Category: Craig’s Lighting Articles

Trends in Outdoor Lighting

The major technological shift to the LED light source has had a major impact on the outdoor stationary lighting market. In its latest solid-state lighting energy savings forecast, the U.S. Department of Energy (DOE) continued to recognize area and roadway lighting market as leading in LED adoption. In this market, DOE estimated 21 percent LED penetration in the installed base in 2015, projecting 91 percent by 2025.

Below is my contribution to the September 2018 issue of tED Magazine, published by the National Association of Electrical Distributors. Reprinted with permission.

The major technological shift to the LED light source has had a major impact on the outdoor stationary lighting market. In its latest solid-state lighting energy savings forecast, the U.S. Department of Energy (DOE) continued to recognize area and roadway lighting market as leading in LED adoption. In this market, DOE estimated 21 percent LED penetration in the installed base in 2015, projecting 91 percent by 2025.

LED’s expanding capabilities are well suited to evolving needs in outdoor lighting, while highly competitive efficacies and declining costs make it steadily more attractive for upgrades. This article identifies key trends in LED outdoor lighting is used as well as technology and design trends impacting the development of LED lighting and controls.

Image courtesy of GE

Efficiency and reliability

The efficacy (lumens/W) of LED luminaires has surpassed that of even high-pressure sodium lamps, with the most efficacious outdoor LED luminaires most readily identifiable under the DesignLights Consortium’s Premium designation in its Qualified Products List. Coupled with much longer life, long average mean time between failures, ruggedness, compact size, and controllability, LED offers a compelling alternative to traditional technologies. Over the past several years, outdoor LED lighting has seen advances in lumen maintenance, color consistency, and light output per LED (which in turn is driving development of smaller, sleeker form factors).

As the technology matures, however, maximum efficacy appears to be beginning to plateau. “When the technology was new, efficiency gains were significant as advances were made, but now that it’s reaching maturity, those gains have slowed significantly,” said Teresa Bair, Product General Manager – Outdoor and Industrial Lighting, Current by GE.

As a result, she added, manufacturers are focusing on new points of differentiation and value, from sleeker form factors to controllability to lighter housing materials. Another area of focus is reliability.

“Competitors are able to replicate efficiency and lumens per watt more easily, but customers quickly realize efficiency does not always translate to reliability, so there is an increasing focus on reliability,” Bair said. “Specifically, driver reliability is becoming an increasingly popular topic.”

Image courtesy of GE

Performance and aesthetics

“Energy efficiency, lumen maintenance, and optical distributions continue to differentiate luminaires on a performance basis,” said Amy-Christina Giacobello, Product Marketing Manager, Lumark, Eaton Lighting. “Good quality differentiators tend to be more in the details of the product qualifications, such as IP rating, vibration ratings, ambient temperature ratings, et cetera.”

Otherwise, quality lighting is becoming more important. “Quality lighting that is placed correctly can help establish feelings of safety and security,” Giacobello went on. “In communities, pedestrians may assume drivers can see them after dark, but if overhead lighting is insufficient, they may be in danger. Pedestrian-scale lighting is lower and spaced more closely together than regular roadway lighting. Using LEDs can further increase safety and security by improving light spread and eliminating dark spots.”

She added that the pedestrian experience is also key to commercial activity. As a result, municipalities are looking for architectural lighting solutions that entice pedestrian traffic. “Generally, cities couldn’t afford to focus on these things in the past, but LED technology makes them much more affordable,” Giacobello said.

Jeff McClow, Senior Product Manager, Hubbell Lighting, said LED technology has changed outdoor lighting in improved light source control, both in the optical and electrical sense. “One important product trend is efficient diffuse and edge-lit solutions that deliver reasonable lighting distributions beyond basic symmetric and slight forward asymmetric shapes,” he said, pointing out that due to energy code changes and design improvements, outdoor LED luminaires continue to undergo rapid product change.

McClow added that customers are looking for cost reductions by leveraging optical distribution to reduce the number of poles required. “The total costs on a project can be driven down by using fewer fixtures with lower wattages,” he said. “This is accomplished by using fixtures with the best photometric performance within the established budget.”

