Category: Research

LRC Study Evaluates the Blue-Light Hazard From Solid-State Lighting

The increasing popularity of LED technology has raised concerns about retinal damage via a mechanism known as blue-light hazard. Research conducted by the Lighting Research Center demonstrated in a majority of cases LED lighting does not present a greater risk of blue-light hazard than traditional sources such as incandescent.

LED technology has ignited widespread interest in the ways that lighting can offer benefits to people, including improved visibility at night, enhanced perceptions of brightness and security, and spectral tuning for management of circadian rhythms. Yet, as illustrated in a recent report from the American Medical Association (AMA), the increasing popularity of LED lighting is also raising new questions and reviving older concerns about unwanted impacts of these light sources, such as light pollution, discomfort glare, circadian disruption, and retinal damage via a mechanism known as blue-light hazard.

A new study from the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute takes a practical, quantitative approach to evaluating light sources for blue-light hazard. Results of the study are published in the International Journal of Occupational Safety and Ergonomics, in an article titled, “Evaluating the Blue-Light Hazard from Solid State Lighting.”

In the study, LRC researchers John Bullough, Andrew Bierman and Mark Rea evaluate the spectral radiant power characteristics of incandescent, fluorescent, LED and daylight sources in terms of current blue-light hazard calculation procedures from the Illuminating Engineering Society and the Commission Internationale de l´Éclairage. The paper provides comparative data to allow meaningful and quantitative comparisons among light sources commonly experienced indoors and outdoors. Particular attention is given to use cases that could potentially affect blue-light hazard.

The study results showed that in the majority of use cases, LEDs do not exhibit greater risk for blue-light hazard than other light sources, including incandescent. LEDs present no special concerns for blue-light hazard over other common light sources in typical use cases because our natural photophobic responses, such as squinting and averting the gaze, limit exposure to bright light. Where photophobic responses might not occur, such as during eye surgery or with premature infants, caution is needed.

Some organizations, such as the AMA, have advised against using LEDs with correlated CCT exceeding 3000K, however, the LRC study found that avoiding blue-light hazard is primarily related to controlling the radiance of light sources, and much less related to spectral distribution, particularly when expressed in terms of CCT.

The LRC study authors note that CCT should not be used as a metric for characterizing the potential for blue-light hazard, citing the fact that an incandescent filament at 2856K within a clear bulb is associated with a greater risk for blue-light hazard than any white LED source, including one of 6500K. The spectral radiance distribution must be known to estimate blue-light hazard, particularly for those cases where photophobic responses might not occur. In these cases, and indeed for general lighting applications, the study authors recommend the use of lenses, baffles, and diffusers to mitigate glare as the primary methods for reducing the risk of blue-light hazard.

Click here to learn more.

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AIA Home Design Trends Survey Finds Growing Popularity of Controls

Wireless features, automated lighting controls, and home automation are becoming more popular in residential projects; the most popular home products demonstrate energy management features. These are just some of the findings from The American Institute of Architects’ (AIA) Home Design Trends Survey covering activity during the second quarter of 2017 that focused on emerging home features, systems and technologies.

Wireless features, automated lighting controls, and home automation are becoming more popular in residential projects; the most popular home products demonstrate energy management features. These are just some of the findings from The American Institute of Architects’ (AIA) Home Design Trends Survey covering activity during the second quarter of 2017 that focused on emerging home features, systems and technologies.

“As more automation products become available, homeowners continue to explore new ways to maintain their spaces with greater ease,” said said AIA Chief Economist, Kermit Baker, PhD, Hon. AIA.

The AIA Home Design Trend Survey is conducted quarterly with a panel of over 500 architecture firms that concentrate their practice in the residential sector. Residential architects are design leaders in shaping how homes function, look, and integrate into communities and this survey helps to identify emerging trends in the housing marketplace. Business conditions are also monitored on a quarterly basis. Future surveys will focus on community design trends (December 2017), and kitchen and bath trends (April 2018).

Most popular spaces

For the sixth consecutive year, outdoor living rooms have taken the top spot in terms of growing consumer interest among special function rooms. Following in second and third for special function rooms are mud rooms and home offices, respectively, as interest in these spaces has seemingly plateaued.

“Prior to the housing downturn, home offices maintained a solid hold as the most requested special function room,” said Baker. “Obviously new home technology offerings have influenced residential design trends, but the impact of the Great Recession can still be seen through homeowner interest in better use of existing space.”

