Consulting Specifying Engineer November December 2025

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NEWS &BUSINESS

7 | Commissioning Giants earn even more in 2025

The 2025 Commissioning Giants earned $993.4 million, an increase over last year.

BUILDING SOLUTIONS

10 | What to know about NEC 2023 in electrical design

NFPA 70: National Electrical Code (NEC) codifies the requirements for safe electrical installations into a single standardized source.

18 | Challenges in designing HVAC systems for critical laboratory research

Designing HVAC systems for cryogenic electron microscopes in cancer research requires precise attention to operational details and performance standards.

NOVEMBER/DECEMBER 2025

26 | Below the surface: The hidden power of aquifers

Aquifers are an increasingly important decarbonization strategy. Understand how to take direct, practical steps to integrate aquifer-based systems into their building designs, promoting sustainable and energy-efficient solutions.

34 | Design basics for booster pumps in high rise buildings

Selecting a booster pump is unique to each building. Considerations for future building growth and changing infrastructure contribute to providing a future-ready and dependable system.

ENGINEERING INSIGHTS

42 | Design health care facilities with energy efficiency and flexibility in mind

In this roundtable, engineers discuss current trends for health care facilities and where the industry is going in the coming years.

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AMARA ROZGUS, Editor-in-Chief ARozgus@WTWHMedia.com

ANNA STEINGRUBER, Associate Editor ASteingruber@WTWHMedia.com

AMANDA PELLICCIONE, Marketing Research Manager APelliccione@WTWHMedia.com

MICHAEL SMITH, Art Director MSmith@WTWHMedia.com

EDITORIAL ADVISORY BOARD

DARREN BRUCE, PE, LEED AP BD+C, Director of Strategic Planning, Mid-Atlantic Region, NV5, Arlington, Va.

MICHAEL CHOW, PE, CEM, CXA, LEED AP BD+C, Principal, Metro CD Engineering LLC, Columbus, Ohio

CINDY COGIL, PE, FASHRAE, Vice President, SmithGroup, Chicago

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.

PAUL ERICKSON, LEED AP BD+C Principal, Affiliated Engineers Inc., Madison, Wis.

ROBERT J. GARRA JR., PE, CDT, Vice President, Electrical Engineer, CannonDesign, Grand Island, N.Y.

JASON GERKE, PE, LEED AP BD+C, CXA, Senior Design Phase Manager, JP Cullen, Milwaukee

JOSHUA D. GREENE, PE, Associate Principal, Simpson Gumpertz & Heger, Waltham, Mass.

RAYMOND GRILL, PE, FSFPE, LEED AP, Principal, Ray Grill Consulting, PLLC, Clifton, Va.

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, LEGACY LEED AP BD+C, Associate Principal, Sector Leader, HED, Chicago

KENNETH KUTSMEDA, PE, LEED AP, Engineering Manager, Jacobs, Philadelphia

DAVID LOWREY, Chief Fire Marshal, Boulder (Colo.) Fire Rescue

JASON MAJERUS, PE, CEM, LEED AP, Principal, DLR Group, Cleveland

JUSTIN MILNE, PE, PMP, Senior Engineer, Southcentral Region, Jensen Hughes, Allen, Texas

CRAIG ROBERTS, CEM, Account Executive, National Technical Services, McKinstry, Powell, Tenn.

SUNONDO ROY, PE, LEED AP, Director, Design Group, Romeoville, Ill.

JONATHAN SAJDAK, PE, Senior Associate/Fire Protection Engineer, Page, Houston

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

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.

TOBY WHITE, PE, LEED AP, Associate, Boston Fire & Life Safety Leader, Arup, Boston

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

How MEP/FP engineers are living a dual reality

This year’s Salary Report reveals high-paying jobs with lots of pitfalls for MEP/FP engineers.

The latest Consulting-Specifying Engineer Salary Report reveals a complex reality for engineers specializing in mechanical, electrical, plumbing and fire protection (MEP/FP) systems: While compensation has reached new heights, so too have professional pressures and technology anxieties. The data highlights that this field is navigating a period of financial uncertainty alongside critical operational challenges.

50 or more hours per week rose from 17% last year to 24% this year.

On the plus side, the longterm trend in compensation is robust. Since 2014, average base salaries for engineering professionals have risen by 23.5%, climbing to $122,456 in 2024. Furthermore, nonsalary compensation — including bonuses and profit sharing — has soared by an even greater 86.8% since 2014, with 73% of engineers receiving an average of $23,760 in 2024.

Amara Rozgus, Editor-in-Chief

This relentless workload, coupled with economic uncertainty and staffing concerns — such as the noted shortage of junior team members — is exactly what keeps one-quarter of engineers awake at night. Looking ahead, technological changes represent both a promise and a threat. While professionals anticipate that tools like artificial intelligence (AI) and advanced smart sensors will be important in the next six months, 44% of respondents express significant concern that AI will replace human decision-making. Engineers, therefore, face a mandate to adapt rapidly, even as 34% report difficulty keeping up with new software and technologies.

However, these financial gains are shadowed by massive workload pressures. The top challenge cited by respondents is the pressure to reduce project timelines and costs (41%), which increased slightly from 37% last year. This was immediately followed by coping with shifting client expectations and demands at 27%, down from 38% last year. This reality translates directly to individual engineers, who report working an average of 43 hours per week, up from last year’s 41 hours per week. And at the higher end of hours worked, the percentage of respondents who worked

The critical shortage of new and up-and-coming engineers remains a pressing issue that threatens the longterm health of the MEP/FP field. One-quarter (25%) of survey participants specifically cited difficulties with having "not enough junior team members to prepare for the future" as a top challenge. This concern is rooted in demographic statistics: the average engineering professional in the survey is 52 years old and only 23% are under the age of 40. Addressing this knowledge transfer gap is vital, especially given that only 7% of respondents are under 30. cse

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Commissioning Giants earn even more in 2025

The 2025 Commissioning Giants earned $993.4 million, an increase over last year.

The Consulting-Specifying Engineer 2025 Commissioning Giants provides information on the top 25 firms based on selfreporting for this year’s rankings.

Total commissioning revenue for these firms was $993.4 million, an increase from $913.4 million last year, an 8.7% increase. Three new firms entered or returned to the list this year: Facility Dynamics Engineering, IMEG and CriticalArc.

Figure 1 shows a complete ranking for 2025, including the three new firms.

On average, commissioning revenue represented 36.2% of a firm’s total gross revenue. This represents an average of $39.7 million, with the top three firms earning $70 million or more. While the percentage of commissioning revenue varied, 52% of firms reported it to be 20% or less of their total gross revenue for the last fiscal year.

The top building types for commissioning revenue included:

34%

•

•

•

•

•

•

7%

5%

6%

8%

• Utilities, public works, transportation: 5%

• K-12 schools: 7%

• Sports or entertainment facilities, convention centers: 1%

• Hotels, motels or resorts: 1%

• Mission critical facilities, not including data centers or hospitals: 2%

• Engineered multi-dwelling buildings, retail complexes, restaurants: 2%

All of the 2025 Commissioning Giants provided commissioning services for projects in North America. Most companies (60%) also offered services in countries based in North America (Canada and Mexico). This data reflects commissioning at all levels: new buildings (49%), whole building (10%), emergency power systems (7%), existing buildings (6%), retro-commissioning (6%), monitoring based (6%), envelope (5%), recommissioning (4%), fire protection systems (3%) and communications systems (3%).

Commissioning Giants firms are predominantly consulting engineering firms (48%). California has the most firms on the list with four, followed by with two each from Georgia, Missouri, New York and Wisconsin. Roughly one-quarter (28%) of firms acquired another company in the last fiscal year. On average, 46% of these firms’ staff were 40 years old or younger and 11% of the staff were female.

Firms reported that the top reasons for commissioning requests were savings (92%), sustainability (88%), mandates (84%), resiliency (80%) and marketability (48%). In order of weighted percentage, anticipated future challenges with commissioning include not enough commissioning authorities or agents, lack of knowledge about commissioning’s worth, lack of funding or buy-in and changing codes and standards. Top corporate chal-

Revenue

earned by Commissioning

Giants

for building types

FIGURE 2: This shows the percentage of last year's commissioning revenue earned by the 2025 Commissioning Giants in the following building types. Data centers and hospitals/ health care facilities were the top building types for commissioning revenue last year. Courtesy: Consulting-Specifying Engineer

Which of the following best describes your company?

3: Nearly half of the 2025 Commissioning Giants firms are consulting engineering firms. Courtesy: Consulting-Specifying Engineer

lenges included quality of younger staff (52%), the economic impact on the construction market (16%) and increasing costs in construction (8%).

Commissioning Giants firms reported an average of 34 certified commissioning authorities or agents or certified commissioning professionals on their staff. Prominent organizations these commissioning

u professionals belong to include ASHRAE, the Building Commissioning Association, the AABC Commissioning Group and the Association of Energy Engineers. cse

FIGURE

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Michelle Stark, PE, CDM Smith, Latham, New York; Pari Natarajan, CDM Smith, Chennai, India; and Hrushikesh Apte, CDM Smith, Pune, India

What to know about NEC 2023 in electrical design

NFPA 70: National Electrical Code (NEC) codifies the requirements for safe electrical installations into a single standardized source.

NFPA 70: National Electrical Code (NEC) is a code in the United States used for the safe installation of electrical equipment and is intended to provide installations essentially free of hazard. The NEC is not a law or design guide or even an instruction manual for untrained people.

Although the NEC is not a law, the NEC and other NFPA codes and standards are adopted and enforceable by most states and various jurisdictions outside of the United States including Mexico, Venezuela, Costa Rica and Columbia. It is one

Table 1: Contents of the 2023 NEC

of the many code series of books published by the NFPA, “a benchmark for safe electrical design, installation and inspection to protect people and property from electrical hazards.”

The NFPA website should be consulted to determine the version of the NEC being enforced locally. The information that follows is based on the 2023 NEC.

The NEC is structured and organized into segments for ease of use and application. There are nine chapters that focus on specific topics. Each chapter contains multiple articles and each article is divided further into parts and sections.

For instance, Chapter 2 (wiring and protection) Article 242 (overvoltage protection) contains eight parts, and Part 1 has three sections (242.1, 242.2 and 242.3). NEC Chapters 1 through 4 present definitions and introduce the foundational aspects of

Chapter

Chapter

Special equipment Provides specialized electrical requirements for unique equipment types.

Chapter 7 Special conditions Addresses electrical systems used under special or abnormal conditions.

Supplements or modifies Chapters 1 through 4

Chapter 8 Communications systems Covers requirements pertaining to communication systems. Not subject to the requirements of Chapters 1 through 7 unless specifically referenced

Chapter

Annexes

TABLE 1: Contents of the 2023 National Electric Code are summarized. Courtesy: CDM Smith

electrical installations, including rules, methods and materials. Chapters 5 through 7 expand on this understanding by focusing on more specialized areas and equipment of electrical installations.