Another performance trend is lower correlated color temperatures (CCTs), driven by the American Medical Association’s (AMA) 2016 community lighting guidelines. Despite some pushback from the lighting industry, the guidelines, which specifically recommend 3000K sources as having a lower potential impact on circadian health, have had a significant impact on customer preference. At one time, this would have required sacrificing energy efficiency, but the efficacy gap between cool- and warm-CCT sources has been diminishing in recent years.

“Aesthetically,” said Bair, “many clients prefer lower CCTs because it more closely replicates what people have grown accustomed to with older metal halide or high-pressure sodium lights. People feel it is more welcoming and aesthetically pleasing, especially in applications such as a residential neighborhood or a park.”

Image courtesy of GE

Control and connectivity

Commercial building energy codes are demanding in terms of control of outdoor lighting, requiring automatic shutoff and light reduction based on time of day or occupancy. As lighting control requirements became widespread and more complex, the industry responded with a standardized NEMA twist-lock ANSI C136.41 control receptacle, now a common feature in outdoor luminaires. This receptacle enables connection to 0-10V or DALI dimming controls as well as sensors and communication devices, providing a control-ready product now and/or for the future.

“Standards create traction in the market as customers have greater confidence in the solution,” said Jay Sachetti, Sr., Marketing Manager, Connected Communities, Eaton Lighting. “The receptacle allows customers to retrofit existing luminaires to LED today with the ability to come back at a later date to update or add connected controls as technology continues to evolve, and know that certain functionalities are already built into the system. Ultimately, these receptacles can provide a connection point and power source for other smart city devices as standards continue to evolve and mature.”

Specifically, these control devices may use wireless communication as a means of connecting the luminaires into a system. Wireless controls have found excellent utility in outdoor lighting, providing remote control and communication without dedicated wiring. This enables programming, measurement, and monitoring of an outdoor lighting system’s performance. “This type of connected network provides unprecedented ability to control a vast network of outdoor lights from one location,” Bair said. “Users can view real-time diagnostics so instead of a streetlight that has burnt out going unnoticed and causing resident complaints, user of the system will have real-time visibility to the performance of all lights within their network. Users can also create various reports to verify actual energy consumption and other parameters of each light fixture, enabling analysis and forecasting for future electricity usage and maintenance requirements.”

She added that the combination of connectivity, bandwidth, data storage, and software provides a platform for implementing Internet of Things (IoT) strategies. By adding third-party software, data collected by the lighting system can be repurposed. By adding sensors, additional capabilities can be incorporated into the system. This allows capabilities such as asset management, gunshot detection, traffic monitoring, and more.

“Distributors should be thinking beyond just the LED lighting fixture,” Bair said. “Start becoming familiar with these emerging sensors and controls, because in the very near future, it will become increasingly rare that a buyer would buy just the fixture. The projects of tomorrow are going to feature these wireless outdoor lighting systems, which means LED fixtures with electronic nodes, sensors, and software. This can open up new revenue streams for distributors willing to expand beyond just fixtures and bulbs.”

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Getting to Know the WELL Building Standard

My monthly lighting column for ELECTRICAL CONTRACTOR covers the WELL Building Standard, which aims to promote building design that supports human health and wellness.

My monthly lighting column for ELECTRICAL CONTRACTOR covers the WELL Building Standard, which aims to promote building design that supports human health and wellness.

Similar to LEED, WELL is a building rating system, covering new and existing buildings, new and existing interiors, and core and shell projects. Designers achieve a WELL rating based on satisfying preconditions and then realizing points through optimization features. It works well with LEED, though its focus again is people instead of systems. In its first three years, more than 120 million square feet of projects in 31 countries were registered or certified through the WELL. In May 2018, the IWBI released the version 2 pilot of the standard.

The WELL standard is based on seven categories, with various features or specifications in each category. One such category is light, including 13 specifications for light output and levels, lighting controls, reflectances, visual comfort, and daylighting. The goal is to improve alertness, mood and productivity while minimizing disruption to the body’s circadian rhythms.

Click here to read it.

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Making the Case for Circadian Lighting

For the September 2018 issue of ELECTRICAL CONTRACTOR, I contributed a feature article about various research that is slowly building a case for circadian lighting, and may inform best practices.