“Not surprisingly demand for greater accessibility features continues to be strong,” Baker added. “Whether it’s a result of generally lower mobility or the aging baby-boomer population, homeowners are preparing for the future.”

Housing market business conditions

  • AIA Home Design Survey Index for Q2 2017 (any score above 50 is positive)
  • Billings: 60
  • Inquiries for new projects: 66 Regional averages: South (64.7), West (63.1), Midwest (58.8), Northeast (48.7)

 

“Activity in the additions and remodeling segments are picking up pace. This is a positive sign for the greater housing market in 2018,” Baker concluded.

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DOE Publishes GATEWAY Report on Tunable Lighting in Three Texas Classrooms

The U.S. Department of Energy’s GATEWAY program has released a new report on a trial installation of tunable-white LED lighting systems in three classrooms in the Carrollton-Farmers Branch Independent School District in Carrollton, TX, which provides valuable insights into the use of this technology in a real-world setting.

The U.S. Department of Energy’s GATEWAY program has released a new report on a trial installation of tunable-white LED lighting systems in three classrooms in the Carrollton-Farmers Branch Independent School District in Carrollton, TX, which provides valuable insights into the use of this technology in a real-world setting.

The LED systems were installed in August 2016 and provide the ability to vary the spectral power distribution (SPD) across four preset conditions associated with nominal CCTs of 3000 K, 3500 K, 4200 K, and 5000 K. The controls also provide for preset scenes to vary the on/off status and dimming level of different luminaire zones within the room, to better support such classroom functions as audiovisual presentations.

Among the findings:

• The reduction in input power for the tunable-white LED lighting system was estimated to be 58% relative to the incumbent fluorescent system, and was attributable to the higher efficacy of the LED luminaires and a reduction in illuminances, which previously exceeded IES-recommended levels.
• Dimming furthered the energy savings in each classroom.
• While the teachers’ usage of the controls varied widely as recorded by the monitoring system, in each case the lighting consistently operated with all or some of the luminaires turned off or dimmed for portions of the school day.
• When the control locations were more easily accessed by the teacher, the dimming level was varied more regularly.
• The teachers used the scene controls regularly but used the SPD controls infrequently.
• Color consistency for the tunable-white LED luminaires was very good, even over the dimming range, with only minor variations in CCT and Duv.
• The two teachers interviewed by DOE appreciated the ability to tailor the lighting to different classroom needs, and felt that the lighting and controls allowed the students to be engaged in choosing the settings for various classroom activities. Both teachers stated that the lighting system improved the overall learning environment.

Click here to get the report.

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DOE Evaluates LED Industrial Luminaires

I wrote the below news item for the September issue of tED Magazine. Reprinted with permission. High- and low-bay luminaires are common in industrial applications such as warehouses and manufacturing…

I wrote the below news item for the September issue of tED Magazine. Reprinted with permission.

High- and low-bay luminaires are common in industrial applications such as warehouses and manufacturing but also certain commercial applications such as big-box stores. “High bay” frequently refers to luminaires mounted at a height over 20 feet, “low bay” up to 20 feet. Due to the greater distance between the luminaire and the task, more light output is required—commonly 5,000 to 20,000 lumens per low-bay luminaire and 15,000 to 100,000 lumens per high-bay luminaire.

According to the U.S. Department of Energy (DOE), industrial luminaires represented 15 percent of all lighting energy consumption in 2015. These luminaires represent a significant amount of wattage and have long operating periods (at least 12 hours per day), making them a suitable candidate for replacement by more-efficient LED alternatives. DOE estimated LED penetration at six percent of this market in 2015, showing plenty of room for growth.

How do these LED alternatives perform? A new DOE CALiPER Snapshot Report profiles current average performance among LED industrial luminaires targeting incumbent HID and fluorescent technology. The results are based on more than 8,000 applicable products listed in the Lighting Facts database.

The report suggests strong improvement in this Lighting Facts category between April 2014 and March 2017, with big gains in light output while wattage remained fairly steady, resulting in an efficacy (lumens/W) increase. Mean efficacy was 115 lumens/W, a 20 percent improvement. In comparison, the mean efficacy of metal halide and fluorescent luminaires is around 70-90 lumens/W. This category is also more efficacious than linear, troffer, area/roadway and parking garage luminaires listed in Lighting Facts. In fact, Lighting Facts’ most efficacious product is a 22,000-lumen high-bay luminaire operating at 210 lumens/W.