Chapter 8 covers communication systems and Chapter 9 contains various tables that are referenced throughout the code and can be used for reference. Informative Annexes A through K are for informational purposes and are not enforceable. Table 1 lists the contents of the 2023 NEC.

The NEC begins with Article 90. This article introduces the code. It states the intent of the NEC, the areas to which the NEC applies and how the NEC is arranged. It discusses how the NEC is enforced and includes mandatory and permissive rule language clarifications, the process for obtaining formal interpretations of the code, procedures for examining equipment for safety and planning for future proofing wiring installations.

For example, Article 90.4(D) recognizes that new products, constructions or materials contained in the 2023 edition may not be available when the edition is adopted, so the authority having jurisdiction may allow those things specified in the previous adopted edition to be used instead.

NEC Chapters 1 through 3

Chapter 1 of the NEC is a general chapter containing two articles: Article 100 and Article 110. Article 100 contains definitions essential to the application of the code. Article 100 was significantly changed in the 2023 edition to organize definitions into one article (versus previous editions that provided definitions in various articles). For article-specific definitions in the 2023 NEC, the specific article is still listed in parenthesis at the end of the definition for ease of use.

Article 110 is the foundation for interpreting and applying the NEC correctly. This is a frequently used chapter when designing electrical systems. Understanding this article is essential, as it focuses on providing safe installations for the installer and end users. Key components of this article include examination, identification, installation, use and product listing (certification) of equipment; mechanical execution of work; conductor materials, terminations and splicing; equipment markings; disconnecting means; enclosure types; available fault current; and spaces about electrical equipment.

A quick history of the NEC

NFPA 70: National Electrical Code (NEC) was first developed in 1897 and now has more than 50 editions as it adapts and advances to the ever-changing electrical industry. While the NEC is updated every three years, the adopted code for each state may differ. Some states, like Arizona, do not adopt a statewide code, which allows each municipality to adopt and amend the NEC as it sees fit. Other states, such as California, adopt the NEC with state-specific amendments.

New York State adopted the 2017 NEC, but New York City enforces the 2008 NEC with city-specific amendments. The current version of the NEC is from 2023; however, as of February 2025, only 17 states have adopted the 2023 NEC; 21 states still enforce the 2020 NEC, six states enforce the 2017 NEC and two states enforce the 2008 NEC. Several states are in the process of updating the version of the NEC to be enforced in their state.

Applying the components of this article keeps people safe. The importance of clear and accessible working space around electrical equipment cannot be emphasized enough. Article 110 provides width, depth and height dimensions for electrical spaces and prescribes dedicated spaces for access, protection and maintenance of equipment. The minimum depth for clear working space is dependent on three conditions:

• Condition 1 specifies the space may have an exposed live part on one side and no live or grounded parts on the other side.

• Condition 2 specifies the space may have exposed live parts on one side and grounded parts on the other side.

• Condition 3 specifies the space may have exposed live parts on both sides.

The height of the working space in relation to electrical equipment and other equipment is defined, along with specifications for access to and egress from working spaces. Part II of Article 110 lists the specifics for electrical systems rated 1,000 volts (V) nominal or less, and Part III lists requirements for electrical systems rated over 1,000 V. This paper focuses on systems 1,000 V and less and does not address the requirements for each voltage class (see Figure 1).

NEC Chapter 2 includes several key articles that provide guidelines for the safe and efficient installation of electrical systems. Proper wiring and protection design ensures safe and efficient power distribution throughout a building. Article 200

‘The NEC is structured and organized into segments for ease of use and application. ’

Learningu

Objectives

• Learn what NFPA 70: National Electrical Code (NEC) is and how electrical engineers might reference it..

• Understand how to interpret and use the NEC for electrical installations.

• Review the basics of the different chapters of the NEC.

BUILDING SOLUTIONS

1:

The working space depth is defined by the voltage-to-ground rating of the equipment and the three conditions pertaining to exposed live parts. The dedicated space pertains to the space above the electrical equipment that must be free and clear of nonelectrical equipment to a minimum height of 6 feet or to the ceiling. Courtesy: CDM Smith

centers on the use and identification of grounded (i.e., neutral) conductors, making sure they are distinguishable from ungrounded (i.e., hot) conductors.

Article 210 encompasses branch circuits. It defines types of branch circuits and specifies requirements for circuit ampacity, receptacle placement and receptacle protective measurements such as ground-fault circuit interrupters (GFCIs) and arcfault circuit interrupters (AFCIs) protections in specific locations.

Article 215 establishes guidelines for feeders, including ampacity requirements, conductor sizing and overcurrent protections. It also details routing and support requirements.

Chapter 2 continues with Article 220, which outlines requirements for branch-circuit, feeder and service load calculations. This article provides methods for calculating electrical loads including applying demand factors for efficient system designs.

Article 225 governs electrical wiring systems running outdoors between structures and includes requirements for height clearances, physical protection and weatherproofing.

Article 230 encompasses service entrance conductors, which are defined as the electrical power that enters a building from a utility source. While Articles 200 through 230 are pertinent to circuits 1,000 V alternating current (ac) or less (considered low voltage), Article 235 governs branch circuit, feeder and services over 1,000 Vac (considered medium voltage).

Article 240 details requirements for overcurrent protection including the selection and installation of fuses and circuit breakers. Article 250 explains grounding and bonding practices to prevent electric shock and reduce the risk of fault currents. Electrical system grounding is critical to safety as it provides a safe path for electrical energy to ground in the case of a fault or an abnormal condition. Chapter 2 is one of the most detailed and safety-oriented chapters in the NEC, to ensure the safe operation and maintenance of electrical systems (see Figure 2).

NEC Chapter 3 outlines the fundamental requirements and specific methods for installing electrical wiring systems in buildings. It begins with Article 300, which sets the groundwork for safe wiring practices including protecting conductors from physical damage, maintaining separation from nonelectrical systems like piping and ensuring adequate working space and support. It also covers underground wiring installations, such as minimum burial depths and sealing of raceways, to prevent moisture ingress.

Article 310 focuses on the use of insulated conductors, detailing acceptable insulation types, voltage ratings (typically up to 2,000 V) and ampacity based on conductor material, size, insulation class and environmental factors. Adjustment and correction factors must be applied in cases like multiple conductors in a raceway or in elevated ambient temperatures.

Article 312 addresses enclosures such as cabinets and meter sockets, specifying the construction quality, mounting, labeling and space needed for proper conductor bending and termination. Article 314 expands on the installation of boxes (outlet, pull and junction types), highlighting volume calculations (box fill), secure mounting and accessibility for splicing and maintenance. Conductors must have enough length for termination and entries must be fitted to prevent abrasion.

Articles 320 through 399 describe individual wiring methods including armored cable, metal-clad cable, flexible and rigid conduits and nonmetallic raceways. Each article covers the permitted uses, installation guidelines, securing methods and physical protection needed for that type of wiring.

Topics also include specialty cables, such as underground feeder, mineral-insulated and optical fiber cables, to ensure materials are selected based on application and environmental exposure. Collectively, Chapter 3 provides the technical foundation to design and install electrical wiring that is code compliant and suited to the physical conditions of the space, while balancing performance, safety and durability.

The importance of NEC Chapter 4

NEC Chapter 4 addresses requirements for general-use electrical equipment, focusing on proper installation and safety. Articles 400 and 402 cover

FIGURE

flexible cords and cables and fixture wires, restricting their use to portable or temporary applications and specifying suitable types such as service junior thermoplastic cable and service, oil-resistant, outdoor and weather-resistant cable. The articles prohibit routing cords through walls or doors and emphasize ampacity limits, strain relief and grounding.

Article 404 outlines rules for switches, including general-use, dimmer and specialty types that require proper grounding, accessibility and appropriate ratings for disconnecting circuits or equipment.

Article 406 covers receptacles and plugs, mandating tamper-resistant devices in residential and child-occupied locations, weatherproofing for outdoor use and protection via GFCI or AFCI based on the area.

Articles 408 and 409 focus on switchboards, switchgear, panelboards and industrial control panels, requiring clear circuit labeling, appropriate working clearances and secure busbar connections. The articles also include provisions for overcurrent protection and proper grounding of panel assemblies.

Articles 410 and 411 provide standards for luminaires, requiring light fixtures to be properly supported, marked for lamp ratings and installed with consideration for recessed applications. Wiring methods must also prevent mechanical stress or overheating.

Articles 422 through 427 address electrical appliances and fixed equipment, such as space heating equipment, regarding disconnecting means, overcurrent protection per the nameplate and safe grounding practices.

Chapter 4 continues with safe and efficient operation practices for certain types of equipment. Article 430 focuses on motors and their control systems, including circuit conductor sizing (typically 125% of full-load current), short-circuit and overload protection and proper disconnect placement. Article 430 ensures controllers are matched to motor ratings for horsepower and voltage.

Article 440 provides requirements for the safe installation and use of air-conditioning and refrigeration equipment.

Articles 445 and 450 govern safe practices for generators, transformers and transformer vaults

including ratings, installation guidelines, grounding and protective measures.

Articles 455, 460, 470 and 480 cover the use and installation of phase converters, capacitors, resistors and reactors and storage batteries.

Article 495 defines safe installation practices and use of equipment over 1,000 V. Overall, Chapter 4 ensures that everyday electrical equipment, ranging from lighting and receptacles to motors and appliances, is installed and protected in a way that minimizes hazards and ensures long-term system reliability.

NEC Chapters 5 through 7

Chapter 5 addresses special occupancies, such as hazardous (classified) locations, health care facilities, park trailers, assembly occupancies and other such spaces, and includes equipment and wiring requirements for these occupancies. Articles 500 through 506 apply to hazardous locations where combustible gases and vapors, ignitable fibers or combustible dusts may be present that can potentially cause explosions or fire.

Each occupancy area is divided into three classes with further divisions and zones:

FIGURE 2: Grounding systems help ensure the electrical system is safe and reliable by providing a path to ground for electrical energy. Proper bonding and grounding allow a low-impedance path to ground, which can stabilize voltage levels and help alleviate electric shock and fire hazards. Courtesy: CDM Smith

BUILDING SOLUTIONS

3: Motor protective devices are to be sized to carry the starting current and to prevent damage to the conductors, controls and motor during a short-circuit or ground-fault event. Coordination with other parts of the NEC is necessary for a properly designed safe and reliable electrical system.

Courtesy: CDM Smith

• Class 1 locations have flammable liquids or vapors present.

• Class II locations contain flammable dust.

• Class III locations contain fibers or flyings.

Each area includes specific conditions that require special precautions and requirements for electrical and electronic equipment and wiring. For instance, for Class I locations, Section 501.15 requires conduit seals to prevent the migration of combustible gases or vapors from a hazardous location to one with a potential source of ignition.

