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Lighting Research Center
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mullar2@rpi.edu
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Troy, N.Y. -  7/10/2017

LRC Releases New Version of Circadian Stimulus Calculator with Expanded Functionality

The Lighting Research Center (LRC) at Rensselaer Polytechnic Institute has released a new version of its free, open-access circadian stimulus (CS) calculator with more robust and flexible functionality to help lighting professionals select light sources and light levels that will increase the potential for circadian-effective light exposure in architectural spaces.

The new calculator provides additional functions not included in the original version, including the ability to:

  • Calculate CS levels in rooms with multiple light sources
  • Combine pre-loaded SPDs from the calculator dropdown and user-supplied SPDs to provide one CS measurement and a single relative SPD
  • Save user SPDs in one file

Lighting professionals can use the CS calculator to compare the effectiveness of various light sources for stimulating the circadian system. The CS calculator utilizes the CS metric, a measure of how one-hour exposure to a light source of a certain SPD and light level stimulates the human circadian system, as measured by acute melatonin suppression. Unlike other proposed metrics, such as melanopic lux or melanopic content, the CS metric takes into account both the absolute and the spectral sensitivity of the circadian system, ranging from 0.1, the threshold for circadian system activation, to 0.7, response saturation. The CS metric was developed by the LRC from several lines of biophysical research, including those from basic retinal neurophysiology, has been validated in controlled experiments, and has been used successfully in numerous field applications by the LRC and others. The LRC has found that exposure to a CS of 0.3 or greater at the eye, for at least one hour in the early part of the day, is effective for stimulating the circadian system and is associated with clinically relevant outcomes, such as reductions in depression and agitation among persons with Alzheimer’s disease, entrainment in U.S. Navy submariners, and improved sleep and mood in office workers. Others have also shown that a CS of 0.3 or greater is associated with better sleep in older adults.

In the October 2016 issue of LD+A, LRC researchers discuss the CS metric and present useful tips to help designers create lighting plans that deliver prescribed amounts of CS. In the article, the authors note that, to use the calculator, designers should formulate a base condition by evaluating the space using the CS calculator and commercially available software such as AGi32. The design can later be fine-tuned by again using the CS calculator, while also accommodating IES recommendations, energy codes, and any client workspace specifications.

Resources

LD+A article: http://www.lrc.rpi.edu/resources/newsroom/LDA_CircadianStimulus_Oct2016.pdf

CS calculator: http://www.lrc.rpi.edu/programs/lightHealth/index.asp 


About the Lighting Research Center
The Lighting Research Center (LRC) at Rensselaer Polytechnic Institute is the world's leading center for lighting research and education. Established in 1988 by the New York State Energy Research and Development Authority (NYSERDA), the LRC conducts research in light and human health, transportation lighting and safety, solid-state lighting, energy efficiency, and plant health. LRC lighting scientists with multidisciplinary expertise in research, technology, design, and human factors, collaborate with a global network of leading manufacturers and government agencies, developing innovative lighting solutions for projects that range from the Boeing 787 Dreamliner to U.S. Navy submarines to hospital neonatal intensive-care units. In 1990, the LRC became the first university research center to offer graduate degrees in lighting and today, offers a M.S. in lighting and a Ph.D. to educate future leaders in lighting. Learn more at www.lrc.rpi.edu.

About Rensselaer Polytechnic Institute
Founded in 1824, Rensselaer Polytechnic Institute is America's first technological research university. Rensselaer encompasses five schools, 32 research centers, more than 145 academic programs, and a dynamic community made up of more than 7,900 students and more than 100,000 living alumni. Rensselaer faculty and alumni include more than 145 National Academy members, six members of the National Inventors Hall of Fame, six National Medal of Technology winners, five National Medal of Science winners, and a Nobel Prize winner in Physics. With nearly 200 years of experience advancing scientific and technological knowledge, Rensselaer remains focused on addressing global challenges with a spirit of ingenuity and collaboration.