Go to www.csemag.com/giants to access the 2023 MEP Giants online submission form.
Submit your rm’s data to be considered for the Consulting-Specifying Engineer 2023 MEP Giants program and be among the top mechanical, electrical, plumbing (MEP) and re protection engineering rms in North America. Your company’s information will be included in the MEP Giants report, featured in the Consulting-Specifying Engineer September 2023 issue and in an online exclusive.
The in-depth analysis of these winning rms appears in September and reveals what’s going on in the industry, including a look at trends over the past several years. Special emphasis will be placed on the Commissioning Giants in a separate report in November.
NOMINATION DEADLINE:
To participate in the 2023 MEP Giants, submit your rm’s information by Friday, April 7, 2023.
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5 | Mechanical engineers value energy-efficient projects
Improved efficiency is key
BUILDING SOLUTIONS
8 | Avoiding total darkness in emergency lighting scenarios
Know the NEC rules related to component failure in emergency lighting fixtures
12 | Lighting efficiency –More than LEDs alone
To be more energy efficient, lighting design is a great place to start
16 | Exploring basic components of a low-voltage electrical system
Electrical projects often require low-voltage systems. Learn about the various equipment
20 | Arc energy reduction requirements for low-voltage equipment
Electrical projects often require low-voltage systems
BUILDING SOLUTIONS
26 | How to transition legacy controls into a smart system
How Baylor University modernized its legacy systems to provide more efficiency
30 | How to design fire alarm visual notification in office hoteling
Office hoteling is on the rise, creating the need to adjust fire alarm design approaches
34 | NFPA 13 performance-based design solutions
This article will discuss two types of designs for fire and life safety systems
40 | Back to basics: Medical gas storage under NFPA 99
The basics of medical gas storage and healthcare spaces detailed in NFPA 99
ENGINEERING INSIGHTS
46 | K-12 roundtable focuses on advanced technologies
HVAC and security systems are being upgraded at K-12 schools
MARCH/APRIL 2023
8
ON THE COVER:
A resort has multiple luminaires by exterior doors, so if more than one was powered by the emergency system, total darkness would be prevented even if one failed. This photo highlights the architectural details of the façade, and also provides wayfinding for the property.
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, LEED AP BD+C, BEMP, Senior Energy Engineer, Oak Park Ill.
KENNETH KUTSMEDA, PE, LEED AP, Engineering Manager, Jacobs, Philadelphia
JULIANNE LAUE, PE, LEED AP BD+C, BEMP, Director of Building Performance, Mortenson, Minneapolis
DAVID LOWREY, Chief Fire Marshal, Boulder (Colo.) Fire Rescue
JASON MAJERUS, PE, CEM, LEED AP, Principal, DLR Group, Cleveland
BRIAN MARTIN, PE, Senior Electrical Technologist, Jacobs, Portland, Ore.
BEN OLEJNICZAK, PE, Senior Project Engineer, Mechanical, ESD, Chicago
GREGORY QUINN, PE, NCEES, LEED AP, Principal, Health Care Market Leader, Affiliated Engineers Inc., Madison, Wis.
BRIAN A. RENER, PE, LEED AP, Principal, Electrical Discipline Leader, SmithGroup, Chicago
SUNONDO ROY, PE, LEED AP, 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
Mechanical engineers value energy-efficient projects
In a recent research study, mechanical engineers indicated improved energy efficiency has grown in importance
Mechanical engineers spend about a quarter of their time (26%) writing the specification for a project. And on average, about a third (36%) of billable hours is spent researching or specifying mechanical systems. As engineering firms consider their employees’ projects and billable hours, it’s important to know this information.
Editor-in-Chief
Consulting engineers specify several different types of mechanical systems into commercial buildings, and they provided feedback on these specifications in the recent “Specifying Considerations for Mechanical Systems Survey,” completed in February 2023 by Consulting-Specifying Engineer.
Respondents to the study indicated the designed or specified the following:
• Pumps: 84%
• Heating and cooling: 84%
• Ventilation: 79%
• Plumbing, piping: 64%
• Refrigeration: 54%
These survey respondents, who have spent an average of 28 years in this industry, specify new construction and retrofit/renovation projects evenly at 35% each. They tend to work with several other experts, with the mechanical engineer having the most input on these systems (62%).
True to most of the HVAC industry trends, improved energy efficiency was listed as the top feature that has grown in importance for mechanical systems (62%). Close behind was availability from the manufacturer (58%), pointing to continuing supply chain issues. When looking toward the future, the top five technologies and services these respondents anticipate are:
To view complete findings, register for the Specifying Considerations for Mechanical Systems Report at www.csemag.com.
SURVEY METHODOLOGY
A survey was emailed to ConsultingSpecifying Engineer audience members and information was collected in February 2023. A total of 163 qualified responses were returned, with a margin of error of +/-7.7% at a 95% confidence level. Participants frequently had the option to select more than one response, thus totals do not always equal 100%.
Amara Rozgus,
Atkore™ Celebrates Winner of its $100,000 Truck of Your Dreams Sweepstakes
No matter what type of job they’re on, all electrical contractors share one thing in common: They need a truck with not only the reliability to handle adverse terrain but also the versatility to serve as a mobile office, command post, tool hauler, and even storm shelter.
Knowing how critical it is to get just the right vehicle, Atkore, a leading global provider of electrical, safety and infrastructure solutions, created the Win the Truck of Your Dreams Sweepstakes to continue delivering on its Building Better Together promise to electrical trade professionals worldwide.
After receiving an overwhelming volume of sweepstakes entries, Atkore selected winning electrical contractor Brian Supplee in a 3rd-party, random drawing. The company held an all-staff celebration for him in February at its Harvey, Illinois headquarters, where Bill Waltz, Atkore President and Chief Executive Officer, presented the grand prize to Supplee, a Project Manager at Ohio-based U.S. Utility Contractor Co., Inc. Before entering the sweepstakes, Supplee relied on Atkore to supply PVC conduit, rigid galvanized steel conduit, and strut products for construction projects.
“Win the Truck of Your Dreams celebrates our electrical contractor customers and underscores Atkore’s commitment to Building Better Together with them,” said Waltz. “Building Better Together is not just a tagline—it’s part of our DNA. It means delivering a full suite of products and solutions from nearly 30 brands to electrical trade professionals whenever and wherever they need them around the world.”
“When you work with Atkore, you have a passionate team behind you, along with the high quality and reputation of long-established brands,” Waltz noted. These include nearly 100-year-old brands like AFC Cable Systems and Unistrut to Allied Tube & Conduit, Cope Cable Tray, FRE Composites, US Tray, Heritage Plastics, and United Poly Systems, as well as many other highly respected brands recognized throughout the industry.
The sweepstakes, won by an Ohio-based electrical contractor, helped underscore Atkore’s commitment to Building Better Together with electrical contractors
Entering the contest provided Supplee with greater insight into the additional ways he can use Atkore products and services to support U.S. Utility’s projects moving forward. “As an instructor and contractor, it’s important for us to have efficiency,” Supplee said. “The tools and training available from Atkore really provide us with that. It’s a lot easier to have a one-stop shop, and one thing I’ve learned from this experience is that Atkore is a total solutions provider.”
“We want to thank our electrical contractor partners for everything they do for society,” Waltz said. “This sweepstakes was an important way to build on our program of monthly giveaways and express our gratitude in a way that is most meaningful to contractors.”
With approximately 47 manufacturing facilities worldwide, Atkore offers an unmatched breadth of electrical products and solutions. The goal is to ensure that electricity safely and efficiently runs through all types of facilities and infrastructure projects worldwide. Whether for roads, bridges, data centers, warehouses, hospitals, manufacturing plants, or high-rise buildings, Atkore supplies products and services that meet electrical contractors’ unique needs.
“Our mission statement is to be the customer’s first choice, and that’s all about what we can do to make the contractor’s life easier,” Waltz said. “That’s innovation. That’s labor-saving solutions. That’s digital tools. That’s having mobile showrooms come to job sites for hands-on demonstrations. That’s delivering a full suite of products wherever and whenever contractors want it. It’s also about listening to their feedback and ideas we can then use to make their lives better.”
Product lines include everything from PVC, HDPE, steel, fiberglass and specialty conduit to armored cable, cable management systems, fasteners, safety and security products and framing systems. Atkore’s array of support resources include online training via Atkore University and a full suite of webinars, the Atkore Virtual Solutions Center with its 3D application environment, mobile showrooms that bring product demos and training directly to worksites, and the Atkore BIM Toolbar plugin for Revit. With all that, Atkore is proud to provide electrical trade professionals with a world-class level of flexibility, training and convenience.
U.S. Utility Contractors Co, Inc., which has been in business since 1989, is a perfect example of the type of electrical contractor Atkore supports every day on a wide range of projects. U.S. Utility works on transmission distribution as well as AT&T communications, traffic signals and highway lighting. Most of its projects are turnkey.
“The thing I like best about being a contractor is taking a project from start to finish,” Supplee said. “After completing it, I like being able to drive by years later and see what we did with a sense of accomplishment.”
He cited U.S. Utility’s work on the Veterans’ Glass City Skyway Bridge over the Maumee River on I-280 in Toledo, completed in 2007, as a particular highlight. “I started that project when I was 26,” Supplee recalled. “It was a four-year project and there were a lot of challenges—from being down in the water, putting in the ground rods, running conduit up for the ground conductors, all the way to being at the very top of the bridge to install the lightning rod and the FAA beacons. I’ve been over that bridge so many times, walked it so many times, I can tell you where everything is. That was the most memorable job for me. It was a statement piece in Toledo.”
meet electrical contractors’ emerging needs. For additional product insights, visit Atkore’s New Products Portal at atkore.com/new-products-portal
Atkore’s role with contractors is to be there with them every step of the way as jobs like that move from conception to completion. “We are committed to making your life as an electrical contractor as easy as possible,” Waltz said. To that end, Atkore continues to focus on new product and service innovations—and on further expanding its product portfolio to
Winning a new truck customized to meet every worksite need and stocked with Atkore products is the stuff electrical contractor dreams are made of—and Atkore is proud to make those dreams a reality.
About Atkore Inc.
Atkore is forging a future where our employees, customers, suppliers, shareholders and communities are building better together—a future focused on serving the customer and powering and protecting the world. With a network of manufacturing and distribution facilities worldwide, Atkore is a leading provider of electrical, safety and infrastructure solutions.
David Repair, PE, LC, Assoc. IALD, LEO A DALY, Omaha, Nebraska
Avoiding total darkness in emergency lighting scenarios
Understand the NEC requirements related to component failure in emergency lighting fixtures
NFPA 70: National Electrical Code Article 700.16 contains code requirements related to the avoidance of total darkness in emergency lighting conditions. Emergency illumination may be provided by batteries integral to luminaires, generator back up or lighting inverters. Some emergency illumination luminaires are controlled with adjacent normal lighting under normal conditions and fully energized under emergency conditions, while other
emergency luminaires are normally off and only energized under emergency conditions.
Updates to NEC in 2020 account for the differences in lighting technology that have emerged since the widespread adoption of LED luminaires. Legacy sources such as fluorescent, incandescent and high-intensity discharge luminaires had lamps that were separate from the luminaire itself. The light source in LED luminaires is a diode integral to the luminaire though, not a separate lamp. Updates to the indicated portion of the NEC were needed to ensure the language was applicable to LED luminaires.
Many engineers remain unaware of how these changes affect design considerations for emergency lighting. While the changes may seem minor, they must be accounted for at the beginning of a project or else risk costly delays in equipment ordering or occupancy. Failure to follow these new requirements can lead authorities having jurisdiction to require rework, which can include reopening finished walls or ceilings, running new conduits, retrofitting power supplies and installing new equipment.
The scope of this article will specifically focus on the portion of NEC Article 700.16 related to system reliability. It should be noted that this article is not intended to be an exhaustive interpretation covering all requirements related to emergency illumination.
There are other code requirements applicable to emergency lighting contained in, for example, the NEC, NFPA 101: Life Safety Code and the International Building Code that are outside the scope of this article that the engineer of record
FIGURE 1: A resort has multiple luminaires by exterior doors, so if more than one was powered by the emergency system, total darkness would be prevented even if one failed. This photo highlights the architectural details of the façade, and also provides wayfinding for the property. Courtesy: LEO A DALY
must be familiar with to ensure a fully codecompliant design.
Emergency lighting code changes
NEC requirements related to the failure of individual lighting elements were first introduced in 1956 and most recently updated in 2020. The 2017 and 2020 code language can be seen below. Note particularly the change in 2020 NEC 700.16(B) to the “failure of any illumination source” compared to the 2017 wording of the “failure of any individual lighting element, such as the burning out of a lamp.”
2017 code language:
700.16 Emergency Illumination
Emergency illumination shall include means of egress lighting, illuminated exit signs and all other luminaires specified as necessary to provide required illumination.
Emergency lighting systems shall be designed and installed so that the failure of any individual lighting element, such as the burning out of a lamp, cannot leave in total darkness any space that requires emergency illumination.
Where high-intensity discharge lighting such as high- and low-pressure sodium, mercury vapor and metal halide is used as the sole source of normal illumination, the emergency lighting system shall be required to operate until normal illumination has been restored.
Where an emergency system is installed, emergency illumination shall be provided in the area of the disconnecting means required by 225.31 and 230.70, as applicable, where the disconnecting means are installed indoors.
2020 code language:
700.16 Emergency Illumination.
A) General. Emergency illumination shall include means of egress lighting, illuminated exit signs and all other luminaires specified as necessary to provide required illumination.
N (B) System Reliability. Emergency lighting systems shall be designed and installed so that the failure of any illumination source cannot leave in total darkness any space that requires emergen-
FIGURE 2: Two emergency fixtures in room, opaque walls. Redundant internal components not needed. One emergency fixture on either side of glass wall. Redundant internal components not needed. One EM fixture in room, opaque walls. Redundant internal components or second emergency fixture needed. Courtesy: LEO A DALY
FIGURE 3: Parking lot fixture can prevent total darkness if backed up by emergency source. One emergency exterior fixture not by any others. Redundant internal components or second emergency fixture needed. Two emergency fixtures near each other. Redundant internal components not needed. Courtesy: LEO A DALY
cy illumination. Control devices in the emergency lighting system shall be listed for use in emergency systems. Listed unit equipment in accordance with 700.12(I) shall be considered as meeting the provisions of this section.
