must take action to get results)

Process and visualize data (actionable data for decision making)

INFORMATION

DATA

Assign meaning to data (organize and contextualize)

Raw data (ie. device data or business data)

Figure 2: Data and information must be meaningfully collected and transformed to provide actionable insight for decision support. Courtesy: HGA consulting-specifying engineer

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BUILDING SOLUTIONS

SMART BUILDINGS

hurdles for interconnecting the islands of building systems, the endless possibilities for intelligent building actions must be carefully considered.

Design process

Vision and team alignment: Leadership support and business alignment across the organization is critical to interdisciplinary success. It often takes a champion with a vision to be the catalyst for an intelligent building initiative and strong project leadership to align multidisciplinary teams from the client, design and construction teams. Collaboration is essential to maximize the opportunities for discovering potential interplay between business units and between systems, but the various teams may not be used to working together. The design process must seek to align teams across business and operations units, including key user groups, facilities, IT, security departments and the client’s project manager to discover common goals that can be achieved through integrated auto-

mation and intelligent data analytics. It’s an engineer’s role to help foster team alignment and lead the client’s teams to define common objectives. Benchmarking and client team alignment: For the best chance to succeed, intelligent building initiatives must be identified from the outset of a project. The engineer should be engaged during the programming phase while there is an opportunity to influence the budget and overall program. The engineer’s first task is to conduct a baseline review to establish the current state of systems, equipment and common practices. After benchmarking the existing baseline conditions and practices, stakeholders from each of the client’s business unit are brought together to participate in a process that will help define the ideal future state. Ideation phase/owner’s project requirements: During an ideation exercise led by the engineer, representatives from each business and operations unit share their individual goals, desired outcomes and metrics for measuring success and establish a

CASE STUDY: Hospital integrates all stakeholders

n late 2016 Aurora Health Care, now Advocate Aurora Health, engaged HGA and Mortenson in a design-build relationship to design the Aurora Sheboygan Memorial Medical Center, described as the “hospital of the future.” Project stakeholders including local and Advocate Aurora Health systemwide leadership, facilities management, information technology, public safety, energy management, construction management and general contractor Mortenson and the HGA design team were engaged from the outset of the project. Planning and design meetings often included representatives from each of these groups. The project goals included innovation around smart patient rooms that control lights, temperature, shades and entertainment through bedside touchscreens; energy savings setbacks in patient rooms and operating suites by interfacing with scheduling systems; and intelligent facilities workflow management and energy conservation through automated fault detection and diagnostics. Advocate Aurora Health was interested in implementing innovative strategies for improving the efficiency of facilities management processes, including intelligent alarm management, predictive maintenance and root cause analysis for system troubleshooting. They knew additional capabilities were available and they asked the design team to help them understand the additional features they could operationalize. HGA led meetings to share a comprehensive vision of how Aurora could maximize its capital investments by connecting facilities, IT, life safety/security and clinical systems to leverage interoperability through exchange of

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data and application of data analytics to surface actionable insights. After laying out several potential options, the design-build team asked Aurora stakeholders to describe their ideal future state for their systems and operations. The HGA and Mortenson team used this vision of the ideal future state, along with knowledge of the current state, as the basis of a roadmap for future functionality. The design-build team conducted an exercise in identifying and prioritizing the organization’s business needs for each user persona including facility director, facility manager, energy manager, staff, physicians and patients. The team created a roadmap for current and future technology strategy by ranking solutions based on their ability to impact those business needs. This produced a prioritized list of system capabilities that could be used to specify system requirements. Budget dictated that some functionality had to be deferred for future projects. System selections, network architecture and space planning were made based on a roadmap that helps ensure scalability and flexibility for future functionality. The HGA and Mortenson team went on to help the Aurora team evaluate technical options for system integration configurations, selection of equipment and software and data analytics tools that fit their operational needs. It was determined that a master systems integrator would be required to deliver the systems integration and data analytics. The MSI scope was to be delivered using Construction Specifications Institute MasterFormat Division 25 specifications. The MSI will have an ongoing www.csemag.com

risk management framework for what should be integrated for their individual business. This ideation session yields many ideas that are analyzed for common themes, consolidated and prioritized based on perceived impact to the overall organization. The main use cases identified through this inclusive process are used to generate the OPR. Prioritized use cases: Early and frequent budgetary updates help the project team prioritize the use cases that can be included in the project. The use cases established in the OPR are budgeted and prioritized by weighing the cost of implementation compared to their anticipated impact and return on investment. Reprioritization is required as changes to the program impact the scope and budget. Use cases that don’t fit within the budget are placed on a technology roadmap for future implementation. Because interdisciplinary business units collaborate on use case prioritization, the use cases that make it into the project will have the greatest impact to the overall business.

Design and construction team alignment: Much like alignment of the client’s business units may have been a new experience for the client’s team, interdisciplinary alignment of the design and construction teams mean that designers and contractors must work together in ways they’re not accustomed to achieve a common outcome which may include early trade partners if they are participants based on the project’s chosen delivery method. Engineers must understand what each other’s systems are capable of and must communicate how their systems will interact and what components to potentially consolidate, to achieve the common goals set by the client’s stakeholders. An engineer or project manager is needed to lead interdisciplinary design team coordination to ensure that the equipment and sequences required for integration and intelligent analytics are specified in the right sections. Construction Specifications Institute MasterFormat Division 25: Building specifications have included provisions for Division 25 to be used for

relationship with the facilities department. Although the MSI will touch on many different systems spanning facilities, IT, life safety/security and clinical departments, the facilities department will be directly responsible for holding the MSI support contract which includes the heating, ventilation and air conditioning and lighting controls. HGA assisted Mortenson in writing the request for proposal to qualify MSIs and participated in the interview process, helping Aurora select the MSI during design phase as an early trade partner. The role of the MSI during design phase was to advise on specific capabilities of its integration and data analytics package and to validate the team’s innovation concepts to ensure they were technically achievable and cost-effective before they were implemented in the field. Regular coordination with the trade partner contractors and frequent budget updates helped ensure scope and budget alignment throughout design. The project design team was composed of strong project management leadership from HGA and Mortenson to manage communications and ensure team alignment among the designers and early trade partners from the fields of low-voltage technology, mechanical, electrical, lighting, architectural and estimating. Team alignment toward the common goals of the integrated mechanical, electrical, plumbing and technology systems was required to complete a successful design that crossed many disciplines. The team learned many lessons about specifying and procuring services and equipment through the course of the project. We learned it’s important to discuss the KPIs that will be measured to define success early in the www.csemag.com

Figure 3: The Aurora Sheboygan Memorial Medical Center is a “hospital of the future” where integrated automation gives the patient enhanced control of their space to promote well-being and healing. Courtesy: HGA

design process so they can be used to help prioritize the value of the proposed integrations. We also learned a great deal about each other’s roles and the capabilities of other systems by interacting with each of the subject matter experts representing their area of expertise. The project is currently moving into construction phase and is anticipated to be completed by 2021. At that time, we’ll be able to see how of efforts have paid off. In the meantime, the HGA and Mortenson team is currently engaged to design the next Advocate Aurora Health facility and are applying the lessons learned from this project. consulting-specifying engineer

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BUILDING SOLUTIONS

SMART BUILDINGS

Figure 4: In this case, a basic commercial scope matrix example is shown with on-site generation and electrochromic glass. The owner has a work order management system and room scheduling. The integrated automation scope provides front-end graphical user interface, gateways and programming to integrate into the main GUI; a main GUI isn’t necessarily required for each separate division of work except for its own startup, programming and commissioning. Controls work could either be completed under the separate scope packages or through the master systems integrator as defined by the partial scopes. The o sees a single day-to-day user interface with a blended operational technology/information technology system for the owner’s team members, however, the MSI may not have complete insight into the owner’s IT. Courtesy: Mortenson

integrated automation since the 2004 MasterFormat was introduced. Division 25 is a versatile section that can be used to specify controls for heating, ventilation and air conditioning, lighting controls and other building systems independent of Division 23 or 26 where the controls responsibility had typically resided. As controls become more open, more sophisticated and increasingly more integrated the skill set required of controls contractors becomes more demanding. Moving controls out of Division 23 and 26 and into Division 25 aligns controls under a single Tier 1 subcontractor who is responsible for their implementation and integration, typically resulting in an more unified controls platform, user interface and digestible data. For buildings that integrate multiple systems, Division 25 may be used to specify the scope of work to be performed by the master systems integrator. The MSI is responsible for programming the sequences of operations among the integrated and interoperable systems. The MSI may also be the controls contractor, but often it’s preferable for the MSI and controls contractor to be separate and for the integration to third-party systems to be agnostic of the controls hardware. The nature by which the controls and/or MSI contractors are scoped and contracted can vary greatly. The specifier must clearly define and delineate their design phase role and their construction role relative to the general contractor or construction manager; mechanical, electrical or plumbing contractor; and other trades. The specifying engineer must work closely with the owner and with a CM to understand how the controls and integration

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scope will be procured so they can specify the work in the correct sections. It’s the specifier’s role to ensure that the required coordination between trades is clearly outlined and that gaps and overlaps between trades are identified and eliminated from documentation; failure to take procurement procedures — often influenced by local markets — into effect could change design and scope intent. Coordinating with procurement partners to leverage tools such as a detailed scope of work matrix, interviews with live demonstrations and/or requiring mockups before award will mitigate scope and cost duplication and assure the owner that the system designed can function as intended. When to engage the MSI: It can be advantageous to engage an MSI during the design process when unique integration concepts or highly integrated systems are considered. It’s not always possible to select contractors during design phase, such as on public or other hard-bid projects. But when possible, the consultant and MSI can play complimentary roles during design phase. The consulting value proposition is to remain vendor and product agnostic, helping the client select solutions that best fit their needs. However, most consultants do not have the “lab“ infrastructure, training or fee required to physically validate that integration capabilities described on product data sheets or in API documentation will perform as expected. The MSI adds value during design phase by performing verification of the planned integration and analytics concepts, allowing the owner and design team freedom to dream of innovative solutions with the assurance their vision is achievable. The MSI also provides frequent updates to the integrated automation cost model that gives the owner a running tally of the impact of their decisions. www.csemag.com

By binding the MSI to deliver the project based on the scope and budget agreed upon during design phase, they are obligated to produce the results that meet the owner and engineer’s expectations. The MSI also may influence equipment selections made by other trades based on opportunities to enhance integration performance without compromising base functionality. While it’s possible to competitively bid the MSI’s scope, it is considerably more difficult than hiring an MSI as a design phase partner through a negotiated contract. The specifier assumes all responsibility for ensuring integrated automation concepts perform as expected and within the owner’s budget. Specifications must be detailed and well-coordinated to ensure scope is bid consistently. The bid selection process must be done systematically to ensure that the accepted bid or bids form a complete solution that conforms to each system specification as well as the integrated automation specifications. The MSI’s skill set is not a commoditized product. In addition to ensuring the MSI has scope captured, the engineer must carefully qualify and evaluate the MSI using past experience and certifications a wide variety of subject matters including controls, integration, networking and cybersecurity.