For the September 2018 issue of ELECTRICAL CONTRACTOR, I contributed a feature article about various research that is slowly building a case for circadian lighting, and may inform best practices.

The LRC found that participants receiving a morning CS of 0.3+ demonstrated greater circadian entrainment than those with a morning CS of 0.15 or lower. They were able to fall asleep faster at bedtime, particularly in winter; experienced higher-quality sleep; and reported lower stress levels.

Check it out here.

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Testing Horticultural Lighting

In May 2018, the Lighting Research Center (LRC) released a cautionary report evaluating potential energy savings for LED horticultural lighting. The LRC found that energy savings is possible with LED, but one should evaluate products based on application efficiency rather than simple luminaire efficacy. In short, rather than generalizing about energy efficiency, the lesson seems to be that some LED products save energy compared to some traditional products, depending on the product and the application.

A news item I contributed to the August issue of tED Magazine. Reprinted with permission.

According to Technavio, the global greenhouse horticulture market is expected to grow at a CAGR of nearly 11 percent from 2017 to 2021. Estimated at 1 billion square feet of growing space in 2017, the horticultural market includes supplemented greenhouses, which use electric lighting to supplement, extend, or replace daylight; non-stacked indoor farms, which use ceiling lighting on plants grown in a horizontal area; and vertical farms, where plants are grown stacked on shelving that typically includes integrated lighting.

For many utilities, horticultural facilities are one of their fastest-growing loads, with lighting constituting the largest portion. As a result, the DesignLights Consortium (DLC) produced a specification for inclusion of LED horticultural products in the Qualified Products List, expected to be released in September. This recognizes the energy-savings potential of LED horticultural lighting and will qualify LED horticultural products for utility rebate programs. Currently, LED lighting has a high penetration in vertical farms but very low penetration in the other two types of horticultural facilities. Initial cost is a significant factor, which often requires justification based on satisfactory energy savings.

Young plants in a greenhouse in the Netherlands

In May 2018, the Lighting Research Center (LRC) released a cautionary report evaluating potential energy savings for LED horticultural lighting. The LRC found that energy savings is possible with LED, but one should evaluate products based on application efficiency rather than simple luminaire efficacy. In short, rather than generalizing about energy efficiency, the lesson seems to be that some LED products save energy compared to some traditional products, depending on the product and the application.

The LRC conducted photometric testing, application simulations, and life-cycle cost analysis for 10 LED horticultural luminaires and 4 traditional luminaires including high-pressure sodium (HPS) and metal halide (MH). The evaluation included 11 luminaire-specific metrics and 5 application-specific metrics, focusing on photosynthetic photon flux density (PPFD), which measures light energy the plants need to grow and is analogous to footcandles in a commercial application.

The LRC discovered a wide variation among products, resulting in some of the tested LED horticultural products saving energy while achieving the same PPFD. The LRC also found that an average three times more LED luminaires were needed to produce the same PPFD as a typical 1000W HPS layout. The number of luminaires and their size produces shading. The LRC found the tested LED luminaires reduced daylight by 13-55 percent compared to 5 percent for HPS.

“Upon analyzing our data, we were intrigued by how intensity distribution and layout emerged as key factors in system performance,” LRC Research Scientist Leora Radetsky stated in an LRC press release.

As a result, the LRC concluded that three of the tested LED luminaires produced a lower life-cycle cost while the remaining seven had a higher life-cycle cost than the two tested 1000W HPS systems.

The findings contradicted a report by the U.S. Department of Energy (DOE) published in December 2017, which claimed potential energy savings of up to 40 percent if all horticultural lighting switched to LED today. The DOE analysis was based on an assumption of a 1:1 replacement of luminaires, which the LRC disputed, and a focus on luminaire rather than application efficiency.

Click here to download the LRC report.

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Lighting for Patient Rooms

One of my contributions to the August issue of tED Magazine is an application story about how to light patient rooms in healthcare buildings.

I contributed this application article to the August issue of tED Magazine, the official publication of the NAED. Reprinted with permission.