N (C) Discharge Lighting. Where high-intensity discharge lighting such as high- and low-pressure sodium, mercury vapor and metal halide is used as the sole source of normal illumination, the emergency lighting system shall be required
Objectives Learningu
• Understand the history and intent of code requirements related to avoiding total darkness in emergency lighting scenarios.
• Become familiar with different strategies for compliance with the code requirements related to emergency lighting scenarios.
• Know how to select and document the solution(s) for avoiding total darkness in emergency lighting scenarios best suited for a given project.
BUILDING SOLUTIONS UILDING
FIGURE 4: Typical wiring diagram for luminaries with dual drivers and dual light engines. Note: Different manufacturers may provide different wiring connections.
Courtesy: LEO A DALY
to operate until normal illumination has been restored.
N (D) Disconnecting Means.
Where an emergency system is installed, emergency illumination shall be provided in the area of the disconnecting means required by 225.31 and 230.70, as applicable, where the disconnecting means are installed indoors.
Interpreting NEC Article 700.16
NFPA 70-2017 Article 700.16 and the 2020 edition of Article 700.16(B) are intended to account for possible manufacturing defects of the light fixture, ensuring that a space containing emergency illumination would not be left in total darkness if one component in an emergency fixture was to fail.
However, lighting designers have had experience with the authority having jurisdiction interpreting this section of code as meaning that the driver also cannot be a single point of failure for the fixture. If the driver fails, then no light is coming out of the fixture and thus the illumination source failed. As such, the conservative interpretation that neither the driver or light board can be a single point of failure for the fixture is assumed for this article.
How to handle emergency lighting scenarios
There are multiple ways to comply with this code requirement. Some are listed below, although the list of strategies indicated is not necessarily exhaustive and there may be additional ways to achieve project compliance.
SCENARIO 1: Multiple fixtures in an interior space
An interior space that has more than one emergency fixture will typically comply with this portion of code. Should one emergency fixture fail, the other emergency fixture(s) in the space would prevent the space from being in total darkness (see Figure 2).
SCENARIO 2: One fixture in an interior space with glass wall
‘ Designers and engineers should pay close attention to NEC Article 700.16 and include features in their project to ensure code compliance.’
With legacy source types, this code section was frequently accounted for by having emergency fixtures furnished with two ballasts and two lamps. If one ballast and/or lamp failed, the fixture would still produce some light and the space in question would not be left in total darkness under emergency conditions.
The updated wording in the 2020 code reflects the industry’s movement away from legacy source types to LEDs by revising the wording from “… any individual lighting element, such as the burning out of a lamp …” to “… any illumination source …”.
There is a line of thinking that says an LED fixture with multiple diodes would inherently comply with the 2020 edition of NEC because the wording “any illumination source” only applies to the diodes themselves. A multidiode LED fixture that has one diode fail can still provide light via the remaining diode(s).
If an interior space has only one emergency fixture, but additional emergency fixtures are on the other side of a glass wall or door, it is reasonable to conclude that light from one of the adjacent emergency fixtures shining through the glass wall or door would prevent the space from being in total darkness in the event of an emergency.
SCENARIO 3: Exterior space with site lighting
For exterior door applications where emergency lighting is provided by a wall pack, recessed downlight or some other form of lighting right outside the door, this section of code can be complied with if there are bollards, pole lights or some other form of site lighting in the area that are also on emergency power. The adjacent site lighting backed up by emergency power would keep the space from being in total darkness should normal power and the fixture by the door both fail (see Figure 3).
SCENARIO 4A: Exterior space with no site lighting (single driver)
A more challenging situation related to this portion of code is an exterior door that has only one emergency fixture adjacent to it without any other site lighting in the vicinity. A common example of this is an exterior door with one emergency wall pack or sconce above it with no other building mounted lighting or site lighting nearby. One possible solution is to add another emergency illumination source near the door, either by adding a second normally on emergency fixture or by adding a normally off exterior emergency lighting unit.
SCENARIO 4B: Exterior space with no site lighting (dual driver)
Sometimes aesthetics or practicality make those options not preferred though. In those situations, a good solution is to specify one emergency fixture with dual drivers and dual light engines (see Figure 4). That way if one driver or light engine fails, half of the fixture will still illuminate and the space will not be left in total darkness.
Understanding manufacturer offerings
Multiple manufacturers offer exterior fixtures that have an option of being provided with dual drivers and dual light engines. They frequently are not available with integral battery backup or integral control sensors or receivers, as the two separate internal circuits would make the connections cumbersome and the physical size of the fixture larger than typically desired. The two drivers can be controlled separately or tied together external to the fixture and controlled by a common remote switch, photocell or time switch. It is typically a good practice to provide notes and/or a detail on the plans to clarify how these fixtures should be connected to ensure the final install matches the design intent. Interior rooms (Figure 2) requiring emergency illumination that only have one light within and no glass walls or doors are another situation to pay special attention to on a per-project basis to determine the best course of action. Small connecting hallways, vestibules and rooms with electrical panels are common examples of this situation.
In the case of these smaller interior rooms, an interior lighting unit such as a “bug-eye” type fixture, if it meets the requirements of Article
700.12(I), would comply with Article 700.16(B) without the general lighting in the room being backed up by emergency power. Manufacturers are generally aware of the requirements listed in Article 700.12(I) and most emergency lighting units available do comply with those requirements.
In situations where adding a second light source and/or adding an emergency lighting unit to the room is not preferred, there are some manufacturers that offer strip lights with the option of having dual drivers and dual light engines (see Figure 4), similar to the approach indicated above for select exterior door applications. If such a fixture were provided in the space, the failure of one driver or light engine would not leave the space in total darkness.
Similar to the exterior fixtures discussed above, these fixtures are usually not available with integral battery backup or integral control sensors or receivers. The lines coming off each driver can usually be controlled separately or tied together outside the fixture and connected to a common control device such as a switch. It is typically a good practice to provide notes and/or a detail on the plans to clarify how these fixtures should be connected as well to ensure the final install matches the design intent.
In conclusion, designers and engineers should pay close attention to NEC Article 700.16 and include features in their project to ensure code compliance. While some AHJs may not be in the habit of putting emergency lighting under scrutiny, this should not be counted on. For the safety of occupants and a smooth occupancy process, it’s important to get this right the first time. cse
David Repair, PE, LC, Assoc. IALD, is an electrical engineer at LEO A DALY with expertise in lighting design with a focus on how lighting systems affect building occupants.
FIGURE 5: Emergency lighting includes illuminated exit signs and all other luminaires specified as necessary to provide required illumination.
Courtesy: LEO A DALY
csemag.com
Emergency lighting
u NFPA 70: National Electrical Code provides guidance on designing emergency lighting systems.
u Emergency lighting includes lighting fixtures and exit signs to guide occupants in the case of an emergency.
Karen Murphy, LC, IALD, LEED AP, HDR, Princeton, New Jersey
Lighting efficiency –More than LEDs alone
As we become more energy efficient, lighting design is a great place to start in the built environment
LED technology has increased efficacy of luminaires resulting in less energy being used to light buildings, however it is not enough to assume that simply using LED technology means that you are producing energy efficient and code compliant designs. Recent code updates have dramatically reduced the permitted connected lighting loads in response to improved equipment capabilities. Between 2016 and 2019, American Society of Heating, Refrigerating and Air-Conditioning Engineers 90.1, energy standard
for sites and buildings except low-rise residential buildings, reduced permitted lighting power densities between 14% and 25%, the largest decrease since fluorescent technology replaced incandescent. Lighting efficiency is about more than using LED technology and calculating lighting power density. To embrace our quest for net zero and to reduce our energy footprint, we need to provide lighting designs that are both thoughtful and intentional. Lighting design should always involve three steps:
• Understand task and ambient illumination needs, as well as meeting any codes and standards that apply
• Specify lighting controls that work with the luminaires and with the occupants.
• Specify lighting equipment that is suitable for the environment and can be easily maintained or recycled.
The first fundamental approach to providing lighting efficient designs is using a task-ambient design approach. Task-ambient design starts by identifying what tasks will be performed, and if those tasks are limited to select areas of a room or occur throughout the room. Often, high-performance tasks that require higher illumination levels are contained to an area that is smaller than the entire room. Instead of illuminating the entire room to the higher illumination level needed for one task, energy can be saved if the higher illumination need is applied only to task performance areas.
FIGURE 1: This shows an example of laboratory lighting that is aligned with the edge of bench eliminating the need for undershelf task lights and luminaires located in the circulation corridor. Courtesy: HDR
Courtesy: HDR
Task-ambient designs can also be achieved using non-uniform fixture selections and placements, or through smaller dimmable control zones. Gone are the days of continuous arrays of recessed troffers applied throughout all spaces. Perhaps, the most easily identified example of task-ambient design is seen in laboratories. Laboratory workbenches and shelving require higher and more uniform illumination than corridors and aisleways; often having fixed locations with sinks, gas accessibility and utility connections. Laboratory workbenches typically have luminaires located over the edge to mitigate shadows. This lighting layout that produces 80-100 footcandles at 36 inches above finished floor on the benchtop, will typically produce 10-30fc in the aisleways without the need for any additional fixtures in the aisles.
Even though these are generally sold as flexible work environments, task-ambient designs should also be used in open office spaces, with desktops spread uniformly through a space. The lighting is often much more uniform, yet like laboratories, these office spaces will sometimes have defined circulation zones, in which the same design approach may be taken. There is also a second layer to the task-ambient approach that is generally applied to open office lighting. This approach provides supplemental task lighting to give the occupant the ability to increase illumination for task specific needs, that are not the dominant task conducted. The majority of office tasks today are computer based, which has lowered the recommended illumination level from 50fc at 30 inches aff to 30fc at 30 inches aff. This does not mean that paper-based tasks no longer occur; however, the illumination needs for paper-based tasks are more limited, sporadic and best addressed through task lights that can be individually controlled as needed.
This also means that these fixtures should not be occupancy sensor controlled, turning on simply because someone is sitting in their chair. The best
‘ Gone are the days of continuous arrays of recessed troffers applied throughout all spaces.’
way to control these task lights are via dimmable vacancy sensors. The person who needs additional illumination must manually turn the light on and is able to adjust to their specific need. However, if they forget to turn off and leave their desk area, the light will automatically turn off. It is important to note that several European standards still require offices to be illuminated with 500 lux; if you are designing to these standards, there is no need for supplemental task lighting.
Understanding the recommended illumination needs for each space is fundamental to providing not only functional, yet energy efficient lighting layouts. Investigate if there are any corporate standards or industry standards related to lighting that must be followed. The Illuminating Engineering Society offers many recommended practices for specialty building types and provides guidance for common applications and exteriors. In these American National Standards Institute approved documents produced by the IES, the illumination tables provide recommendations for both rooms and tasks. When reviewing, be sure to take your time and read the tables — including footnotes. Understand how
Objectives
• Know the three steps lighting design should always involve.
• Learn the importance for each role on a project team to understand lighting controls for a design.
• Understand the difference between task-ambient lighting design approach and a lighting controls design approach and which scenarios each would be applied.
FIGURE 2: This shows an example of open office lighting that locates the luminaires over the work zone only, leaving the corridor free of unnecessary additional fixtures.
BUILDING SOLUTIONS UILDING
‘ Lighting controls offer the largest opportunity for energy saving today.’
building occupants plan to utilize the rooms. Is the equipment fixed or is it flexible? Lighting designs tailored to space utilization and visual performance needs will not only conserve energy, this approach will also enhance occupant comfort. Quality lighting must balance brightness and uniformity within visual task areas to avoid an environment that causes eye strain and fatigue.
Taking time to understand space utilization within the built environment is instrumental for the second energy conservation design approach –lighting controls. Lighting controls offer the largest opportunity for energy saving today. Lighting controls are also the most difficult and overlooked aspect of lighting construction documentation. Due to the plethora of driver types, control protocols, proprietary addressable systems and lack of standardized componentry with LED technology and the associated control devices and systems, it is next to impossible to document a fully detailed control riser, device placement and competitive bid specification identifying all apparatuses.
If you rely on manufacturers or manufacturer reps to prepare your control specifications and wiring diagrams, you should realize that you are providing a proprietary bid package. The most effective method to offer a competitive bid package is to provide a performance specification. This requires clear communication of all critical components and how the system is to function. Remember to coordinate and communicate any interconnections with other building systems, such as the mechanical building automation system and audio-visual systems. This involves differentiating between primary triggers and overrides, which cannot be achieved simply by showing control devices on a plan. The most effective way to communicate performance is through schedules and verbiage – a written sequence of operation for each control zone.
For instance, “occupancy sensor turns lights on and off; daylight harvesting photocell overrides intensity maintaining 30fc on desktops.” The way each and every luminaire is controlled is integral to a lighting design, and every professional lighting designer should develop a documentation system that clearly communicates how each luminaire is controlled. Lighting controls must be understood by multiple project team members, not just the electrical contractor who needs to install them.
Clients
Lighting controls should be presented alongside lighting designs for client buy-in. This is often the best time to seek client feedback for how they intend to utilize the space. If the end user does not understand how the system is designed to work and what adjustability it has; the system will not be fully utilized at its optimum.
Electrical engineers
The electrical engineer will need to understand the lighting controls to assure the circuiting is aligned with the control zones and how the emergency lights are controlled. If the lighting designer specifies control zones, these are groupings of luminaires that all act together. One zone may be comprised of one or more relay. One circuit may feed multiple relays, yet one relay cannot be fed from multiple circuits. When emergency lights are controlled, there are typically two methods that can be used and must always be UL924 compliant. One method control uses a UL924 compliant transfer device that switches the luminaire from a normal circuit to an emergency circuit. Another type of UL924 compliant switching device senses the unswitched normal circuit, and when this transmits down the control signals are bypassed leaving the emergency circuit on.