Articles 511 through 516 apply to areas or places that contain fuels, oils and paint-type solvents. These places include commercial garages, cannabis oil equipment and manufacturing facilities and aircraft hangars.

Article 517 pertains to health care facilities including hospitals and nursing homes.

Article 518 covers buildings, structures or places designed as gathering spaces for 100 people or more, including auditoriums, casinos, courtrooms and museums.

Articles 520 through 540 are for gathering places such as theaters, carnivals and television studios.

Articles 545 through 555 are for specific types of buildings or places such as agricultural buildings, mobile homes and marinas.

Article 590 applies to temporary installations.

NEC Chapter 6 provides specialized electrical requirements for unique equipment types to ensure safety, reliability and code compliance under various conditions. Article 600 covers electric signs and outline lighting, detailing how these systems must be constructed, wired, grounded and installed.

Articles 604 and 605 include safe practices for manufactured wiring systems and office furnishings.

Article 610 has information pertaining to cranes and hoists.

Article 620 outlines requirements for elevators, escalators and moving walks for power supply, control circuits, signal devices and lighting. These systems must remain safe under normal and emergency conditions; Article 620 therefore emphasizes fire recall features, accessible disconnecting means and dedicated machine room lighting and receptacles.

Articles 625 through 685 pertain to different types of systems and equipment and their use and installation requirements. For instance, Article 680 provides guidelines for the installation of electrical systems for swimming pools and fountains.

Articles 690 and 691 focus on solar photovoltaic (PV) systems, addressing installation of gridtied, stand-alone and hybrid systems. It includes requirements for PV modules, inverters, conductors, disconnects, grounding, rapid shutdown (690.12) and system labeling.

Articles 692 and 694 focus on fuel cell and wind electric systems. The articles define requirements for wiring, grounding and protection to ensure a safe and efficient operating system.

Finally, Article 695 governs fire pump installations, requiring a dedicated and dependable power supply that can withstand fire conditions. Overcurrent protection must not interfere with pump operation during starting currents and wiring must be routed separately and protected from damage.

FIGURE

Collectively, Chapter 6 ensures that specialized systems — whether for life safety, vertical transport, renewable energy or signage — operate safely, remain serviceable and perform as intended in critical environments.

NEC Chapter 7 addresses electrical systems used under special or abnormal conditions, including emergency systems, legally required standby, optional standby, fire alarm systems and critical operations power systems. The chapter focuses on reliability, continuity of power and safe operation during outages or emergencies. Circuit types and classes along with cable systems are discussed and installation requirements are listed for safe and reliable operation of these types of specialized circuits.

Article 705 specifically covers interconnected power sources, such as solar PV, wind turbines, generators, fuel cells and battery energy storage systems, that operate in parallel with the primary power source. It includes requirements for interconnection, overcurrent protection, labeling, anti-islanding and coordination to ensure safe operation with or without grid support. Chapter 7 ensures essential systems function safely under demanding conditions.

NEC Chapters 8 and 9, plus Annexes

NEC Chapter 8 addresses requirements pertaining to communication systems. Communications systems include telephones, radio and television antennas, satellite dishes, closed-circuit TVs, cable TV systems and network-powered broadband communications not under control of the utility. These systems are not covered in Chapters 1 through 4 nor in the specialty areas of Chapters 5 through 7 except where other chapters are specifically cited in Chapter 8.

NEC Chapter 9 consists of the tables referenced throughout the NEC. The tables pertain to conductor, cable and conduit properties including bend dimensions and raceway fill properties. Power source limitations for Classes 2 and 3 power supplies and for the power supplies of power-limited fire alarm systems are also specified.

Annexes A through K are not part of the enforceable NEC and while they are provided for informational purposes, they have significance. They provide information such as product safety referenced standards, example calculations, additional tables for the proper implementation of code articles and guidance to meet additional standards such as Americans with Disabilities Act standards in buildings.

The NEC Handbook is a companion guide to the NEC. It provides additional context, explanations and examples to help users understand and apply the code more effectively. The Handbook includes commentary from experts, illustrations and practical examples that clarify the intent and application of the code requirements. It is designed to be a helpful resource for electrical professionals, inspectors and engineers who need to interpret and implement the NEC in their work.

BUILDING SOLUTIONS

NEC insights

uUpdated every three years, the NFPA 70: National Electrical Code (NEC) is enforced differently across states and jurisdictions, with the 2023 NEC currently adopted by some states while others continue using earlier editions.

uWithin the NEC, each article is subdivided into parts and sections that prescribe detailed requirements for topics such as grounding, overcurrent protection, conductor sizing and equipment installation to ensure electrical safety and reliability.

As an electrical engineer in the industrial consulting world, there are several critical parts of the NEC that are used more often than others to ensure safe and compliant electrical installations. Working clearances about electrical equipment is important during the design and installation process and requirements can be found in Article 110.

Breaker sizing is an important aspect of electrical design and is covered in various articles of the NEC including Article 240 for determining the appropriate size of overcurrent protection devices and Article 430 for guidelines on sizing circuit conductors and overcurrent protection devices for motors and their control systems.

Once overcurrent protection is designed Article 310 is used to size the conductors based on insulation type, voltage, ampacity and installation factors (such as routing underground or overhead). Article 250 provides guidance on the sizing of ground conductors based on the size of the service-entrance conductors or the feeder conductors.

FIGURE 4: NEC Chapters 6 and 7 can be used together to properly design microgrids using renewable energy sources. Article 690 details the requirements of photovoltaic electrical energy systems, including arrays, inverters and controllers. Article 705 defines the connections to a primary source of electricity such as the utility grid. Articles 706 and 710 include guidelines for energy storage systems and their installation and operation as stand-alone systems. Courtesy: CDM Smith

Conduit type and sizing is covered in Chapter 3 and the tables in Chapter 9 pertain to conductor, cable and conduit properties, including bend dimensions and raceway fill properties. These are a few examples of the NEC that are used on a frequent basis when designing electrical systems. cse

Michelle Stark, PE, is an electrical engineer with CDM Smith. Pari Natarajan is an electrical engineer with CDM Smith. Hrushikesh Apte is an electrical engineer with CDM Smith.

BUILDING SOLUTIONS

Craig Barbee, PE, Smith Seckman Reid, Nashville, Tennessee

Challenges in designing HVAC systems for critical laboratory research

Designing mechanical systems for cryogenic electron microscopes in cancer research requires precise attention to operational details and performance standards to ensure both project success and sustained high-resolution imaging.

OObjectives

• Gain insight into the stringent requirements governing technically sensitive equipment in cancer research.

• Understand the key challenges involved in achieving compliance with these demanding standards.

• Learn about an effective HVAC system approach that supports success in critical performance applications

ver two decades ago, a child was diagnosed with bone cancer in the femur at an early age, requiring hospitalization and treatment. At that time, cancer research and treatment options were far less advanced than those available today. Modern advancements in research technology have significantly improved the landscape of cancer treatment. Breakthrough equipment now allows scientists to examine cancer cell replication at the molecular level in greater detail, unlocking new possibilities for drug discovery and offering promising strategies to prevent or halt the progression of this disease.

As a mechanical engineer with a strong interest in the technical aspects of the field, this opportunity to design the mechanical systems supporting a cryo-electron microscope (cryo-EM) research facility presented a valuable opportunity to engage in a highly challenging and rewarding endeavor. For those unfamiliar with similar work, this type of project involves meeting stringent environmental requirements, overcoming complex heating, ventilation and air conditioning (HVAC) challenges to maintain compliance and under-

standing key considerations essential for the successful design of future cryo-electron microscope research facilities.

In 2018 and 2024, a leading pediatric cancer research center completed projects to install multiple advanced cryo-EMs. These powerful tools allow scientists to see extremely small biological structures in 3D, down nearly to the level of individual molecules. This detailed view helps researchers better understand how proteins function, how healthy and diseased cells differ and how to potentially stop the spread of cancer cells. Only a couple of institutions in the United States are believed to have similar research capabilities.

The initial 2018 programmatic layout for the cryo-EM center included two microscopy suites, a grid clip (specimen preparation) room and associated anterooms, totaling approximately 3,500 square feet. The selected location was an existing basement level, formerly occupied by administrative functions. This strategically chosen location enabled physical and structural isolation of the cryo-EM systems from the rest of the building, minimizing vibration transmission that could degrade imaging resolution.

To achieve this, the existing structural slab was excavated, and a new, independent structural foundation was constructed. The microscope systems were mounted on a dedicated concrete slab supported by vibration isolators to ensure mechanical and acoustic decoupling from the main building structure.

In parallel with the design of new HVAC systems required for the specialized environmental demands of the microscopy suites, a comprehensive assessment of the building’s existing mechanical

infrastructure was conducted. The analysis aimed to determine whether the current systems could support the thermal, clean air and humidity control needs for the cryo-EM systems, and whether new infrastructure would be necessary.

It was determined that several elements of the current system did not meet the strict environmental specifications provided by the equipment manufacturer. For example, conventional variable air volume systems with reheat and two-by-two diffusers produced air velocities exceeding allowable limits for cryo-EM imaging environments. Additionally, the existing chilled water-cooling coil system lacked the moisture removal capacity for humidity control necessary for sample preparation in the grid clip room.

A critical factor to address these challenges was the review of the microscope equipment vendor’s pre-installation specifications. These documents provided essential performance criteria, allowing the engineering and architectural teams to select HVAC solutions tailored to the system’s sensitivity to temperature fluctuations, humidity, airflow patterns and vibration.

Key functional spaces within the program include the cryo-EM suites, grid clip room and a shared vestibule that functions as a transitional buffer zone. Each space is subject to distinct environmental parameters, but must operate together to ensure overall system integrity. In particular,

the grid clip room, where biological specimens are prepared for imaging, demands exceptionally low humidity levels to prevent the formation of ice crystals during cryogenic freezing.

Temperature and relative humidity (RH) requirements within the room meant maintaining 72°F and below 20% RH. Failure to meet this criterion would compromise sample integrity and image clarity, impeding the research objectives.

Grid clip room criteria informed the HVAC approach. Temperature and RH requirements within the room were necessary to maintain 72°F and below 20% RH. Though it was necessary to maintain an environment with this low of RH, static electricity for slide preparation was not a concern for the users.

In a cryo-EM specimen preparation room, stringent control of environmental conditions — particularly temperature and dry RH — is critical to preserving sample integrity and ensuring high-quality transformation of a substance into a glass, or a non-crystalline solid. Exposure to even modest levels of ambient moisture can lead to the formation of crystalline ice, ice contamination or uneven sample thinning, which compromise structural resolution.

‘Each space is subject to distinct environmental parameters, but must operate together to ensure overall system integrity.’