Americans receive healthcare in more than 10,000 inpatient healthcare buildings in the United States, representing about 2.4 billion sq.ft., according to the 2012 U.S. Commercial Buildings Energy Consumption Study.

In these buildings, one of the most important spaces is the patient room, serving multiple functions related to both effective caregiving and patient recovery and comfort. Multiple studies demonstrated that well-designed rooms can increase patient satisfaction and reduce accidents, infection, stays, and pain medication, ideas that now drive mainstream patient room design.

This article introduces basic lighting design principles for patient rooms and then dives into new thinking such as circadian lighting. It is based on the Illuminating Engineering Society’s (IES) ANSI/IES RP-29-16, Lighting for Hospitals and Healthcare Facilities, and the Lighting Research Center’s Lighting Patterns for Healthy Buildings website.

Patient room lighting

Patient rooms are multifunctional spaces, including tasks ranging from sleep to cleaning, requiring a flexible lighting design. The first step is to divide the room into zones, typically patient, caregiver, and family. To serve these zones, the lighting system should be layered to provide ambient, accent, and task (exam) lighting. To address variation of lighting needs in each zone, these layers should be separately controlled, with further zoning based on need. Dimming or multilevel controls are recommended, with the patient having control of patient zone lighting from the bed. All controls should have proper indicators or otherwise be properly labeled.

Higher light levels are appropriate during the day than at night. Daylight is highly desirable. In multi-patient rooms, the designer must provide dedicated lighting to each patient, noting ceiling curtain tracks that may divide the room. At night, night lighting should be provided allowing safe travel to the bathroom, while sufficient light should be provided for caregivers. At night, caregiver light levels can be lower than during the day, as their eyes are considered adapted for lower light levels. Still, it can be challenging to design illumination that both facilitates sleep and staff work.

Generally, designers should put comfort first by avoiding sources of direct and reflected glare on room surfaces, TV screens, and personal electronic devices. Overall, the design should facilitate relaxation, while giving the patient as much control over their environment as possible. In some cases, a residential touch such as wall sconces can make patients feel more at home.

In the patient zone, lighting should be provided with an understanding many patients spend much of their time lying on a bed reading or watching TV, with the most critically ill sometimes having only the ceiling above as their view. Patient ambient lighting may be controlled at both the entrance and patient controls, such as a pillow speaker handheld and integrated bed control. Similarly, the patient will be given a personally controllable reading light. Patient examination is often illuminated by downlights with control conveniently accessed by the caregiver.

The above recommendations are for general patient room lighting. Note there are many specialized room types, such as airborne-infection isolation rooms, protective environment (PE) rooms, critical care, obstetrical care, nursery, neonatal intensive-care, pediatric, geriatric extended-stay, and psychiatric rooms. Each will have particular lighting needs. In pediatric patient rooms, for example, the finishes are often more colorful and playful, and family members typically remain with the patient throughout their stay. Consult IES-RP-29-16 for more information about lighting design considerations for these spaces.

Circadian lighting

The relationship between light and circadian response is becoming increasingly understood, resulting in new design considerations. These considerations are particularly important in healthcare environments, where facilitating healthy sleep is important. In its recommended practice for healthcare lighting design, the IES states, “Increasingly, facilities recognize the need for 24-hour circadian rhythm-supportive lighting schemes.”

The key factors in circadian entrainment are intensity (amount of light falling on eye’s photoreceptors, requiring vertical lighting), spectrum (wavelength of the light, commonly associated with correlated color temperature), timing (when light falls on the eye), and duration (the cumulative amount of light exposure during the day).
The Lighting Research Center (LRC) has conducted a significant amount of research in this area and produced a metric and recommendations. The metric is circadian stimulus, or CS, with 0.1 being the threshold for circadian response and 0.7 being the saturation point, and with 0.3+ recommended for at least one hour in the early part of the day. The recommendations can be found at LightingPatternsforHealthyBuildings.org.

In patient rooms, LRC recommends a high CS during the day and a low CS in the evening. As an example, in a single-patient room, one option is to install recessed linear luminaires, a wall-mounted direct/indirect task light over the bed, a few downlights at the entrance and perimeter, and a recessed linear wallwasher, with all luminaires fitted with LED sources.