Control manufacturer/reps
The vendor must understand the desired performance of the lighting control system, the approved luminaire driver types, and the reflected ceiling plans in order to provide accurate pricing and shop drawings. Field programmable systems often include a field technician who travels to the job site to program and start-up the system. This technician is often not the person who curates the shop drawing submittals; however, the technician will be relying on the shop drawings during field startup. Therefore, it is important that the sequence of operation provided in bid documents is reiterated and thoroughly examined during the shop drawing submittal and review process.
Commissioning agents
The commissioning agent will need to understand how the system is meant to perform under all conditions. This understanding allows them to
establish proper testing methods to assure the system is functioning as designed prior to owner occupancy and training.
Understanding and respecting the important role that each member plays in the process helps guide the production of clear and concise constructions documentation.
Understanding luminaire construction is also important when balancing luminaire efficacy and performance. For instance, a luminaire without a lens will produce more delivered lumens per watt than a luminaire without a lens. That does not mean that luminaires without lenses should be used. LED modules are very bright point sources that are not comfortable for direct viewing. If you need to close your eyes to be comfortable, it does not matter how much more efficient the luminaire is – it is not working effectively. An indirect fixture used where no occupant will have a direct view may not need a lens to prevent glare yet may require a lens in order to create a batwing distribution for more even illumination with fewer fixtures. This also does not mean that only fixtures with lenses should be used. There are other ways to conceal direct views and improve photometric distribution through housing, reflectors and even the LED array design.
As we look to increase lighting efficiency and decrease our carbon footprint, it is also important
to keep life cycle efficiency in mind. Can the driver and LED arrays be field replaced, or is a whole new fixture needed when it reaches end of life? LEDs do not last forever. They will produce less light over time and need to be replaced. The published life for LED performance luminaires is when these are expected to dim to 70% of their initial delivered lumens, while the published life for LED decorative luminaires is when these are expected to dim to 50% of their initial delivered lumens.
Lighting maintenance impacts our carbon footprint, making this important to specify luminaires that are suitable for the environments the products are placed within. Temperature extremes, water, vibration and impacts can all shorten the expected life of luminaires that are not designed for these conditions. It will not matter if the luminaire has field serviceable LEDs and drivers if the luminaire, itself, does not last long enough to be serviced. Reducing facility maintenance makes for happy clients and a happy planet. cse
Karen Murphy, LC, IALD, LEED AP, is the Director of Lighting Design at HDR. With more than 30 years of experience as a lighting designer, Murphy provides lighting solutions that support visual performance, enhance design concepts, promote energy efficiency and respects operation and maintenance concerns.
FIGURE 3: This shows an example of a portion of a control schedule identifying the sequence of operations for a lighting control system that appears on construction documentation. Courtesy: HDR
csemag.com
Lighting Efficiency
u Energy efficiency can be achieved in lighting design by paying attention to a few key factors.
u Lighting controls can reduce energy use by ensuring lights are turned on and off at specific times, or by reducing ambient light when daylighting can illuminate a space.
Exploring basic components of a low-voltage electrical system
Electrical projects often require low-voltage systems. Learn about the various equipment here
Voltage class can be defined in several different ways. For electrical design engineers, low-voltage is below 1,000 volts and representative of what is typically seen in commercial and residential applications. For telecommunications engineers, however, low-voltage is usually defined as 48 V and lower.
The most common application for commercial projects is bringing 480 V/277 V into the building and then stepping down to 208 V/120 V. When
moving forward in specifying and sizing components, design teams must carefully consider basic components of the low-voltage system, main codes, standards and common practices.
Switchboard and low-voltage switchgear
These two terms are often used interchangeably, but in actuality, they are technically different. Both are required to be service entrance rated when placed after the medium-voltage utility transformer. The biggest differences are: testing standards, ampere ratings, short-circuit testing, cost, reliability and physical size.
There are also many other differences such as breaker types used in each. Switchgear is used more often than switchboards in critical facilities such as hospitals and data centers, where increased power continuity is a priority.
Design teams should have a discussion with the clients to identify the priorities for system selection. It is crucial to establish whether the project is primarily driven by budget, schedule, reliability, sustainability, ease of maintenance and/or any other factors the electrical engineer needs to account for during design. Another factor to consider is space availability, especially because electrical equipment such as panelboards, switchboards/switchgears, etc., requires working clearances (refer to NFPA 70: National Electrical Code section 110.26 for all working clearances requirement).
• The width of working spaces in front of the equipment should be the width of the equipment or 30 inches, whichever is greater.
• The workspace shall be clear and extend from the floor/grade/platform to a height of 6.5 feet or the height of the equipment, whichever is greater.
FIGURE 1: Electrical engineers review the system at Quarry Run Regional Operations Center, located in the Southwestern United States. Courtesy: Dror Baldinger, FAIA, Page Southerland Page
Objectives Learningu
• Identify major electrical gear for a lowvoltage project.
• Explore best practices for specifying and sizing major electrical gear.
• Determine code requirements for a project’s design and partner with the building owner to ensure the project’s outcome.
• Follow NFPA 70 Table 110.26(A)(1) for the depth of working spaces.
• Most of the owner’s project requirements indicate spare wall space for future expansion when it comes to sizing new electrical rooms.
Feeders and branch circuits
Just like switchboard and switchgear, feeder and branch circuits are sometimes used interchangeably. Per NFPA 70, feeders include all circuit conductors between the service equipment, the source of separately derived systems or another power supply source and the final branch circuit overcurrent device. Branch circuit, on the other hand, is the circuit conductor between the final overcurrent device protecting the circuit and the outlet(s) or load. They follow different code sections.
Branch circuits:
• General requirements: NFPA 70 Article 210.
• Sizing: NFPA 70 Article 210.19(A)(1) and Article 310.
Exception: If the overcurrent protective device is listed for operation at 100% of its rating, the allowable ampacity of the branch-circuit conductor is allowed to be a sum of continuous and noncontinuous loads.
Feeders:
• General requirements: NFPA 70 Article 215.
• Sizing: NFPA 70 Article 215.2(A)(1) and Article 310.
• Size of the feeder's circuit grounded conductor: NFPA 70 Article 250.122.
For sizing conductors in low-voltage system, designers often use table 310.16 (NEC 2020). Weight, electrical capacity and cost are major considerations when selecting aluminum or copper for an electrical application. Copper offers a better electrical capacity per volume. However, aluminum has better capacity per weight. Aluminum conductors frequently are used from the secondary of the utility transformer to a building’s switchboard/ switchgear and feeders between panels. Contractor needs to be careful with wire termination with aluminum conductors to avoid damage during installation. However, some critical applications, such as for hospitals, government projects and data centers, may not allow aluminum on the project.
Selecting transformers
Typically, transformers in low-voltage systems refer to dry-type 480 V/208 V (delta-wye), threephase, stepdown transformers. Electrical engineers should refer to NFPA 70 Article 450 for transformers, its feeders and overcurrent protective device sizing. Some important considerations for transformer design include:
u Low-voltage electrical systems can be used in commercial and residential locations and is classified as either less than 48 volts or less than 1,000 volts, depending on the application.
u The codes and many other considerations will determine electrical equipment, such as switchgear and switchboards, transfer switches and generators.
FIGURE 2: Mechanical rooms typically include several low-voltage systems. This shows the Quarry Run Regional Operations Center, located in the Southwestern United States. Courtesy: Dror Baldinger, FAIA, Page Southerland Page
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Table 1: Understanding voltage
Voltage class
Low-voltage
Ultrahigh voltage
TABLE 1: ANSI C84.1: Electric Power Systems and Equipment – Voltage Ratings and IEEE 141: Recommended Practice for Electric Power Distribution for Industrial Plants divide system voltage into voltage classes. Courtesy: Page Southerland Page Inc.
Voltage range (AC)
kV to 1,000 kV
1,000 kV
Transformers are sized based on the calculated demand load. Typically, designers try to leave 25% spare capacity for future expansion.
The most efficient transformers tend to have lower temperature rise and the higher the insulation temperature rating, the longer the expected lifespan. Additionally, transformers can be built with copper or aluminum windings. Aluminum transformers are cheaper but are physically larger and should be selected based on project priorities and available space.
How to select panelboards
There are many considerations when specifying panelboards, including:
• Location.
• Interrupting rating.
• Accessories.
• Rating.
• Mounting.
• Enclosure.
• Height, branch circuit quantities.
• Working clearances.
• Arc flash/personal protective equipment.
Electrical engineers should consider where to place the panel to assure the voltage drop for the branch circuits meets NFPA 70 requirements. If space programming allows, a small electrical closet is typically placed in every 10,000 square feet of the floor plan.
Panels should also be rated appropriately to withstand available fault — this is required per NFPA 70 Article 110.9. The system can be either fully rated or series rated. In a series-rated system, each device needs to only be rated for the available fault current at its terminals. The advantage here is that the equipment costs are lower, while
the disadvantage is that the available fault current must be calculated at each device's location in the system. For context, data centers, government and health care projects in most cases will only allow fully rated systems.
Personnel safety is the most important aspect to keep in mind when specifying electrical systems. Occupational Health and Safety Administration and NFPA 70E: Standard for Electrical Safety in the Workplace require arc flash warning hazard label indicating:
• Nominal system voltage.
• Available fault current at the service overcurrent protective devices.
• Clearing time of service overcurrent protective devices based on the available fault current at the service equipment.
• Date the label was applied (see NEC 110.16(B)).
Standby generators for low-voltage power
Standby generators can be installed on a project to provide electrical power if the primary power gets interrupted. A prime rated generator is used as a primary power source. For typical applications, designers use a standby rated generator to comply with requirements of NFPA 70 Articles 700, 701, 702 and 708. The generators are classified by class, type and level.
Class is the minimum time in hours for which the emergency power supply system is designed to operate at its rated load without refueling/recharging. Most common is two hours for all life safety equipment and Class 8 (eight hours) when utility power is not considered to be a reliable source and the fire pump is connected to generator. For data centers and health care facilities, the run time can vary between 48 and 96 hours.
Type is maximum transfer time in seconds; most common is Type 10 for Life safety and Type 60 for legally required. NFPA 110: Standard for Emergency and Standby Power Systems recognizes two levels for equipment installation, performance and maintenance requirements:
‘ Personnel safety is the most important aspect to keep in mind when specifying electrical systems. ’
• Level 1 applications: Life safety illumination, public safety communication systems, fire pumps, ventilation equipment (NEC Article 700) where the loss of power results in loss of human life.
• Level 2 applications: Heating and refrigeration systems, sewage disposal, some industrial processes (NEC Article 701) less critical to human life and safety.
The most commonly used codes and standards include NFPA 110; NFPA 70 (Article 445, 700, 701, 702, 708); NFPA 1: Fire Code; NFPA 30: Flammable and Combustible Liquids Code; and NFPA 99: Health Care Facilities Code.
There are many aspects to consider when specifying a generator and a best practice is to contact the generator representative to confirm the clearances meet or exceed NFPA 37: Standard for the Installation and Use of Stationary Combustion Engines and Gas Turbines Subsection 4.1.4 (as they vary by manufacturer and size), fuel storage options and noise requirements.
When sizing generators, designers often use manufacturer genset sizing software to assign load and steps and provide the most cost-efficient design. Additional items to keep in mind are load banks and generator tap box as required per code.
Considering the automatic transfer switch
There are several considerations and options for choosing an automatic transfer switch, or ATS, such as:
• Open or close transitions.
• Bypass switch.
• 3-pole versus 4-pole.
Table 2: Differences between switchboard and switchgear
Cost/reliability
Size/space
Lower cost/higher chances of power trip outage
Switchboards require less room as they work primarily through front access.
• Service entrance rated.
• 3-cycle versus 30-cycle.
Higher cost/increased power continuity
Switchgear require both rear and front access for cable terminations, and more space. Requires physical vertical barriers between sections.
• Ampere interrupting capacity (AIC) rating versus withstand closing current rating (WCR).
• Each branch (emergency, legally required, optional standby, equipment, critical and life safety) typically has its own ATS.
Per UL 1008, transfer switches have WCR, which is either based on a specific device or ability to withstand and close into a fault current until a protective devices opens.
Most branch breakers in low-voltage systems are UL 489 listed. For this, a 3-cycle ATS is sufficient. Similar to switchgear, 30-cycle ATS makes it easier to coordinate the system to assure power reliability, but it is more expensive. A four-pole ATS is required when ground fault sensing is required per NFPA 70 or per the owner’s project requirements.
To ensure a project’s success within any building type, designers are recommended reviewing and thoughtfully considering appropriate code sections, while also coordinating and collaborating with other disciplines. Importantly, when specifying low-voltage systems, it is key to coordinate with the client to determine whether the project is driven by budget, schedule, reliability, sustainability, ease of maintenance or space availability and go from there to best meet or exceed the client’s needs and requirements. cse
Yevgeniya Baikadanova, PE, is principal and founder of IPQ LLC. She is a former associate principal at Page.
TABLE 2: There are several differences between switchboards and switchgear. Switchgear is used more often than switchboards in mission critical facilities. Courtesy: Page Southerland Page Inc.
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William McGugan, PE, CDM Smith, Raleigh, North Carolina
Arc energy reduction requirements for low-voltage equipment
The 2014 edition of the National Electrical Code created requirements for arc energy reduction for overcurrent protective devices 1,200 A or greater
Since its inclusion in the 2014 edition of the NFPA 70: National Electrical Code, known as NEC, multiple articles have been written in various publications discussing Article 240.87 Arc Energy Reduction. Most articles have focused on providing general information about the methods that may be used to reduce arc energy in electrical systems. This article will build on those by discussing updates included in the 2020 and 2023 versions of the NEC pertaining to Article 240.87, to provide a deeper technical understanding of the article and to present case studies on how major power systems analysis software may be used to verify that the goals of Article 240.87 are satisfied.
Objectives
• Understand the basic requirements of NEC 240.87.
• Know the importance of arc energy reduction methods and arcing current.
• Learn how different arc energy reduction methods are calculated.
