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LEUKOS - The journal of the Illuminating Engineering Society of North America
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The Journal of the Illuminating Engineering Society of North America    Volume 2     Number 2     OCTOBER 2005

Publisher's data


Editorial:

LUMINOUS PENURY

Articles:

LIGHT, LIGHTING, AND HEALTH: ISSUES FOR CONSIDERATION

J.A. VEITCH

Research into the effects of light on biology, behavior, and health is a rapidly-advancing field. This paper sets out issues for consideration in three areas: research areas in which knowledge is needed; topics that the lighting community should address to lay a strong foundation for application of this knowledge; and, ways in which the lighting community might facilitate the interdisciplinary work needed in order for basic research to lead to application.

REFLECTIONS ON RELATIONSHIPS IN BEHAVIORAL LIGHTING RESEARCH

P.R. BOYCE

Science is the study of relationships. The reality, strength, and stability of any claimed scientific relationship can be evaluated on the basis of such characteristics as statistical significance, effect size, magnitude and direction, reliability, cause, convergence, specificity and predictability. Relationships come in different forms. The problems inherent in relationships based on vague, remote, or diluted variables are considered. A checklist of questions that should be asked about any claimed scientific relationship is given.

SENSITIVITY ANALYSIS OF GLARE RATING METRICS

I. ASHDOWN

Visual Comfort Probability (VCP) and Unified Glare Rating (UGR) metrics can be sensitive to small changes in observer position, luminous intensity distribution, and luminaire discretization. Whereas these metrics were originally intended for comparison of luminaires under standardized conditions, they are nowadays offered as photometric analysis tools in lighting design software. The sensitivity of these metrics to changes in input parameters is examined, and recommended guidelines for their calculation and interpretation are proposed.

LIGHTING FOR THE ELDERLY: THE EFFECTS OF LIGHT SOURCE SPECTRUM AND ILLUMINANCE ON COLOR DISCRIMINATION AND PREFERENCE

D.A. O’CONNOR AND R.G. DAVIS

The effects of light source type and illuminance were investigated for a group of elderly subjects and a group of young subjects. Three light sources were used—a halogen source, a 3000K compact fluorescent source, and a 5000K compact fluorescent source—at three illuminances. Subjects completed a color discrimination task and several preference rating scales. Results showed that changes in illuminance produced much larger changes in subjects’ performance and preference than changes in light source, and that the color discrimination performance of the elderly group was more strongly affected by illuminance than that of the young group.

VALIDATION OF HIGH DYNAMIC RANGE IMAGING TO LUMINANCE MEASUREMENT

S. ANAOKAR AND M. MOECK

High dynamic range imaging is a set of techniques that allows for a far greater dynamic range of exposure than normal digital imaging techniques. The intention is to accurately represent the dynamic range of lighting levels found in real scenes, ranging from direct sunlight to deep shadows. Various software packages have emerged that translate these HDR images into high resolution luminance maps. This paper tests the accuracy of one such package, taking into consideration different Munsell hues, values, and chroma. It investigates the impact of different light spectra, spatial frequency, vignetting, and thermal noise on the accuracy of luminance measurements and determines the potential errors.

SHORT-WAVELENGTH CONTENT OF LED HEADLAMPS AND DISCOMFORT GLARE

M. SIVAK, B. SCHOETTLE, T. MINODA, AND M.J. FLANNAGAN

Three light-emitting diode (LED) headlamps were tested (with correlated color temperatures of 4000, 4800, and 6600 K), as well as a tungsten-halogen headlamp and a high intensity discharge (HID) headlamp. Subjects seated in a stationary vehicle rated discomfort from brief presentations of stimuli that produced illuminances of 0.25, 0.5, and 1 lux. As predicted in our previous analytical study, we found that—when they appear bluer than current tungsten-halogen or HID headlamps—LED headlamps tend to produce more discomfort glare.

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