Challenges and opportunities

Tearing down the silos in which we’ve grown accustomed to working and moving technology earlier into the design and procurement, conversation is a transformative process with potential for disruption that requires teams to work together more closely than they may be used to. Alignment of client, design, procurement and construction teams requires cross-discipline coordination and enhanced cost-benefit/risk-reward analysis; it can take time to

learn each other’s vocabularies and skill sets. Team unity around clearly defined goals is key to successfully navigating projects with the complexity of deep integration and intelligent automation. As fast as technology is moving, there are factors that contribute to a momentum that is resistant to change. Consulting and construction are coin-operated businesses and labor is required to create new specification sections. Also, a knowledgeable spec writer is required to keep specifications including Division 25 and other high-tech systems current. Specifiers must keep pace with industry advances and owner demands, so it’s incumbent on us to build flexibility into our specifications to continue to adapt to meet the demand. Today’s buildings can be a significant improvement over traditional siloed systems that work independently and present alarms and data rather than intelligence and insights. We’re beginning to tap the potential intelligent buildings have to offer and to do so we’ll need to adapt how we think of collaboration to successfully deliver projects that drive value for our clients. The future of automation will be based on buildings that are self-aware and able to react dynamically to the occupants and changing environmental conditions. It will provide occupants with more options for taking control of their own personal comfort and will self-optimize and improve operator’s ability to manage. cse Brad Kult is the director of technology design and planning services at HGA. He is a 2019 ConsultingSpecifying Engineer 40 Under 40 award winner. Neil Osten is a mechanical, electrical and plumbing design phase manager with Mortenson. He is a 2019 Consulting-Specifying Engineer 40 Under 40 award winner.

Figure 5: This is a basic commercial scope matrix example with onsite generation and electrochromic glass. The owner has a work order management system and room scheduling. The master system integrator provides complete low voltage systems, controls and integration of systems and contract may be shared with owner blending operation technology with information technology. The owner and the owner’s team members see a single day-to-day user interface with a blended OT/IT system that can be segregated by user (administrator, facilities operations, employees, etc.). While these divisions of scope are examples and aren’t all-encompassing, they are meant to highlight how muddy the waters can become to achieve common work results. Courtesy: Mortenson www.csemag.com

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By Kenneth Kutsmeda, PE, LEED AP, Jacobs, Philadelphia

Evaluating power quality for mission critical facilities Mission critical and data center facilities that use sensitive power electronics have small tolerances for power source deviations. Power quality and the mitigation of problems affecting power quality are very important to the continuous operation of the facility

EEE Standard 1100 defines power quality as “the concept of powering and grounding sensitive equipment in a matter that is suitable to the operation of that equipment.” Power quality can be summarized as the “compatibility between what comes out of an electric outlet and the load that is plugged into it,” according to Alexandra Von Meier in the book “Electric power systems: a conceptual introduction.” The electrical load or equipment that is connected to an electrical circuit has a certain power tolerance range that is required to allow it to function properly. Any power source deviations outside that power tolerance range can affect the operation of • Learn about what causes power source deviations (poor power that equipment. quality). Power source deviations or distur• Understand the impacts of bances most commonly include the power quality on facilities like following:

Learning

OBJECTIVES

mission critical and data centers.

• Review different mitigation techniques that will help power quality.

• Interruptions. • Voltage variations. • Waveform variations.

Some equipment — motors, heaters and incandescent lighting, for example — have a wider power tolerance range and can accept larger deviations in power (poor power quality). Reduction in voltage may make the motor operate at slower speeds or the incandescent light operate with less lumens. Other equipment, such as power electronics and information technology equipment have a much smaller power tolerance range. Slight deviations in power can cause this type of equipment to malfunction, fail prematurely or not operate at all. Many businesses and facilities rely on sensitive power electronics and IT equipment to proper-

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ly operate their industries. As this trend continues to grow more important, having good power quality and keeping the power source within the tolerance range of the equipment becomes paramount. Poor quality power can cause malfunctions and failures that could severely affect the operation of the facility. This is particularly true with mission critical type facilities that relay on the power electronics for safety or data centers where the entire facility is made up of IT equipment.

Interruptions The most commonly recognized power source deviation is the interruption of power or power outage. This is when there is a break in the supply of power and the load or equipment becomes de-energized. Obviously, the total loss of power is outside the tolerance range for any piece of electrical equipment causing that piece of equipment not to operate. Depending on the type of outage, the interruption can last a few seconds or potentially for multiple days. Another issue with interruptions is the unexpected shutdown of equipment. Older facilities and processing facilities have operating systems that must go through a shutdown sequence to make sure the running processes have correctly terminated before turning off. Sudden shutdowns can stop processes midway, causing computational issues and/ or physical damage. Newer facilities like cloud data centers provide redundancy at the software level not the hardware level so that processes continue to function during an unexpected outage. Interruptions can be caused by events external to the facility such as damage to a utility transformer or transmission line. Interruptions also can be www.csemag.com

Figure 1: Power distribution units with K4 rated transformers serve the data center information technology equipment. Courtesy: Jacobs

caused by internal events such as a fault that trips open a protection device, damage to distribution equipment/wiring and required maintenance.

Voltage variations

Another type of power source deviation is voltage variations. Voltage variations are brief instances where the voltage increases or decreases beyond the normal level. If the voltage increases or decreases outside the voltage tolerance range of the equipment it will affect the operation of that equipment. The following are different types of voltage variations that can occur. • Voltage sag: Decrease or reduction in root mean square voltage below nominal voltage, typically lasting from a cycle to a few seconds. • Voltage swell: Increase or escalation in RMS voltage above nominal voltage, typically lasting from a cycle to a few seconds. • Voltage flicker: Random or repetitive variations in RMS voltage. • Voltage spikes/surges: High increases of voltage for very short periods of time. • Undervoltage/overvoltage: Small decreases and increases in voltage for longer periods of time.

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The most commonly recognized power source deviation is the interruption of power or power outage. This is when there is a break in the supply of power and the load or equipment becomes de-energized.

Voltage sags are the most common power disturbance. A voltage sag occurs when the RMS voltage decreases to 10% to 90% below the nominal voltage for less than a couple of seconds. Voltage sags are typically the result of an abrupt increase in load such as large motors starting or electric heaters turning on. They also can be caused by short circuits and faults that draw large amounts of current or rapid increases in impedance caused by loose connections. Voltage swells are the exact opposite of voltage sags. A voltage swell occurs when the RMS voltage increases to 10% to 80% above the nominal voltage for less than a couple of seconds. Voltage swells typically are caused when there is an abrupt reduction in load on a circuit. Voltage swells also can be caused by a damaged or loose neutral connection. Majority of voltage sags and swells are caused or generated by events occurring internal to the facility. Voltage flicker occurs when there’s random or repetitive variations in RMS voltage between 90% consulting-specifying engineer

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ing. Power electronics equipment, however, has insufficient internal energy storage to ride through sags in voltage. If the voltage sag is low enough or for a long enough duration, it could fall outside the tolerance of the equipment causing it to malfunction, fail or turn off. Voltage spikes can cause internal damage to power electronics that are not designed to withstand that kind of influx of power.

Waveform variations

Figure 2: Commissioning the power conditioning capabilities of the uninterruptible power supply is shown. Courtesy: Jacobs

and 110% nominal voltage. Voltage flicker is most noticeable with lighting. The variation in voltage makes the lights flicker or have flashes of brightness. Voltage flicker is caused by machinery or motors with rapid fluctuations in load such as large motors during startup, machines that use static frequency converters and elevators. Voltage flickering also can be caused by loose connections. Voltage spikes/surges are both when high increases of voltage occur for very short periods of time. Spikes last 3 nanoseconds or less, while surges last more than 3 nanoseconds. Internally voltage spikes/ surges can be caused by short circuits, tripped circuit breakers and by a buildup of static electricity that suddenly discharges. Externally, voltage spikes/surges are caused by lightning strikes, damaged power lines and utility power outages. Undervoltage or brownout occurs when the voltage drops to below 90% of nominal voltage for more than a minute. This is typically done by the utility to decrease demand and reduce load during an emergency rather than cause a power outage or blackout. Overvoltage is the opposite and occurs when voltage rises to above 110% of nominal voltage for more than a minute. Overvoltage generally occurs due to poor regulation of power or malfunctions of the electrical power distribution system. As indicated previously, sags do not disturb motors, heaters, incandescent and fluorescent light-

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Another type of power source deviation is waveform variations. The oscillation of voltage and current ideally follows in the form of a sinusoidal shape. Waveform variation occurs when the voltage or current waveform is altered from a sinusoidal shape. The distortion to the voltage and current waveform is often described as harmonics. Harmonics refers to a component of the waveform that oscillates more rapid than nominal frequency. Harmonic have frequencies that are integer multipliers of the waveform’s fundamental frequency (60 hertz fundamental; second harmonic = 120 hertz; third harmonic =180 hertz; and fourth harmonic = 240 hertz). Total harmonic distortion is the summation of all the harmonic components of the voltage or current waveform compared to the fundamental component. Linear loads like household appliances draw current that is sinusoidal in nature and do not distort the waveforms (no harmonics). Nonlinear loads such as switch-mode power supplies, variable speed drives, computers and uninterruptible power supplies draw current in high-amplitude short pulses that create significant distortion in the electrical current and voltage wave shape (harmonics). Harmonics or distortions in the waveform will travel back into the power source and affect other equipment connected to that same source. Most power sources can accommodate a certain level of harmonic currents, however as those harmonic currents become more significant, the following issues can occur. • Overheating of electrical distribution equipment and cables. • Equipment malfunctions. • Higher voltages and circulating currents. • Vibrations and buzzing. • False tripping of protection devices. • Generator failures. • Increased energy losses and overheating causing component failure. www.csemag.com