While the 2014, 2020 and, to a lesser extent, the 2017 versions of the NEC are discussed in this article, any references to the NEC that do not indicate a specific year or edition refer to the 2023 version only. Essential to understanding how to meet the requirements of 240.87 is IEEE 1584: Guide for Performing Arc-Flash Hazard Calculations. Unless otherwise noted, any references to IEEE 1584 in this article refer to the latest version, 2018, and its subsequent addenda. NFPA 70E: Standard for Electrical Safety in the Workplace provides requirements for safe work practices, including those required by NEC 240.87. Additionally, 240.67 arc energy reduction for fuses will only be tangentially mentioned in this article.
Important edits and additions to the NEC’s arc energy reduction requirements include the following:
NEC 2017
• Added 240.67, which requires arc energy reduction when fuses are 1,200 A or greater (240.87 is part of a section specific to circuit breakers).
• Added instantaneous pickup and instantaneous override as options for arc energy reduction.
• Added clarification that temporary instantaneous pickup adjustments are not satisfactory.
• NEC 2023 included no major changes to 240.87.
240.87 states, “Where the highest continuous current trip setting for which the actual overcurrent device installed in a circuit breaker is rated or can be adjusted is 1,200 amperes or higher,” the three sub paragraphs shall apply. These three subparagraphs are (A) documentation, (B) method to
reduce clearing time and (C) performance testing.
240.87(A) Documentation has, since its inception, been straightforward in requiring that information about the system be recorded and available to personnel authorized to work on the equipment. The 2020 version of the NEC added a sentence further detailing these requirements, requiring proof that whatever method is used for arc energy reduction works and is in use.
240.87(A) and 240.87(B) note that the arc energy reduction method “be set to operate at less than the available arcing current,” i.e., that the arc energy reduction system will actually operate based upon the specific system’s characteristics. The writer of this piece assumes these requirements were added to prevent the situation where an unscrupulous system operator would circumvent the intent of 240.87 (protecting personnel) by merely installing an arc energy reduction system but not actually having it operational.
FIGURE 2: Arc flash maintenance system scenarios — selective coordination yields high arc flash hazards, sacrificing selective coordination reduces arc flash hazards. Courtesy: CDM Smith
It is important to note that the available arcing current is different from the more commonly encountered available short-circuit current. The available short-circuit current, often called the bolted-fault current, can be found at a given bus by reducing the electrical system to its Thevenin equivalent with zero fault impedance. The available arcing current is similar, with the addition of the impedance of a prospective arc included. At face value, this seems a simple calculation, but in practice, IEEE 1584 uses a selection of five different equations based on parameters such as the elec-
trode configuration, nominal system voltage and electrode gap to determine. Arc flash analysis software can be used to accurately determine the arcing fault current.
It is also vital for personnel to understand that arc energy reduction at one overcurrent-protective device or bus is dependent not on that overcurrent protective device, but on the next overcurrent-protective device(s) upstream or on the line-side of that device. For feeder circuit breakers installed on a switchgear, this could be the main circuit break-
er; for that same main circuit breaker, protection would need to be provided by the feeder circuit breaker or relay feeding the main. Exceptions to this may include certain types of energy-reducing active arc flash mitigation systems that reduce the fault energy without the assistance of overcurrent protective devices tripping.
240.87(B) provides a list of acceptable means to reduce arc energies, including: zone-selective interlocking, differential relaying, energy-reducing
maintenance switching with local status indicator, energy-reducing active arc flash mitigation system, a permanent instantaneous trip setting, an instantaneous override or an approved equivalent means. Each of these methods, including their advantages and disadvantages, is discussed in the following paragraphs. Note that, as stated earlier, all the methods must be set to operate below the available arcing current.
Zone-selective interlocking
ZSI is, at its most simple, a communication system. Overcurrent protective devices are connected such that they communicate with each other when they pick up or “see” a high-level fault condition, allowing instantaneous tripping in certain situations. If both a feeder overcurrent protective device and an upstream main overcurrent protective device pickup on a fault current, the system will operate as usual (i.e., if properly coordinated, the feeder breaker will first attempt to trip the fault). If that same main overcurrent protective device picks up a fault current but none of its associated feeder overcurrent protective device do, the main overcurrent protective device will trip with no intentional delay, regardless of its short-time or instantaneous pickup settings/delays. ZSI systems are generally most common in switchgear systems and can be moderately expensive, especially when interlocking feeder circuit breakers from one switchgear with overcurrent protective devices of a separate switchgear. ZSI is often installed in new switchgear installations. Figure 1 presents a basic visual of a ZSI system for (a) a fault within the ZSI-protected zone and (b) a fault outside the ZSI-protected zone.
Advantages: Fast-acting, allows intelligent zone isolation and selective coordination.
Disadvantages: Moderately expensive, requires interlocking wiring and more advanced circuit breakers, may not be an option between different busses and may not work across multiple manufacturers.
Differential relaying
Differential Relay (ANSI device No. 87) has been used for decades to efficiently detect and isolate faults within a zone of protection, whether that be a bus, cable, transformer or other equipment. As the name implies, if the difference in value between
FIGURE 3: Instantaneous method — sacrificed coordination — curves overlap creating race condition for faults above ~12 kA. Courtesy: CDM Smith
the currents entering and exiting a node is not zero or within a prescribed setting, the relay will trip all such devices. Differential relaying, due to its cost, is usually restricted to large or critical switchgear, transformer, motor or generator systems.
Advantages: Extremely fast-acting, does not impact selective coordination. Modern relay systems provide some security against nuisance tripping.
Disadvantages: Expensive — each circuit requires current transformers and associated wiring; current transformers must be properly matched and/or of sufficient quality and size to prevent through-fault nuisance tripping.
Energy-reducing maintenance switching with local status indicator
Maintenance switching with local status indication generally involves a physical switch and light installed on a piece of equipment. If personnel are going to work on said equipment energized, they would toggle the switch, which would send a signal to the next upstream overcurrent protective device to lower its instantaneous settings to minimum. This allows for a system to maintain coordination under normal operating conditions while also limiting arc hazards to personnel during maintenance or other activities.
It is important to reiterate that to be effective, the maintenance switch must lower the instantaneous setting of the upstream overcurrent protective device, not of the device in the cubicle or equipment associated with the work. Maintenance switching is often found in new switchgear installations, though can be retrofitted into existing systems. Figure 2 presents a basic time-current curve for a circuit breaker system with maintenance switching (a) inactive and (b) active.
Advantages: Relatively cheap compared to the other arc reduction options, excepting instantaneous trip/override; may be installed in new or existing systems; provides both selective coordination and personnel protection.
Disadvantages: Relies on administrative controls to ensure personnel use the system properly for protection — if the system is not engaged when working on equipment, the personnel may not be protected. If the system is not disengaged after work is complete, the system may experience nui-
CASE STUDY: Arc energy protection schemes
DIFFERENT ARC ENERGY REDUCTION METHODS used on a standardized simple electrical system
While the above discussion provides a general overview of 240.87 and its methods, it is beneficial to understand how the different methods may be included in an arc flash study. This section presents multiple examples as case studies of various arc energy reduction methods on a standardized simple electrical system.
The case study electrical system consists of a utility at 480 V with an available three-phase available fault current of 30 kA and a switchgear having one main circuit breaker of 4,000 A and several feeder circuit breakers of smaller rating. For this case study, the bolted-fault current of 30 kA yields an arcing fault current of approximately 20.8 kA. All calculations were performed using SKM PowerTools software. For this case study, we will assume the feeder circuit breakers are appropriately sized and selectively coordinated with downstream equipment. Standard circuit breakers and relays from major manufacturers were simulated; for methods, such as the arc flash relay or UFES system, manufacturer-reported operating times were utilized.
All calculations are based upon a simplified system; as such, only broad generalizations should be taken from the results. Arc flash calculations specific to a given system should be performed where necessary per NEC, OSHA, NFPA 70E and other standards or requirements. In these case studies, the UFES performed best, producing an arc flash of almost negligible value. The arc flash relay and differential relaying methods produced similar results, with the arc flash relay performing slightly better thanks to the inclusion of light-sensing. The ZSI system for the circuit breaker used in these case studies had a slight delay compared to the minimum instantaneous delay, which resulted in it having a slightly higher incident energy than the maintenance switching option. All methods simulated, except for the base instantaneous pickup, produced incident energy results below the relatively common rating of regular/daily arc flash personal protective equipment (12 cal/cm2).
In this example, the “base” method is built upon selective coordination with the feeder circuit breakers only, as a time delay is introduced, this would not satisfy the requirements to use an instantaneous pickup setting to satisfy 240.87. The “instantaneous pickup” scenario satisfies 240.87 but sacrifices selective coordination, potentially creating a race condition for high-level faults downstream of the feeder circuit breakers. Figure 3 shows an example of the coordination of the instantaneous pickup scenario with sacrificed coordination; Figure 4 shows an example of the “coordination” of the overcurrent protective devices when the maintenance switch is engaged.
sance tripping. In theory, the local status indicator should limit such occurrences, but anecdotally, the latter can be common.
Arc energy-reducing active arc flash mitigation system
Multiple types of energy-reducing active arc flash mitigation systems exist. One of the most
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common is an arc flash relay system, which normally uses both light sensors and overcurrent pickup to detect an arc flash event and isolate the equipment. Such systems have been around for over a decade and can generally be installed in both new and existing equipment.
Another type of active arc flash mitigation system is the ultrafast earthing switch, which introduces a controlled three-phase line-to-ground fault when sensing arc fault conditions; this fault (of
essentially zero impedance) effectively redirects the fault current to an area where it can be contained in a safe manner. UFES systems have advanced greatly in recent years, going from large contraptions that are little more than electrodes fired from shotgun shells into the ground to units that can be installed as parts integral to a switchgear setup.
Arc-quenching is a third type of active arc flash mitigation system that is similar to the arc flash relay system in structure — light sensors and current transformers — and the UFES system in response time. Whereas UFES systems introduce a controlled three-phase bolted fault, arc-quenching systems introduce current-limiting devices to control and redirect the fault current.
Advantages: Regardless the technology, active arc flash mitigation systems provide extremely quick response times to detect and/or isolate an arc. Additionally, while passive arc energy reduction systems — specifically arc-rated equipment — only contain an arc when the exterior doors are closed, active arc energy reduction systems operate irrespective of whether the equipment is open or closed.
Disadvantages: Cost, especially for a UFES system can be high. While an arc flash relay system is little more than point sensors and/or fiber optic cable coupled with standard overcurrent relays (where possible, using CTs and relays already installed) a UFES system is sacrificial in nature. New systems have been developed that contain the introduced fault into a chamber that can be replaced, the replacement equipment can still be expensive.
A permanent instantaneous trip setting or instantaneous override for arc energy
“Permanent” was added by this author to highlight a key aspect of this requirement that “temporary adjustment of the instantaneous trip setting to achieve arc energy reduction shall not be permitted.” While essentially the same in electrical characteristics as the energy-reducing maintenance switching method, temporary adjustment of the instantaneous setting does not provide the same controls that would ensure the personnel adjusted the correct overcurrent protective device or that other personnel may have unknowingly “corrected” the temporarily adjusted setting.
FIGURE 4: Maintenance switching method — if not disabled after work, miscoordination for faults above ~7 kA. Courtesy: CDM Smith
Advantages: As most overcurrent protective devices rated for 1,200 A or greater have an adjustable instantaneous setting, this method (along with the instantaneous override method) likely provides the cheapest and most common means of reducing arc energy.
Disadvantages: As overcurrent protective devices have the twofold and often opposed goals of increasing system coordination and reducing system arc energies, it may not be possible for an instantaneous trip setting to be set low enough to interrupt the arcing fault current.
An instantaneous override is essentially the maximum instantaneous pickup of a circuit breaker and is not an adjustable setting. Refer to the instantaneous trip setting paragraph above for application details.
An approved equivalent means — as the industry’s understanding of arc flash continues to grow and mature, new and novel means of arc energy reduction will likely continue to be developed.
240.87(C) Performance testing requires the arc energy reduction system be tested when first
installed to prove its efficacy. Primary current injection (i.e., testing the whole overcurrent detection system, not only the circuit breaker or relay inputs) or another approved method is required. For most arc energy reduction systems, the testing is different from usual overcurrent testing: introduce a current in the primary system and observe how long it takes the system to send a trip signal. Some systems, such as those that use light-sensing, would need additional testing.
Ultimately, the choice of which arc energy reduction system to use is dependent on a number of factors unique to every system, including the type of equipment, the personnel that will operate and maintain it, cost constraints, etc. In many cases, instantaneous settings may provide adequate reduction of arc flash energy while still maintaining coordination. Where that is not possible, the other arc energy reduction options become necessary. cse
William McGugan, PE, is an electrical engineer with CDM Smith with a focus on the design and analysis of electrical power systems.
Arc energy
u Low-voltage electrical systems and technology require electrical engineers to consider arc energy reduction.
u Zone-selective interlocking systems detect high-level fault conditions, allowing instantaneous tripping in certain situations.
u NFPA 70: National Electrical Code Article 240.87 is vital to electrical engineers working on these systems, as it discusses arc energy reduction.
In critical power facilities a power loss is COSTLY. When your facility has Sequence of Event Recorders from Cyber Sciences installed, you can quickly identify the root cause of the incident and any sequential cascading events. This provides a clear picture of what happened, and what is needed to restore power faster. With our solutions in place, you can relax knowing we are keeping watch over your critical applications.
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Aaron Szalaj, PE, Stanley Consultants, Denver
How to transition legacy campus building controls into a smart system
How Baylor University modernized its legacy systems to provide more efficiency
Chartered in 1845, Baylor University is the oldest continuously operated university in Texas. Twenty years later the Baptist private institution merged with Waco University and made Waco its home. Today Baylor is every bit the nationally ranked scholastic educator and research institution, matriculating more than 17,000 students annually. Naturally, it was decided that its legacy campus building controls needed to be updated into a smart system.
the capabilities of today’s systems. At Baylor, the software running the systems and equipment was proprietary, which limited replacement parts and upgrades to one vendor.
The lack of an open protocol control system was exposed when the utility manager Aramark worked with Baylor, its client and Stanley Consultants, its owners engineer, to install a pilot program to test whether new, nonproprietary equipment could be installed in the science lab, as the owner and its operator sought access to a wider range of equipment choices.