During the day, the linear light, task light, and wallwasher dim over the course of the day until reaching 25 percent of full output in the evening. The downlights remain at full output during most of the day until dimming to 50 percent in the evening. All lighting adjusts from 5000K in the morning to 3000K midday and 3500K in the late afternoon and evening. Alternately, the wallwasher could tune to a saturated blue light. LRC calculated that this design would provide a stimulating 0.3 CS in the morning, adjust to 0.2 midday, and decline to 0.1 in the late afternoon and evening.

Patient room lighting

Patient rooms are a highly sensitive application demanding extraordinary functionality, comfort, and flexibility. As such, lighting designs must accommodate these customer demands. For help, some manufacturers produce specialized product lines around healthcare environments and offer deep application expertise.

Hunterdon Healthcare Cardiac Expansion, designed by Nadaskay Kopelson Architects. Photo by Halkin|Mason Photography. Image courtesy of Visa Lighting.

Below is a dual-occupancy patient room lighted for optimal circadian entrainment in the morning (top), afternoon (middle), and evening (bottom). Image courtesy of the Lighting Research Center.

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ELECTRICAL CONTRACTOR on Lighting Rebates

My contribution to the July issue of ELECTRICAL CONTRACTOR talks about trends in lighting rebates.

My contribution to the July 2018 issue of ELECTRICAL CONTRACTOR talks about trends in lighting rebates, notably:

  • LED rebates level out
  • New lighting categories are being covered
  • DLC Premium differentiates LED market and gains some traction
  • Lighting control rebates are widely available and relatively stable in rebate amounts
  • Networked control rebates debut

Click here to read it.

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A Fresh Look at Office Lighting

What’s new in office lighting? Find out by reading this article I wrote for the July issue of tED Magazine.

Below is an article I wrote for the July issue of tED Magazine, the official publication of the NAED. Reprinted with permission.

Open ceilings, collaborative workspaces, microleasing, and unique designs that inspire occupants and reinforce brand are just some of the trends reshaping the modern office and driving innovative lighting designs.

“Say goodbye to the clear patterns of light throughout a space,” said Jerry Mix, President, Finelite. “Today’s demand is for tailored lighting determined by the architecture.”

The LED and subsequent intelligent control revolutions have supported these office trends. In the high end of the market, the desire to maximize the value of human value translates to a stronger focus on lighting solutions that support a personalized, productive space as well as foster collaboration.

“In the past, there was a stronger priority placed on creating a certain aesthetic and look independent of what the occupants needed,” said Gary Trott, VP Marketing, Intelligent Lighting, Cree, Inc. “Spaces may have been beautiful at a glance, but people may have disliked working in them. Now the balance has shifted so that while the space is still designed to look great, it is also designed to be an effective space where people can work collaboratively and comfortably.”

The key is control, both in the optical and electrical sense.

Quality lighting

“The size of the office lighting segment has not seen much change in the last few years,” Mix said. “However, the demand for quality lighting is very strong.”

By quality lighting, he means designs that go beyond the traditional cookie cutter direct lighting layouts by embracing a layered lighting approach oriented toward visual comfort and optimal function. This may include direct/indirect lighting, integrated wall washing for vertical illumination, and supplemental task lighting for major work areas. The LED source has delivered compact form factors, flexible configurations, and the ability to precisely specify light output and distribution, enabling highly customized lighting designs. Meanwhile, LED performance and color quality have both improved, while costs have declined as the technology matures.

Image courtesy of Finelite.

Connected lighting

According to Trott, the biggest advance in LED lighting over the past few years has been controls being more integrated and approachable. Dimming, once requiring a special ballast and imposing a cost premium for fluorescent lighting, is typically standard or a standard option for LED. Connected lighting packages are now a common offering by luminaire manufacturers.

Connected intelligent lighting consists of luminaires able to communicate (connected) within a programmable (intelligent) system. The system may be luminaire-based, with all controls integrated into the luminaire; room-based, offering autonomous, out-of-the-box energy code compliance; or building-/enterprise-based, offering global programming, control, and data collection.