Efficacy for about two-thirds of the products exceeded 105 lumens/W, the threshold for inclusion in the DesignLights Consortium’s (DLC) Qualified Products List (QPL). At the high end, about a quarter of the products were rated over 130 lumens/W, the threshold for DLC QPL Premium listing.

DOE found that a majority of the Lighting Facts-listed industrial luminaires emitted comparable light output as their metal halide and fluorescent counterparts. Mean light output was 18,000 lumens, far exceeding the DLC QPL minimum requirement of 5,000 lumens. About one-half produced 11,000-22,000 lumens. About two percent, or 150 products, emitted more than 50,000 lumens, which is able to match the output of 1000W metal halide luminaires.

Color quality for the Lighting Facts-listed industrial luminaires was similar to that of their conventional counterparts. About one-half offered a correlated color temperature (CCT) of at least 5000K, which is a very visually cool shade of white light. A significant portion of the remainder had a CCT of 4000K, with some available at 3000K and 3500K. About two-thirds of the luminaires offered a color rendering index (CRI) rating in the 80s, with most of the rest having a CRI in the 70s.

“In terms of the data captured by LED Lighting Facts and reported in the new Snapshot, LED industrial products offer a compelling alternative to incumbent products,” James Brodrick, DOE SSL Program manager wrote in his April 12, 2017 SSL Postings. “While the report focuses on basic photometric characteristics, choosing a product for a specific installation requires a more comprehensive analysis, including light distribution, projected lifetime, lumen maintenance and cost.”

Click here to read the report.

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DOE Publishes GATEWAY Report on OLEDs in an Office Space

The Department of Energy’s GATEWAY program recently published a new report on a project prominently featuring OLED lighting at the Rochester, NY offices of DeJoy, Knauf & Blood, LLP, an…

The Department of Energy’s GATEWAY program recently published a new report on a project prominently featuring OLED lighting at the Rochester, NY offices of DeJoy, Knauf & Blood, LLP, an accounting firm. One of the firm’s founding partners, David DeJoy, is also co-founder and CEO of OLEDWorks, the only US-based OLED manufacturer.

Among the key findings:

• The OLED panels are almost all driven by dedicated OLED drivers, and two of the luminaire types incorporate OLED panels with integral drivers, eliminating installation of a remote driver.
• The OLED luminaires are dimmable in almost all areas and exhibit virtually no flicker that would exceed the guidelines of the IEEE Standard P1789-2015 in either maximum or minimum output range of the dimmer.
• In nine months of operation, there have been no OLED panel or driver failures.
• While the efficacies of the OLED luminaires (21-58 lm/W) are well below those of the LED products (80-90 lm/W), projected efficacy for the next generation of OLED panels is 80-90 lm/W.
• The exposed OLED panels deliver soft, minimal-shadow lighting that makes faces and expressions visible and increases room brightness by delivering light to vertical surfaces. At the panel luminances used, this is achieved without employees reporting glare.
• Feedback from employees indicates they find the lighting system functional and enjoyable.

Click here to read the report.

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Norma Frank on Maintaining Streetlighting

Norma Frank, CLMC recently contributed a maintenance column to LD+A that talks about LED streetlighting maintenance. Traditionally, HID luminaires are cleaned when they are relamped, limiting light loss imposed by…

Norma Frank, CLMC recently contributed a maintenance column to LD+A that talks about LED streetlighting maintenance.

Traditionally, HID luminaires are cleaned when they are relamped, limiting light loss imposed by luminaire dirt depreciation (LDD). As stated above, LED luminaires promise much longer service life. They may present a different failure mode based on output rather than mortality along a curve that in time produces a steady failure rate. As a result, LDD’s significance as a light loss factor may be much greater for LED roadway and area luminaires, potentially reducing useful life.

She points out that what’s been missing is evidence upon which maintenance recommendations can be made, which was addressed in a study conducted by VTTI:

The IES engaged the Virginia Tech Transportation Institute to study and quantify LDD in a range of LED roadway luminaire types. The resulting report, Measure and Report Luminaire Dirt Depreciation (LDD) in LED Luminaires for Street and Roadway Lighting Applications (IES RES-1-16), provides an excellent start to understanding this issue and making maintenance recommendations.

Click here to read the article.