Objectives
• Learn how a consulting engineer provides value to a building automation system upgrade.
• Understand the technical steps needed to update building automation equipment when performing this type of upgrade.
• Explore how to manage a large number of stakeholders that are typically involved in a project such as this.
Baylor has changed with the times and so has its stately South Texas campus that has grown to 1,000 acres. The same is true for the campus utility systems. As with many U.S. campuses, Baylor grew in a more ad hoc manner, rather than adhering to a master plan and campus utilities followed that pattern. Common features included old steam tunnels and piping, manual light switches, no energy meters and wiring from the early 1900s, such as the nob and tube type. Every building was operated separately by manual control.
Pilot installation underlines need for a campuswide smart system
Automatic building controls didn’t arrive in the industry until the 1970s and ’80s. The state-of-theart up to this time limited controls to individual buildings. Comprehensive network controls weren’t available.
Over the decades, Baylor pieced together the vendor’s campuswide system, but it did not have
The pilot program involved installing a new lab hood controller from an outside vendor. The project experienced a problem when the lab hood’s controller would not communicate with the incumbent building control system via BACnet. This realization instigated a vendor evaluation for the sitewide building automation system upgrade.
The pilot exposed a critical vulnerability and major question regarding the campus utility operation going forward: The equipment and system controllers couldn’t embrace all vendor options. Moreso, the software that ran the legacy building controller was going to be unsupported or retired within the next year. Should the entire campus system be scrapped and replaced with a BACnet capable system?
University officials and Aramark, which operates campus utilities under a maintenance contract, came to the realization that its building systems have come to the end of their useful lives. It was time to install a smart system that allowed a central center to control all campus building systems. Baylor found itself in a situation mirrored by most established universities: It was time for a change
and control system update. It was time to bring a smart building concept to the old, stately campus.
The irony of the dilemma posed by the pilot installation was that the new equipment and building controllers did actually communicate. After a two-day investigation by field technicians, it was discovered that an incorrect access code had been punched into the equipment controller that prevented the two software programs from talking.
Consulting engineers should consider a pilot program
As the Baylor example shows, before making a high-stakes decision for or against a campuswide controls upgrade, it’s a good idea to set up a pilot program to test new equipment. This approach exemplifies the role of the consulting engineer, who serves as an independent, trusted adviser in a situation that involves many biased stakeholders with differing opinions regarding technology.
Baylor set up a pilot controller made by a different vendor than the original equipment using industry standard communication protocol or BACnet, which is becoming the industry standard for building automated controls. A wall panel was installed that managed a ventilation hood in a laboratory. Three different manufacturers were interviewed, including the incumbent vendor, to ask if their varied instrumentation could communicate with the controller and prove the open protocol.
The pilot program showed that the two new vendors would have to replace approximately 10% more building equipment throughout campus than the incumbent’s overlay system would require,
therefore adding project cost. There was also the possibility of less functionality with new vendor equipment. The incumbent vendor had the ability to retrieve information from and communicate with the old system equipment and in addition, was also BACnet certified.
Although the client’s preference was to install a system that could accommodate a variety of equipment vendors, Baylor and Aramark chose the incumbent vendor to update its systems and as-required equipment.
Despite the final choice of vendors, the pilot program proved that a nonvendor specific device communicating BACnet can connect and communicate natively with the updated system.
Ultimately, less than 10% of the BAS equipment had to be replaced. Approximately 25 panels were replaced to enhance data communications and network capabilities. Another 70 panels had to have firmware upgrades performed to allow them to integrate with the new system. New buildings that were in construction were already incorporating the new technology.
Design and installation challenges of a smart system
Accurate documents: With any large, long serving and complex asset, such as a power or water treatment plant and in this case a sprawling campus, changes and adjustments are made. New build-
‘ Automatic building controls didn’t arrive in the industry until the 1970s and ’80s.’
FIGURE 1: Pictured is the Baylor University Sciences building, which was a part of the legacy campus building controls that needed to be updated into a smart system.
Courtesy: Baylor University
BUILDING SOLUTIONS UILDING
ings and utilities are added. In the case of control systems, how does the consulting engineer know what’s there, the exact location and whether the asset is working?
Incomplete documentation of current systems is the norm. The first task of the consulting engineer is to recreate, update and verify a complete set of documents that include additions of wiring, conduits, relays, switches, various BAS and network equipment.
‘ The consulting engineer’s role is to smooth the ruffles caused by turnovers.’
People and resources: When installing an overlay system of controls, it’s necessary to have a team of building maintenance staff and managers available to work with the new equipment installers and programmers. This can become tricky because in a university’s case, the best time to install new technology is during the winter holiday, given heavy use of the buildings such as the Baylor Sciences Building. However, that’s also the traditional holiday for maintenance staff, so it took coordinating many moving pieces to schedule the installations.
Related resources had to be upgraded at Baylor. Its servers, required to handle a larger data flow, had to be upgraded, as well as the obsolete server operating system. Add to this the risk of bricking or when an older piece of equipment doesn’t respond
to a firmware upgrade. At Baylor, equipment was purchased at extra cost to mitigate the bricking risk and none was experienced; however, the vendor had encountered it on other projects. Bricking is costly, because it requires a purchase of entirely new equipment and software.
The consulting engineer’s role is vital in solving the people and resources puzzle. The consulting engineer has the experience and expertise to anticipate potential issues and move quickly to resolve them before they become serious. The engineer assigns responsibilities and ownership of various project activities to individuals and follows up to make sure they are taken care of.
Supply chain issues: Since COVID-19 hit, the supply chain has been disrupted. For example, when upgrading network components, replacing building equipment or adding network drops to expand the network orders need to be placed more in advance. Delivery times that took weeks now take months.
Cybersecurity with a smart system: Baylor and its operator incorporated security into its controls from the start. They engaged all stakeholders, including the server, IT and security team in conversations about what changes were being made. As decisions were made to design and optimize the network, the stakeholders contributed and achieved their goals as well.
The decision was made that while upgrading new building controls, the campus system would migrate to a new utilities command and control
FIGURE 2: Pictured is the side of the Baylor University Sciences building. Courtesy: Baylor University
network. This network handles all data traffic for maintenance and operations of the campus and it runs separately from the faculty and staff network that operated on the old network. The campus operations, faculty and staff networks were managed separately for security purposes.
For example, vendors who previously had to send technicians on-site to upgrade controls to a smart system could tap into the campus operations systems with their laptops, tablets or phones. From the project’s start, vendor network specialists worked with the campus IT, server and security team to ensure they had secure connections and allowed vendors to negotiate through firewalls remotely. This is the right way to make cybersecurity part of the original controls design, rather than react to a negative event later with a bolted-on solution.
The role of the consulting engineer in the security and resources side of the project was to provide continuity from a systems perspective during staff turnover that occurred. The installation of a new smart system for a district is a long-term project and without knowing how to get purchase orders executed and getting things done by asking the right people for approvals can create chaos. The consulting engineer’s role is to smooth the ruffles caused by turnovers.
Benefits and capabilities of the new smart system
Baylor University’s two-year smart systems controls update brings an integrated control center that accesses all campus building and utility data. The data is the foundation of the consolidated building controls pyramid. The systems controlled include hydronics, fire control and fire alarm, lighting, emergency alarms and heating, ventilation and air conditioning.
Managers can access the smart system via a web interface on personal computers or mobile apps. Scientist users can access the lab controls to see if lab equipment is operating correctly. Vendors can upgrade software remotely instead of sending a technician to the site.
The future will bring energy cost reduction measures, such as temperature resets, occupancy sensors, sophisticated air exchange controls and Internet of Things capabilities. It will open the world to what the client wants to do and advertise
an energy-efficient, environmentally friendly, sustainable and safe campus.
The role and value of consulting engineers
The consulting engineer’s role in a control systems upgrade is valuable inasmuch that the consultant comes from a neutral point of view. The consulting engineer must be vendor agnostic. The consultant is not trying to make more money from selling more equipment or software bells and whistles. The consulting engineer advises the client on what they really need, versus what’s not necessary for effective controls. The consulting engineer’s role is more referee than invested player. The engineer wants to make the project work; and if not, why doesn’t it work?
In this case, one vendor was telling the consultant the outside vendor’s equipment wasn’t BACnet certified, while the vendor insisted that it was. Without the consulting engineer screening out the arguments and getting to the facts, the incorrect data entry at the device may not have been discovered. The consulting engineer must have the technical expertise to screen out the many persuasive arguments of vendors and do so dispassionately.
The ability to communicate complex technology in simple terms was important. The Stanley Consultants team could explain what the client couldn’t understand or mistrusted about the vendor. The result was to heal the relationship between vendor and facilities manager. cse
Aaron Szalaj, PE, is principal control systems engineer and control systems group manager in the Denver office of Stanley Consultants.
csemag.com
Smart systems
u Pilot installations can show an organization issues or answers before installing all new systems because they may not be necessary.
u Using accurate documents and collaborating with the correct staff and resources ensures the most efficient solutions.
u The consulting engineer must be vendor agnostic and have the technical expertise to screen out the arguments and get to the facts.
FIGURE 3: Pictured is Baylor University’s Pat Neff Hall, which was also part of the transition to a smart system.
Courtesy: Baylor University
BUILDING SOLUTIONS UILDING
Matthew Christopher Lausch, SET, NICET Level IV, Jensen Hughes, Baltimore
How to design fire alarm visual notification in office hoteling
Office hoteling is on the rise, creating the need to adjust fire alarm design approaches that better accommodate deaf and hard of hearing occupants
Office hoteling began in the 1990s, however, a significant increase has occurred since the global COVID-19 pandemic. The current trend toward remote and hybrid work is causing employers to rethink how office space is used with conventional assigned seating gradually being replaced by shared workspaces.
Many businesses and companies have started downsizing their office spaces. While solutions like hoteling may offer benefits for the company and its employees, moving toward a flexible seating model raises concerns about how to incorporate fire protection accommodations for deaf and hard of hearing persons.
Developing guidelines to address and improve the level of fire safety for deaf and hard of hearing employees in business occupancies where office hoteling is used is essential.
How office hoteling affects deaf, hard of hearing
While office hoteling provides a variety of benefits for both companies and employees, one of the major drawbacks is unassigned seating, which prevents personalization of the space. This can be especially problematic for people with certain types of disabilities.
For example, employees who use wheelchairs may require larger workspaces while those with visual or hearing disabilities may need specific technology to do their work.
Hoteling poses some unique challenges for deaf and hard of hearing employees specifically when it comes to fire safety. Standard fire alarm audible notification appliances may not be effective for alerting all deaf and hard of hearing people. Systems equipped with visual appliances may be more beneficial as they provide a more appropriate means for emergency notification for this demographic.
It is estimated that 15% of U.S. adults ages 18 and older have some trouble hearing while 3.6% consider themselves to be deaf or have serious difficulty hearing. These numbers are projected to increase to 73 million (22.6%) by 2060. With regard to the workplace, the National Deaf Center reported that only 53% of deaf people were employed in 2017 with many opting out of the workforce due to burn out from facing countless barriers, few accommodations and considerable bias.
In a traditional office setting, a deaf or hard of hearing employee may be able to choose a permanent workspace that allows them consistent access to visual fire alarm signals and other accommodations. However, because hoteling only allows for a limited number of workstations or private offices, spaces with necessary accommodations may be unavailable or already reserved. Consequently, the employee may have to accept a space that does not adequately accommodate their disability.
For example, a deaf person may not be able to see a visual notification appliance from their workstation or private offices may not be equipped with them at all.
Under Title I of the Americans with Disabilities Act, employers with 15 or more employees are required to provide reasonable accommodations for the known disability of a qualified employee provided it does not impose significant difficulty or expense when considering the employer’s size, financial resources and nature and structure of its operation. Fire alarms with visual notification appliances fall under the definition of reasonable accommodations as they are modifications that enable people with disabilities to have equal employment opportunities.
Fire codes related to visual fire alarms
NFPA 72: National Fire Alarm and Signaling Code, NFPA 101: Life Safety Code, the International Building Code and the ADA all provide standards for installation and placement of fire alarm visual notification appliances.
IBC 2021 section 907.5.2.3.1 requires fire alarms with visual appliances to be placed in all public and common use areas. Public use areas are spaces made available to the general public while common use areas are circulation paths, rooms, spaces or elements not for public use and are made available for the shared use of two or more people. These spaces include, but are not limited to, hallways, lobbies, restrooms, classrooms, cafeterias, conference rooms and break rooms. The 2010 ADA Standards for Accessible Design (Sections 215 and 702) adds to this by requiring fire alarm systems to have permanently installed audible and visual alarms complying with NFPA 72 in these spaces.
Both the IBC and ADA provide additional standards for visual notifications in employee work areas. An employee work area is defined by IBC and the 2010 ADA standards as all or any portion of a space used only by employees for work and does not include corridors, toilet rooms, kitchenettes and break rooms. ADA 215.3 specifically requires that, where employee work areas have audible alarms, the wiring system be designed so that compliant visual alarms can be integrated into the alarm system. IBC 2021 section 907.5.2.3.1 goes on to state that notification appliance circuits serving employee work areas shall be initially designed
Private offices with visual notification
FIGURE 2: Approach 1: private offices with visual notification appliances (based on a fixed number). Courtesy: Jensen Hughes
with not less than 20% spare capacity to account for the potential of adding visual notification appliances in the future.
States have the ability to apply more restrictive standards. For example, Section 215.3 of the 2018 Illinois Accessibility Code differs from ADA 215.3 in that all work areas with audible alarm coverage are required to provide compliant visual alarms, not just the capability for adding visual notification appliances in the future. Because IBC 2021
‘ Hoteling poses some unique challenges for deaf and hard of hearing employees specifically when it comes to fire safety. ’
section 907.5.2.1.1 requires audible alarms to be heard in every occupiable space within a business occupancy — inclusive of rooms or enclosed spaces designed for occupants engaged at labor — all occupiable work areas, including private offices, will need fire alarms with visual notification.
Visual notification for office hoteling
When employers and building owners are aware that deaf or hard of hearing employees occupy office hoteling space, they must make accommodations by providing fire alarm appliances with visual notification capabilities. The challenge is, how do you determine the correct quantity of visual notification appliances to effectively accommodate all current and future deaf and hard of hearing employees?