Connected lighting provides the opportunity to accelerate energy cost savings while enabling improved user experiences. According to the DesignLights Consortium, these systems can produce average lighting energy savings of 47 percent. They are the key to unlocking the possibilities of circadian lighting and the Internet of Things (IoT), both of which are developing as potentially transformative trends.

“Intelligent lighting is a very important trend,” Trott said. “In fact, we believe this trend is going to be larger than the LED revolution because LED lighting is the perfect platform for smart buildings.”

The IoT is a concept defining buildings in which systems are integrated, programmable, and providing measuring for business process improvement and monitoring for maintenance. With installation almost everywhere in a building, microprocessing, connectivity, bandwidth, and sensors, intelligent lighting is positioned as a strong candidate for serving as IoT infrastructure.

“Over the past three years, enabling the IoT with lighting has gone from a catchphrase to something real,” Trott said. “We see customers today who are utilizing the data captured by their intelligent lighting system to create value beyond lighting. Owners and operators have a better understanding of how their buildings are being used so they can better optimize the space. We’re at the beginning of this trend, and that’s a great place to be.”

He encouraged electrical distributors to familiarize themselves with connected lighting, adding, “Connected lighting and the IoT can be intimidating, but most people are already experiencing it on a daily basis through their smart phones. If you are not selecting an LED luminaire that can be connected and is IoT-enabled, any light you put in is obsolete from day one.”

Image courtesy of Finelite.

Color tuning

An extension of the larger trend of integrated lighting control, color-tunable lighting is a developing trend that according to Trott is revolutionizing office lighting.

“In the past, lighting had very static conditions, only allowing people to switch between ON and OFF in one color,” he said. “Now that LED lighting is programmable across an entire enterprise, it has made color changing and dimming far more approachable, allowing for control in the level of illumination that is projected throughout the day.”

With tunable-white, users can adjust color temperature to preference or space need. General lighting color output can be programmed to match the color quality of external daylight conditions, a benefit for occupants working in spaces lacking windows. While these are currently the most significant applications for tunable-white lighting in office environments, color can also be programmed to be cooler in the morning and warmer in the evening to support circadian lighting strategies and promote alertness.

“We are seeing an interest in tunable lighting and controls,” Mix said. “People are starting to value the impact lighting has on supporting employee wellbeing and preference.”

He believes circadian lighting is going to be a major trend in the future, with user-friendly controls, further research, and the experience of early adopters being key to unlocking its potential. Circadian lighting is a lighting system designed to promote circadian health, typically involving cooler, high-output light in the morning tapering off to warmer, lower-output light in the evening. “It is very important that circadian applications have a plan and have circadian goals in place,” Mix said, “so that the application can be realized with the proper lighting and control specifications.”

Final word

“Get ready,” concluded Mix. “The lighting world is going to be full of new and exciting applications.”

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ELECTRICAL CONTRACTOR Covers Study Putting TLED Lamps to the Test

The California Lighting Technology Center (CLTC) recently collaborated with Pacific Gas & Electric Co. to evaluate TLED lamps across a range of luminaires.

The California Lighting Technology Center (CLTC) recently collaborated with Pacific Gas & Electric Co. to evaluate TLED lamps across a range of luminaires. The CLTC wanted to go beyond troffers, the focus of ample previous industry testing, and study performance in commercial buildings with other luminaire types, such as pendants, wraps, cove lights and wallwashers.

That’s the subject of an article I contributed to the June issue of ELECTRICAL CONTRACTOR. Check it out here.

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OLED Evaluation

Accounting firm DeJoy, Knauf & Blood LLP (DKB) invited DOE to evaluate a diverse installation of OLED lighting at its Rochester, NY offices comprising about 14,000 sq.ft. One of DKB’s founding partners is a co-founder and CEO of OLEDWorks LLC, the only U.S.-based OLED manufacturer. DOE published the resulting GATEWAY report in 2017, reporting significant energy and quality improvements over the previous fluorescent T8 lighting while gaining insights into OLED’s effectiveness in a real-world setting.

Below is another of my contributions to the May 2018 issue of tED Magazine. Reprinted with permission.