Tolerances and limits

One of the most widely used tools for determining the power tolerance ranges for IT equipment is the Information Technology Industry Council curve. The ITIC curve (previously the CBEMA curve) was published by the technical committee of ITIC. The curve illustrates the voltage envelope and tolerances (magnitude and duration of voltage variations) that can typically be tolerated by most IT equipment. The vertical axis represents the percentage of voltage and the horizontal axis represents time. In the middle of the curve is the “no interruption in function region.” In this area computers, servers, power distribution units, programable logic controllers and telecommunication equipment operate properly. Above that middle acceptable region is the “prohibited region,” which involves the equipment tolerance for excessive voltages. Voltage spikes or surges in this region can cause damage to the IT equipment. At the bottom of the curve is the “no damage region,” which represents the equipment tolerance for reduction in voltage. Voltage sags and interruptions in this area can cause the equipment to stop functioning (shut off), but it should not cause damage to the equipment. The goal of the curve is to be a reference for determining the withstand capabilities of various IT loads for protection from power quality issues such as voltage variations. National standards do not currently exist for enforcing THD limits. IEEE 519-1992: IEEE Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems is a useful document for understanding harmonics. The standard does make recommendations for acceptable levels of harmonic distortion: “Computers and allied equipment, such as programmable controllers, frequently require ac sources that have no more than 5% harmonic voltage distortion factor [THD], with the largest single harmonic being no more than 3% of the fundamental voltage. Higher levels of harmonics result in erratic, sometimes subtle, malfunctions of the equipment that can, in some cases, have serious consequences.” It should be noted that the harmonic values in the IEEE standard are suggestions. It is recommended that you try to keep the THD values as low as possible to ensure proper operation of equipment and extend the life expectancy of the equipment.

Solutions

UPSs are commonly used for improving power quality in mission critical type facilities (call enters, emergency operation centers, etc.) that rely highly on their power electronic equipment and data centers that have large amounts of IT equipment. The primary function of the UPS system is to provide backup power during a power outage or interruption.

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The backup power is provided from a direct current power storage device, usually batteries or kinetic energy flywheels. For some facilities, the UPS can provide enough power/time to allow the systems to go through a proper shutdown sequence. In mission critical facilities or for longer outages, the UPS generally provides the power bridge until the facilities generators can start and supply power. In addition to eliminating the interruption deviation, the UPS can also help with waveform variations and voltage variations. Power that flows

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National standards do not currently exist for enforcing total harmonic distortion limits.

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through a double-conversion type UPS is also often referred to as conditioned power. The UPS rectifies (breaks down) the alternating current power into DC power and then inverts (remanufactures) the DC power back into a conditioned AC sine wave. Because the AC sine wave is remanufactured, it can be higher quality than the original wave, therefore eliminating any variations. The UPS system can also eliminate any voltage sags or undervoltage in the system by drawing additional power/voltage from the batteries to compensate for the decrease in voltage. The goal of the UPS is to provide uninterruptible power with a conditioned sinusoidal waveform at a constant nondeviating voltage. One issue the older thyristor-based UPS systems had was the amount of harmonic distortion it caused on the upstream systems. The 6-pulse thyristor-based rectifier had a 30% current THD and the 12-pulse thyristor-based rectifier had a 12% current total harmonic distortion. This caused upstream equipment such as generators to be oversized to compensate. Most double-conversion UPS systems today are insulated gate bipolar transistor-based that have reduced the current total harmonic distortion to 3%. Surge protection devices are electrical devices installed to protect against voltage surges and spikes in the electrical power system. The SPD device attempts to limit the voltage supplied to an electric device by either blocking or shorting current to reduce the voltage below a certain threshold. Lightning arrestors also can be used to protect against voltage spikes caused by lightning. Lightning arrestors typically have a high voltage terminal and a ground terminal. During a lightning strike, the current travels along the conductor to the arrestor. At the arrestor, the surge current is then diverted through the arrestor to the ground. consulting-specifying engineer

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Harmonic mitigation

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Two methods for compensating for harmonics include using 200% neutrals and K-rated transformers. The theoretical maximum current the triplen harmonic can produce is 173% of the phase current. The 200% neutral is used to compensate for that additional heat caused by the harmonic current heat in the conductor. K-rated transformers are used in the same manner, to compensate or manage the additional heat generated by the harmonic currents. Standard transformers are not designed to handle the high harmonic currents produced by nonlinear loads. K rated transformers are designed to

cel the harmonic current. Because they can be connected in parallel, the active filter can be a flexible, high-performance and cost-effective solutions used to mitigate power quality issues. The harmonic mitigating transformer is a phase-shifting transformer that uses electromagnetic flux cancellation to treat harmonics instead of filters and capacitors. Unlike K-rated transformers that compensate for harmonics, the HMT transformer eliminates the harmonic.

Power factor corrected

To ensure that electronic devices did not have a significant cumulative effect on the power system, standards like Inter-

Power quality can mean different things to different operations. Facilities like mission critical and data center facilities with sensitive electronics and IT equipment have small tolerances for deviations in power. reduce the heating effects of harmonic currents produced by nonlinear loads. UL developed a rating system described in UL 1561 to indicate the capability of the transformer to handle harmonic loads. Typical K ratings include K4 (discharge lighting, programmable logic controllers, solid state controls), K13 (telecom/IT equipment, health care, testing equipment) and K20 (mainframe computers, solid state motor drives, operating room equipment). Methods for reducing harmonics in the power system include passive filters, active filters and harmonic mitigating transformers. Passive filters are based on a combination of inductors, capacitors and resistors that correct the phase current or convert nonlinear loads to linear. These types of filters do not rely on external power sources and do not contain active components such as transistors. Active filters are devices connected in parallel with the systems load to be corrected. These types of filters are more complex. They actively monitor the nonlinear currents and generate or inject currents opposite the harmonics to can-

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national Electrotechnical Commission 61000-3-2 were established to set limits on power factor degradation and harmonic distortion introduced by power supplies. In data centers where there are large amounts of nonlinear IT equipment this standard forced the computer vendors have transition from older switched mode power supplies to power factor corrected power supply technology. The switched mode power supplies created distortion in the current and voltage waveforms causing high harmonics. The goal of the PFC power supply is to make the power factor as close to one as possible, where the current waveform is proportional to the voltage waveform. The PFC uses filters and/or electronic switching elements to force the input AC current to be sinusoidal with minimal distortion and in phase with the input voltage. By minimizing the distortion of the waveforms, the PFC power supply reduces the harmonics. Other types of facilities may use capacitor banks to correct power factor and improve power quality by offsetting inductive loads like large electrical motors.

consulting-specifying engineer

Other solutions

Other solutions for managing power quality may include: • Measure and locate the power quality. Two important factors in providing high power quality is determining if you have any power quality issues and what type of power quality problem exists. Once that is determined a proper plan can be derived to mitigate those power quality problems. Installing continuous power quality meters throughout the system can help detect power quality problems. The power quality meter should include the ability to capture and view waveforms, detect disturbances like voltage sags, voltage swells measure harmonic power flow and provide alarms when measurements are outside a set tolerance range. • Power distribution design: Separate sensitive loads from poor power quality source. • Specify variable frequency drives with line reactors or 12-pulse front ends • Design generators with proper pitch or alternator designs to handle power quality or even leading power factor data center loads. • Select grounding systems that help reduce power quality issues. Power quality can mean different things to different operations. Facilities like mission critical and data center facilities with sensitive electronics and IT equipment have small tolerances for deviations in power. These types of facilities are called upon to operate 24/7 and rely on high quality power to keep the systems operating normally. cse

Kenneth Kutsmeda is engineering manager for the mission critical sector at Jacobs. He is a member of the ConsultingSpecifying Engineer editorial advisory board and was a 2010 Consulting-Specifying Engineer 40 Under 40 winner. www.csemag.com

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By Nick Holway, PE, CDM Smith, Boston

Designing for power quality Engineers should follow four steps during the project life cycle to reduce harmonic distortion and provide consistent, high-quality power

evices using power electronics can produce distortion in electrical distribution systems, and it’s up to the electrical engineer to apply effective solutions to mitigate this added distortion. These solutions will ensure high-quality power is maintained within a nonresidential building, especially one with sensitive equipment or unique applications. “Dirty power” is a phrase that is often used to explain unexpected behavior in the context of an electrical system. A noisy electrical system is painfully unpleasant for facility managers, owners, operators and customers. These difficulties are commonly communicated back to the electrical engineers who supported the design. For many, the path of least resistance is to assign blame to the power utility company. In many cases, this snap judgment is inaccurate or neglectful. Careful analysis of the electrical system may identify opportunities to improve power quality at the facility.

Figure 1: Passive filters were installed adjacent to 150 horsepower variable frequency drives. Courtesy: CDM Smith

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Transient risks to power quality

A few suspects promptly come to mind when considering how a facility’s power source could be destabilized: lightning strikes, switching transients, starting large motors and failing equipment. Surge protection devices are designed to redirect transient overvoltages caused by lightning strikes and switching transients. Controllers for large motors are commonly designed and specified to minimize voltage sags. Protective devices and relays are designed to monitor system parameters and isolate components from faults due failing equipment. Each of these transient conditions merits substantial individual engineering attention. This discussion, however, will focus on an expanding area of concern that is far more common and much less transient in nature.

