Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Proven Method Available to Significantly Reduce Energy Consumption in Street Lighting

04.11.2009
Improved measurement techniques could cut costs and improve visibility perception

Experts at Rensselaer Polytechnic Institute’s Lighting Research Center (LRC) estimate that about half of the approximately 13 million streetlights in America have the opportunity to significantly reduce energy consumption by as much as 50 percent, translating to an annual savings of 1 billion kWh, and a reduction in power plant CO2 emissions of 546,000 tons per year.

LRC researchers demonstrated in multiple field tests that, by using what they describe as a Unified System of Photometry, a street lighting system can be designed to reduce energy use while maintaining or improving perceptions of visibility, safety, and security.

“In nighttime conditions, the human eye is more sensitive to short-wavelength light, which produces ‘cool’ tones like blue or green, as opposed to long-wavelength light, which produces ‘warm’ tones like yellow and red,” said LRC Director of Energy Programs Peter Morante. “By replacing traditional, yellowish high-pressure sodium (HPS) lights with ‘cool’ white light sources, such as induction, fluorescent, ceramic metal halide, or LEDs, we can actually reduce the amount of electric power used for lighting while maintaining or even improving visibility in nighttime conditions.”

The eye has two types of visual receptors in the retina, cones and rods. The current system of photometry—the measurement of visible light in terms of human perception for certain activities like reading and seeing fine details—is based on how some cones respond to different wavelengths. Cones are the dominant visual receptor under photopic (daylight) lighting conditions. Rods function primarily under very dim conditions. According to Morante, it is necessary to redefine the luminous efficacy functions needed for nighttime applications where electric lighting is used and both rods and cones contribute to vision The LRC’s Unified System of Photometry was designed to characterize light at any level, including the mesopic level where both rods and cones operate.

LRC field demonstration results from the past few years in rural and suburban areas of Connecticut, Massachusetts, and Texas verified that by implementing the Unified System of Photometry the street lighting system consumed 30 to 50 percent less electric power and the residents believed they could see better and said they felt safer, when compared to lighting systems designed using the traditional system of photometry. The Unified System of Photometry provides an objective method for optimizing light source spectra for minimal energy use while maintaining good visibility, according to the LRC researcher team.

There is now renewed interest in the research, according to Morante, as an increasing number of cities and towns across the country are examining ways to save energy either through a reduction or a change in outdoor lighting. And the interest seems to be spreading.

According to LRC Director Mark Rea, Ph.D., researchers around the world are also concluding that the current system of photometry could use some updating to better characterize light source performance under nighttime conditions. The International Commission on Illumination, also known as the CIE from its French title, the Commission Internationale de l'Eclairage, will be releasing its own form of unified photometry for outdoor lighting, explained Rea, a long-standing CIE member.

A full report detailing energy use, consumer acceptance and perceptions, visibility, and light levels for one of the LRC’s field tests in the City of Groton, Connecticut, was published last year and is available for free download at: www.lrc.rpi.edu/researchAreas/pdf/GrotonFinalReport.pdf.

In the LRC field studies, the mesopic street lighting system met all utility requirements and, in addition to significant reductions in energy consumption, was preferred by residents over the yellow-appearing HPS system.

The following selected technical papers explain the Unified System of Photometry:

• Rea, M., J.D. Bullough, J.P. Freyssinier, and A. Bierman. 2004. A proposed Unified System of Photometry. Lighting Research and Technology 36(2): 85-111.

• Rea, M., Z. Yuan, and A. Bierman. 2009. The Unified System of Photometry Applied to Remote Airfield Lighting. Lighting Research and Technology 41(1): 51-70.

In January 2009, the Alliance for Solid-State Illumination Systems and Technologies (ASSIST) published a volume in its ASSIST recommends series, “Outdoor Lighting: Visual Efficacy,” which also describes the Unified System of Photometry. The publication can be downloaded for free by visiting http://www.lrc.rpi.edu/programs/solidstate/assist/recommends/outdoorlighting.asp.

Learn more about LRC’s outdoor and street lighting research at these LRC Program pages:
• LRC Automotive and Street Lighting: www.lrc.rpi.edu/researchAreas/automotive.asp

• LRC Outdoor Lighting: www.lrc.rpi.edu/researchAreas/outdoor.asp

About the Lighting Research Center
The Lighting Research Center (LRC) is part of Rensselaer Polytechnic Institute of Troy, N.Y., and is the leading university-based research center devoted to lighting. The LRC offers the world's premier graduate education in lighting, including one- and two-year master's programs and a Ph.D. program. Since 1988 the LRC has built an international reputation as a reliable source for objective information about lighting technologies, applications, and products. The LRC also provides training programs for government agencies, utilities, contractors, lighting designers, and other lighting professionals.

Mary Cimo | Newswise Science News
Further information:
http://www.lrc.rpi.edu

More articles from Power and Electrical Engineering:

nachricht Did you know that the wrapping of Easter eggs benefits from specialty light sources?
13.04.2017 | Heraeus Noblelight GmbH

nachricht To e-, or not to e-, the question for the exotic 'Si-III' phase of silicon
05.04.2017 | Carnegie Institution for Science

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Early organic carbon got deep burial in mantle

25.04.2017 | Earth Sciences

A room with a view - or how cultural differences matter in room size perception

25.04.2017 | Life Sciences

Warm winds: New insight into what weakens Antarctic ice shelves

25.04.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>