FIGURE 1: Desiccant and blower coil arrangement serving the grid clip room. Courtesy: Smith Seckman Reid

BUILDING SOLUTIONS

The temperature in the grid clip room should typically remain stable between 68°F to 72°F to ensure consistent physical handling conditions and prevent condensation. However, relative humidity should be kept low — often below 20% — to minimize the risk of airborne water vapor condensing on cold surfaces such as plunge-freezing apparatus or grids exposed during blotting and transfer. Excess humidity can interfere with rapid vitrification by introducing water crystals, while dry conditions help preserve samples and reduce contamination from frost.

Achieving and maintaining such dry conditions requires robust HVAC systems, often supplemented with industrial-grade dehumidifiers and sealed room designs to limit moisture ingress. Continuous monitoring of temperature and RH is essential. Strict adherence to these environmental controls enhances reproducibility and ensures the optimal preservation of ultrastructural details in cryo-EM analysis.

Knowing that a typical chilled water air handling unit (AHU) that delivers 50°F leaving air tempera-

ture off the cooling coil is not capable of delivering the necessary dry air requirements for the space conditions, we drew from our experience with ice rinks to help inform this decision and decided on a desiccant unit application.

Using a desiccant dehumidifier to dry a space — such as a cryo-EM specimen preparation room — presents several technical and operational challenges. While desiccant dehumidifiers are effective at maintaining very low RH levels, particularly in cooler environments, their deployment in a controlled laboratory setting involves careful planning and maintenance.

Heat management in the laboratory

Desiccant dehumidifiers function by passing air through a rotating wheel coated with a silica gel, which absorbs moisture. To regenerate the desiccant, hot air is used to drive off the collected moisture. There are two separate air streams: the process air side and the regeneration side. This regeneration process generates significant heat for both airstreams, which must be managed to prevent unwanted temperature fluctuations in the controlled space.

Excess heat from the dehumidifier can interfere with temperature control and may necessitate additional cooling infrastructure. Rejecting the hot, moist airstream off the regenerative side of the desiccant wheel was done by discharging it into the large return duct main right at the riser. The process airstream required some form of post-cooling due to elevated discharge temperatures. There was not a small package system for 600 cubic feet per minute (cfm) of air that provided both desiccant and post cooling. So, a chilled water fan coil unit was installed that mixed the hot process dry air with house ventilation air to provide post-cooling and comfort to the slide prep room.

Air exchange and pressure control

Desiccant systems require a separate air stream for regeneration, which often involves venting hot, moist air out of the room. This airflow can create pressure differentials that compromise room sealing or introduce unfiltered air, potentially affecting sample sterility and environmental stability. Maintaining positive or neutral pressure in the room while operating a desiccant system may require additional air balancing and integration with building HVAC sys-

FIGURE 2: A cryo-EM room with ventilation and wall panel layout. Courtesy: Smith Seckman Reid

tems. Locating this unit within the mechanical room and using the house air serving this room accommodated for that potential pressure offset.

Space and installation requirements

These units are generally larger and more complex than standard dehumidifiers. They require ductwork, heat exchangers and venting systems that must be carefully integrated into the room's infrastructure. For retrofitting existing labs or tight prep rooms, space limitations and structural constraints complicated installation.

Maintenance and reliability

Desiccant systems involve moving parts, high temperatures and exposure to moisture — all of which contribute to wear and tear over time. Regular maintenance is required to ensure consistent performance, including checking desiccant rotor condition, inspecting seals and maintaining heaters

‘Desiccant systems involve moving parts, high temperatures and exposure to moisture — all of which contribute to wear and tear over time.’

and blowers. Inadequate maintenance can lead to degraded humidity control or equipment failure.

Despite these challenges, desiccant dehumidifiers remain one of the few reliable options for achieving ultra-dry conditions in sensitive environments. However, their successful use depends on careful environmental design, ongoing monitoring and coordination with other systems to maintain the stable conditions required for cryo-EM specimen preparation.

In selecting the (DAU-1) unit, the system needed to deliver as little as 17.5 grains/pound of moisture to the room. This met the space requirements, allowed for the absorption of any moisture given off by the

FIGURE 3: A cryoEM room wall panel layout. Courtesy: Smith Seckman Reid

BUILDING SOLUTIONS

4: Construction progress for a cryo-EM room. Courtesy: Smith Seckman Reid

occupants and kept the room below 20 RH. Finding space above the ceiling for the desiccant unit was a challenge due to its 32-inch height. In the end, it was suspended in an adjacent mechanical room where it could sit lower than the typical ceiling grid and then routed the discharge duct over to a fan coil unit.

Cryo-EM laboratory room criteria

The cryo-EM room criteria by far had the most stringent requirements. Designing the mechanical HVAC systems for a cryo-EM facility requires a high level of technical engineering precision. Cryo-EM microscopes are extremely sensitive instruments that demand tightly controlled environmental conditions, often beyond standard laboratory specifications. The mechanical system must support stable temperature, low vibration, stable humidity control, clean air quality and isolation from electromagnetic and acoustic disturbances. Here's a breakdown of the key engineering considerations:

Temperature control:

Cryo-EM instruments are highly sensitive to thermal fluctuations, which can cause mechanical drift, image distortion and misalignment over time.

The HVAC system must:

• Maintain a room temperature between 6°F to 71.6°F, with a stability of ± 1.8°F over 24 hours.

• Use low-velocity displacement ventilation, chilled beams or chilled radiant panel systems to prevent drafts and temperature gradients.

Relative humidity control:

The microscope rooms' moderate RH (40%–50%) is typically maintained to balance corrosion protection with static control.

• Humidity control is achieved via the AHU, provided through the ventilation air. No source of moisture or human occupants residing in the room during testing.

• Use of reheat coils allows finer modulation of constant temperature from a constant air volume box and maintains RH.

Vibration isolation

Mechanical vibrations, even from building systems or foot traffic, can severely impact cryo-EM imaging.

All mechanical equipment (fans, compressors, pumps) must be vibration-isolated using spring mounts, inertia bases and acoustic pads.

Ductwork should use flexible connections near microscope rooms to prevent transmission of structure-borne vibration.

Air movement

Air velocity within the microscope room was not to exceed 83.3 mm/s (3.28 in/s). This threshold included all sources of potential air movement, such as occupant activity, door motion and airflow from HVAC supply diffusers. To maintain proper room pressurization while minimizing airflow disturbances, ventilation was designed to be decentralized — ideally with supply positioned low in the corners of the room and a central return to facilitate heat removal from the equipment.

However, because the space was limited and being renovated, the room's layout made low-level air supply unfeasible. To achieve the required ventilation for pressurization and low-velocity distribution, three two-inch by four-inch high-ef-

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BUILDING SOLUTIONS

ficiency particulate air (HEPA) diffusers with 51% free area, each delivering 50 cfm, were installed. This configuration resulted in a discharge velocity of approximately 2.45 in/s, while diffuser locations were strategically decentralized and positioned along the room perimeter to maintain airflow uniformity and minimize disruption.

‘Designing the mechanical HVAC systems

for a cryo-EM facility requires a high level of technical engineering precision.

’

A key thermal management challenge within the microscope room involved rejecting the significant heat load generated by the cryo-EM system and associated auxiliary equipment. Traditional cooling with low-velocity diffusers through house air was not viable, as this approach would have required additional ceiling grid space that was not available. Instead, passive cooling panels were installed along the walls. This solution effectively managed equipment-generated heat while eliminating excess air movement and noise, which were both critical to maintaining the microscope’s imaging performance.

Air quality and filtration

Clean air is essential to prevent dust and particulates from contaminating sensitive optical components. Systems included HEPA or ultra-low particulate air filtration (99.99%+ efficiency) at terminal diffusers. Positive pressure control in the microscope room prevented infiltration of unfiltered air.

Electromagnetic and acoustic interference mitigation

Laboratory insights

u Cryogenic electron microscopes require highly specific environmental conditions to function properly and efficiently.

u Designing laboratories in a retrofit building project presents unique challenges with space considerations, existing mechanical systems and vibration concerns.

HVAC and other building components can generate electromagnetic fields and noise that interfere with the microscope’s imaging system. The equipment must be in a part of the building that is isolated from sources of fluctuating magnetic fields, such as those generated by elevators, transformers or motors.

System zoning and redundancy

Microscope rooms, prep rooms and control areas often require separate zones with different

environmental conditions. Zoned HVAC systems with independent controls to allow adjustments of each area to its specific needs.

Redundancy (N+1 design) in critical systems (chillers, AHUs and humidifiers) ensures reliability for continuous cryo-EM operations. The existing building’s space constraints limited certain systems that could be provided with redundancy, though chilled water redundancy in the plant and emergency power were available.

Monitoring and control

An integrated building management system is crucial for real-time oversight. This included high-accuracy sensors to monitor temperature, oxygen levels, humidity and air pressure. Alarms and historical logging allow facility staff to respond quickly to deviations.

Designing the anteroom

An anteroom outside of a cryo-electron microscopy room acts as a buffer zone, minimizing rapid fluctuations in temperature, pressure and humidity from outside when doors are open. This protects the microscope’s high-resolution imaging by maintaining thermal stability.

The room also maintains cleanliness and particulate control by allowing personnel to don and doff personal protective equipment outside the microscope room. It also provides security and access control to limit and monitor who enters the lab space.

In summary, the mechanical HVAC system for a cryo-EM facility is a highly specialized, engineered environment that supports the microscope’s physical and analytical performance. It must be tightly integrated with architectural, structural, electrical and lab design systems to ensure long-term stability, reliability and scientific fidelity.

Maintaining a highly sophisticated piece of equipment and its associated HVAC systems requires that the owner’s operators and maintenance personnel understand the equipment and the operational nuances of the HVAC serving it to continue future successes in cutting-edge drug discovery. cse

Craig Barbee, PE, is a Senior Mechanical Engineer with Smith Seckman Reid.

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Victoria Brinemugha, PE, SmithGroup, Detroit

Below the surface: The hidden power of aquifers

Aquifers are an increasingly important decarbonization strategy. Understand how to take direct, practical steps to integrate aquifer-based systems into their building designs, promoting sustainable and energyefficient solutions.

As engineers, our mission isn't just to design systems, it's to reimagine how those systems interact with the world around us. As the science of building climate control evolves rapidly, the path to a sustainable, carbon-free future requires that we expand our knowledge and rethink our choices. This is why we must recognize the hidden power of using underground aquifers as thermal storage systems to efficiently heat and cool buildings.

Objectives Learningu

• Define what an aquifer is and identify key benefits of aquifers in heating and cooling buildings, especially in terms of stable underground temperatures.

• Recognize the historical context and early innovations involving aquifer-based thermal systems.

• Analyze how geology and clean energy principles are being combined in modern ATES designs.

