|LED Lighting Applications and Demonstration
Tools to Evaluate Outdoor Lighting
A global trend to replace conventional outdoor lighting with LEDs led to the development of tools for evaluating and selecting both LED and conventional outdoor luminaires: a new metric rooted in the concept of application efficacy, a free online calculator based on this metric, and methods to assess discomfort glare and mesopic efficiency.
The Potential of Outdoor Lighting for Stimulating the Human Circadian System
The Lighting Research Center and ASSIST sought to provide a quantitative analysis of the impact of light at night, particularly from streetlights of different spectral power distributions, on the human circadian system.
Snap-In LED Module for Outdoor Luminaires
LRC researchers developed an energy-efficient, snap-in LED module for lighting systems using the LRC’s patented scattered photon extraction (SPE) technology. Each individual module can be easily fixed or disassembled from the luminaire as needed.
Effect of Colored Luminous Surrounds on LED Discomfort Glare
The LRC investigated the connection between discomfort glare perception and the SPD of a luminous area surrounding a white LED array, taking into consideration the luminous surround spectrum, brightness perception, and the effect of a luminous surround on an LED array glare stimulus.
Reducing Flicker from AC LEDs
LRC researchers sought to create a new circuit design for AC LEDs with targeted benchmarks to ensure acceptable flicker levels and system performance.
LED Lighting for Multi-family Housing
The LRC and ASSIST have published a guide for multi-family housing owners and facility managers on how to upgrade to LED lighting.
Electronic Walls and Ceilings Offer Adaptable Solid-State Lighting
Solid-state lighting offers new ways to think about how we light our spaces. The LRC has developed a flexible interior infrastructure that integrates solid-state lighting with other building materials and systems, allowing for rapid reconfigurations of built-in lighting.
Understanding White Light Source Color Rendering and Appearance
In 2002, the LRC and ASSIST began a long-term study of subjective preferences using psychophysical experiments to understand how observers perceive white light sources and what they prefer in terms of object color rendering and the white hue or tint of a light source.
Perceptions of White Light Sources of Different Color Temperatures
The Lighting Research Center and ASSIST conducted a series of experiments to measure perceptions of white illumination from light sources of different CCTs.
Dimming Behaviors of LED Replacement Lamps
LRC researchers investigated the dimming performance of commercially available LED and CFL replacement lamps and the performance variations among different dimmers. Human factors experiments were then designed to determine users' expectations for lamp dimming, which became the basis for ASSIST's technology-neutral lamp dimming recommendation.
LED Replacement for Linear Fluorescent Lamps
The LRC investigated solutions for and built a prototype of an LED replacement for 4-foot linear T8 fluorescent lamps using remote phosphor technology.
Designing a Better Recessed Downlight Using SPE Technology
The LRC developed a highly efficient LED downlight to replace an equivalent 75W incandescent or 26–32W CFL downlight.
Development of an Energy-Efficent, Ultra-thin LED Luminaire
The LRC explored a novel "ultra-thin" LED luminaire concept to replace downlight, accent, and wall-wash luminaires using incandescent and halogen technologies.
LED Lighting for Supermarket Freezer Display Cases
In 2002, the LRC began investigating the possibility of using LEDs in supermarket refrigerator and freezer display cases, where fluorescent lamps are a common but not ideal technology for cold environments.
Efficiency Testing for Freezer Case Lighting
Current industry practice rewards freezer lighting for its luminaire efficacy measured at room temperature. To obtain realistic data, the evaluation method must consider the application environment. ASSIST has published a technology-neutral method for evaluating the performance of luminaires used in freezer cases.
LED Systems for Greenhouse Plant Lighting
The LRC investigated the potential use of LED lighting systems for plants grown in greenhouses.
Improving LED Light Output and Efficacy Through SPE™
The LRC’s Scattered Photon Extraction (SPE™) improves LED light output by up to 60% through the extraction of backscattered photons. The innovative package design combines remote-phosphor technology with optimally shaped secondary optics.
Estimating LED Life
Early 21st century claims purported LED lighting to last 100,000 hours. The LRC, however, showed that LED life could be far less, depending on the luminaire design and installation. Through its Alliance for Solid-State Illumination Systems and Technologies (ASSIST), the LRC developed a recommended test method for estimating LED life for general lighting.
Degradation of LED Encapsulants
This study evaluated the effects of short-wavelength radiation and thermal stress on the degradation of an epoxy LED encapsulant, with and without phosphor in the medium.
Managing Heat in the LED System’s Remote Phosphor Layer
LRC researchers investigated methods to reduce the operating temperature of the remote phosphor layer and the resulting effects on LED performance.
Measuring LED Lens Surface Temperature with Thermocouples
The LRC conducted a study to understand the problems in using thermocouples to measure LED lens surface temperature and to find a solution to improve measurement accuracy.
Predicting LED System Failure through Real-time Changes
This study sought to identify electrical and thermal parameters in a single-die InGaN LED package that could give real-time signals of impending failure while in use.
Minimizing Flicker from SSL Systems
To assess the ability of individuals to perceive light source flicker directly and indirectly, and to understand the role of flicker characteristics on comfort, the LRC conducted laboratory studies under flickering patterns differing in frequency, modulation depth, duty cycle and waveform shape.
Estimating the Junction Temperature of AC LEDs
LRC researchers developed an alternative method of estimating AC LED junction temperature and thermal resistance.
SPETM Technology for Mixed-Color LEDs
The LRC hypothesized that a new approach using SPETM optics with optical diffusers could improve the spatial color uniformity of mixed-color LED systems without sacrificing much efficiency.