Nonlinear load risks

Modern technology has changed the landscape of power distribution and control. We have all witnessed the market growth of battery-powered vehicles, adjustable speed drives and data centers. Battery chargers recharge the batteries that power electric cars. Variable frequency drives play a critical role in modern facilities and energy conservation measures. Today, servers and digital storage are components of nearly all modern buildings. These devices share a common thread — the power electronic devices with nonlinear load profiles. The ideal sinusoidal waveform we all know so well is effectively mutilated by nonlinear load. Unlike a linear load, the impedance of a nonlinear load varies without a proportional relationship to the applied voltage. This unique impedance results in nonsinusoidal current. The choppy current waveform interacts with overall system impedance, which impacts voltage. As these currents make their way through the distribution network, the risk of operation beyond design constraints increases. www.csemag.com

Sensitive equipment, such as computers, may not operate as intended or fail when supplied with a distorted source of power. Transformers, motors, generators, capacitors, conductors and computer equipment are all susceptible to harmonic distortion. Transformers, generators and conductors can overheat. Capacitors are vulnerable to harmonic resonance. Motor torque can oscillate, causing excessive vibration and strain on the motor shaft.

Analyzing harmonics

Fourier series analysis allows engineers to deconstruct the nonsinusoidal waveform into individual sinusoidal components or harmonics. The choppy complicated waveform can now be described as a series of sinusoidal waveforms at multiples of the fundamental frequency. For example, the first order harmonic component of a 60-hertz system is 60 hertz, the second order harmonic component is 120 hertz and the third order harmonic component is 180 hertz. Harmonic components are grouped by rotation of phasors with respect to the fundamental frequency. Third, sixth and ninth harmonics rotate in-phase with fundamental frequency and are described as zero-sequence harmonics. Second and fifth harmonics rotate in the opposite direction of fundamental frequency and are described as negative sequence. Fourth and seventh harmonics rotate in the same direction as fundamental frequency and are described as positive sequence Power system analysis software allows engineers to analyze harmonics during design and during the construction phase after equipment is procured and installed. Studying harmonics during the design phase provides engineers with an opportunity to incorporate harmonic mitigation equipment and strategies into the design. Harmonic mitigation equipment requires space for installation. Studying harmonics during the construction phase allows engineers to model asbuilt conditions and check harmonic distortion before operation. Performance testing during construction allows for verification that harmonic distortion is within the specified tolerances.

Minimizing harmful effects of nonlinear loads

IEEE Standard 519 provides goals for electrical engineers to minimize the harmful effects introduced by nonlinear loads. Analysis of a power distribution system with respect to Standard 519 is becoming increasingly important in the modern marketplace where nonlinear loads currently are present or proposed. Limitations for individual harmonics, total harmonic distortion, total demand distortion and current distortion are identified within the standard. Criteria for measuring harmonic distortion are also provided within the standard. It is important to

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Four steps to reduce harmonic distortion 1. Preliminary harmonics study. Model the network and loads using power system analysis software. Calculate short circuit and maximum demand. Establish the point of common coupling and analyze harmonic distortion.

2. Design development. Review the results of the harmonic analysis. Determine the need for additional harmonic mitigation. Determine the impact of harmonics on sources of standby power. Design and specify products to mitigate distortion. Specify performance testing procedures to measure distortion during project startup. Consider including power monitoring devices and systems to allow for nonintrusive performance testing. Memorialize the harmonic analysis by revising the model to include mitigation equipment. Document the results of the preliminary harmonic study before procurement or the bid phase. There are many methods to reduce harmonic distortion within a system. A wide range of products are available to engineers and end users. Several products with advantages and disadvantages are listed in Table 1 to provide guidance.

3. Final harmonic study. Incorporate as-built conditions into the model. Review results of the final analysis with respect to performance requirements. Recommend additional harmonic mitigation equipment if as-built conditions have introduced additional challenges. Consider specifying an independent third-party analysis for projects where a conflict of interest is a concern.

4. Performance testing. Measure values in compliance with the latest standard of IEEE Standard 519. Specify testing procedures to reflect worst-case operating scenarios. Coordinate performance testing procedures with the owner to avoid surprises or impacts to operation. Review results for compliance with performance criteria. Discuss unexpected test results with all stakeholders and evaluate if additional engineering, analysis or testing is needed to provide a reliable system. Document test results as benchmarks for future projects.

review and clarify the definitions used in IEEE standard 519 because the concepts and criteria are technical in nature.

Standard 519 definitions

Learning

OBJECTIVES

• Understand how power quality can impact electrical system reliability.

Point of common coupling: “Point on a public power supply system, electrical- • Gain the ability to identify applications ly nearest to a particular load, at which where improvements are other loads are or could be, connected. recommended. The PCC is a point located upstream of • Learn engineering methods to the considered installation.” protect equipment and optimize The limitations identified for total performance. harmonic distortion are applicable to the PCC. The limitations identified for TDD are a function of short-circuit ratio at the PCC. The first step of a harmonic analysis must identify the location of the PCC and clarify the decision to choose that consulting-specifying engineer

September 2019

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location. The PCC sets the stage for establishing the interface between the user and power supplier. A rule-of-thumb for commercial systems with a utility service transformer is to establish the PCC on the secondary side of the service transformer. A rule-of-thumb for industrial facilities with campus-style distribution is to establish the PCC on the primary side of the distribution transformer or upstream distribution switchgear serving the facility. Total harmonic distortion: “The ratio of the root mean square of the harmonic content, considering harmonic components up to the 50th order and specifically excluding interharmonics, expressed as a percent of the fundamental. Harmonic components of order greater than 50 may be included when necessary.” THD limitations identified under Table 1 of IEEE 1547 vary based on the voltage applied to the PCC. The tightest requirements for THD are for low-voltage systems. Total demand distortion: “The ratio of the root mean square of the harmonic content, considering harmonic components up to the 50th order and specifically excluding interharmonics, expressed as a percent of the maximum demand current. Harmonic components of order greater than 50 may be included when necessary.”

TDD limitations vary based on short-circuit ratio. Goals for TDD are arguably as important as THD. The goals for harmonic current distortion are critical to review when specifying sources of standby power. Short-circuit ratio (ISC/IL): “At a particular location the ratio of the available short-circuit current, in amperes, to the load current, in amperes.” Shortcircuit current must be calculated to analyze TDD. Maximum demand load current (IL): “This current value is established at the point of common coupling and should be taken as the sum of the currents corresponding to the maximum demand during each of the previous months divided by 12.” IEEE 519 Table 2 footnote C further clarifies maximum demand load current as current at the PCC during normal load operating conditions. Load calculations considering diversity must be developed to evaluate TDD. Table 1 of IEEE 519 identifies recommendations for voltage distortion limits. Individual harmonic distortion limits and total harmonic distortion limits are identified for a range of voltages at the point of common coupling. Table 2 of IEEE 519 identifies recommendations for current distortion limits. Distortion limits for groups of individual harmonic orders are

Table 1: Harmonic mitigation products Product Passive filter

Description

Advantages

Disadvantages

Shunts specific harmonic components. Commonly applied as an “add-on” to variable frequency drives.

Tuning will target specific harmful components.

• Does not mitigate the full spectrum of harmonics.

Sine wave filter

Tuned to shunt VFD carrier frequency.

Allows for longer cable distance applications or use of noninverter duty rated motors.

Benefit to the individual load served by the filter only.

Harmonic correction unit

Injects phase-shifted harmonic current directly into the system.

Bus-level application (main switchgear, switchboard, motor control center, panel).

• Unit heat rejection.

• Must be used in conjunction with a line reactor for optimal performance.

• Requires adding line reactors to downstream nonlinear load. • Expensive.

AC line reactor

DC bus choke

Increases source impedance. Commonly specified for VFDs. Provided in combination with power factor correction capacitors to mitigate resonance. Reactor between diodes and DC bus.

• Cost-effective. • No-brainer for VFD applications. • Doubles as a current-limiting device. • Smaller than AC line reactor. • Protects against current surges.

12- or 18-pulse rectifier assembly

Integrated solution for VFDs.

Excellent performance under specific conditions.

• Typically used in tandem with other products to provide comprehensive mitigation. • Typically used in conjunction with other products to provide comprehensive mitigation. • Inefficient. • Large footprint. • Not effective when operated at light load.

Active front end

Integrated solution for variable speed drives. AC to DC to AC power architecture.

Replacement consideration for aging 12- and 18-pulse drives that are no longer supported.

• Expensive. • Complicated power electronics.

Table 1: This is a summary of products used to mitigate harmonic distortion. Mitigation techniques and offerings are application dependent and can be used in conjunction with other products. Advantages and disadvantages are identified. Courtesy: CDM Smith

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www.csemag.com

CASE STUDY: Performing a harmonic analysis

harmonic analysis to study system operation and mitigation methods of a design-build wastewater treatment plant was conducted in April 2015 in Boston. Performance testing was completed at the wastewater treatment plant located in Washington, D.C., after substantial completion in March 2016. Active harmonic filters used to mitigate harmonic distortion, and performance testing was completed under multiple operating scenarios using Power Analytics DesignBase software. This project involved extending 4,160-volt campus power distribution to several new facilities. Each facility was provided with a unit substation to reduce voltage to 480 volts, 3-phase. Each unit substation distributes power to a variety of 480-volt motor control centers. The wastewater treatment process includes redundant process trains for solids removal, dewatering, thermal hydrolysis and anaerobic digestion. Due to the quantity of equipment needed to process the wastewater redundant 480-volt main-tie-main, MCCs are provided for the dewatering, thermal hydrolysis and anerobic digestion process trains. A single main-tie-main 480-volt MCC is provided for the solids processing train. Variation and efficiency requirements for the process flow necessitated the use of variable frequency drives for a large percentage of the process motors. In addition to process load, mechanical heating, ventilation and air conditioning equipment for building conditioning included nonlinear load for fans and cooling equipment used to condition each facility. Variable speed motor horsepower ranged from 5 horsepower for small chemical pumps to 250 horsepower for dewatering centrifuges. The majority of VFDs serving the process motors were packaged integral with the motor control centers. VFDs less than 50 horsepower were six-pulse pulse-width modulation design with 5% input line reactors. VFDs larger than 50 horsepower were required by technical specifications and owner standards to be 18-pulse design. Active front-end regenerative drives were used to control the large dewatering centrifuge main drives and back drives. Each main-tie-main motor control center was constructed with redundant active harmonic filters. Under normal operating conditions, the MCC tie breaker is open and each active filter serves one-half of the bus. During maintenance, the tie breaker is closed and both active filters operate in tandem. Careful consideration of the current transformer placement (additional current transformers and wiring are required) is needed to allow redundant active harmonic filters to operate in a singleended condition. A preliminary harmonic study was developed early in the design phase to determine the rating of each active harmonic filter. Active harmonic filters are specified in

