Industry News




 

04/24/2013

New LED Lamps Light Street, Not Sky

 
New LED streetlamps focus on lighting specific areas so that nothing goes to waste.  Will these energy savers become the norm?

Let this stat sink in: 98% of lamp's energy goes to lighting the street instead of the night sky

Streetlights illuminate the night, shining upon roadways and sidewalks across the world, but these ubiquitous elements of the urban environment are notoriously inefficient and major contributors to light pollution that washes out the night sky. Recent innovations in light emitting diodes (LEDs) have improved the energy efficiency of streetlights, but, until now, their glow still wastefully radiated beyond the intended area.

A team of researchers from Taiwan and Mexico has developed a new lighting system design that harnesses high-efficiency LEDs and ensures they shine only where they're needed, sparing surrounding homes and the evening sky from unwanted illumination. The team reported their findings today in the Optical Society's (OSA) open-access journal Optics Express.

A unique feature of the new LED system is its adaptability to different street lamp layouts, "to all kinds of streets and roads, providing a uniform illumination with high energy efficiency," says co-author Ching-Cherng Sun of National Central University in Taiwan. For example, some modern lamps that line a thoroughfare or suburban sidewalk lean into the middle of the road, lighting the street from above.

But more often, lamps are posted to one side of a street, or alternating in a "zig-zag" pattern from one side to the other – a layout that may be more efficient for roads with high traffic flow. The new design provides flexibility to be used for different illumination requests while maintaining a high efficiency, Sun says.

The proposed lamp is based on a novel three-part lighting fixture. The first part contains a cluster of LEDs, each of which is fitted with a special lens, called a Total Internal Reflection (TIR) lens, that focuses the light so the rays are parallel to one another instead of intersecting—a process called collimation. These lens-covered LEDs are mounted inside a reflecting cavity, which "recycles" the light and ensures that as much of it as possible is used to illuminate the target.

Finally, as the light leaves the lamp it passes through a diffuser or filter that cuts down on unwanted glare. The combination of collimation and filtering also allows researchers to control the beam's shape: the present design yields a rectangular light pattern ideally suited for street lighting, the researchers say.

The team tested their design's performance by analyzing how little the beam would spread as it hit its target—a road or sidewalk 10 meters or more away from the source of the light. They quantified the lamp's performance using something called optical utilization factor (OUF), a number that describes the relationship between the flow rate of light at the target and the flow rate of light coming directly out of the LEDs.

Higher OUF indicates better performance. Simulations show that the new design achieves an OUF of 51 to 81 percent, greatly outperforming a recent "excellent" design that reached 45 percent. Furthermore, the proposed streetlamp meets high expectations for power and brightness. And light pollution is also significantly reduced: for conventional street lamps, up to a fifth of their total energy is directed horizontally or upward into the sky. The best LED streetlamps reduce this to a tenth of their total energy. In the new model, just 2 percent of the lamp's total energy would contribute to light pollution.

In addition to cutting light pollution and glare, the new model could also save energy. "A general LED street light could reduce power consumption by 40 to 60 percent," Sun says; the increased efficiency of the proposed design would likely save an additional 10 to 50 percent. Furthermore, he adds, the module would be simple to fabricate, since it comprises just four parts, including a type of LED bulb commonly used in the lighting industry.

Sun's team expects to finish a prototype of their design in the next 3 to 6 months, and to begin practical installations of the new street lamp as early as next year.

 

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Our mission is to help our customers manage their buildings' energy costs, improve reliability, and enhance performance while having a positive impact on the environment.
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04/16/2014

The U.S. Army plans to start development of a solar array that will provide about 25% of the annual installation electricity requirement of Fort Huachuca, Arizona.

04/15/2014

The EPA's annual greenhouse gas emissions report is now available.

04/14/2014

Are you what some would call a “climate-change denier”? If so, you'll want to read this.

04/10/2014
Los Angeles has remained the top city for ENERGY STAR certified building since 2008, while Washington, D.C. continues to hold onto second place for the fifth consecutive year, according to a new list released by the EPA.
04/09/2014
Green construction has grown massively over a short period of time.
04/07/2014
Field demonstrations of newly proven energy-efficient technologies are yielding valuable results for the U.S. Navy, helping it meet energy goals.
04/03/2014
Building owners in Chicago now have more options when it comes to getting their building energy data verified.
04/01/2014
According to a new report from Eaton, such outages are up 15% in 2013 over 2012 and over half of those surveyed believe that downtime could have been prevented.
03/31/2014
The newly revised ANSI/ASHRAE Standard 105-2014, Standard Methods of Determining, Expressing, and Comparing Building Energy Performance and Greenhouse Gas Emissions, aims to provide a consistent method of measuring, expressing, and comparing the energy performance of buildings.
03/27/2014
Facility managers face an every expanding array of sustainability choices and challenges, but for the next generation of FMs, green practices could be second nature as sustainability literacy enters the K-12 school system.
03/25/2014
While the economic recession explains the decline in sales in 2008 and 2009, it is much less clear why sales have continued to fall.
03/24/2014
University of Washington (UW) scientists have built the thinnest known LED that can be used as a source of light energy in electronics.
03/21/2014
Mississippi Governor Phil Bryant signed Senate Bill 2378 into law, effectively enacting the state’s first building code.
03/19/2014
In an attempt to improve building energy performance, the DOE’s National Renewable Energy Laboratory has released a web-based tool called the Technology Performance Exchange, or TPEx.
03/18/2014
Could green building practices pose unanticipated life-safety hazards?
03/13/2014
Worried about workplace violence in your facility? Researchers have discovered that “mindfully observing” high-risk employees can avert danger and workplace violence.
03/11/2014
Through the DOE’s Building Energy Codes Program, every dollar the DOE has spent on building energy codes over the past two decades has resulted in $400 in energy cost savings.
03/07/2014
It is possible to harvest energy from Earth's thermal infrared emission into outer space, according to new research from the Harvard School of Engineering and Applied Sciences.
03/05/2014
Is your building prepared to handle an emergency?
03/04/2014
NASCAR revealed five newly installed charging stations for employee use.
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