Aquifers have quietly supported agriculture, ecosystems and human development for centuries, operating beneath the surface as natural underground reservoirs. Though often overlooked, they’ve played a vital role in sustaining life and shaping our environment. Figure 1 illustrates various system applications for all types of ground source systems. The first ATES modelling research was conducted by Kazman and Rabimov in the early 1970s, and several sources indicate that this technology was being developed in Shanghai, China, as early as the 1960s.

In recent years, these aquifers have emerged as unexpected allies in the race toward zero-carbon buildings and climate-resilient cities. By leveraging their unique thermal properties, engineers are designing systems that use aquifers not only to store water but to regulate temperatures in the built

environment, offering heating in winter and cooling in the summer, as shown in Figure 2.

The idea is simple but genius: aquifers maintain a stable temperature year-round, making them perfect for aquifer thermal energy storage (ATES) systems. In summer, excess heat is pumped underground; in winter, that stored warmth is drawn back up to heat buildings. It’s like nature’s own energy bank, sitting quietly beneath the surface. To achieve the climate change mitigation targets, increasing attention has to be paid to the decarbonization of the thermal energy sector.

ATES can be mistaken for ground source heat pumps (GSHP) because they are considered openloop piping systems with water wells. The primary difference between an ATES system and a GSHP lies in how they utilize the earth's thermal energy. An ATES system stores thermal energy in an aquifer, while a GSHP extracts heat directly from the ground.

Who is involved?

The installation of an ATES system is a multidisciplinary effort involving several key stakeholders, as shown in Figure 3. Hydrogeologists and geotechnical engineers play a crucial role in evaluating subsurface conditions and aquifer suitability, thereby laying the groundwork for effective system design. Mechanical engineers create building design energy models to validate the adequate annual capacity of the system. They often collaborate with civil engineers to develop the infrastructure, including wells, heat exchangers and distribution networks. Environmental consultants ensure the project complies with regulatory standards and assess its ecological impact. Project developers and energy planners coordinate logistics, budgeting and integration with existing energy systems to ensure seamless operation. Local gov-

FIGURE 1: The organization of ground energy systems. Courtesy: SmithGroup

ernment agencies play a critical role in permitting and regulatory oversight, while drilling contractors and construction teams handle the physical installation. Finally, system integrators and automation specialists ensure the ATES system operates efficiently when the building is functional.

Utilizing Darcy’s Law in underground aquifers for heating and cooling

In 1856, Henry Philibert Gaspard Darcy, in a report on the construction of the Dijon, France, municipal water system, published a relationship for the flow rate of water in sand filters. He developed the Darcy Law formula, which plays a fundamental role in understanding how underground aquifers can be used for thermal energy storage. It describes the movement of water through porous materials, such as the soil and rock layers that make up an aquifer.

According to this principle, the rate at which water flows, which is known as discharge, is directly proportional to both the hydraulic gradient (the change in water pressure over a given distance) and the hydraulic conductivity (a measure of how easily water can move through the material). This relationship is critical when designing systems like ATES, as it helps engineers predict how water— and the thermal energy it carries—will behave underground.

The Darcy formula is as follows;

Q = kiA

‘Aquifer thermal energy storage can be mistaken for ground source heat pumps because they are considered open-loop piping systems with water wells.’

Where;

Q is the discharge (volume of water flowing per unit time)

K is the hydraulic conductivity (a property of the aquifer material)

I is the hydraulic gradient (change in water pressure over distance)

A is the cross-sectional area of flow

Understanding the relationship between Darcy's Law and its impact on the ATES system is crucial for every engineer's comprehension.

• Groundwater flow and heat transfer: ATES systems involve extracting and injecting groundwater to store and retrieve thermal energy. Darcy's Law is fundamental to describing this groundwater flow within the aquifer. The flow process in the reservoir conforms to Darcy's law and follows the mass conservation equation.

csemag.com

Aquifer insights

u In recent years, these aquifers have emerged as unexpected allies in the race toward zero-carbon buildings and climateresilient cities.

uUnderstanding the relationship between Darcy's Law and its impact on the ATES system is crucial for every engineer's comprehension.

BUILDING SOLUTIONS

• Aquifer characterization: Darcy's Law helps characterize the hydraulic conductivity of the aquifer, which are key properties influencing groundwater movement and, consequently, the transport of stored heat.

• Thermal transport: The rate and direction of groundwater flow, governed by Darcy's Law, directly impact the advective transport of heat within the aquifer.

• System design and optimization: Understanding groundwater flow using Darcy's Law is crucial for designing ATES systems, including well placement, pumping rates and predicting the movement of thermal plumes within the aquifer.

• Evaluating efficiency and performance: Darcy's Law, through its connection to groundwater flow, is used in modeling and assessing the efficiency and performance of ATES systems, helping to minimize thermal losses and maximize energy recovery.

Aquifers can be characterized in several ways, but two broad categories are confined (sometimes referred to as artesian aquifers) and unconfined (sometimes referred to as water table aquifers). As shown in Figure 4, the volume of water flowing per unit of time is influenced by the hydraulic gradient, which is related to pressure. It is important to note that increased pressure on the well influences the energy storage capability of the system.

Single-well closed-loop dipole systems

Engineers include ATES as one part of a wider set of pump-and-reinject techniques in aquifer-based geothermal systems. ATES delivers strong benefits in certain situations, but it doesn’t suit every aquifer or every application. Some formations can’t support it, and other methods may perform better in different contexts. That’s why experts continue to push the boundaries of geothermal design.

FIGURE 2: The differences in an underground aquifer in the summer and winter. Courtesy: SmithGroup

FIGURE 3: Key players involved with installing an aquifer thermal energy storage system. Courtesy: SmithGroup

A contractor in Minnesota has developed a closed-loop dipole configuration for aquifer-based geothermal systems. This approach uses a single well equipped with a downhole heat exchanger positioned within the aquifer. Unlike open-loop systems and groundwater pump-and-reinject designs, the closed-loop dipole system facilitates thermal exchange directly within the aquifer without extracting groundwater to the surface.

Maintaining thermal exchange below ground helps reduce operational and regulatory challenges. The system limits geochemical risks, including fouling, scaling and biofilm development by avoiding oxygen contact, pressure variation and intermixing of distinct groundwater layers. These design characteristics are especially suitable for stratified aquifers, where lateral flow patterns support efficient heat dispersion.

In contrast to bidirectional ATES systems, it eliminates the need for surface-level infrastructure such as heat exchangers, trenching, and reinjection systems. This makes the design useful for applications with space constraints, such as phased urban development.

Overall, single-well dipole systems provide a method for utilizing the thermal properties of groundwater while maintaining aquifer structure. This design supports long-term system reliability and can simplify implementation processes in geothermal energy planning.

Design factors in aquifers

Climate: It’s essential to leverage the relatively stable temperature of the earth beneath the surface, which averages around 55°F across the U.S. year-round; slightly cooler in northern regions and warmer in southern regions. Weather patterns vary across different regions of the country, and these differences play a key role in assessing the viability of an ATES system. Areas with pronounced seasonal changes—such as hot summers and cold winters— enhance system performance by offering “free” thermal energy that can be stored and reused. ATES systems are particularly effective in temperate zones with well-defined seasons, like the Midwest.

Energy storage: To ensure sustainable delivery of heating and cooling, the ATES system should be engineered to be balanced; that is, to store and use equal amounts of heat and cool on average over each annual cycle. A balanced system is less likely to induce long-term temperature changes in the

aquifer or experience thermal interference of the warm and cool groundwater plumes in the aquifer, leading to a reduction of energy storage efficiency.

Load calculations: Preliminary load calculations by the design engineer can help determine the building’s heating and cooling demands, guiding the required bore piping length and depth for proper system installation.

Site considerations: The availability of land at the building or campus location is a key factor when selecting this system, especially where space is limited. Unlike the vertical/horizontal closedloop geothermal design, which requires a higher number of boreholes spaced farther apart, the ATES system uses significantly fewer boreholes. Typical borehole depths range from 200 to 2000 feet, compared to geothermal systems that typically reach depths of 70 to 500 feet.

Training and education: The training program encompasses both commercial and residential applications, making it valuable for installers, contractors, architects, engineers and anyone seeking to acquire practical knowledge of advanced heat pump technologies.

Codes, regulations and ordinances: Unlike a traditional open-loop GWHP, the closed-loop water being directed into the well is potable and includes only permitted chemical additives and concentrations. In the unlikely event of a leak, the impact on the aquifer would be negligible, which tends to reassure regulatory stakeholders. Typically, the primary permitting requirement for an ATES system will be an underground injection control (UIC) registration.

FIGURE 4: The difference between two major types of aquifers: unconfined and confined.

Courtesy: SmithGroup

‘Aquifers can be characterized

in several ways, but two broad categories are confined and unconfined.

’

‘

BUILDING SOLUTIONS

Capturing heat that is typically rejected or lost during the heating cycle can be redirected to support other building systems, such as generating domestic hot water.

Certain manufacturers have obtained preliminary approval from the authority having jurisdiction in Michigan and a few other states.

Soil profile analysis: Performing a soil profile analysis is a key component in the design of an ATES system. It provides insight into subsurface characteristics that influence thermal efficiency, groundwater flow dynamics, and the overall feasibility and durability of the system. Table 1 outlines an effective approach.

Before moving forward with the design of an ATES system, it's helpful to complete a soil profile analysis, including water flow testing. This process provides valuable insights that can guide the decision-making process. Ideally, this analysis should be conducted early in the project to help ensure that the design is both feasible and well-informed from the start.

Associated equipment

The ATES system connects to the building through a heat exchanger, typically installed indoors, that facilitates the transfer of temperature to the building's piping loop, as shown in Figure 5. While several connection configurations can be explored when designing the building side, this article focuses on a water-to-air heat pump system for illustration purposes.

The temperature differential usually ranges from 10°F to 15°F between the warm side and cool side of the heat exchanger. Other mechanical equipment includes base-mounted pumps, air separators, expansion tanks, valves, VFDs and distribution equipment, which can be water side or air side.

In open-loop systems, a small number of wells (usually one to three) provide groundwater to a plate and frame heat exchanger that interfaces with the building loop. After passing through the heat exchanger, all the groundwater is returned to the ground through a similar number of injection (or reinjection) wells.

When budget permits, capturing heat that is typically rejected or lost during the heating cycle can be redirected to support other building systems, such as generating domestic hot water. This approach efficiently boosts system performance, especially during shoulder seasons, and may also help balance the annual heating and cooling loads.

Compared to conventional technologies, ATES systems achieve energy cost savings between 40% and 70%, and carbon dioxide savings of up to several thousand tons per year. The spatial separation between the injection and production wells helps safeguard groundwater tables during energy exchange, while enabling the system to operate at optimal efficiency.