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Figure 2: This single-line diagram shows the pre-dewatering and digester facilities. Courtesy: CDM Smith

increments of 50 amperes. The anaerobic digester facility was calculated to demand the most nonlinear load. An upsized active harmonic filter (100 amperes) was initially considered for the anaerobic digester MCCs but eliminated after completing a detailed harmonic analysis. The minimum size active harmonic filter (50 amperes) was selected and specified for each main on each maintie-main motor control center. A detailed harmonic study was completed after procurement of all equipment. The point of common coupling was chosen to be the 4,160-volt side of each substation transformer serving the process trains. Considering that future modifications to the 4,160-volt campus distribution were possible, the PCC was selected on the primary side of the distribution transformer. Distortion at each low voltage bus also was calculated to examine current distortion at the motor control centers. The results of the harmonic analysis were developed and reviewed for compliance with IEEE 519. After substantial completion, a performance test was conducted to verify and document harmonic distortion throughout the system. The performance test included two scenarios. One scenario examined harmonic distortion under extreme process conditions (maximum demand). A second scenario examined harmonic distortion at 50% process conditions. While not applicable to IEEE 519 goals, examining harmonic conditions at typical operation points is advisable to review performance under normal operating conditions. The results of the performance test were reviewed and determined to be in compliance with criteria specified. Note that the analysis and testing performed for this case study were in compliance with IEEE 519-1992. consulting-specifying engineer

September 2019

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Table 2: Bus distortion calculations Total harmonic voltage indices Volts root means squared (volts)

kilovolts · T 1

TIF 2

Total harmonic distortion (%)

Bus name

V1 (volts)

50035A-BUS

4,144.67

4,144.8

15.58

0.77

50065B-BUS

4,115.15

4,116.59

21.64

2.29

ASS6 BUS B

4,157.45

4,158.16

11.28

1.85

ASS-6, BUS-C

4,190.26

4190.5

6.71

1.08 3.98

DB_MCC1_A

471.84

472.21

37.57

DB_MCC1_B

476.74

477.03

44.52

3.45

DB_MCC2_A

472.13

472.5

37.04

3.96 3.45

DB_MCC2_B

476.25

476.53

44.52

PDB_MCC1_A

469.93

469.99

37.04

1.6

PDB_MCC1_B

465.9

466.1

44.64

2.94

PDB_MCC2_A

462.62

462.74

50.54

2.25

PDB_MCC2_B

465.48

465.82

74.28

3.81

SWBD-SOLD-12A

463.46

463.97

75.51

4.69

SWBD-SOLD-12B

463.64

464.14

67.23

4.68

SWBD-THP-1

463.25

463.37

54.43

2.19

SWBD-THP-2

465.99

466.33

54.3

3.86

NOTES: 1 Kilovolts · T or kV-T product: Inductive influence expressed in terms of the product of root mean square voltage magnitude, in kilovolts, times its telephone influence factor. Source: IEEE Standard 519 2 Telephone influence factor (TIF): For a voltage or current wave in an electric supply circuit, the ratio of the square root of the sum of the squares of the weighted root mean square values of all the sine-wave components (including alternating current waves both fundamental and harmonics) to the root mean square value (unweighted) of the entire wave. Source: IEEE Standard 519

Table 2: Calculated voltage distortion (total harmonic distortion) is shown for each bus studied. Courtesy: CDM Smith

SPEC SMARTER. COMMERCIAL TANKLESS WATER HEATING

www.noritz.com/case-studies

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identified (for example, third through 11th harmonic). Total demand distortion limits also are identified. The goals for current distortion are grouped by shortcircuit ratio. Note that power generation equipment, such as standby generators, is subject to the most stringent current distortion limitations. Part 4 of IEEE 519 identifies criteria for measuring harmonics. An assessment of real-life harmonic distortion against calculated values is recommended before project closeout. Instruments used to measure harmonics should comply with IEC 61000-4-7 and IEC 61000-4-30. Specify submittal requirements for instruments and procedures used to measure harmonic levels to allow for engineering review and approval.

tion may apply to an individual installation. From an efficiency perspective, it is easy to dismiss harmonic analysis when designing an upgrade that does not add nonlinear load. Due diligence, however, must be exercised to prevent unforeseen issues. Engineers can minimize exposure to project risk by analyzing harmonics and specifying methods to mitigate unacceptable distortion. cse

Nick Holway is a senior electrical engineer at CDM Smith with more than 10 years of experience working in the electrical engineering field, providing design, engineering and construction support of power systems for municipal, industrial and private clients.

Confirming specifications Always bear in mind that the criteria established to limit harmonic distortion is based on steady-state worst-case conditions. Transient conditions that exceed the limitations are entirely possible. The limitations identified by these standards are recommendations only. IEEE 519 does not cover means and methods to protect motors driven by variable frequency drives from damage. Inverter duty motors per National Electrical Manufacturers Association MG1 (Part 31), VFD cables, insulated bearings and additional load side filtering devices may be recommended to prevent circulating currents, premature bearing failure or stator insulation failure. Installation guidelines from VFD manufacturers often recommend VFD cable. It is important to consult with the manufacturer for the VFD, particularly for large motor applications, to determine additional needs before completing an electrical design. Generator selection and specification must consider the nature of the loads being served. Inductive loads such as constant speed motors and transformers may be impacted when operating within an environment with harmonic distortion. Changing the impedance of a system may exacerbate harmonic distortion that was previously not obvious. Calculations may not reflect actual conditions. Performance testing provides a means to verify operation is within specified guidelines. Goals for harmonic distortion are not legal requirements. However, contractual requirements to limit harmonic distorSeptember 2019

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BUILDING SOLUTIONS

CODES AND STANDARDS

By Cory Duggin, PE, LEED AP BD+C, BEMP, TLC Engineering Solutions, Brentwood, Tennessee; and Tony Esposito, PE, LEED AP, TLC Engineering Solutions, Philadelphia

Determining which boiler system to design There are many different configurations of boilers; learn about the three primary types used for environmental and process systems

here are many advantages to using boilers as a primary component of a central energy plant. Boilers are pressure vessels in which fluids, most often water, are heated. The term boiler also includes vessels in which the fluid does not necessarily boil or vaporize. Boilers are widely accepted for many applications and are an established heating source for generating heating hot water, domestic hot water and steam, particularly in colder climates or large facilities. When designing central heating plants, there are several types of boilers and applicable codes to consider. While there are many different configurations of boilers, three primary types widely used for environmental and process systems include steam, noncondensing hot water and condensing hot water. In the past, steam boilers were very common, but are routinely being minimized or eliminated in current design practice due to their limited efficiency, specialized operation and maintenance requirements and high-pressure steam systems add safety concerns. The primary advantage of steam is the ability to distribute a greater quantity of heat in a smaller volume, via the latent heat of vaporization and superheat. One of the downsides is the piping is pressurized and Figure 1: The recently opened, award-winning Baptist M.D. Anderson Cancer Center in Jacksonville, Florida, incorporates condensing boilers for heating hot water. These are very high efficiency; the ones shown are gas-fired boilers. Courtesy: TLC Engineering Solutions

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requires condensate return as typically enough heat is lost in distribution to cause a phase change from vapor to liquid. Most steam systems currently exist on large campuses or in health care facilities. However, even health care facilities have started to move to point of use steam generators for their sterilizers, cooking and humidification, while using hot water boilers for the heating and domestic hot water (also known as service water heating, or SWH). Hot water boilers don’t sufficiently heat the water to vaporize it at their operating pressure, so they don’t have the advantage of storing the additional latent heat of vaporization in the fluid like steam boilers. Noncondensing boilers are typically designed with hotter return water temperatures to avoid condensing in their heat exchangers because they aren’t rust resistant. Condensing boilers have nearly become the standard practice boiler for most designs because of their increased efficiency. They use cold return water to condense water out of the combustion products to recover some of the lost heat from the exhaust flue. Because they are designed for condensing, their heat exchangers are stainless steel. The key is to ensure the return heating hot water temperature is below the dewpoint of the combustion products, which is about 125 F for natural gas. As the return heating hot water temperature gets further below the combustion dewpoint temperature(125 F), more water is condensed and the efficiency approaches 100%. The typical operational efficiency for condensing boilers is about 95%. When compared to the typical thermal efficiency of noncondensing hot water boilers at 80%, the increase in performance is substantial. Heating coils in buildings do have to be sized for a higher delta T in order to facilitate the colder return water temperature, which can increase the cost of the coils but decreases pumping energy. While not a boiler in the historic context of steam, the use of heat recovery or heat pump chillers to create heating hot water is also becoming more common, www.csemag.com

especially when looking toward a carbon-free future. Heat recovery chillers can produce 140 F heating hot water while reducing the load on the chilled water loop, so they typically operate with a heating performance of three to four coefficient of performance. If the benefit of both the heating hot water and chilled water is accounted for, the coefficient of performance can increase to as high as seven. They also have the advantage of not requiring on-site combustion as they use electricity for operation. This is an advantage for projects looking to reduce Scope 1 carbon emissions or pursuing certain third-party certifications, such as Living Building Challenge.