OLED continues to develop as a complementary technology to LED. In 2016, the Department of Energy (DOE) published two reports about the technology: the first, a market assessment, and the second, a GATEWAY report evaluating Acuity Brands’ Trilia OLED lighting system installed in an office application.

More recently, accounting firm DeJoy, Knauf & Blood LLP (DKB) invited DOE to evaluate a diverse installation of OLED lighting at its Rochester, NY offices comprising about 14,000 sq.ft. One of DKB’s founding partners is a co-founder and CEO of OLEDWorks LLC, the only U.S.-based OLED manufacturer. DOE published the resulting GATEWAY report in 2017, reporting significant energy and quality improvements over the previous fluorescent T8 lighting while gaining insights into OLED’s effectiveness in a real-world setting.

The office lighting project features LED lighting with OLED in a supporting role, taking advantage of its strengths and distinctive aesthetic. Acuity Mark LED Slot 2 linear LED luminaires provide general lighting in open offices. Acuity Gotham EVO downlights provide general lighting in private offices, complemented by OLED task lights by OLED Devices. OLED pendants by Acuity, Birot, Designplan, OMLED, and Visa feature prominently in spaces such as break/copy/conference rooms, lounge, and reception desk.

All of the OLED luminaires use OLEDWorks panels and feature dedicated OLED drivers (mounted remotely except for two, which integrate the drivers). When Acuity introduced the Peerless hybrid LED/OLED Olessence luminaire in 2017, which promises an efficacy of 71-81 lumens/W, DKB replaced some of the LED linear products in the open offices. DOE did not test them in its evaluation.

Measured efficacy for the previously installed OLED luminaires ranges from 21 to 58 lumens/W, lower than the LED luminaires (80-90 lumens/W). They are warm in color appearance (around 3000K) and render colors at a measured 79-91 CRI. Nearly all connected to 0-10V dimming controls and dim without flicker. In the nine months of operation, no luminaire failures were reported. Overall, DOE found the OLED lighting to provide comfortable brightness, illumination on vertical surfaces as well as the workplane, and soft, diffuse lighting quality. The total connected load for the LED and OLED lighting is 0.6 W/sq.ft.

This project demonstrates OLED lighting has come a long way over the past five years, though demand continues to be inhibited by its cost premium and low efficacy relative to LED luminaires. Another issue is that as the OLED panels age, they draw more power, which requires compensation in electrical circuit sizing and lighting power calculations. (DOE recommends using an additional power draw of about 15 percent when performing lighting power density calculations.) Next-generation OLED products, however, promise efficacies that are competitive with LED, 90 CRI, and a lifetime of 30,000 to 50,000 hours. This may position OLED well as a complementary technology to LED for general lighting.

Download the DOE GATEWAY report at bit.ly/2ynRiC1.

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Circadian Lighting 101

Circadian lighting describes lighting systems designed to support human health by stimulating the body’s circadian system. While a young trend, it is potentially transformative in how we design and use lighting. This article provides a basic introduction to the topic.

Below is my contribution to the June 2018 issue of tED Magazine, the official publication of the NAED. Reprinted with permission.

Circadian lighting describes lighting systems designed to support human health by stimulating the body’s circadian system. While a young trend, it is potentially transformative in how we design and use lighting.

Circadian health

The body’s circadian system regulates digestion, hormone release, the timing of alertness and sleepiness, and other bodily functions. It is synchronized with the 24-hour day by exposure to light and darkness. These 24-hour biological cycles are called circadian rhythms. Disruptions to the circadian system can lead to poor sleep and health problems.

In the early 2000s, scientists discovered a third type of light-sensitive cell in the human eye, believed related to circadian response and not vision. This discovery eventually led to an understanding that how we design lighting systems can affect circadian health.

Circadian lighting

For millions of years, sunrise and sunset synchronized the human body clock. Today, Americans on average spend most of their lives under electric lighting. Traditionally, this lighting was designed with an emphasis on light levels delivered on a horizontal workplane, typically with no variation in light level or wavelength (associated with color perception).

The problem is this approach may not deliver sufficient light to the eye itself. The key factors in circadian-effective lighting are amount of light falling on the eye, spectrum (wavelength), and timing and duration of exposure. Vertical illumination is considered the most important, with spectrum (shifting from cool to warm over the day) acting as an entrainer.

