LED Recessed Luminaire

Recessed LED luminaires, also known as lay-ins or troffers, feature an LED light engine in a traditional recessed luminaire form factor with dimensions 2'x2' and 2'x4'. This lab evaluation project will compare the light characteristics of the LED versus a linear fluorescent fixture of the same size and dimming capabilities while evaluating energy savings and cost for workpaper development.

Southern California Edison (SCE) conducted the Recessed Light-Emitting Diode (LED) Luminaire Emerging Technologies (ET) Assessment Project to compare the efficiency of LED technology with that of linear fluorescent (LF) technology. Nearly five million LF fixtures are currently installed in small and large offices. These fixtures, if replaced with LED fixtures that yield a 25% efficiency gain, can result in 200 Gigawatts (GWh) in energy savings with a mere 10% market penetration in SCE territory. LED troffers consist of an LED light engine in a traditional recessed LF luminaire form factor. Because LEDs are known for their high efficacy and long useful life, this project assessed the feasibility of replacing LF troffers that have a similar efficacy and life with their LED counterparts. The specific objective of this project was to compare 2x2 and 2x4 LED lay-in troffers to the incumbent linear fluorescent (LF) technology. The results of this technology assessment are intended to provide sufficient data to the Energy Efficiency (EE) programs for them to determine whether Recessed LED Luminaires should be included in the itemized incentive program. SCE tested and analyzed current LED technology relative to the LF technology in terms of lumen output, energy savings, and cost. Due to a high volume of inquiries into LED T-8 tube replacements, two LED T-8 tubes were also tested. 12 LF troffers were tested in various combinations of lamps and fixture types. Fixture types included prismatic lens, basket, non-planar, and parabolic, which are the typical fixtures used in the industry. SCE tested all the fixtures on hand at the SCE Lighting Technology Test Center (LTTC) in Irwindale, CA, using the integrating sphere and the mock-up office space. The in-house testing gave good insight into how the troffers would perform in a realworld environment. LED data not specifically tested in the lab were extracted from the Design Light Consortium’s (DLC’s) qualified list and from manufacturer’s lab data, thereby allowing the test design to include a robust set of comparison permutations using a larger sample size. Photometric and power data plotted on a graph showed an overlap in performance between the LF and LED technologies. Considering that there are two to four LF lamps in a fixture, with various types of lamps such as T5, T8, and high-output lamps, performance is wide spread for the incumbent technology. The efficacy of LEDs studied in this project ranged from 60-115 lm/W, compared to the LFs’ 38-84 lm/W. Although bare LF lamps are highly efficacious, some of the light is lost when installed into a fixture. Similar efficacy means similar performance, which may result in lower energy savings. Table ES-1 summarizes the energy savings, demand reduction for the LF, and LED 2x2 technologies.