• Identify the impacts of office hoteling on deaf and hard of hearing employees.
• Understand codes related to visual fire alarm notification appliances.
• Learn two new fire alarm visual notification design approaches that better accommodate deaf and hard of hearing occupants when office hoteling is used.
BUILDING SOLUTIONS UILDING
Offices with visual notification, based on deaf occupants
One fire alarm design approach that can be employed to determine the number of visual notification appliances is based off Table 224.4 in the 2010 ADA Standards for Accessible Design (see Figure 1).
Table 224.4 establishes the minimum number of required guest rooms with communication features based on the total number of guest rooms in the hotel. For example, if a hotel has 51 guest rooms, the minimum number of guest rooms with communication features would be seven. In this model, the number of rooms with communication features equates to approximately 12% to 15% of the total number of guest rooms on the lower end of the range and 8% to 9% on the upper end. A similar table that identifies the same quantities can be found in IBC 2021 Table 907.5.2.3.2.
For the purposes of determining quantities of visual fire alarms in employee work areas in business occupancies, this table can be easily converted to establish standards for the minimum number of recommended private offices with fire alarm visual notification appliances. Although the same numbers would be used, “Guest Rooms” and “Communication Features” would be replaced with “Private Offices” and “Fire Alarm Visual Notification Appliances.” The new table would be as shown in Figure 2.
While the above approach is perfectly viable and could provide an effective means for integrating visual alarms, it does not take into consideration the actual percentages of deaf and hard of hearing people. A different approach would be to employ a similar table but calculate the percentage of private
offices with visual alarms using statistical data for deaf and hearing hard of hearing people. As mentioned, 15% of the U.S. population over the age of 18 have some trouble with hearing with numbers expected to increase in the future. In the first approach (see Figure 2), the number of private offices with visual alarms equates to approximately 8% to 9% of the total number of guest rooms on the upper end of the range. These numbers might be considered low when compared to current statistics and future projections for deaf and hard of hearing people. Identifying this key discrepancy leads to the conclusion that the number of private offices with fire alarm visual notifications should be increased.
A second approach is to integrate visual alarms into 15% of the total number of private offices on a single floor. This percentage is above the minimum 8% to 9% range used in the first approach and correlates directly to the actual statistics of deaf and hard of hearing people in the U.S. This feasible approach is considered a best practice and should be employed for commercial clients who use hoteling in private office spaces. The revised chart would be as shown in Figure 3.
Advantages, disadvantages in office hoteling approaches
There are several benefits to using either of the options that were previously described. Each approach is very straightforward, cost-effective and easily implemented with only a minimal number of fire alarm visual notification appliances required. Both approaches also allow flexibility to choose which specific private offices receive fire alarm visual notification appliances and change the appliances as needed. Private offices with fire alarm visual appliances can be strategically determined to fit the specific needs of the owner and occupants.
Using percentages that reflect the actual statistics for deaf and hard of hearing persons to calculate the number of private offices with visual alarms offers additional advantages. It can provide quantities that more effectively meet accommodation needs and allow for better planning when it comes to adjustments for increases and peak quantities. There is also more congruity between each range as the number of private offices requiring visual alarms is set at 15% of the total number of private offices.
FIGURE 3: Approach 2: private offices with visual notification appliances (based on percentages of deaf and hard of hearing persons). Courtesy: Jensen Hughes
‘ Building owners and companies have legal, moral and ethical responsibilities to provide safe environments that are inclusive and accommodating for all occupants, including deaf or hard of hearing workers.
’
One problem with both approaches is that deaf and hard of hearing employees would be limited to using only the private offices containing fire alarm visual notification appliances. The only way to provide maximum flexibility would be to outfit all private offices with visual appliances so any private office could be occupied. That is neither practical nor very economical. While this problem cannot be solved through the design process, creating a hoteling reservation process where specific offices are identified as deaf and hard of hearing accessible and then matching them with individuals who possess those credentials, would address this issue. Also, depending on the number of people trying to use the space, there may not be enough private offices with fire alarm visual notification appliances to accommodate all deaf or hard of hearing workers.
It is crucial that companies consider the impacts of office hoteling in business occupancies. Building owners and companies have legal, moral and ethical responsibilities to provide safe environments that are inclusive and accommodating for all occupants, including deaf or hard of hearing workers. The recommended fire alarm visual notification appliance design approaches presented provide guidelines to address and improve the level of safety for deaf and hard of hearing employees in business occupancies where office hoteling is used. These best practices will bridge the current gap that exists between the applicable code requirements and increased usage of office hoteling. cse
Matthew Christopher Lausch, SET, NICET Level IV, is a midAtlantic operations leader with Jensen Hughes. He has more than 26 years of fire alarm industry experience that includes design, installation, testing and commissioning as a contractor, manufacturer and consultant.
Office hoteling
u In office hoteling situations, fire and life safety systems must be designed to notify the deaf and hard of hearing.
u Several codes, standards and guidelines determine how to design mass notification systems and emergency communication systems.
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This article will discuss two types of designs for fire and life safety systems: prescriptive and performance-based design
All building and fire protection system designs must adhere to a set of criteria that are specific to the goals and objectives of a project. There are multiple NFPA committees that revise prescriptive codes and standards, like NFPA 13: Standard for the Installation of Sprinkler Systems, every few years.
In fact, there are currently five technical committees focused just on NFPA 13. The revisions to the codes and standards reflect advancements in industry knowledge and lessons learned from realworld fire events.
For example, the Station Nightclub Fire of 2003 prompted the National Institute of Standards and Technology to recommend a revision to model code that all existing nightclubs with an occupancy of over 100 people must be retrofitted with a sprinkler system and all new nightclubs must be built with a sprinkler system. Over the decades, dozens of fire events have contributed to the criteria of prescriptive fire codes, at the cost of life and property.
Objectives
• Identify the differences between prescriptive and performance-based design criteria for fire and life safety systems as well as the benefits and drawbacks of both design types.
• Understand how a building’s use directly affects the design of a fire and life safety system.
• Distinguish when performancebased design should and should not be considered.
NFPA 13 states that “Nothing in this standard is intended to prevent the use of systems, methods or devices of equivalent or superior quality, strength, fire resistance, effectiveness, durability and safety over those prescribed by in this standard.”
This guidance has been in the standard since the 1983 edition was issued. It continues to state that technical documentation proving equivalency shall be submitted to the authority having jurisdiction (AHJ) that approves the use of performance-based
design. Furthermore, NFPA 13 section 1.7 allows for new technology and alternate arrangements as long as the level of safety is not lowered. This section is very important as it shows that NFPA recognizes that there are multiple ways of achieving life and property protection, so long as the highest level of safety is maintained.
Prescriptive criteria
Examples of prescriptive criteria included in recent editions of NFPA 13 include:
• ESFR Sprinklers for Palletized, Solid-Piled or Rack Storage of Class I Through Class IV and Group A Plastic Commodities.
• Protection of Exposed Expanded Group A Plastics.
• General Requirements for Ceiling and In-Rack Sprinklers Protecting Rack Storage.
• Control Mode Density/Area Sprinkler Protection Criteria for Palletized, Solid-Piled, Bin Box, Shelf or Back-to-Back Shelf Storage of Class I Through Class IV Commodities.
The standard is full of criteria for several different water-based suppression applications, varying building uses and commodity arrays. Selection of the appropriate criteria requires the design professional to obtain specific knowledge of many items, including but not limited to: commodity classification and volume, storage layout, interior finish types, aisle widths and ceiling heights.
A significant limitation of prescriptive criteria is that it requires the facilities to be built and operated within the very specific requirements enforced by NFPA 13. This includes operational
‘ The standard is full of criteria for several different water-based suppression applications, varying building uses and commodity arrays. ’
factors such as fixture types, product types, storage methods, aisles, storage and ceiling heights, etc. That way, the associated design densities, water flows, sprinkler and pipe sizes and pipe and sprinkler arrangements of the sprinkler system are effective.
If one variable is not within the intent of the regulations of the criteria listed in the standard, then other options, prescriptive or performancebased, must be researched.
Performance-based design
Performance-based approaches date back to the 1970s when the United States General Service Administration developed goal-oriented approaches to building fire safety. In 1985, British Regulations published a performance-based document. Following Britain over the next 10 years, New Zealand, Australia, Japan and the Nordic Region all published their own performance-based design documents.
Later, NFPA 101: Life Safety Code was amended to allow for performance-based equivalencies in 2000 and the United States International Code Council amended International Building Code to include a performance option in the year 2003. Performance-based suppression criteria are based on goals and objectives identified by the stakeholders of a project. These goals give the stakeholders specific objectives that must be met for an acceptable outcome. Examples might include:
Atmospheric temperature
If the temperature in a room exceeds 600°F for a specified period of time, the structural integrity of the building is compromised and the test fails. Heavy timber is a another construction type being used in buildings; it would be of use to know if and when atmosphere in a room reaches 149°F, because that is when pyrolysis of mass timber begins.
Furthermore, if the temperature in a room gets too hot and the interior finish ignites, perhaps the building loses its one-of-a-kind historical feature. In turn, the fire test would be considered failed and the stakeholder would know that the fire protection design needs to be modified to prevent that design fire scenario.
Fire spread
If a fire jumps from the storage bay where ignition occurred to another bay before the suppression systems can control it, the test might be considered a failure because the sprinkler system wasn’t robust enough to control the fire before additional property became involved. The stakeholder would know what sprinkler configuration is truly necessary, based on the proposed use of the space.
Egress
If the prescriptive requirements related to building egress, such as number of exits, distance to an exit, or hallway widths of a building cannot be met due to a retrofit or change in occupancy, then performance-based criteria might include a modeled fire in this space and a subsequent egress model to prove that the building can be fully egressed before the conditions become untenable..
These are a few examples of performance-based criteria that are tailored to the goals and objectives of the stakeholder and the expertise of the fire protection engineers.
The Society of Fire Protection Engineers provides a two-phase process of using performancebased design.
FIGURE 1: By quantifying the occupancy and commodity type, fire protection engineers can identify a potential fire scenario and determine what sprinkler design components will be necessary.
Courtesy: Telgian Engineering & Consulting LLC
BUILDING SOLUTIONS UILDING
2: A vital component to solving fire protection challenges, full-scale fire testing examines difficult to protect commodities, storage or display arrangements and rack configurations. Courtesy: Telgian Engineering & Consulting LLC
Performance-based design process
PHASE 1
• Determine scope of project.
• Define the goals of the project.
• Identify the project’s objectives.
• Establish performance criteria.
• Create fire scenarios and trial designs.
• Evaluate in design brief.
PHASE 2
• Determine if the design meets performance criteria
• If it does not, repeat Phase 1.
• If it does, select final design.
• Create design documents.
Building use effect on design
A building’s use and construction type are the driving factors for fire protection requirements. Every building has a related risk depending on what its purpose. In addition to several specific uses, NFPA 13 has a quantified risk based on varying occupancy and hazard classifications.
There are five occupancy types per NFPA 13:
• Light hazard.
• Ordinary hazard group 1.
• Ordinary hazard group 2.
• Extra hazard group 1.
• Extra hazard group 2.
The differences between each group are the quantified risk based on the use of the space, especially for storage, manufacturing or processing of product, as well as the quantity and volume of contents in the space, content combustibility, content heat release rate, presence of flammable or combustible liquids and intended storage heights. The use of the space is a requisite for the types of items and activities within it.
Furthermore, if the building will be used for storage, the commodity will need to be classified as class I, II, III, IV and plastics. Plastics are classified into group A, B or C. Group A is subcategorized into expanded or nonexpanded. Expanded group A plastics are “airy” plastics, such as packing peanuts or foam. Nonexpanded plastics are any other type of plastic in which the density is not reduced by air, like plastic totes for example.
Each classification has requirements in relation to what material the commodity is stored on or in, how many layers of commodity there are within the storage box, if there is extra material within the box for packing and the volume of each material in proportion to the entire package. Commodity can also be classified as exposed or nonexposed; exposed commodity is stored within packaging that absorbs water while nonexposed would be storage-wrapped in plastic so water (or any fire suppressant that would otherwise extinguish the fuel source) cannot seep in.
Whether prescriptive or performance-based, this sort of specific information is necessary to ensure appropriate protection of the hazard. Ultimately, the purpose of commodity classifications is to choose the sprinkler system best suited for the types of contents and the challenges with the method of storage. For more information on commodity classifications, read “Commodity Classifications in NFPA 13” by Brian O’Connor.
By quantifying the occupancy and commodity type, fire protection engineers can identify a potential fire scenario because they know how hot and
FIGURE
Performance-based design BENEFITS
• Testing and designs are specific to each project and fire scenario.
• Construction cost savings, especially for retrofit projects where part of the existing system can be salvaged as part of the new design.
• Multiple scenarios can be tested to create flexibility in design options, unlike prescriptive where only one arrangement and design is permanent.
• Could lessen other fire protection requirements (i.e., allows for larger compartments or reduced fire resistance ratings than prescriptive, increased egress time for occupants).
• Accounts for realistic hydraulic characteristics that aren’t addressed in code due to simplification assumptions.
• Revolutionizes the fire protection industry’s understanding of fire behavior.
Prescriptive design
BENEFITS
• Formally accepted and recognized throughout the United States or jurisdiction of application.
• Manufacturers and suppliers have products required by code in constant production.
• Codes reference formally published fire tests by American Society for Testing and Materials and United Laboratories.
fast specific contents burn based on historical data from general lab testing. Then, they can determine what sprinkler design components will be necessary. The design components of a sprinkler system affected by the use of the building (occupancy and commodity type) are the number of required sprinklers, sprinkler spacing, water supply requirements and potential need for a pump or a water storage tank, sprinkler density discharge, pipe sizes and system hydraulics.
Benefits and drawbacks
A prescriptive approach and a performance-based design approach both have advantages and disadvantages. Some are listed below. Performance-based design of fire protection systems has both benefits and drawbacks. Many items here are referenced in “Performance-Based Fire Safety Design” by Morgan J. Hurley and Eric R. Rosenbaum.