Metric

As circadian stimulation involves a non-visual response to light, it required a dedicated metric. Several metrics have been proposed, such as melanopic lux, melanopic content, and circadian stimulus (CS).

CS was developed by the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute. This metric indicates how well a one-hour exposure to a light source producing a certain light level and wavelength of light stimulates the circadian system, based on its ability to suppress the hormone melatonin. It ranges from 0.1, the threshold for circadian activation, to 0.7, which represents saturation. The LRC found exposure to a 0.3+ CS is effective for stimulation. The LRC offers an online calculator enabling designers to produce a CS value for their designs, available at www.lrc.rpi.edu/programs/lightHealth/index.asp.

Design templates

To provide design guidance, the LRC developed Lighting Patterns for Healthy Buildings (www.lightingpatternsforhealthybuildings.org), sponsored by the Light and Health Alliance. This site contains baselines and model alternative designs for typical spaces in various building types, including schools, healthcare buildings, senior facilities, and office buildings. Each pattern presents lighting plans, renderings, and generic luminaire information.

As an example, consider a small (20×22 ft.) windowless classroom with an occupancy of the teacher plus 16 students. Pendant 32W T8 luminaires are mounted on a 9.5-ft. ceiling with a 2×4 ceiling grid. While delivering satisfactory task light levels, the lighting system produces a CS of 0.16, too low for good circadian system activation.

An alternate, circadian-friendly design might replace the fluorescents with dedicated LED pendant luminaires with supplemental LED wallwashers along one wall. In the morning, all lighting is at full output with a very cool correlated color temperature (CCT) of 6500K, producing an active CS of 0.42 (see Figure 1). In the afternoon, the light dims to 40 percent of full output while warming to 3000K, reducing CS to 0.15 (Figure 2). The system operates efficiently and produces satisfactory light levels while featuring sufficient vertical illumination and flexibility to support circadian stimulus.

Putting it to the test

The LRC recently concluded a study at a series of Federal office buildings and discovered that people working under circadian-effective lighting had better sleep and were more alert during working hours.

In an earlier study led by LRC Director Dr. Mariana Figueiro, the researchers measured light levels in five Federal buildings, which were designed to maximize daylight availability for their indoor workspaces. Though some spaces featured large and numerous windows, the LRC discovered workers were not receiving enough light, due to a number of factors such as seasonal variation and window shading. As a result, the LRC theorized that supplemental task lighting could be effective at boosting CS.

In a subsequent study, the LRC tested this theory by installing circadian-effective task lighting (designed by LRC and shown in Figure 3) in two Federal office buildings and two embassies. The embassies are located in Iceland and Latvia, which experience far fewer daylight hours during the winter. Daysimeters measured the amount of CS received by each of the study’s 68 participants before and then during the two-day intervention.

The new lighting was found to significantly improve CS, resulting in participants self-reporting less sleepiness and greater energy and alertness. The findings were consistent across all four buildings. According to Figueiro, the study confirmed previous LRC studies by demonstrating that high CS during the day better aligns circadian rhythms and increases alertness during the workday.

Healthier lighting?

Built on the latest scientific understanding of the relationship between light and circadian health, circadian lighting is a new and emerging trend in the lighting field. With the recent introduction of metrics and model designs, and with equipment readily available, it is increasingly actionable in commercial buildings. Research suggests it can influence circadian health and alertness during working hours. Implementation need not be complex, though it requires education, extra effort, and expanded design practices to better incorporate vertical light levels, layered lighting, and flexibility.

In this rendering of a small classroom, morning lighting is at full output with a very cool CCT of 6500K, producing an effective level of CS. Image courtesy of the Lighting Research Center.

The lighting in the afternoon in this small classroom dims to 40 percent of full output while warming to 3000K, reducing CS. Image courtesy of the Lighting Research Center.

LRC-designed task lights delivered sufficient light to the eye at least one hour per morning during a two-day study at four Federal office buildings, resulting in self-reported scores reflected improved mood and vitality. Image courtesy of the Lighting Research Center.

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