Codes and standards

There are several codes governing the design of boiler systems. In the building industry the most relevant are the International Mechanical Code, International Energy Conservation Code and ASHRAE Standard 90.1: Energy Efficiency for Buildings Except Low-Rise Residential Buildings. Chapter 10 of the 2018 IMC describes the design requirements for boilers, water heaters, expansion tanks and other pressure vessels. Section 1004 states that “boilers must be designed, constructed and certified in accordance with the American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Section I or IV.” There also are requirements for clearances and valves based on the pressure and capacity of the boiler. The requirements of this code are to ensure the design of safe boiler systems. The IECC and ASHRAE 90.1 both govern the energy-efficiency requirements of heating hot water and domestic hot water boiler systems. The standards have several similar requirements, but some that are different, so it’s important to know which you are designing around. The 2018 IECC and ASHRAE 90.1-2016 have similar efficiency requirements with respect to boilers. The pertinent sections and their equivalent in the other standard are shown in Table 1. Except for some slight changes in wording, the requirements are the same in both standards, including the specific minimum efficiencies and turn down requirements. It is important to understand that the service water heating section in both ASHRAE 90.1-2016 (section 7) and IECC-2018 (C404) are mandatory. There is a change underway for how we design heating hot water systems. The historic default has been to use combustion to produce steam or hot water that can be circulated through buildings. Several utilities have recently put moratoriums on new gas services, such as Consolidated Edison in Westchester County, New York, and National Grid in Long Island, New York, which means new facilities will have to produce their heating hot water and domestic hot water by other means. Also, the New York city council recently based the Climate Mobilization Act, which sets carbon emissions limits for covered buildings. There

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Figure 2: Halifax Health Medical Center, Daytona Beach, Florida, uses steam boilers to serve their heating and sterilization loads. Courtesy: TLC Engineering Solutions

Table 1: Comparing standards and guidelines Requirement Boiler room isolation Boiler turndown Minimum efficiency Pump isolation Service water heating High-input service water heating systems

ASHRAE 90.1-2016

IECC-2018

No equivalent

C402.5.3

6.5.4.1

C403.3.4

Table 6.8.1-6

Table C403.3.2(5)

6.5.4.3.2

C403.4.5

C404

7.5.3

C404.2.1

Table 1: The energy efficiency requirements of boilers in ASHRAE Standard 90.1-2016 and International Energy Conservation Code-2018 are compared. Courtesy: TLC Engineering Solutions.

are multiple reasons for this change. Some areas are planning for a fully electrified, carbon-free future. Others are just responding to supply and demand. Other countries are making the change as well. The United Kingdom and Netherlands are reducing their gas production and consumption in response to aggressive climate goals. As engineers, we need to be ready with innovative solutions to provide efficiently generated heating hot water and domestic hot water for our clients’ facilities. cse

Learning

OBJECTIVES

• Understand the difference between condensing and noncondensing hot water boilers. • Learn about electrical alternatives for producing hot water. • Recognize the code sections applicable to boiler system designs.

Cory Duggin is a principal with TLC Engineering Solutions PEAK Institute. He is a member of the Consulting-Specifying Engineer editorial advisory board. Tony Esposito is a managing principal at TLC Engineering Solutions. consulting-specifying engineer

September 2019

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BUILDING SOLUTIONS

CODES AND STANDARDS

By Jacob Haddadin, EIT and Stephanie Khouri, CCJM Engineers Ltd., Chicago

Introduction to boilers for the entry-level engineer Entry-level consulting engineers should understand the definition and applications of a commercial hydronic boiler

hen beginning a career in consulting mechanical engineering, there is a lot to learn. Specifications can seem like a foreign language and the details of mechanical equipment can overwhelm the young engineer. With regards to hydronic heating systems, the beginning of this navigation starts with the commercial hydronic boiler. The hydronic boiler is the heart of the hydronic heating system. The heating system consists of many parts including the boiler itself, the piping distribution, pumps, central and terminal devices that deliver the hot water to where it’s needed and building automation systems to control how much heat is being delivered. The boiler is a pressurized vessel that burns combustible fuel to heat water that is used to heat a commercial building.

What defines a hydronic boiler?

A hydronic boiler can be either a condensing or noncondensing boiler. Both types of boilers can be either a fireor a water-tube boiler. When selecting a fire-tube boiler, it can be categorized either as a wetback or a dryback boiler. Figure 1: This boiler diagram shows the difference between dryback and wetback boilers. Courtesy: CCJM Engineers

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Since we will use the term Btu/hour frequently throughout this article, a definition is in order. The Btu is the heat required to raise the temperature of 1 pound of water by 1 F. The heating capacity of boilers is rated in Btu/hour; 1,000 Btu/hour is referred to as MBH. A condensing boiler typically ranges from 400 MBH up to 3 million Btu/hour and a noncondensing boiler typically ranges from 400 MBH up to 6 million Btu. A condensing boiler has two heat exchangers and a lower temperature of combustion products (around 130 F). Efficiencies of condensing boilers reach up to 98%. This is accomplished by condensing water vapor and other components in the exhaust gases to recover latent heat of vaporization while preheating the entering water stream. The condensate is acidic, with a pH between 3 and 4. The majority of condensing boiler combustion chambers are stainless steel construction to withstand the acidic condensate. In comparison, a noncondensing boiler has a single combustion chamber and a single heat exchanger with higher temperature products of combustion (around 350 F). Their combustion chambers are not required to be acid corrosion resistant because the flue gases don’t condense and acidify. Also, the heat of the flue gases is wasted when the products of combustion are discharged straight out the exhaust flue. In short, a condensing boiler has a higher initial cost due to the corrosion-resistant construction and multiple heat exchangers and it is more cost-efficient to operate. Where budget is a concern, engineers should choose noncondensing boilers. A commercial hydronic boiler can be either a fireor water-tube boiler. Water-tube boilers consist of water flowing through tubes that are encased by hot combustion gases. Conversely, fire-tube boilers consist of hot combustion gases passing through tubes surrounded by water. Fire-tube boilers are further classified by the type of reversal chamber between www.csemag.com

Figure 2: This sample condensing boiler installation detail shows all the components typically in a condensing boiler installation. The main components that distinguish a condensing boiler are the neutralization kit and stainless steel AL-29-4C flue. Courtesy: CCJM Engineers

passes (see Figure 1) through which flue gases travel through the furnace. If the reversal chamber is surrounded by water, it is defined as a wetback boiler and if the reversal chamber contains a lined rear wall, it is a dryback boiler. Fire-tube boilers also have much longer fire-up times and require longer adaptation periods to altering demands due to their high thermal mass (high volume of water in the boiler). These types of boilers also require regular and difficult maintenance periods. Water-tube boilers have relatively fast fire-up times and respond easily to frequently changing demands due to their small thermal mass (low overall water volume) compared to equivalent fire-tube boilers.

Boiler definitions and classifications

After navigating which type of commercial hydronic boiler will best serves the needs of a particular project, one must then dive into the specifications that will define and describe the boiler for the project. A specification for a boiler can have confusing verbiage that is difficult to navigate. Key components include its burner, combustion chamber, heat exchanger, controls and exhaust stack. The burner of a boiler provides the flames that heat the water in the boiler, while the combustion chamber is the area within the boiler where fuel is burned to heat the water. This chamber holds the burner and is usually made of cast iron or steel. The heat exchanger of a boiler allows the transfer of the heat produced by the burners to the water in the boiler. To set the water

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‘

A specification for a boiler can have confusing verbiage that is difficult to navigate. Key components include its burner, combustion chamber, heat exchanger, controls and exhaust stack.

’

temperature, ignition, air and fuel supply mixtures and internal pressure, every boiler will have systems controls. These systems controls also contain a safety control to ensure that the internal pressures in the boiler don’t get too high. These safety controls ensure that the water temperature stays within a safe range and the system is running as designed. The final component of a boiler is the exhaust stack. The exhaust stack contains all of the pipes used to carry exhaust gases from the boiler to the outside of the build- • Provide a primer for young engineers to understand the ing. This component is crucial to the safety basics of condensing hydronic of the system because of the toxicity of carboilers. bon monoxide in any building. • Know the difference between the When choosing a hydronic boiler, common types of commercial another key term to look at is its turndown hydronic boilers. ratio. The turndown ratio of a boiler is the • Learn about the specifications ratio between full boiler output and the used when selecting commercial hydronic boilers. boiler output when operating at low fire.

consulting-specifying engineer

Learning

OBJECTIVES

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BUILDING SOLUTIONS

CODES AND STANDARDS

1.2 Summary A. Section includes gas-fired, [pulse-combustion] [fire-tube] [water-tube] [water-jacketed] condensing boilers, trim and accessories for generating [hot water] [and] [steam]. To follow the type of boiler illustrated in Figure 1, we would edit the following raw specification sections as shown below while confirming the features with the basis of design condensing boiler:

Figure 3: An elementary school heating plant has two condensing boilers and hot water distribution pumps. Courtesy: CCJM Engineers

Typical boiler turndown is 4:1 meaning a 400-horespower boiler with a turndown of 4:1 will modulate down to 100 horsepower before cycling off. When an engineer needs to develop a boiler specification for a specific project, they typically look in their company’s custom master specification library or one of the model master specifications like the American Institute of Architect’s MasterSpec library to look for the applicable master specification under Division 23. Specifically, they would look for section 23 52 16 condensing boilers, section 23 52 33 watertube boilers or section 23 52 39 fire-tube boilers, depending on the specific type of boiler the project engineer for the project has selected in the basis of design. One of these specifications would be selected and edited for the project. To demonstrate how a master specification is edited for a particular project, we will use specification section 23 52 16 condensing boilers for a boiler being implemented in a local public school district. Part 1 of the condensing boiler specification will the general description what type of condensing boiler is being described in the section of this article titled “What defines a hot water boiler?” Part 1: General 1.1 Related documents A. Drawings and general provisions of the contract, including general and supplementary conditions and Division 01 specification sections, apply to this section.