ATES systems still encounter challenges, including significant initial capital investment and the necessity for large-scale applications to ensure a viable return on investment. Compared to standard open-loop geothermal systems, ATES systems require a more complex pre-investigation and are typically more sensitive to groundwater flow and aquifer heterogeneities. Surface water, and some

FIGURE 5: A sample piping schematic diagram. Courtesy: SmithGroup

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BUILDING SOLUTIONS

Effective

approaches to soil profile analysis for aquifers

Parameter

Why It Matters

Hydraulic Conductivity Influences water flow and heat transfer

Thermal Conductivity Affects energy storage efficiency

Aquifer Thickness

Determines storage efficiency

Natural Hydraulic Gradient Impacts thermal plume movement

Soil Texture & Composition Guides borehole placement

TABLE 1: This table demonstrates best practices for a soil profile analysis for an aquifer thermal energy storage system.

Courtesy: SmithGroup

groundwater, aquifers may contain pollutants or minerals that could contaminate sensitive drinking or irrigation water sources.

Best practices for aquifers

To reduce the risk of injected water short-circuiting back into the production well, the injection well should be positioned downstream from it, following the natural direction of aquifer flow. There may be occasions when the aquifer water is found to be contaminated. In such cases, coordination with local authorities is initiated to address the issue. During the drilling, development and pump testing phases,

water from the aquifer is brought to the surface. If contamination is detected, special treatment may be necessary and can be provided by designated waste management companies that can deal with the cuttings and tailings from borehole drilling. The project team will provide guidance and account for it in the budget on a case-by-case basis.

Drilling obstructions can sometimes cause a borehole to deviate from its intended path — most often in the upper, near-surface layers of the geology at shallow depths. It's best to consult with the installer to determine whether to drill through the obstruction, adjust the borehole's position slightly, or seek further guidance from a geologist or project manager.

A minimum setback of 15 feet from the building should be maintained when placing the well. Additionally, all site utilities must be properly coordinated to ensure seamless integration into the building systems. cse

Victoria Brinemugha, PE, is a mechanical engineer at SmithGroup with expertise in HVAC design and project management.

25_010646_Consulting_Specifying_Engineer_NOV Mod: September 8, 2025 4:15 PM Print: 09/23/25 page 1 v2.5

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Lauren Plant, WSP USA Buildings, Dallas

Design basics for booster pumps in high rise buildings

Selecting a booster pump is unique to each building. Considerations for future building growth and changing infrastructure contribute to providing a future-ready and dependable system.

Booster pumps serving domestic water and fire systems in high-rise buildings are designed for specific challenges. These challenges include building height, available water pressure and ensuring the domestic water system works properly.

High-rise buildings are defined by the International General Code Development Committee. The definition in Section 202 of the 2024 International Fire Code (IFC) states that a high-rise building is a building with an occupied floor more than 75 feet above the lowest level of fire department vehicle access. The definition of a high-rise building can be amended by any local authority having jurisdiction, so it is important to confirm the definition for each project location. This article will utilize the IFC definition for high-rise buildings and focus on buildings between four and 20 stories tall. The design strategy for buildings with more than 20 stories is different to accommodate the pressure rating and performance of common pipe materials. There are multiple types of booster pumps, and each has specific benefits for a high-rise building application.

There are two categories for booster pumps: single-stage and multistage. A multistage pump is two or more impellers working in series on the same shaft connected to the motor, while a single-stage pump is a single impeller controlling the motor. In a multistage pump assembly, each pump boosts the pressure by a specific amount, and when they work in series, the output pressure is the design demand. The pumps also work together, controlled by a variable frequency drive located within the control panel to accommodate the variable flow rate to match the building demand.

A multistage booster pump is beneficial for a high-pressure application. Multistage pumps typically use less energy and are easier to maintain because smaller pumps can be changed out. In many cases, a multistage pump assembly has N+1

FIGURE 1: Example of a vertical multistage domestic water booster pump. The unit has four pumps working together in series. Courtesy: WSP

‘There are two categories for booster pumps: single-stage and multistage. ’

Table 1: Booster pump comparison

Single-Stage Pump Multistage Pump

Can accommodate higher flow rates Can accommodate higher pressure requirements

Dependable design

Full on/off operation

Long service life

Must be replaced to increase capacity

More components and points of failure

Adjustable energy usage based on demand

More maintenance required

Can be expandable to provide flexibility

TABLE 1: A table comparing single stage and multistage booster pumps. Courtesy: WSP

redundancy (where N is the total number of pumps required to meet the system demand and 1 is an equal-sized spare pump provided), which allows the removal of a pump for maintenance without impacting the building system performance. Finally, multistage pumps provide flexibility for both flow and pressure, which is key for buildings that have a variable demand or plans for future growth. Multiple pumps can work together to share the demand equally or be designed to work in a specific sequence.

A single-stage booster pump is beneficial for a higher flow application. Single-stage pumps are also dependable and have a long service life. This is beneficial for systems such as fire protection, where durability and dependability are critical.

International Plumbing Code requirements

Every domestic water booster pump must meet specific code requirements. A few sections in Chapter 6 of the 2024 International Plumbing Code (IPC) are important when designing booster pumps. Section 602.3.5 of the IPC states that all booster pumps must be rated for the transport of potable water and that every booster pump must have access to pump parts for repair. For domestic water, this means meeting the National Sanitation Foundation (NSF) 61: Drinking Water System Components – Health Effects requirements. When looking at pump selections, this means ensuring that the pump is either a split-case or a skid-mounted assembly. With a split case, either vertical or horizontal, the pump enclosure can split apart along an axis to provide access to the pump components for repair. Multistage pumps are open, and each pump can be removed, so access to the pump assembly components is available, while single-stage pumps must be a split case type pump to provide access.

FIGURE 2: A detail of a vertical multistage domestic water booster pump assembly. The unit is a triplex skid mounted assembly with a hydro-pneumatic tank, control panel with variable frequency drive capabilities, and a pump bypass. Courtesy: WSP

IPC Section 604.3 states that the pipe sizes and water distribution system must be sized based on peak demand for both flow rate and pressure for the system. For domestic water systems, the required pressure is based on the highest elevation of the most remote fixture and the type of plumbing fixture the booster pump is serving. Common required pressures based on fixture type can be found in IPC Table 604.3.

Certain buildings, like health care facilities, may include equipment that requires higher flow rates and pressures than plumbing fixtures, so it is important to understand the building’s system characteristics. During design, the specific flow and pressure demand should be used for system calculations to

Objectives

• Learn the common types of domestic water booster pumps available and some benefits of each type.

• Identify domestic water booster pump design criteria and common sources of pressure loss to a domestic water service.

• Understand the variables that impact pressure calculations for domestic water system design.

BUILDING SOLUTIONS

Table 2: Pressure conversion rates

TABLE 2: An example of the pressure conversion rate between pounds per square inch (psi) and feet of head (feet). This conversion is used for pressure lift calculations in building water systems. The example shows various building levels and the associated pressure required to deliver water to each level.

Courtesy: WSP

‘Booster pumps are also used for fire suppression systems that require fire pumps.

ensure that an adequate water flow rate and pressure are available at each location or fixture in the system.

On the incoming side of the booster pump, we must design for the minimum pressure available from the utility as required by IPC Section 604.6. Booster pumps are installed when the incoming pressure is insufficient to meet the building requirements.

It is equally important to understand the residual pressure available from the utility on the incoming side, as it is the pressure required on the outgoing side to adequately serve the building. In many cases, the utility is a system of street mains, but it could be a different source, such as a well or water storage tank, so it is also important to identify and confirm your source location and type.

The domestic water system within any building has limitations to consider when it comes to increasing the system pressure. IPC Section 604.8 states that the maximum allowable building water pressure is 80 psi static pressure at the fixture. This section in IPC states that where the pressure is anticipated to exceed 80 psi, a water pressure reducing valve is to be installed that conforms to American Society of Safety Engineers Standard 1003, which includes a strainer.

For high-rise buildings, this maximum allowable pressure is an important consideration. When the criteria for the booster pump is to serve the most distant fixture, the fixtures on lower levels will experience higher pressures that can, in some cases, exceed the maximum allowed pressure. To accommodate this when designing a domestic water booster pump for a high-rise building, pressure zones are almost always required.

Pressure zones and multiple booster pumps

Pressure zones can reduce the flow rate required for each of the zone booster pump(s) and reduce

the number of pressure-reducing valves required to serve the fixtures on lower levels of the building. To determine where to divide the building domestic water system into zones, start with the required pressure at the maximum height above the source and the available water supply source residual pressure at the building peak flow rate. The available residual pressure also informs the design for how many levels of the building can be adequately served from the utility pressure. In some applications, where the required pressure at the highest level creates a system that exceeds 80 psi at multiple levels of the building, multiple pressure zones and multiple pressure booster pump assemblies are best practice.

Multiple booster pump systems can increase the building system flexibility for future available pressure and simplify the domestic water system maintenance and controls. IPC Section 604.8 identifies additional requirements that are to be considered when including water pressure reducing valves or regulators as needed in a high-rise domestic water system.

Booster pumps are also used for fire suppression systems that require fire pumps. Similar to domestic water, the system water source is frequently a street main supply, but it is important to confirm the system source to ensure the design can accommodate the available pressure. Single-stage pumps are more commonly used for fire systems. Single-stage pumps also operate with a set flow rate and pressure that match the steady-state conditions of a fire water system. Most importantly, single-stage pumps are dependable and have a long service life because they have fewer components that require maintenance and a simplified path for water to flow through when in operation. These qualities are important to consider when selecting a required booster pump for a life safety system.

Single-stage pumps

Single-stage pumps provide many benefits applicable to a high-rise building. First, single-stage pumps are capable of increasing water pressure at high flow rates, like those required for a standpipe system. The maximum allowable pressure for a fire water system is 175 psi for hose connections. Similar to domestic water in high-rise buildings, where the supply pressure exceeds 175 psi on any of the lower levels, a pressure-reducing valve must be installed.

BUILDING SOLUTIONS

FIGURE 3: An example of flow test data documented on a hydraulic graph. The example shows how to document the static pressure, residual pressure, and determine the available pressure at the building domestic water system flow rate. Courtesy: WSP

‘

Each building design needs to determine the available incoming water pressure.

’

Unlike domestic water systems, designing pressure zones to serve multiple floors cannot be utilized with the same vertical standpipe. NFPA 14: Standard for the Installation of Standpipe and Hose Systems Section 10.5.1.1 states that each vertical standpipe system zone must have one or more of the following components:

• Connection to a fire service main or utility.

• Separate fire pump.

• Separate outlet from a multistage multiport fire pump.

• Separate water storage tank.

NFPA 14 Section 10.2.4 describes the maximum allowable pressure at the standpipe hose connections. The maximum allowable pressure is 175 psi for the safety of firefighters and people utilizing the system. The minimum pressure required at the hydraulically most remote hose connection is dependent on the type of standpipe system installed for the specific type of building.