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CSIL: U.S. Luminaire Market $12.9 Billion in 2016

CSIL recently published the 2017 edition of its report, The Lighting Fixtures Market in the United States. Running about 200 pages, the report covers market size and trend, international trade,…

CSIL recently published the 2017 edition of its report, The Lighting Fixtures Market in the United States.

Running about 200 pages, the report covers market size and trend, international trade, distribution channels and reference prices, market segmentation and product characteristics, financial key indicators, sales data, short profiles and market shares of the major local and international players.

Excerpt:

“In 2016, the US production of lighting fixtures amounted to USD 12.9 billion. In 2015, it overcame the pre-crisis level and in 2016 continued its positive trend (+11.6% on the previous year). More specifically, the production of residential lighting remained stable, ending the negative trend that characterized the previous years; while the production of professional luminaires kept on growing at high rates. On the other hand, international trade faced a setback as both imports and exports contracted by respectively 9% and 8%. The value of domestic market in 2016 is estimated to be USD 20.3 billion, with a 3% increase compared to 2015. Even if positive, the growth registered in 2016 is much lower than the rates characterizing the previous years. Such a slowdown can be explained partly by the contraction of international trade and partly because of a softness in market demand that began in the second half of 2016. Such a weakness in internal demand is expected to continue in 2017, for which CSIL estimates an even slower growth (+2%). The market is expected to pick up in 2018 (+3.5%) and further improve in 2019 and 2020 (+4% each). The LED-based segment reached 51.4% of the total market in 2016; it has been growing especially for the outdoor lighting applications, where today it accounts for around 70% (10 percentage points more than the year before). Overall, in 2016, the growth rate of LED fixtures consumption was 26%.”

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2015 RECS Shows Energy-Efficient Lighting Adoption in Homes

Produced by the Department of Energy’s Energy Information Administration (EIA), the 2015 Residential Energy Consumption Survey (RECS) shows growing adoption of energy-efficient lighting in homes. The 2015 RECS shows that…

Produced by the Department of Energy’s Energy Information Administration (EIA), the 2015 Residential Energy Consumption Survey (RECS) shows growing adoption of energy-efficient lighting in homes. The 2015 RECS shows that a majority of U.S. homes feature more than one type of lamp, primarily a mix of incandescent and CFL. But LED adoption was growing, with the percentage of homes reporting at least one LED lamp installed approaching one-third.

Click here to learn about this and other interesting findings at the EIA website.

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IES Publishes Research on LED LDD

LED area and roadway lighting promises energy and maintenance cost savings, but the longevity of the LED light source presents a hitch. Traditionally, luminaires are cleaned upon relamping. If relamping…

LED area and roadway lighting promises energy and maintenance cost savings, but the longevity of the LED light source presents a hitch. Traditionally, luminaires are cleaned upon relamping. If relamping does not occur, dirt buildup becomes a more important maintenance factor. That being said, it is claimed LED luminaires are less prone to dirt accumulation. So what’s an appropriate cleaning interval?

In 2016, the Illuminating Engineering Society published an important maintenance study conducted by the Virginia Tech Transportation Institute as IES-RES-1-16. Specifically, VTTI looked at luminaire dirt depreciation (LDD) in LED roadway luminaires, impact on light distribution and the efficacy of different cleaning methods.

The study evaluated the impact on dirt and various cleaning methods on a range of luminaire types in both in a laboratory and in the field. While insufficient sampling did not yield new LDD curves, the authors were able to recommend a linear LDD rate for consideration. Key findings:

* LDD is different for LED luminaires and can be significant at end of life
* An alcohol solution or mild detergent solution can be safely applied to many luminaires and is more effective at mitigating LDD during cleaning than dry wipe or plain water
* Minimum potential LDD and change in lighting uniformity rates are +1 percent per year LDD and +1 percent per year uniformity change for luminaires with flat glass luminaire optics, and +3 percent per year LDD and no uniformity change for luminaires with no luminaire optics.

These findings and plenty more can be found in the study, which is available free for download here.

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2017 Lighting Outlook

tED Magazine recently published a lighting supplement that featured a 2017 Lighting Outlook, based on surveys conducted by the magazine and LightNOW of lighting manufacturers, electrical distributors and electrical contractors….

tED Magazine recently published a lighting supplement that featured a 2017 Lighting Outlook, based on surveys conducted by the magazine and LightNOW of lighting manufacturers, electrical distributors and electrical contractors. The results show a positive outlook for the year among all three market segments (example manufacturer results shown below).

Click here to check it out.

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