Performance-based approaches are well suited for retrofit projects because fire tests could be designed to use existing pipe sizes or sprinkler types. If part of a building’s existing system is
• Costly upfront.
DRAWBACKS
• Requires extra time; could take time to conduct testing and get prior approval from authority having jurisdiction.
• Validation and verification of experiment uncertainties; ways to offset uncertainty in performance testing are conducting sensitivity analyses and applying realistic safety factors.
• Requires extra planning of test materials, lab time, test construction and team meetings.
DRAWBACKS
• Revisions are made on a three-year cycle so fire protection for new technology isn’t represented until long after it’s being used in the real world.
• Only protects for fire scenarios that have already happened.
• Suppresses innovation by specifying materials and methods that closely resemble but are often not exact representations of a scenario.
• Assumes hydraulic simplifications that aren’t always representative of realworld water and fire behavior.
• Installation of prescriptive system could cost the end user significantly more to install and maintain.
• Unique construction type, building use, commodity type and architectural features are not represented in the code.
‘ A building’s use and construction type
are the driving factors for fire protection requirements. Every building has a related risk depending on what its purpose. ’
proven to be sufficient, the owner(s) can save significant spend in construction costs that would have otherwise been spent gutting and replacing an entire sprinkler system to match exactly what NFPA 13 prescriptions require. Appropriately designed performance-based systems can also provide significantly more flexibility in building use and suppression system life cycle maintenance costs for the owner.
Practical applications for performance-based design
Our world is continually evolving with new technologies and materials that currently fall out-
BUILDING SOLUTIONS UILDING
‘ Performance-based solutions function brilliantly to bridge the gap to fire safety. ’
side the parameters of codes and standards in the fire protection environment. While professionals at NFPA and other regulatory agencies struggle to keep up with our evolving world, performance-based solutions function brilliantly to bridge the gap to fire safety. Additionally, user flexibility, life cycle costs, construction spend and generally improved levels of fire safety might make sense for new and future projects that are underrepresented in our current guidelines.
Examples include:
• Automatic storage retrieval systems.
• Electric vehicle charging areas.
• Car stackers.
• Lithium-ion electric bicycles sold in retail establishments.
• Green building materials not yet listed in code.
• Unique interior finishes and historical buildings.
• Unique occupancy combinations in buildings.
• Retrofitting an existing space to protect new products, processing or manufacturing models.
NFPA 13’s allowance for performance-based design can help revolutionize the industry’s knowledge of fire and protection technology. Real-world, innovative, long-term, cost-effective solutions can be developed with engineering expertise. cse
Hannah Murray is a fire protection consultant at Telgian Engineering & Consulting LLC, where she performs fire protection system surveys and testing, hydraulic analyses and code summaries and meets with various jurisdictions regarding performance-based designs.
BUILDING SOLUTIONS UILDING
Nick Waters, PE, CHFM, CHC, Dewberry, Charlotte, North Carolina; and Hailey Stewart-Hofer, EI, ASSE 6060, Dewberry, Raleigh, North Carolina
Back to basics:
Medical gas storage under NFPA 99
This covers the basics of medical gas storage and the requirements for health care spaces detailed in NFPA 99
At times, health care facilities use spaces to store medical gases — medical oxygen, nitrogen, nitrous oxide and others — that are noncompliant based on the requirements in the 2021 edition of NFPA 99: Health Care Facilities Code. This code specifies many health care facility requirements including operational, mechanical, electrical and architectural for the storage of such medical gases. Misses on the code typically occur when closets, storage rooms and other spaces are repurposed for the storage of these gases. As a result, challenges for facility managers include:
• Unable to create designated spaces for medical gases.
• Efforts to maintain compliance become inconsistent.
• NFPA 99 requirements can be misinterpreted.
• Requirements may not be known.
Medical gas definitions NFPA 99
The following are critical definitions from NFPA 99-2021 to review before we go further.
• Container: A low-pressure, vacuum insulated vessel containing gases in liquid form.
• Cryogenic fluid central supply system: At a health care facility, an equipment assembly supplies compressed gas with a cryogenic fluid that terminates at the source valve.
• Cylinder: A supply tank for high-pressure gases with pressures that may exceed 13.8 kilopascals (kPa) or 2,000 pounds per square inch (psi) gauge.
• Medical gas: See medical support gas or patient medical gas below.
• Learn about what NFPA 99 covers for medical gas storage requirements.
• Differentiate between the different types of medical gas storage rooms and their requirements.
• Know the common NFPA 99 compliance issues for medical gas storage rooms.
The purpose of this article is to provide health care facility professionals with instructional guidance to help them reach NFPA 99 compliance associated with the storage of medical gases. Readers are advised to consult the NFPA 99 text itself, and this article will help with the initial understanding of the requirements.
• Medical support gas: Nitrogen or instrument air used for any medical support purpose (e.g., to remove excess moisture from instruments, to operate medical-surgical tools). This gas may be used in laboratories and is not respired as part of any treatment. It falls under the general requirements for medical gases.
• Manifold: A device for connecting the outlets of one or more gas cylinders to the central piping system for that specific gas.
FIGURE 1: Example storage rooms.
Courtesy: Dewberry
• Nonflammable: Not readily capable of burning with a flame and not liable to ignite and burn when exposed to flame.
• Oxidizing gas: A gas that supports combustion.
• Patient medical gas: Piped gases — such as oxygen, nitrous oxide, helium, carbon dioxide and medical air — that are used in the application of or calibration of medical devices for human respiration.
How medical gas storage rooms are used
Medical gas storage rooms are used to store frequently used medical gases. These include but are not limited to: oxidizing gases, such as oxygen and nitrous oxide, and inert gases, such as nitrogen, carbon dioxide and medical air. The use of medical gas storage rooms is regulated by NFPA 99 (along with other codes), which establishes the requirements for the design, construction, installation and use of medical gas storage rooms in health care facilities.
In addition to supplying health care practitioners with essential resources, gas storage rooms allow for safety in the storage and fulfillment of these gases. Although not covered in this article, medical gas storage compliance also requires an in-depth hazard analysis which is outlined in NFPA 55: Compressed Gases and Cryogenic Fluids Codes, 2020 edition. These analyses take such subjects as flammability, toxicity and explosivity of the gases into account.
• Reference Table 6.2.1 in NFPA 55 for the design and number of control areas per floor.
• Reference Table 6.3.1.1 in NFPA 55 for a list of all gases and the maximum allowable quantity (MAQ) of all varieties of gases within different sizes and types of control areas.
There are several types of gas storage rooms and each has specific characteristics as well as design and operational requirements depending on the type of gases being stored. First, gas storage rooms are characterized as either indoor rooms — a room within the interior of the health care facility itself — or outdoor areas — an outdoor enclosure that meets gas storage requirements.
Secondly, gas storage rooms are either with a central supply — a system for piping medical gases to different functional areas within the health care facility — or without a central supply, in which gases are stored independently and retrieved for use in other areas.
Requirements for all types of storage: All storage rooms (except for rooms with storage only of less than 300 cubic feet of nonflammable gases at standard temperature and pressure, known as STP) — whether they feature central supply systems or not — have shared requirements in terms of signage, temperature limits, accessibility, finishes and restraints.
Signage: For example, source locations containing both inert gases and positive pressure gases other than oxygen and medical air must have their doors labeled as follows (see Figure1): CAUTION
Positive Pressure Gases
No Smoking or Open Flame Room May Have Insufficient Oxygen Open Door and Allow Room to Ventilate Before Entering
Meanwhile, source locations containing only oxygen or medical air must have their doors labeled as follows:
Medical Gases
No Smoking or Open Flame
Proximity: In terms of proximity, full containers and cylinders must be segregated from all others (empty cylinders, etc.) — a commonly missed
FIGURE 2: Interior storage with central supply for carbon dioxide.
Courtesy: Dewberry
BUILDING SOLUTIONS UILDING
requirement, especially considering the constant activity of medical practice.
High-temperature limit: All areas with cylinders, whether they have central supply or not, must not exceed 125°F.
Finishes and racks: The finishes of the interior spaces or the exterior enclosures must be made of noncombustible materials (interiors can be limited-combustible materials), as well as any racks/ shelves/supports for cylinders must be made of noncombustible materials (or limited-combustible materials).
Other: In general, these areas should have access to move cylinders with hand trucks, have lockable doors or gates and have proper restraints to prevent the cylinders from falling (whether full or empty). Other requirements are exclusion of: any fuel-fired equipment, heating elements greater than 266oF, flammable gas, flammable liquid or flammable vapors.
Best practice: It is best to use oxygen sensors and alarms in gas storage rooms to detect any harmful leaks and maintain 3 feet of clearance within each storage room around cylinders/containers and walkways for easy movement of cylinders. Neither of these suggestions is explicitly outlined in the language of NFPA 99.
Requirements for storage with a central supply included
A central supply system can be composed entirely of manifolds or the system may be a combination of manifolds and stored cylinders or containers. These systems can be located either within a single room in the health care facility (interior) or in an outdoor enclosure (exterior).
• Interior: Interior central supply systems locations are permitted to store manifolds for gas cylinders, manifolds for cryogenic liquid containers, in-building emergency reserves, instrument air standby headers, individual components on the oxygen side of the concentrator sources. Design and construction of interior central supply rooms, excluding cryogenic fluid center supply systems, have specific requirements outlined in NFPA 99. To highlight one of the indoor requirements specifically, rooms containing oxygen, nitrous oxide or other oxidizers shall be separated from the rest of the building by walls or floors with one-hour fire ratings and with doors and other openings with a ¾-hour rating. These rooms also require emergency power and specific ventilation which includes low-wall intakes (see Figure 2).
• Exterior: Exterior central supply system locations are permitted to store manifolds for gas cylinders, manifolds for liquid cryogenic containers, cryogenic fluid central supply and individual components on the oxygen side of the concentrator sources together. Exterior storage locations with central supply have less stringent, but unique requirements. Some of these unique requirements are protection from prolonged contact with moisture and soil, well drained area and special considerations when associated with natural elements (e.g., exposure to the sun) (see Figure 3).
• Important limitations: The following central supply systems are not permitted to be located within any of the interior or exterior storage rooms with central supply mentioned in the sections above: medical air central compressor supply sources, medical-surgical vacuum central supply sources, waste anesthetic gas disposal central supply sources, instrument air compressor central supply sources, any other compressors, vacuum pump or electrically powered machinery and compressors, dryers and air receivers used to supply oxygen concentrators.
FIGURE 3: Exterior storage with central supply for nitrogen. Courtesy: Dewberry
FIGURE 4: Interior storage only for medical air. Courtesy: Dewberry
Requirements for storage without a central supply included
Any storage that does not include a central supply system will feature cylinders or containers that are not in use. Similar to the central supply systems, these can be located either within the interior of the health care facility or in an outdoor enclosure.
Interior: Interior storage rooms have unique requirements based on the volume of gases stored within those rooms. Specifically, storage spaces with fewer than 300 cubic feet of nonflammable gases (at STP), 300 to 3,000 cubic feet of nonflammable gases (at STP) or greater than 3,000 cubic feet of nonflammable gases (at STP) will differ in requirements for the ventilation, electrical and architectural features. Rooms with greater than 3,000 cubic feet of nonflammable gases (at STP) require walls or floors with one-hour fire ratings and with doors and other openings with a ¾-hour rating. Rooms with greater than 300 cubic feet of nonflammable gases (at STP) require specific ventilation which includes low-wall intakes (see Figure 4).
Exterior: Exterior storage locations without central supply have less stringent requirements. One item to note is specific requirements for location as it relates to building exits, wall openings, intakes, property lines and combustibles (see Figure 5).
Although there are many similarities in the requirements of the different room types and number of gases stored, health care facility professionals need to understand the differences and limitations to each to confirm that their facility is constructed and operated within the NFPA 99 requirements. A matrix to review your facility’s compliance with NFPA 99 can be helpful (see Figure 6).
For user convenience, NFPA 99 outlines the typical medical gas cylinder’s volume and weight at STP for common cylinders seen in health care facilities (example: B, D, E, H) in the appendix under Table
CASE STUDY: Upgrading storage to meet NFPA 99 requirements
A HOSPITAL FACILITY (client) reached out to provide a study of two locations within a hospital facility where medical gases were being stored, including cryogenic fluids, nitrogen, oxygen, medical air, nitrous oxide and carbon dioxide.
Dewberry was asked to check that the storage methods were compliant, especially concerning:
• Types of gases stored in each room.
• Quantities of gases stored in each room.
• Ventilation requirements.
• Electrical requirements.
Dewberry was asked to check for oxygen sensors and alarms that would detect substantial displacement of oxygen by the unintentional release of gas in the room as well because these sensors and alarms could prevent potential asphyxiation.
The team assembled a report, which featured upgrades required to make the space meet gas storage room requirements of NFPA 99, NFPA 55 and local fire codes. The report was presented to facility administrators so they could make the necessary changes.
The proposed changes included a new exhaust fan (powered by the facility’s essential electrical system), low-wall exhaust inlet, new emergency lighting and new rated doors. It also advised upgrading/repairing rated walls, adding fire dampers and setting a quantity limit of gases. The client then requested a proposal for design documents for construction, which Dewberry delivered.
Although misses are common, in most cases, there is no intentionality on the part of health care facility professionals. More often, miscommunication arises between health care practitioners and facility managers responsible for meeting code requirements.
Conducting a storage audit at your facility and establishing standard for communications between these teams supports compliance with NFPA 99 and the health and safety of the teams.
A.11.3.5. This table provides an easy way to determine how much gas is stored in each type of cylinder when evaluating spaces with various cylinder sizes. It is also common for cylinders to list the content’s total cubic feet at STP on the exterior of the cylinder.
What types of medical gas storage room problems exist?
Medical facilities that do not meet NFPA 99’s medical gas storage room requirements often end up that way unintentionally. Specifically, requirements may not be completely understood or health care staff may place medical gas cylinders in a room not specifically designed for that use. In doing so, facilities may inadvertently be out of compliance and at risk for penalties, citations and even human injury or death.