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Part 2: Products 2.1 Forced-draft, fire-tube, condensing boilers A. Manufacturer: Design note: Select manufacturers from owner’s approved list, if applicable or based on engineer preference and local engineering and maintenance support. B. Description: Factory-fabricated, -assembled and -tested, fire-tube condensing boiler with heat exchanger sealed pressure tight, built on a steel base, including insulated jacket; fluegas vent; combustion-air intake connections; water supply, return and condensate drain connections; and controls. Water-heating service only. C. Heat exchanger: Nonferrous, corrosion-resistant combustion chamber. D. Pressure vessel: Carbon steel with welded heads and tube connections. E. Burner: [Natural] [Propane] gas, forced draft. Design note: Pick whichever is common for the region. F. Blower: Centrifugal fan to operate during each burner firing sequence and to prepurge and postpurge the combustion chamber. 1. Motors: Comply with National Electrical Manufacturers Association designation, temperature rating, service factor and efficiency requirements for motors specified in Section 230513 “Common Motor Requirements for HVAC Equipment.” a. Motor sizes: Minimum size as indicated; if not indicated, large enough so driven load will not require motor to operate in service factor range above 1.0. G. Gas train: Combination gas valve with manual shut-off and pressure regulator. H. Ignition: Spark ignition with 100% mainvalve shut-off with electronic flame supervision. I. Casing: 1. Jacket: [Sheet metal] [Plastic], with snap-in or interlocking closures. 2. Control compartment enclosures: NEMA 250, Type 1A. 3. Finish: [Baked-enamel] [Powder-coated] protective finish. www.csemag.com

CASE STUDY: Comparing hydronic heating systems

4. Insulation: Minimum 2-inch-thick, [mineral-fiber] [polyurethane-foam] insulation surrounding the heat exchanger. 5. Combustion-air connections: Inlet and vent duct collars. J. Capacities and characteristics: 1. Heating medium: Hot water. 2. Design water-pressure rating: [160 pounds/ square inch gage] Design note: This is the standard working pressure for American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Section IV Heating Boilers Class. 3. Safety relief valve setting: Design note: Value ranges from 30 psig up to the design waterpressure rating and is selected by the consulting engineer based on the highest pressure point in the system, in psig. 4. Entering-water temperature: Design note: Value is based on the project design requirement, in degrees F. 5. Leaving-water temperature: Design note: Value is based on the project design requirement, in degrees F. 6. Design water flow rate: Design note: Value is based on the project design requirement, in gallons/minute. 7. Minimum water flow rate: Design note: This value is based on the basis of design boiler’s stated minimum flow requirement, in gpm. 8. Design pressure drop: Design note: Value is based on the basis of design boiler listed pressure drop, in psig. 9. Minimum efficiency annual fuel utilization efficiency: Design note: Value is based on the basis of design boiler listed efficiency in percentage. 10. Minimum thermal efficiency: Design note: Value is based on the basis of design boiler listed thermal efficiency in percentage. 11. Minimum combustion efficiency: Design note: Value is based on the basis of design boiler listed combustion efficiency in percentage. 12. American Gas Association input: Design note: Value is based on the basis of design boiler listed data, in MBH. 13. Gas input: Design note: Value is based on the basis of design boiler listed data, in cubic feet per hour. 14. AGA output capacity: Design note: Value is based on the basis of design boiler listed data, in MBH. 15. Department of Energy output capacity: Design note: Optional value is based on the basis of design boiler listed data, in MBH. 16. Equivalent direct radiation: Design note: Value is based on the basis of design boiler, listed data as EDR. www.csemag.com

he following shows the range of sizes hydronic heating systems can span. One is a relatively small hydronic heating plant in an elementary school annex and the other is one of the largest heating plants in a massive district heating plant at O’Hare International Airport in Chicago. The school project includes two 500 MBH (input) gas-fired, condensing water-tube boilers (see Figures 1 and 2). The system operates at 150 F supply and 120 F return water temperature. It is a variable primary flow system primarily serving perimeter hydronic terminal heating equipment including cabinet heaters, fin-tube radiators and radiant heating panels (Figure 3). In contrast, the O’Hare International Airport heating plant consists of eight 75,000 MBH water-tube high-temperature water HTW boilers split into two fully redundant plants delivering 410 F water at 400 PSIG operating pressure. While most systems operating at this temperature are high-pressure steam plants, the airport operates their system under high pressure to maintain a high-temperature water system. Heat exchangers at each terminal develop conventional 180 F water for air handling units and terminal devices in a decoupled tertiary loop. The plant is currently in the construction process of replacing all eight existing boilers with new, higher efficiency, lower NOX-emitting water-tube boilers.

17. Blower: a. Motor horsepower: Design note: Value is based on the basis of design boiler listed data. b. Revolutions/minute: Design note: Value is based on the basis of design boiler listed data. 18. Electrical characteristics: a. Volts: [115] [208] [230] [460] Design note: Value is based on the basis of design boiler listed data and project conditions. b. Phase: [Single] [Three] Design note: Value is based on the basis of design boiler listed data and project conditions. c. Hertz: [50] [60] Design note: 60 hertz is the standard in the U.S. d. Full-load amperes: Design note: Value is based on the basis of design boiler listed data. e. Minimum circuit ampacity: Design note: Value is based on the basis of design boiler listed data, for wire sizing. f. Maximum overcurrent protection: Design note: Value is based on the basis of design boiler listed data, for power circuit breaker sizing. Note that this specification’s edits are for a standard condensing boiler project in the U.S. For a given project, the young engineer should request more guidance from the project engineer and customize the options and construction to match owner requirements, local code requirements and project budget. Once the verbiage and classification are consulting-specifying engineer

September 2019

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BUILDING SOLUTIONS

CODES AND STANDARDS

defined for a commercial hydronic boiler, the specifications can then reflect the boiler being used for the project. To properly specify the boiler, the consulting engineer needs to understand the application considerations of the boiler chosen.

Commercial application considerations Commercial boilers are used typically in hospitals, offices, hotels and schools. These boilers typically work with heat output from 6,000 MBH to as low as 400 MBH. Commercial condensing boilers are available in fire- and water-tube designs. They typically use propane or natural gas to provide hot water. These systems in a condensing mode operation can have fuel efficiency as high as 98%, depending on the extent of condensing to capture the latent heat of the flue gas by the return water. Most architectural projects with large amount of glazing will favor the hydronic boiler because it is an efficient and costeffective boiler to be used for heating schools, offices and other commercial buildings. Overhead air heating doesn’t work well with tall glazing higher than 5 feet, so some type of local perimeter heating, whether baseboard or radiant ceiling panels, provides an effective solution. For most applications and regions in the U.S., hydronic heating generally provides a more cost-effective solution than electric heating. Although gas boilers are typical 10% to 25% higher in price than their oil-fired counterparts — the quick payback due to lower natural gas prices per gallons/minute of heated water compared to oil boilers makes it worth the investment. Natural gas-fired boilers also boast approximately 10% higher AFUE than oil-fired boilers, a measure for a boiler’s combustion efficiency. Fuel oil also frequently lacks the pipeline infraFigure 4: This photo shows one of the structure, which means existing 75,000 MBH boilers under maincertain means of resuptenance at an international airport. Courply and storage have to be tesy: CCJM Engineers taken into consideration.

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CONSULTING-SPECIFYING ENGINEER

Oil has its advantages in terms of providing maximum heat; the boilers are capable of supplying the amount of heat required to reach a certain setpoint two times faster than natural gas boilers due to the higher temperatures oil burns at. The higher burning temperatures also ensure lower amounts of condensation, which leads to a longer life span of the boiler if the boiler construction isn’t corrosion resistant. Condensing boilers are the most popular commercial water boiler due to the high combustion energy efficiency levels they are able to achieve. However, multiple important factors should be taken into consideration when deciding whether the initial price increase, typically in the 30% cost premium range, is worth it for the system, whether it be a new or retrofit project. Beyond first cost, system operation also plays a significant role in their selection. Generally, condensing boilers operate at lower supply and return water temperatures, typically 160 F supply and 130 F return, to achieve their optimal energy savings. Systems in northern climates that require a higher supply temperature during peak heating season tend to operate outside the condensing return water temperature for much of the heating season. They do provide high energy efficiency during the shoulder months when only lower-quality heat is adequate. Condensing boilers achieve their highest efficiencies around 98% when the return water temperature is as low as possible, typically around 80 F. However, typical return water temperatures for conventional hydronic systems is around 130 F, which yields overall boiler efficiency around 90%. The lower hot water return temperature aids in condensing the flue gases produced from the combustion of natural gas, which in turn causes a release of energy that heats the return water before entering the combustion chamber of the boiler and thus raising the overall efficiency of the boiler. They are available in fire- and water-tube configurations. If the system is expected to be running at high supply and return temperatures for most of its operating hours, a condensing boiler system will not be the optimal system selection because the hot water return temperature will always be too high for condensing operation. The equipment that is being served by the boilers also should be one of the deciding factors for the boiler type. Some terminal heating equipment require higher temperature heating fluid to ensure proper operation. Radiant ceiling panels are a good example of such equipment that perform most optimally at supply temperatures around 180 F. For systems with a large number of these devices, a condensing boiler may not the optimal choice. Conversely, applications such as underfloor heating and variable air volume box reheats and installations in milder winwww.csemag.com

ter climates (Department of Energy and International Code Council climate zones 2, 3 and 4) are excellent for taking advantage of the benefits of condensing boilers with lower supply water temperatures around 150 F to 160 F.

Hybrid systems Combining condensing and noncondensing boilers in the same system, also called a hybrid system, can help improve overall system efficiency. As discussed above, the return water to the boiler has to be a low enough temperature for the flue gases to condense. Usually, this happens when the weather conditions do not require the boiler system to be firing at high combustion, which usually happens around the shoulder seasons of fall and spring. This is where hybrid systems are optimal by selecting just enough condensing boilers to pick up the load for the shoulder months along with lower water temperature loops such as reheats and underfloor heating, if they are part of the project. By doing so, the system minimizes capital investment in condensing boilers and at the same time takes advantage of the higher efficiencies condensing boilers are capable of for a significant portion of the year. After selecting the suitable condensing boiler for the application, special precautions have to be

taken into consideration when designing the flue exhaust stack and condensate drainage. Both the gaseous exhaust and condensate from a condensing boiler are moderately acidic. Therefore, the flue for condensing boilers is typically fabricated with AL29-4C stainless steel to resist corrosion. A neutralization kit containing calcium carbonate (limestone chips) on the boilerâ&#x20AC;&#x2122;s drain line is required to neutralize the acid before releasing into the sanitary drain system. The condensate that drains to the neutralizing basin has to be corrosion-resistant while complying with local plumbing code-acceptable materials. Sizing and routing of the exhaust and drainage is usually specified per the boiler manufacturerâ&#x20AC;&#x2122;s recommendations. cse Jacob Haddadin is a mechanical engineer at CCJM Engineers and a recent graduate from the Illinois Institute of Technology, with hands-on commercial building mechanical design experience covering multifamily residential, educational and laboratory facilities and commissioning. Stephanie Khouri is a mechanical engineer at CCJM Engineers and a recent graduate of Marquette University developing her mechanical design experience with commercial and educational facilities.

