Engineering topics

Royer, Michael P.

Publications and source records attributed to Royer, Michael P..

5 records

DOE OSTI2022

A method and tool to determine the colorimetric and photobiological properties of light transmitted through glass and other optical materials

Here we describe a framework and provides a computational tool to characterize the color quality and biological potential of light that is transmitted through glass and other optical materials. The IES TM-30 framework and Excel computation tool were adapted to evaluate color quality, with measures from CIE S 026, UL 24480, and the WELL Building Standard v2 added to evaluate biological potential. The user selects a pre-transmittance spectral power distribution (SPD), such as for a CIE D-Series Illuminant, Planckian radiation, electric lamp, or measurement of daylight at a building site. The tool allows a user to populate a database with spectral data for glazing or other optical materials, comprising spectral transmission and the spectral reflectance of both sides. The user creates a unit with one, two, or three panes of glazing or other optical materials, and the tool calculates the composite spectral transmittance accounting for reflections between materials. The tool computes the transmitted SPD, then determines colorimetric and photobiological outputs using the transmitted SPD as the test source. Glass, window, and skylight manufacturers can employ the tool to optimize glazing spectral transmission to achieve intentional colorimetric and photobiological performance with transmitted light. Electric lighting manufacturers, designers, and researchers can use the tool to evaluate the impact of glazing units and other optical materials on the color quality and biological potential of transmitted light.

36 MATERIALS SCIENCE↗

DOE OSTI2021

A better future

We report in some ways, lighting is dramatically different than it was at the turn of the century: LEDs are now ubiquitous and there is growing awareness of the important role of lighting beyond facilitating visual tasks. In other ways, lighting science and practice have not changed in decades. Many core lighting metrics with known limitations—such as V λ (97 years old), the 1931 CIE 2° standard colorimetric observer (90 years old), and CRI (47 years old)—remain in use despite the availability of alternatives based on more recent research. There are also the practices of specifying the quantity of illumination based on average horizontal illuminance, managing contrast with maximum to minimum or similar ratios, and addressing energy use with lighting power density. Never mind the traditional lamp and luminaire form factors that still predominate despite the very different emission characteristics of LEDs. As LEDs mature in the next decades, outdated metrics and practices could become an even greater impediment to optimizing the value generated per Watt—for performance, productivity, wellbeing, or satisfaction.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2021

Can color-mixed system technology improve lighting quality and energy efficiency?

LEDs have made tremendous inroads in the architectural lighting market but have yet to reach their potentials for energy efficiency or delivering benefit to building occupants. Progress in color-mixed systems can contribute to both goals with anticipated benefits for luminous efficacy, application efficacy, human health, plant growth, and general satisfaction. These benefits can be achieved because unlike static, broadband white light emitters that are ubiquitous today, color-mixed systems offer spectral flexibility. The prospect of widespread implementation of tunable lighting by the 2030s is exciting, but it will require overcoming several challenges and greater responsibility from the specifier. Now is the time to begin planning and developing effective strategies for deploying color-mixed LED systems. Here we examine the pros, cons, and development path for this technology.

Royer, Michael P.↗

DOE OSTI2021

Examining Perceptual Luminance Uniformity of Simulated Luminaire Patterns

Luminaire luminance uniformity is an important aspect that can affect perceived lighting quality, discomfort glare, and efficacy. While several metrics have been proposed to characterize luminance uniformity, previous studies have shown that current metrics such as Max:Min or Avg:Min luminance ratios can be insensitive to important differences in luminance gradient that may affect perceived uniformity. In an attempt to resolve this issue, previous studies incorporated a contrast sensitivity function for the human eye based on spatial frequency, such as in the UHVS metric; however, this metric has not been comprehensively studied in relation to perceived uniformity ratings. The study presented in this paper aimed to examine the relationship between the UHVS metric and perceived uniformity ratings. Specifically, the study used a web-based questionnaire that presented simulated luminance patterns and asked participants to assess uniformity using a two-alternative forced-choice procedure. Responses were collected and analyzed from 94 participants. The results showed a significant correlation and relationship between the UHVS metric and perceived uniformity. However, comparisons between patterns that had similar UHVS and between patterns that had larger differences in UHVS did not yield consistent results. These results suggest that the UHVS metric might be used for general guidance but may warrant further studies to better understand its sensitivity and improve its alignment with perceived uniformity ratings.

Abboushi, Belal K.↗

DOE OSTI2020

Readying for a Color-Mixed Future Luminous Efficacy on the Horizon

If history repeats itself, lighting 20 years from now will be substantially different than what it is today. Twenty years ago, LEDs were a novelty, not quite ready for use in architectural lighting systems. A little more than 20 years before that, rare-earth tri-phosphor T8 fluorescent lamps were beginning to replace broadband halophosphate T12 fluorescent lamps, which themselves became the predominant source of lumens in the United States around the middle of the last century. At each step in this evolution, new lighting metrics have been developed to address differences in performance, and they in turn guided technology development. For example, in the 1960s, it was CRI and CCT, and more recently it has been LM-79 and TM-30.

Royer, Michael P.↗