FIGURE 5: Exterior storage only for nitrogen and nitrous oxide. Courtesy: Dewberry
BUILDING SOLUTIONS UILDING
Fortunately, facility professionals can develop a better understanding of the code to keep their facilities in compliance. Additionally, they can become aware of some of the most common misinterpretations and address them directly. The following list consists of some common NFPA 99 storage room errors that the authors have seen in the field.
Rooms are misapplied or not understood: The NFPA 99 requirements for medical gas storage are different depending on the type of room involved. Additionally, noncompliant storage rooms are often used for the storage of medical gases without taking compliance into consideration. It’s important to fully understand the type of room in consideration and be familiar with the NFPA 99 requirements for that room type based on the descriptions above.
Rooms do not have correct features, such as electrical, signage or exhaust/ventilation: In addition to the signage requirements described above
that are often missed, most storage rooms require ventilation. This ventilation can be achieved with natural ventilation, but typically (due to building layout) is mechanical ventilation. This requires low-wall exhaust, negative pressure and a means of makeup air. Mechanical ventilation exhaust is required to be on the facility’s essential electrical system as well. Natural ventilation requirements are in NFPA 99 Chapter 9.3.6.5.2 and requirements for mechanical ventilation can be found in Chapter 9.3.6.5.3. Rooms are often observed without exhaust systems or not meeting the specific requirements of these code sections. Emergency electrical provisions is also a requirement on most of the room types that is frequently missed.
The quantity of gas or number of containers exceeds the limits of the rooms: NFPA 99 has specific requirements regarding the amount of gas that can be stored in a room, with respect to less than 300
FIGURE 6: NFPA 99 medical gas storage room design and construction requirements matrix. Courtesy: Dewberry
cubic feet of nonflammable gases at STP, between 300 cubic feet and 3,000 cubic feet of nonflammable gasses at STP and greater than 3,000 cubic feet of nonflammable gasses. It is critical not to exceed these thresholds. Often, it is missed that a room is designed for a certain threshold and is exceeding that threshold with the total cubic feet of stored gases in the room (not counting empty cylinder’s volume).
Manifolds or cryogenics are located too close to equipment in violation of requirements: Manifolds and cryogenics have unique requirements in terms of their proximity to other containers. If located outdoors, they must be installed in an enclosure used only for the enclosure of those containers and they must comply with minimum distance requirements. If located indoors, they must be installed within a room used only for those types of containers.
Design or construction does not include appropriate fire-rated walls and doors: As noted above, NFPA 99 requires that storage rooms with central supply of oxidizers and storage rooms without central supply and greater than 3,000 cubic feet of nonflammable gases at STP must be separated from the rest of the building by walls and floors having a one-hour fire resistance rating. They must also feature doors and other opening protectives having a ¾-hour fire protection rating. This is often missed when medical gases are placed in a room without proper design.
Outdoor storage is too close to building exits or air intakes: NFPA 99 requires that outdoor storage areas for medical gases must be located at a specific distance from building exits and air intakes. This is to prevent the spread of gas should a leak occur.
Medical gases are not stored behind locked doors: NFPA 99 requires that storage areas for medical gases must be locked when not in use. This is to prevent unauthorized access to the gases.
Medical gases lack restraints or fastening against tipping or falling: NFPA 99 requires that containers of medical gases are restrained or fastened against tipping or falling. This is to prevent accidents or leaks should a container fall over.
Incompatible central supply systems stored together: As mention in a previous section, NFPA 99 outlines central supply systems that can and cannot be stored together. This precaution prevents hazardous mistakes and potential risks if gases were to mix with machinery-based equipment, etc.
Facilities and respiratory staff fail to communicate on appropriate storage: Facility professionals must provide respiratory staff with appropriate guidance as they access and use medical gases. Respiratory staff may not understand the quantity limits of a certain room based on the design and construction of the room.
Other medical gas regulations
Health care facility professionals should also take note of other regulations that may apply to medical gas storage practices based on the type, location or region of facilities, as well as any risks associated with those aspects (e.g., higher likelihood of natural disasters).
For example, NFPA 55 has additional limitations on hazardous materials per control area. It includes limitations on the number of control areas per floor that should be observed in accordance with NFPA 99 requirements. Similarly, the local fire codes should be referenced when looking for additional limitations on storage quantities. Typically, the local fire codes expand upon the limitations outlined within NFPA 99 and NFPA 55.
Additionally, facility professionals should understand the code edition(s) currently enforced for their facility and study each edition. This article is written based on the 2021 edition of NFPA 99, which may have different requirements than what is enforced at a particular facility.
Additionally, if a storage room was constructed under a different code edition and was compliant at the time of construction, it is allowed to remain as it was originally constructed as long as the local authority having jurisdiction has determined the system is not a hazard to life. This can be found specifically in Chapter 1, Administration, of NFPA 99. Therefore, it is be important to study the edition that was enforced at the time of construction as well. cse
Nick Walters, PE, CHFM, CHC, is an associate and senior project manager at Dewberry. He has more than 12 years of experience as a mechanical engineer and project manager specializing in engineering for health care facilities.
Hailey Stewart-Hofer, EI, ASSE 6060, is a staff engineer at Dewberry. She works in the firm’s plumbing, fire protection and medical gas department.
‘ Facility professionals can develop a better understanding of the code to keep their facilities in compliance. ’
ENGINEERING INSIGHTS
K-12 roundtable focuses on advanced technologies
HVAC and security systems are being upgraded at K-12 schools
CSE: What are the current trends in K-12 school projects?
Misty DuPré: We see quite a few trends relating to safety and security, advanced technology and hygiene within new designs of K-12 school sites and classroom settings.
• As a result of recent events, campus security is on the forefront of changing designs.
• Related to health safety and hygiene, plumbing fixtures are trending to be touch-free.
• Technology provisions are continuously improving, from the classroom setting to the maintenance personnel.
• In the classroom, projectors and smart boards are quickly being replaced with large, 72-inch touch-screen interactive monitors to support more effective and engaging teaching methods.
Maureen McDonald: Current trends in K–12 projects include upgrading HVAC and controls, adding HVAC to coastal area schools, adding HVAC to gyms and auditoriums, increasing focus on indoor air quality and monitoring, increasing use of technology, accommodating changes in class size, focusing on energy management tied to sustainability and greenhouse gas
reductions and highlighting public-private partnerships as a financing mechanism.
Steven Mrak: Recently, Peter Basso Associates have seen a resurgence in vocational training education spaces. As more school districts support the notion that college or university may not be the next step for all graduates, these vocational curriculums include welding/metal shops, construction trades, robotics, nursing/emergency medical technician and more. The occupation specific education and training allows students to potentially step right into a fulfilling career straight from high school. These types of spaces can become very mechanical, electrical and plumbing engineering intense from an infrastructure standpoint. In addition, living in the postpandemic world, K-12 schools have seen a renewed focus on the importance of IAQ. Upgraded ventilation systems and filtration are top of mind now for our clients.
different definitions and different levels of importance to today’s K-12 school district facility directors. As the districts balance their priorities, newer mechanical technologies (or maybe just newer to the K-12 market) can be designed around to meet individual district needs. Extended range air-to-air heat pumps using carbon dioxide as refrigerant may be useful as a district looks to decarbonize in northern climates. In conjunction, as photovoltaic panel costs continue to decrease, return on investment improves and northern installations become more practical.
K-12 school insights
uAfter COVID-19, many K-12 school buildings were upgraded to improve their indoor environmental quality.
u Technology and new learning techniques are changing the way engineers design systems within K-12 schools.
Steve Reigh: We are seeing an increased focus on energy efficiency and indoor environment quality. Districts want to spend less money on their energy bills and provide better environments for their occupants. COVID-19 has brought IEQ to the forefront of discussions when selecting systems for buildings. ASHRAE has released resources for bettering buildings to help both engineers and building owners understand best practices for good IEQ moving forward.
CSE: What future trends should engineers expect?
Steven Mrak: Decarbonization, carbon neutral, net zero, zero energy — all have
Steve Reigh: The application of energy codes pushing lower and lower energy requirements is pushing engineers to fully decouple ventilation air from heating and cooling energy. This is a direct attack on unnecessarily spent fan energy, which can be a quite large component of the energy consumption pie chart of a building’s total energy usage. If this type of system is used in conjunction with a displacement ventilation type system, it has the added benefit of great IAQ, which has been of great concern for schools the last 10 to 15 years.
Misty DuPré: As funding becomes available, schools will continue to invest in safety and security, hygiene and technology.
Maureen McDonald: Engineers should expect continued push for increased efficiency of HVAC, improved monitoring for IAQ, flexibility in HVAC systems to accommodate class size changes, increased interest in use of natural gas versus electricity, interest in HVAC technologies that reduce greenhouse gas emis-
In the Physical Sciences Building at
High School
Unified School District, the design incorporated exposed structural elements to highlight the engineered systems within the building. By design, students are able to see how the cabling, ductwork and piping are running throughout the building, making the technology they are learning about come more to life. Some key elements to the design included acid waste piping from laboratories, fume hood exhaust and daylight harvesting. Courtesy: Salas O'Brien
sions and increased focus on overall sustainability and the effect of operations on climate change.
CSE: Tell us about a recent project you’ve worked on that’s innovative, largescale or otherwise noteworthy.
Maureen McDonald: Our recent Pomona Unified School District project located in Pomona, California, includes upgrading HVAC at 20 schools. Due to different conditions at each site, the HVAC technologies being employed include single-zone gas packs, single-zone split systems with gas heat, multizone air handling units, single-zone heat pumps, electric heat pumps, direct expansion split systems, mini splits, air cooled chillers and condensers, ductless split systems, cooling towers and boilers. Because a lot of the previous HVAC equipment is end-of-life, the schedule has been flexible to address premature failures. Additionally, due to the deadlines associated with COVID-19 relief funding and the supply change challenges, work has had to be flexibly scheduled around school sessions. Regarding safe-
ty, there have been zero safety incidents recorded on this project.
Misty DuPré: One project we were recently involved in is the new science, technology, engineering and math classroom building at Aliso Niguel High School. This modern, two-story design incorporated open space, natural lighting and exposed structural elements to highlight the engineered systems within the building. By design, students are able to see how the cabling, ductwork and piping are running throughout the building, making the technology they are learning about come more to life. Some key elements to the design included acid waste piping from laboratories, fume hood exhaust and daylight harvesting.
Steve Reigh: A recent school in Monroe, Washington, that finished construction right as the pandemic started used an enhanced envelope, displacement ventilation, high-efficiency filtration, 100% outside air with energy recovery and an air source heat recovery heat pump to reduce the energy consumption of the classroom building while providing great IEQ to the facility. The project cost estimate came
Participants
Maureen McDonald, LEED AP
Director, Energy Services
Southland Industries Garden Grove, California
Steven Mrak, PE Vice President
Peter Basso Associates Inc. Troy, Michigan
Steve Reigh, PE, HBDP
Engineering Leader
DLR Group Washington, D.C.
in 15% over budget at the end of design development and the integrated design team of all disciplines in-house at DLR Group put their heads together to find creative ways to reduce costs without sacrificing the IEQ and energy goals of the overall team. Everybody sharpened their pencils and gave a little equally to allow the project bid to come in at exactly the budget and retained all of the originally proposed energy conservation measures.
Steven Mrak: A joint venture between the Marygrove Conservancy, University of Michigan – School of Education, Detroit Public School Community District, Starfish Family Services and IFF, the Marygrove Early Education Center in Detroit established a critical piece of the overall P-20 cradle-to-career campus transformation. Ranging from six weeks old up to 5 years old, the students of the early education center represent a diverse student community within a diverse
Misty DuPré, PE Principal
Salas O'Brien Vista, California
FIGURE 1:
Aliso Niguel
Capistrano
ENGINEERING INSIGHTS NGINEERING
Marygrove campus community. Mechanically, the building is served by a vertical geo-exchange field, dedicated outdoor air system with energy recovery and efficient water-to-air heat pumps. A water-to-water heat pump provides low temperature heating water to radiant floor systems throughout each classroom.
CSE: As classroom needs change and as viruses and pandemics evolve, how are you adapting learning environments for different uses and learning styles?
Maureen McDonald: Schools are looking for outdoor learning areas, decreasing class sizes, monitoring IAQ at the classroom level and upgrading HVAC and controls.
Steven Mrak: IAQ has been front and center in our designs, especially since the COVID-19 pandemic. A higher awareness of total air changes per hour and how that relates to higher-efficiency filtration systems. Prepandemic, it was common for schools to use MERV 8 filters on standard classroom unit ventilators due to cost and frequency of require service. Post-pandemic, we have
seen a renewed interest from districts to employ higher MERV rated filters, which sometimes require rebalancing of systems or fan motor upgrades. Also, implementing a control strategy that includes a pre and post-occupancy purge of student spaces provides a higher level of IAQ.
CSE: Describe a recent project in which you addressed indoor air quality issues to account for health concerns.
Steven Mrak: In the midst of the COVID-19 epidemic, we were approached by several public school districts that wanted our assistance in evaluating their existing building HVAC systems, regarding air filtration and ASHRAE recommended minimum air changes. Our efforts consisted of field verification, review of existing airflow balance reports and ventilation calculations. Through our efforts, these districts were made aware of specific HVAC systems and rooms throughout their buildings that did not meet current ASHRAE recommendations. They now have the ability to selectively target these spaces for improvements.
Maureen McDonald: A recent project that addresses IAQ issues to account for health concerns is the upgrading of HVAC and controls for Pomona Unified School District. Funded by COVID-19 relief funds and driven by the role ventilation plays in the spread of COVID-19, this project was initiated in 2021 and is slated for completion in 2024. Facing urgency to improve air quality and meet fund deadlines, the project specifically involves selecting different HVAC technologies (single-zone gas packs, single-zone split systems with gas heat, multizone air handling units, single-zone heat pumps, electric heat pumps, direct exchange split systems, mini splits, air cooled chillers and condensers, ductless split systems, cooling towers and boilers) to address different conditions at each site. cse
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FIGURE 2: The Salem Woods Elementary School HVAC system was designed by DLR Group in Monroe, Washington. This diagram shows the heat recovery air to water chiller system. Courtesy: DLR Group
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