Extracting More Light From LEDs
An LED’s efficiency is limited by its inability to extract some of the light generated by the chip’s active layer. One reason for this light loss is the refractive index mismatch between the chip and the surrounding medium. The LRC conducted a two-part study: an optical ray-tracing analysis to understand what factors influence light extraction, and a laboratory study to quantify the refractive indices of commercial encapsulants.
White SPE LEDs with Multi-phosphor Layers
Recent LEDs have improved their color properties by combining multiple phosphors instead of using a single yellow phosphor. The common practice is to create a random mixture of multiple phosphors that is spread around the LED chip. In this study, LRC researchers questioned the impact of randomly mixing the phosphors versus stacking different phosphors in layers, as well as the effect of the order of the layers.
Techniques to Improve Green Phosphor for Superior White LEDs
LRC researchers investigated a “green” phosphor for its performance and ability to improve the efficacy and color of a white LED.
Optimizing Remote-phosphor LEDs with Optical Ray-tracing
LRC researchers developed a method to determine the MFP of a phosphor layer that can be used in optical ray-tracing analysis to obtain accurate results.
Accelerated Life-test Method for LED Drivers
The LRC conducted a study to understand what factors influence the failure modes of standalone LED drivers, and to develop an accelerated test method to predict the useful life of an LED driver.
Bringing Advanced, Energy-Efficient LED Lighting to Aviation
Since 2005, the LRC has conducted lighting research as part of the Federal Aviation Administration’s Center of Excellence for Airport Technology. Research in the areas of solid-state lighting and vision science are providing new lighting solutions that benefit the aviation industry.
Long-term Evaluation of LED Airfield Luminaires
LRC researchers conducted a long-term performance evaluation of LED airfield luminaires under operating temperatures that covered a range of realistic conditions, as a first step toward establishing a functional definition of useful life for these lighting systems.
Standalone PV-LED Lighting for Aviation
The LRC conducted a study to understand the factors that affect the performance of standalone PV-LED lighting systems, especially how the charge controller affects total system performance.
LED Blue Taxiway Luminaires
The LRC explored new luminaire designs and methods of transferring heat from the LED junction to the optics in order to minimize snow and ice buildup on blue airport taxiway luminaires.
Remote Airfield Lighting Systems
Many remote communities, such as those in Alaska, depend on air transport for business and emergency aid. Night landings at remote airfields are often dangerous. The LRC explored ways to help make night landings at remote airports safer and area communities more accessible.
Redefining White Light Chromaticity Boundaries for Aviation
The LRC conducted a human factors investigation of the boundaries in chromaticity space that people perceive as white and recommended new aviation white boundaries that were independent of the color limitations of incandescent sources.
Requirements for Runway Guard Lights
The LRC conducted laboratory human factors experiments to determine the appropriate luminous intensity and other operating parameters of LEDs used in runway guard lights in order to provide acceptable visibility and safety.
LED Aviation Signal Brightness
LED signal lights have narrower spectral distributions than incandescent (filtered and unfiltered) signals, resulting in more saturated colors. Since color saturation increases the perception of brightness, the Federal Aviation Administration (FAA) asked the LRC to develop a set of “brightness correction factors” for white, green, and blue signal lights.
LED Aircraft Cabin Lighting for the 787 Dreamliner
The LRC partnered with Boeing to develop innovative and efficient lighting solutions for use aboard the 787 Dreamliner jet, a next-generation commercial airplane with energy-efficiency and passenger experience in mind.
Measurement Method for Characterizing OLED Panels for Lighting Applications
LRC researchers investigated an imaging-based photometric and colorimetric measurement method for long-term testing of OLED panels.
Professional LED Lighting Education
In 2001, the LRC began offering the first unbiased, research-based workshop for lighting designers, architects, and engineers on how to build successful LED lighting products and applications.
LED Lighting Summer Internship for Undergraduates
An eight-week paid summer internship program for undergraduates and recent graduates from engineering, physics, science, architecture, or industrial design who are interested in conducting research and learning more about the LED lighting field.
Outdoor Lighting Institute
A two-day course for engineers, lighting designers, municipal officials, utility personnel and others that provides the knowledge and tools needed to develop outdoor lighting installations that substantially reduce energy use and light pollution while improving safety and security
A two-day, hands-on course about the latest developments in photometric testing and evaluation, including new testing requirements for solid-state light sources and systems.
International SSL Activities
In its global activities, the LRC provides information, technical training and guidance, and works to bring together public and private enterprises to focus on solutions to increase consumer accessibility to safe and energy-efficient lighting, particularly LED lighting systems that can work fluidly with off-grid or on-site renewable energy power generation systems.
Supporting South Asia Through LED Lighting Technology
In 2009, the LRC became the knowledge partner of the Regional Centre for Lighting (RCL) in South Asia, a Sri Lanka-based lighting research facility funded by the U.S. Agency for International Development and the Sri Lanka Sustainable Energy Authority. The RCL’s mission is to advance sustainable lighting and make it affordable to improve the well-being of the citizens and the eight countries within the region.
Testing LED Lighting Products for Lighting Africa Program
Lighting Africa, a joint program of the ICF and The World Bank, is aimed at helping 250 million people in Sub-Saharan Africa gain access to non-fossil fuel-based, low cost, high quality, safe, and reliable lighting products by the year 2030. The LRC is supporting the project through lab testing for quality assurance of off-grid lighting products developed by manufacturers for the Lighting Africa program.
= ASSIST Project