Each building design needs to determine the available incoming water pressure. A fire flow test can be performed, and the data from that test can determine and design the booster pumps required for a building's fire water and domestic water system. NFPA 291: Recommended Practice for Fire Flow Testing and Marking of Hydrants provides guidance for how to perform the fire water flow test. Sections 4.4.5 and 4.4.6 state the number of fire hydrants to be used for the flow test. The number depends upon the strength of the distribution system and the distance from the test location. The flow test must utilize enough hydrants for at least a 10% reduction in pressure. The result of the flow test includes multiple pieces of information. The first is the static pressure. The static pressure is the pressure that exists in the distribution system when no hydrants are flowing. The next piece of information is the residual pressure, which is the pressure that exists in the distribution system when water is flowing from the hydrants during the flow test. The flow test can be performed at any time, so it is important to note the time and date on the flow test data.

Section A.4.3.1 in NFPA 291 states that the flow test does not need to be conducted during

peak demand time. If a flow test is performed in the morning, then more pressure may be available compared to the middle of the day. Factors such as irrigation or temporary higher demand in surrounding buildings can significantly impact the available pressure.

Section A.4.15.1 states that the data should not be more than five years old because conditions can change over time. The two main conditions that may change are the condition of the distribution system pipe and the system demand. Both can change significantly over time. Because the design and construction process can take multiple years to complete, it is important to have a flow test performed during design and prior to equipment submittal and installation. The area surrounding a building site can develop significantly during design and construction, and the state of infrastructure may also change.

With this information, the next step is to utilize a hydraulic graph to determine how much pressure will be available at the specific building flow rate. A hydraulic graph is unique because it is a logarithmic graph specific to determining the flow and pressure relationship.

Creating a campus plan

Considerations for a campus master plan and future surrounding infrastructure capacity is best practice when designing a central plant system. Specifically, high-rise buildings with plans for additional vertical expansion could have significantly different available pressure at the time of the vertical

expansion. One strategy for future vertical expansion and unknown water pressure is to provide space and connections for a future booster pump from the water entrance downstream of the building backflow preventer. This strategy is beneficial when the vertical expansion planned is a significant portion of the building, and when the timeline for the vertical expansion is unknown or more than five years in the future. Space for future equipment provides the most flexibility and the lowest initial cost.

Another strategy for future planning a high-rise building is to provide a booster pump adequately sized for the full known build out and pressure reducing valves for the lower levels as needed. This strategy is beneficial when a project has limited mechanical space or when vertical expansion is planned to be designed and constructed in the near future. This strategy is also beneficial for projects with low available water pressure, because a booster pump assembly is necessary to serve the building. There is a higher initial cost with a booster pump sized for the full build-out, but the building system will need minimal modifications with the future vertical expansion.

Finally, future vertical expansion and unknown water pressure can be designed for with a multistage expandable pump. By leaving space for additional pumps on the pump skid assembly, the system can be adjusted in the future to the additional demand and available incoming pressure. This strategy is beneficial for projects with shell space that is unknown within the building or for future vertical expansion that could have a signifi-

FIGURE 4: An example of an incoming domestic water service to a hospital and the system equipment. The flow diagram includes the design pressure losses associated with water flowing through each piece of equipment to determine the available water pressure incoming to the domestic water booster pump.

Courtesy: WSP

BUILDING SOLUTIONS

‘Domestic water booster pumps for high-rise buildings must also be designed to overcome the pressure losses from piping and equipment in the system upstream to the booster pump assembly. ’

cantly higher demand and pressure requirement. This strategy is also beneficial for projects with limited mechanical space, because the additional pumps will be incorporated into the pump skid instead of requiring additional space when expanded. When an expandable booster pump assembly is provided, the pipe sizes and controls have capacity installed for the future with the base design products, and the future modifications are minimal. An expandable pump assembly provides flexibility and a lower future cost as well as minimal disruption to the building system when the additional pumps are installed.

Domestic water pumps

csemag.com

Pump insights

u Booster pump systems for high-rise buildings are designed to address challenges of water pressure and flow, with single-stage pumps suited for highflow applications and multistage pumps offering energy efficiency, redundancy and flexibility for variable demand.

u Every booster pump must meet strict code requirements, including accessibility for pump maintenance and compliance with potable water standards, ensuring the pump delivers reliable performance throughout the building system.

Domestic water booster pumps for high-rise buildings must also be designed to overcome the pressure losses from piping and equipment in the system upstream to the booster pump assembly.

The first component of a building water system that can contribute to pressure loss is the water service pipe. This applies to both domestic and fire water.

The pressure loss incurred is based on the flow through a specific pipe size serving the building and accumulates per foot of pipe. In most cases, the pressure loss for the service pipe is not significant, but it must be calculated and considered. The second component that contributes to pressure loss is the backflow preventer. The pressure loss through the backflow preventer assembly depends on the model number and flow rate, and it can be found from the manufacturer’s published information. Typically, the loss through a backflow preventer is 10 psi.

A pressurized water storage tank can also contribute to pressure loss to the system. Typically,

the loss through a water storage tank is 5 psi. One of the most significant components in a building's water system that contributes to pressure loss is the water softener. Because water softeners have a maximum allowable pressure for the equipment, it is best practice to put the softener system upstream of the booster pump in a high-rise building. In most cases, the pressure required for a high-rise building exceeds the allowable pressure for the water softener assembly.

By putting it upstream, the softener system is protected and efficiently serves the building. A water softener assembly has a pressure loss at continuous flow and peak flow. Both pressure loss values can be found in the manufacturer’s published information.

In most cases, the pressure loss through a water softener at peak flow is 25 psi, so it can significantly change the booster pump design. The booster pump is sized with the peak flow pressure loss from the water softener as a conservative approach because the flow demand is variable in a building's domestic water system and can change over time.

Finally, the water meter can also contribute to pressure loss to the system. The pressure loss from the meter depends on the meter size and flow rate, but in most cases, this is 10 psi. A flow diagram of all the equipment included in your domestic water system can help ensure that all the pressure loss contributors are accounted for, and we know the incoming water pressure to design for at the booster pump.

The incoming water pressure available at the booster pump should be compared to the selected booster pump’s net positive suction head required (NPSHr), or the minimum pressure required on the incoming side of a pump, to avoid cavitation. The NPSHr value is specific to each pump and can be obtained from manufacturer data. Factors for calculating the NPSHr value include absolute pressure, vapor pressure, liquid temperature and specific pressure losses through the pump components. cse

Lauren Plant is a Senior Plumbing Consultant at WSP USA Buildings. She has 10 years of experience in MEP systems, primarily for health care applications.

CASE STUDY

California-based nutraceutical manufacturer meets large, spiking hot-water demand with tankless and tank system.

CHALLENGE:

A California-based nutraceutical manufacturer required a hot water system that could handle sudden, large spikes in demand without temperature fluctuations or downtime, while maintaining strict sanitation standards.

SOLUTION:

Noritz designed a hybrid system combining multiple commercial tankless units with storage tanks, ensuring both instant recovery and consistent water temperature. The modular design allowed for easy future expansion.

RESULT:

The new setup now delivers reliable hot water for all production shifts, eliminates previous shortfall issues, reduces energy waste, and provides a scalable, lowmaintenance solution that supports the company’s growing operational needs.

SUMMARY: A leading California nutraceutical manufacturer faced frequent challenges meeting its facility’s large, spiking hot water demands. With strict production and sanitation requirements to uphold, the company needed a dependable, energy-efficient solution that could handle rapid changes in usage without sacrificing temperature consistency. Their previous system struggled to keep up, leading to production slowdowns and excessive energy use.

Noritz collaborated with the installation team to design a hybrid tankless and tank system that combined the best of both technologies: the endless supply of tankless units with the immediate capacity of storage tanks. The system featured modular scalability, allowing the facility to easily expand capacity as production grows.

Installed over a single weekend to minimize downtime, the new configuration ensures stable performance during peak demand, rapid recovery times, and improved operational efficiency. The manufacturer now enjoys consistent hot water delivery across all shifts, with energy and maintenance savings contributing to long-term cost reductions.

This project highlights the versatility and reliability of Noritz commercial systems in meeting complex industrial demands—proving that a properly engineered hybrid setup can provide both flexibility and peace of mind for large-scale, process-driven operations.

1-866-766-7489 commercial@noritz.com

Design health care facilities with energy efficiency and flexibility in mind

In this roundtable, engineers discuss current trends for health care facilities and where the industry is going in the coming years.

CSE: What are the biggest engineering trends in hospitals, health care facilities and medical campus projects?

Caleb Marvin: Cardiovascular procedures and inspections are on the rise as the population ages. Health care systems are expanding these services at their current facilities or purchasing older facilities to upgrade into dedicated cardiovascular units. In response to this specialty, the demand for uninterrupted power supply (UPS), power conditioner, generator and air handling unit replacements or upgrades is on the rise to serve the advanced tech-

nology used in catheterization (Cath) and electrophysiology (EP) labs. The mechanical, electrical and plumbing (MEP) infrastructure to support this highly sophisticated equipment requires careful planning and coordination to help ensure optimal performance of the facility.

Brad Reuther: One big engineering trend in hospitals is a reduction in the use of steam. Maintenance staff are stretched thin and fewer people know how to properly maintain steam systems. Condensing hot water boilers operating at lower temperatures and reduced thermal losses from the piping systems provide significant energy savings. Lower-temperature hot

water systems also open the door for additional heating equipment types and energy recovery options.

Meagan Gibbs: We are experiencing a strong push towards flexibility and scalability in health care projects. Hospitals are moving away from static, single-purpose spaces and are instead investing in universal rooms and adaptable platforms that can pivot between acuity levels or transform into surge capacity when needed. Another big trend is the integration of research, education and care within a single ecosystem. A recent project for a cancer center we designed shows how innovation districts can create a place for scientists, clinicians and patients to be under one roof, helping to accelerate discovery-to-care pathways. Behavioral health continues to rise in prominence, with systems prioritizing purpose-built facilities that destigmatize care while improving access.

Jason Butler: A focus on sustainability is the biggest current trend in health care facility design.

John Bowling: The need for additional operating rooms, cath labs and imaging equipment upgrades seems to be the largest trend in existing hospitals.

Darren Harvey: Trends I’m seeing include electrification, microgrids, reduced overall energy usage, a reduction/removal of piped nitrous oxide systems, water reclamation, water storage and water quality.

FIGURE 1: A new bi-plane neuro operating room at MaineHealth's Maine Medical Center. Courtesy: Fitzemeyer & Tocci Associates Inc.

Participants

A focus on redundancy and resilience for MEP and technology systems is also common.