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Enhancing efficiency in industrial and manufacturing facilities From high-tech automation to energy-saving lighting and HVAC systems, there is more than meets the eye when it comes to warehouses and factories CSE: What’s the biggest trend in industrial/manufacturing facility and warehouse projects? Justin M. Harvey: One of the biggest trends in the industrial/manufacturing facility and warehouse projects is the push to provide smaller warehouses in more locations closer the end users. There is such a push in many industries right now for immediate delivery of goods that companies are having to re-evaluate their position on large distribution centers and think more about regional and local hubs to serve their communities. Doug Sandridge: For warehouses, it’s faster turnover resulting in lower inventory. Also, we’re seeing increased ventilation and temperature control for cold production facilities. CSE: What trends do you think are on the horizon for such projects? Sandridge: Technology includes auto storage and retrieval systems and energy-efficient building systems for lighting, heating, ventilation, air conditioning and refrigeration. Harvey: We’re seeing more and more interest from clients on the height of their storage systems, the effects that has on

the fire protection systems in their buildings. There’s also a growing focus on how evolving automated storage and retrieval systems are interacting with the everchanging infrastructure. CSE: What types of challenges do you encounter for these types of projects that you might not face on other types of structures? Harvey: We are constantly coordinating lighting controls and owner-requested light levels across warehouses with the latest adopted energy codes, including the use of daylighting within these spaces. We’re helping our clients be on the forefront of this industry, investigating new methods of material handling, code review to meet the latest requirements of the owner’s insurance carriers and maximizing the owner’s budgets within the construction of their buildings through more efficient use of their required mechanical, electrical, plumbing and fire protection systems. Sandridge: We see moisture control in cold storage and production facilities. CSE: How are industrial/manufacturing facility and warehouse buildings being designed to be more energy efficient?

Jason Danielson Electrical Specialist Stanley Consultants Muscatine, Iowa

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September 2019

consulting-specifying engineer

Justin M. Harvey, PE, LEED AP BD+C Warehouse and Distribution Practice Director/Associate Henderson Engineers Houston

Jason Danielson: One of the easiest ways to reduce energy usage in a renovation is to replace the older technology light fixtures with LED and incorporate automatic lighting controls. It’s possible to reduce the total light fixture count and cut energy usage by 30% to 60% or more. With inclusion of automatic lighting controls, the energy usage can drop even further. For a new design, it’s best to start with LED and a lighting control system with occupancy and daylight sensors. Many of our projects conform to ASHRAE Standard 90.1-2013, which includes requirements for separately monitoring energy usage of HVAC, interior lighting, exterior lighting and receptacle circuits. With an advanced metering system and programmable controls these energy systems can be tweaked by the end user to locate and resolve energy use issues. Sandridge: We’re using destratification fans, tighter seals around loading docks and better control of overhead doors to refrigerated areas. CSE: What are engineers doing to ensure such projects (both new and existing structures) meet challenges associated with emerging technologies? Doug Sandridge, PE Principal RTM Engineering Consultants Wheat Ridge, Colorado

www.csemag.com

Sandridge: They’re keeping up with regulations and new innovations is equipment and systems. Harvey: Our company strives to be a part of the design team early on to help with the space planning of each building and to assist with the location and sizes of the critical systems for each project. By joining the conversation early, engineers can help the owners understand the intricacies of the adopted codes within their jurisdiction, as amendments and omissions vary from jurisdiction to jurisdiction. Having open and communicative relationships with the authorities having jurisdiction creates pathways for discussion that streamline the design and review processes and help maintain the project’s timeline. CSE: How are engineers designing these kinds of projects to keep costs down while offering appealing features, complying with relevant codes and meeting client needs? Harvey: As is the case with most proj-

ects, these require collaboration among the design team as well as a shared understanding of the owner’s needs and project goals. Open communication is the biggest factor that helps keep the cost of these projects down. Understanding the implications of a decision not just for the system being discussed, but how that system interacts with the other disciplines, is key to delivering a project on budget. Sandridge: They’re truly understanding the owner’s criteria and vetting it in some cases (custom design versus industry norms). CSE: Please explain some of the codes, standards and guidelines you commonly use during the project’s design process. Which codes/ standards should engineers be most aware of? Harvey: The International Code Council issues its international series of codes every three years and these are typically what we reference when designing the majority of the work that Henderwww.csemag.com

Figure 1: This rendering shows a steam turbine generator facility that features a bridge crane and support spaces. Image created in Lighting Analysts AGi32 software. Courtesy: Stanley Consultants

son does. These include the International Mechanical Code, International Plumbing Code, International Energy Conservation Code and International Building Code. We use NFPA 70: National Electrical Code for our electrical designs. Engineers need to be in contact with their AHJs on every project, to verify what version of these codes apply to their projects and be familiar with the changes between each version of these codes. In recent years, large changes have been made to the energy codes, both within the IECC and ASHRAE Standard 90.1, which requires diligence on the part of the engineers to know how those updates apply to these projects. Sandridge: Depending on the facility, we use current good manufacturing practice from the Food and Drug Administration, U.S. Department of Agriculture, Occupational Safety and Health Administration and industry best practices (where the experience comes in). Danielson: ASHRAE 90.1-2010 and newer are the major driver for electrical energy efficiency and controls that are required on many of our projects. States are adopting various versions of ASHRAE 90.1; and the older versions are more relaxed on the requirements, so it will depend on the location of the project on what is required. Most U.S. government projects require ASHRAE 90.1-2013 for lighting controls and energy monitoring. There are criteria for most types of facilities called Unified Facilities Criteria for government work. These documents pro-

vide guidelines and requirements for the various disciplines that must be met or the design will not be accepted. CSE: How are codes, standards or guidelines for energy efficiency impacting the design of such projects? Danielson: I’m seeing an increased upfront cost for the material and labor for the installation of these sophisticated energy-saving systems, namely lighting controls and advanced metering. The client should eventually see it payoff in the energy savings, especially in an area with higher energy costs. I’m also seeing an increase in design time and specification writing. The design and specification of these systems is becoming more complex as each iteration of the code is more stringent. For lighting designs we’re having to search more and more for basis of design LED lighting fixtures that can meet the stricter lighting power density (watts/square foot). This puts more pressure on industry to keep up with the codes. We’re also having to get more detailed in design to accurately convey the control system in the drawings for a contractor. Harvey: Energy code updates seem to have the largest changes between versions of the adopted codes currently. Controls requirements are being updated in each version, as new technologies come out and they become more mainstream. From the lighting control updates for switching

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and automatic controls to the addition of daylighting requirements within the energy codes, these have cost and functionality impacts on the office and warehouse spaces incorporated in these codes. CSE: What are some of the biggest challenges when considering code compliance and designing or working with existing buildings? Harvey: The biggest challenge centers around the analysis of the existing construction to determine whether the updates being performed to the project can match existing construction or if the percentage of work is such that it requires the entire building to be updated. Owners often assume that they won’t have to update to a current code, but that determination is dependent on the scope of work being performed. Danielson: It’s possible that the entire space under renovation may need to be brought up to code, depending on the extent of work requested by the client

and the age of the facility. Let’s say the client wants new updated lighting in a few spaces. After a code analysis on the project, this may require a complete gut and rebuild with updated fixtures, life safety appurtenances and controls. Clients may not have anticipated this amount of required renovation and may be caught off guard with the cost and level of redesign required. This is all predicated on which codes apply to the project but is always something to be aware of before proceeding.

on the responsibilities dictated to the owner by the utility provider. Regularly, generators are required on these projects, so it’s up to the engineer to coordinate with the owner to determine backup capacity, what equipment is being backed up and the physical size of this equipment on the site plan. Sandridge: Yes — efficient motors and alternative power sources.

CSE: Are there any issues unique to designing electrical/power systems for these types of facilities?

CSE: What kind of lighting designs have you incorporated into an industrial/manufacturing facility or warehouse project, either for energy efficiency or to increase the occupant’s experience?

Harvey: Given the size of these types of projects, it’s typical to have multiple meters for several tenants grouped together on the side of the building. Each electrical utility has different standards that must be adhered to and some are more stringent than others. These requirements will affect the design and the cost based

Danielson: The lighting design depends on the height and type of the facility and the layout of shelving, equipment and other obstructions, but LED lights are almost always used in my designs. If we have narrow aisles, we may opt for continuous linear fixtures. If it’s more open and a taller ceiling, we would

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consider high-bay round lights. Assuming ASHRAE 90.1-2013 applies, controls could include all or some of the following: occupancy sensors, daylight sensors, bi-level lighting (partial on to 50%, manual on to full output), automatic partial or full off or scheduled off. Some other considerations include the environment. If it’s hazardous-rated for explosive gases or dust, we’d want to specify hazardous-rated fixtures. If it’s likely there will be a lot of dust, we would consider specifying fixtures with a dust shedding cone or cover on top to prevent dust build up that can clog the large heatsinks of high-bay LED fixtures. Some dust can be flammable and cause chain-reaction explosions if it were to catch fire from an overheated fixture. Harvey: Realistically, high-bay LED fixtures are a must to meet the needs of the currently adopted energy codes while maintaining the maximum/minimum values of illumination to meet the egress requirements set forth by the adopted

Figure 2: Henderson Engineers provided the mechanical, electrical and plumbing design services for the Lowe’s e-commerce distribution center in Coopertown, Tennessee. Courtesy: Lowe’s

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Figure 3: A rendered image of a storage warehouse shows incorporated forklift shelving, a small office and a restroom. Image created in Lighting Analysts AGi32 software. Courtesy: Stanley Consultants

building codes. With the various distributions and fixture types that are available now and that have gone through the vetting process with the brand name manufacturers, the options continue to increase, while the cost continues to decrease. With their advantages across all aspects of design, itâ&#x20AC;&#x2122;s tough to justify other light sources when starting a new warehouse or manufacturing facility project. CSE: How have the trends in fire/life safety changed on such projects? Harvey: One of the biggest trends in the warehouse and industrial/manufacturing practice right now is the request from owners for larger and larger buildings. The clear height of these buildings continues to increase for high-pile storage warehouses, but codes and standards have not been designed to accommodate these heights in some cases. FM Global has standards that limit building heights to 45 feet and there are owners who are requesting higher clear heights. In these instances, itâ&#x20AC;&#x2122;s up to the owner to determine what best serves their building and relay that information to the design team. cse

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