Skip to main content
OSTI.GOVU.S. Department of Energy Office of Scientific and Technical Information
U.S. Department of Energy
Office of Scientific and Technical Information
 

The Position Index of Overhead LED Sources Under Different Spectral Power Distributions and Background Luminances

Journal Article · · LEUKOS
 [1];  [1];  [1];  [1];  [1]
  1. Pacific Northwest National Laboratory (PNNL), Portland, OR (United States)
+ Show Author Affiliations
The position index was developed by Luckiesh and Guth in 1949 and is widely used in discomfort glare models to account for the position of the glare source when predicting the presence and magnitude of visual discomfort. The applicability of this index to modern LED sources has not been evaluated; however, it is of concern due to potentially higher luminance levels of LEDs compared to the sources used by Luckiesh and Guth. Furthermore, the position index of overhead sources beyond 60° above the line of sight has not been quantified. An experiment was conducted using a hemispherical apparatus with LED sources. The position of the light source, background luminance, the spectral power distribution, and anchor (starting luminance level before adjustment) were varied and two procedures were used to determine the position index of these sources. Data from 29 participants indicate that overhead sources located 60° or 80° above the line of sight were detectable and their position index can be quantified. The position index values were found to be higher than those reported in previous studies, suggesting that anchor bias and the small luminance range in previous studies likely influenced their position index values. No differences were found in position index values by spectral power distribution, background luminance, participant age group, or eyeglass wearing. In conclusion, the position index values reported in this study account for range and anchor bias, providing a better estimate that should be incorporated into discomfort glare models.
Research Organization:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Building Technologies Office
Grant/Contract Number:
AC05-76RL01830
OSTI ID:
3006469
Report Number(s):
PNNL-SA--187014
Journal Information:
LEUKOS, Journal Name: LEUKOS Journal Issue: 1 Vol. 21; ISSN 1550-2716; ISSN 1550-2724
Publisher:
Illuminating Engineering Society of North AmericaCopyright Statement
Country of Publication:
United States
Language:
English

References (26)

P.30: Effect of the Correlated Color Temperature of Light on Overhead Glare in Offices journal June 2013
The position index of a glare source at the borderline between comfort and discomfort (BCD) in the whole visual field journal May 2009
An epidemiological approach to daylight discomfort glare journal February 2017
Evaluation methods and development of a new glare prediction model for daylight environments with the use of CCD cameras journal July 2006
A Purkinje image-based system for an assessment of the density and transmittance spectra of the human crystalline lens in vivo journal October 2020
Discomfort Glare: Range Effects journal January 1981
The Influence of Spectral Composition on Discomfort Glare for Large-Size Sources journal January 1996
The Effect of Overhead Glare on Visual Discomfort journal July 2000
Overhead Glare and Visual Discomfort journal January 2003
Spectral sensitivity for extrafoveal discomfort glare journal July 2009
Review of Factors Influencing Discomfort Glare Perception from Daylight journal February 2018
Measuring Discomfort from Glare: Recommendations for Good Practice journal September 2020
Discomfort glare: What do we actually know? journal April 2012
Effect of different coloured luminous surrounds on LED discomfort glare perception journal February 2013
Discomfort glare evaluation: The influence of anchor bias in luminance adjustments journal October 2017
Recommended methods for conducting human factors experiments on the subjective evaluation of colour rendition journal June 2021
What to measure and report in studies of discomfort from glare for pedestrian applications journal June 2022
Predicting discomfort from glare with pedestrian-scale lighting: A comparison of candidate models using four independent datasets journal April 2023
Discomfort Glare in Lighted Streets journal January 1940
Review on age-related differences in non-visual effects of light: melatonin suppression, circadian phase shift and pupillary light reflex in children to older adults journal June 2023
Chromatic adaptation and the relationship between lamp spectrum and brightness journal March 2006
Sensitivity Analysis of Glare Rating Metrics journal October 2005
Research Methods to Avoid Bias in Categorical Ratings of Brightness journal January 2009
Geometrical Assessment of Ocular Exposure to Envirmmental UV Radiation -Implications for Ophthalmic Epidemiology journal January 1999
Discomfort and Disability Glare from Halogen and HID Headlamp Systems conference March 2002
Headlamp Parameters and Glare conference March 2004

Similar Records

The Effect of Luminance Pattern on Nighttime Discomfort Glare Response (CRADA Final Report)
Technical Report · Mon Sep 29 20:00:00 EDT 2025 · OSTI ID:3006359
Discomfort Glare: What Do We Actually Know?
Journal Article · Thu Apr 19 00:00:00 EDT 2012 · Lighting Research and Technology · OSTI ID:1225620
White LEDs with limit luminous efficacy
Journal Article · Thu Jan 14 23:00:00 EST 2016 · AIP Conference Proceedings · OSTI ID:22494447

Related Subjects

Discomfort glare
LED
overhead glare
position index