Richard Vedvik: The nation's health care system is plagued by existing infrastructure that is beyond its useful life, often due to deteriorated physical condition, limited availability of replacement parts or overall structural wear. This trend highlights the urgent need for comprehensive assessments and upgrades to ensure operational reliability.

Jon Sajdak: One trend in the industry is the use of mass timber construction. Mass timber can support initiatives for sustainability, expedited construction schedules and aesthetic appeal. This may not be appropriate for all projects, but it is an option that has become more popular in comparison to typical steel or concrete construction. One misconception is that the wood used in mass timber construction would be dangerous since it’s a com-

John Bowling, PE, CHC

Sr. Project Manager Dewberry

Raleigh, N.C.

Jason Butler, PE Principal, Healthcare Fitzemeyer & Tocci Associates Inc. Woburn, Mass.

Meagan Gibbs, PE, ASSE 6020

Healthcare Engineering Area Market Sector Leader

HDR

Kansas City, Mo.

• Identify how new energy codes and considerations are impacting the design of new and existing hospitals.

• Understand how to design for continuous operation and multiple uses across health care campuses.

• Learn how changes in the health care industry are changing design.

bustible material. However, mass timber has inherent fire resistance properties and should not be compared to typical lightweight wood construction. This is primarily due to charring at the surface that acts as a self-insulator to the remaining part of the member when exposed to fire.

CSE: What types of challenges do you encounter for these types of projects that you might not face on other types of structures?

Caleb Marvin: Renovations in ambulatory surgery centers (ASC) or hospitals to retrofit existing operating rooms to Cath or EP labs create unique challenges and tax existing infrastructure. Many existing ASCs were designed to meet the minimum program and code requirements for the original design, often within a tight budget. Existing generators at these facilities may not be sized to handle the additional electrical load of the equipment. Replacing the existing generator or adding capacity creates complications with the existing distribution that need to be identified early in a project. Many facilities do not have a UPS, which is required to protect the patients in the event of a loss of the normal systems. These systems require a lot of space and reject a lot of heat that must be accounted for.

Darren Harvey, PE, LEED AP Principal

Smith Seckman Reid Inc

Dallas

Caleb Marvin, PE

Senior Associate Certus Consulting Engineers

Dallas

Brad Reuther, PE, LEED AP Mechanical Engineer SmithGroup

Detroit

Jon Sajdak, PE Fire Protection

Engineering Director Stantec

Houston

Richard Vedvik, PE

MEPT Quality Director

IMEG

Rock Island, Ill.

FIGURE 2: An inpatient corridor at Lisa Dean Moseley Foundation Institute for Cancer and Blood Disorders at Nemours Children's Hospital. Courtesy: HDR

ENGINEERING INSIGHTS

Brad Reuther: A significant challenge for many health care facility types is the need for continuous operation. Renovation projects often involve complex phasing to be incorporated into the design. This may involve temporary relocation of some functions to create an empty chair where construction can start and progress area by area until the renovation is complete. Phasing boundaries must take into consideration patient care functions, infection control, life safety, construction logistics and the availability of MEP systems to provide the required services at each stage. These projects often benefit from early contractor involvement to reduce the risk of surprises during construction.

Meagan Gibbs: Hospitals are some of the most complex building types to design. Unlike a corporate office or school, hospitals operate 24/7 and must maintain critical systems with zero downtime. That means design and construction phasing, infection control risk assessments and redundant utilities are part of every project. Hospitals carry unique regulatory frameworks, including Facility Guidelines Institute recommendations to Joint Commission requirements, that demand precise com-

pliance. Health care projects also involve highly integrated systems: MEP, structural, IT, medical equipment and operations must be coordinated precisely. The engineering challenge is less about designing isolated systems and more about ensuring an entire ecosystem functions reliably under constant demand.

Jason Butler: The myriad of codes, standards and regulatory bodies is a challenge for health care projects, as well as the overriding emphasis on reliability and patient/staff safety.

John Bowling: For medical gas systems, we sometimes find that vacuum systems do not meet current waste anesthetic gas disposal requirements.

Darren Harvey: Hospitals are most often owned by the operators and are constructed for a 50-year lifespan. The desire for more redundancy and resiliency in a hospital facility often challenges both the initial budget/quality of systems and operational budget needs. A balance of both is often needed to have a successful outcome. Space and infrastructure planning for future systems can be an effective approach to maintain the initial project budget.

Richard Vedvik: As the health care system expands or remodels departments, the existing infrastructure is commonly left out of the early budgeting process. This oversight leads to significant issues, such as unforeseen costs for essential upgrades to MEP systems. Unlike other structures where infrastructure might be simpler, health care projects demand uninterrupted operations, making phased implementations complex and requiring careful coordination to avoid disrupting patient care.

Jon Sajdak: Opening protectives and the treatment of penetrations are some of the primary challenges that are present in health care facilities. Health care occupancies have numerous fire- and smoke-rated assemblies, including but not limited to smoke barriers, fire barriers and smoke partitions. Each wall type has specific opening protective and penetration requirements, which must be closely coordinated during

design and installation. Doors and windows in these assemblies are required to have specific ratings, fire and/or smoke dampers and penetrations that must be sealed. Firestop systems are commonly used for treating penetrations and are required to have specific F and T ratings.

CSE: What are engineers doing to ensure such projects (both new and existing structures) meet challenges associated with emerging technologies?

Caleb Marvin: Proper planning when designing these types of spaces is crucial. The design engineer must study the existing electrical distribution system from the generator to the main distribution panel planned to serve the equipment. The equipment for cath and EP procedures requires a significant amount of power added to the distribution. A load study consisting of metering described in NFPA 70: National Electrical Code Article 220.87 and power quality assessment should be performed to verify existing demand and ensure that the existing infrastructure can support the additional loads. Along with the higher electrical demand, the equipment also requires significant cooling. Pretesting of existing HVAC systems is often needed to determine available capacity as the engineer plans required upgrades to support the new equipment.

Brad Reuther: Health care facilities are in a constant state of change as new treatment methods are developed and technology advances are implemented. Older existing facilities require creative solutions and different system considerations to overcome constraints such as tight floor-to-floor heights. New facilities can be designed with systems sized with spare capacity and flexibility to accommodate changes in space use or equipment. Equipment rooms can also have extra space or be designed to expand if additional equipment is needed.

Meagan Gibbs: The pace of technology adoption in health care is accelerating.

FIGURE 3: An example of a hospital electrical room at the University of Iowa Acute Leukemia Center. Courtesy: IMEG Corp.

Robotics, AI-enabled diagnostics, real-time location tracking, telehealth and immersive training all place new demands on infrastructure. Our approach is to design flexible, high-capacity backbones into facilities. Designing robust data and electrical distribution systems that can support both current needs and unanticipated future technologies without major renovation is essential. In existing buildings, it is important to implement modular infrastructure upgrades, such as universal cable pathways and adaptable mechanical systems, so that facilities can absorb technology without disruptive downtime.

John Bowling: For existing hospitals, during our schematic design phase, we identify systems that may be at the end of their useful life. Usually, the client will recognize that a controlled changeout is better than an unplanned shutdown if the equipment fails later. These are ideal times to evaluate new technologies. For greenfield hospitals, most owners are hesitant to apply new technologies that do not have a reduced initial cost or if they complicate the maintenance of the solution.

Darren Harvey: Emerging technologies can be challenging from several standpoints, including allocating budgets for systems that aren't fully understood or often implemented, understanding the responsibility matrix for these systems, building emerging technology systems without hitting proprietary infrastructure needs that drive up costs, getting the systems to operate correctly and implementing training before seeing the first patients. Collaboration between the owner, design professionals, vendors and installing contractors is crucial during the design, installation and systems startup phases to make sure the new technologies are successful. This collaboration leverages the lessons learned across multiple entities.

Richard Vedvik: Engineers should be consulted during the programming and planning phases of a project, to ensure necessary infrastructure upgrades are

accounted for in both the project budget and project timeframe. When an engineering team has historical knowledge of the campus, they are an essential part of the health care team, helping establish equipment replacement priorities.

CSE: What types of smart buildings or campuses are you designing for hospital clients? Outline the automation and controls, integration and any cutting-edge technology.

VFD-Induce d Shaf t Volt age Destroys Bearings!

Electrical bearing damage causes unplanned downtime

Protect motor bearings with AEGIS® Shaft Grounding Rings

Variable frequency drives (VFDs) are used to control pumping systems. But VFDs create a motor shaft voltage that discharges through the bearings, blasting millions of pits in bearing surfaces. Both motor and equipment bearings are at risk. These discharges degrade the bearing grease and cause bearing fluting, premature failure, and costly downtime.

By channeling VFD-induced discharges safely to ground, AEGIS® Shaft Grounding Rings prevent electrical bearing damage. Proven in millions of installations worldwide, AEGIS® Rings provide unmatched protection of motors against electrical bearing damage, motor failure, and unplanned downtime.

See our shaft grounding case studies and resources for pump users, contractors, and manufacturers at: est-aegis.com /case-studies

ENGINEERING INSIGHTS

Brad Reuther: Advancements in controls and integration capabilities provide increased ability to monitor, analyze and adjust building systems to maintain patient and staff comfort while also optimizing energy efficiency. The build-

ing automation system (BAS) can bring together data from various systems such as HVAC, plumbing, lighting, power, fire alarm and security. Software packages can then analyze this data to automatically identify, diagnose and prioritize oper-

STEAM POWERS THE WORLD

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ational faults within building systems. This can help building operators address problems quickly before they result in additional issues. Energy management information system software packages take this a step further with data visualizations, utility data analysis, automated optimizations and operations and maintenance process improvements.

Meagan Gibbs: Smart hospitals are becoming a new benchmark. We are deploying automation systems that integrate patient tracking, asset management, energy controls and predictive maintenance into a single digital platform. When designing a Midwest hospital’s recent expansions, we incorporated Internet of Things-enabled systems that allow realtime monitoring of energy use, room conditions and clinical workflows. This data can be used to improve efficiency and patient experience simultaneously. We are also embedding AI-ready infrastructure into new projects so that analytics can drive operational decisions, from patient throughput to energy optimization.

Jason Butler: There is definitely a need for facilities to streamline their building operation. One strategy is increased controls, automation and intelligent fault diagnostics. A driver of this is the deficiency of employment in facilities, as well as the pipeline, much like the engineering industry as a whole. The challenge for many facilities is that the existing control systems often need significant upgrades to realize the benefits of these smart building strategies and the price tag of those upgrades often presents a barrier to get initiatives like that approved and funded. cse

High Amperage Automatic Transfer Switch Docking Stations are engineered to deliver unmatched performance where power restoration is needed. Ensuring a seamless transition to backup power, preventing costly downtime and maintaining business continuity.

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EDITOR: Amara Rozgus, WTWH Media, 1111 Superior Ave, Suite 1120, Cleveland, OH 44114

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