TINSSL News

DOE’s SSL Testing Program: CALiPER Round Three

by Matthew D’Alessio, Residential Initiatives Intern

Overview
Round 3 of the Department of Energy's (DOE) Commercially Available LED Product Evaluation and Reporting (CALiPER) Program was conducted June through August 2007. The CALiPER program tests products which are commercially available. These products are purchased through distributors or other market mechanisms. Sample products are also tested if requested by DOE SSL programs or if there is no market for small quantity purchases of a particular product. Twenty-four products representing a range of manufacturers, designs, and applications were tested following procedures outlined by the Illuminating Engineering Society of North America (IESNA) Lighting Measurement-79 (LM-79) guidelines in their current draft form. The key components of this testing method include:

Requires testing at the luminaire level; SSL fixtures along with SSL source. This is because procedures for testing devices and arrays have not yet been adopted as luminaire heat dissipation affects LED device performance. Also, the amount of light emitted by a fixture cannot be reliably predicted based on the available specification information of LED devices.

Products must be stabilized at thermal equilibrium prior to testing.

The procedures outlined by LM-79 account for LED performance alterations resulting from high operational temperatures. Manufacturer specification information for LEDs is compiled under ideal conditions where device and fixture are not integrated. Heat sink design, drive electronics, and device interaction therefore affect the performance of LED luminaires due to heat related issues. For this reason, LM-79 addresses efficacy at the luminaire level and requires replacement devices to be tested in appropriate standard lamp-holders depending on geometry and/or intended device use.

Round 3 test results show improvement over previous testing rounds. SSL products tested in Round 3 clearly show superior luminaire efficacy to incandescent products as well as match, and in some products surpass, CFL product efficacy. Performance was particularly noticed in applications for concentrated light such as task lights, downlights, and outdoor area lighting.

Manufacturer data often overstates SSL product performance for any of several reasons, for example due to controlled testing procedures that do not consider realistic device installation and operation. Round 3, however, found that of the 17 of 24 products accompanied by manufacturer efficacy or output data, only four were found to be overstated. These four products were found to be 25-90 percent overstated. Meanwhile, seven of the 17 products submitted with manufacturer data were within +/- 10 percent of the CALiPER Round 3 findings.

Round 3 gathered photometric data through Goniophotometers and Integrated Sphere Spectroradiometers. A Spectroradiometer determines radiant energy through the combination of functions of a spectroscope and radiometer. A Goniophotometer is a photometer that measures directional light distribution characteristics for light sources and fixtures. The photometric information gathered may include: total luminous flux (lumens), luminous intensity (candelas) in one or more directions, chromaticity coordinates, correlated color temperature (CCT), and color rendering index (CRI)

Findings by Topic

For Downlight applications, Round 3 found:

A wide range of product performance was observed in SSL products. Therefore, product comparisons must be done on an application-by-application basis, taking into consideration the specific requirements of a particular lighting application.

The SSL downlights clearly surpass incandescent product efficacy.

The SSL downlights and SSL directional replacement lamps have efficacies similar to CFL downlights (with one SSL product clearly exceeding CFL luminaire efficacy).

On average the SSL downlights and SSL directional replacement lamps achieve similar light output to CFL and incandescent downlights.

Some of the SSL downlights and SSL R30 lamps have tighter beam and field angles than the CFL benchmark products.

The SSL downlights and SSL R30 lamps have higher Center Beam Candle Power (CBCP) than the CFL benchmark products.

For General Lighting applications or Non-Directional Replacement Lamps, Round 3 found:

On average, performance had improved by a multiple of three over Round 2 test results but light output remained questionable for use as a replacement for current lamps. Interested parties are strongly encouraged to investigate individual products themselves.

For Task and Under-Cabinet applications, Round 3 found:

SSL luminaires can exceed Fluorescent products in light output and luminaire efficacy while maintaining similar color temperature and CRI values.

For Outdoor Lamps, Round 3 found:

Based on typical device wattages used, wall lamp SSL products are estimated to exceed incandescent and halogen efficacy two to three times and match CFL luminaire efficacy. Device wattage assumptions were used because of the five outdoor SSL products tested, all lacked benchmark comparison products.

Large area and parking SSL products provided suitable efficacy ratings.

For Off-State Power Consumption, Round 3 found:

All but one task and under-cabinet SSL products’ “effective efficacy” was affected by off-state power consumption. Better switch and electrical efficiency design is desired to alleviate “vampire charges” during off-state conditions. “Effective Efficacy” incorporates average power consumption over time. A luminaire’s effective efficacy will decrease if off-state power is being drawn while a luminaire’s switch is in the “off” position.

For Color Quality, Round 3 found:

The average CRI rating for the SSL products tested was 76, with a minimum of 52 and maximum of 95. Round 3 testing included phosphor conversion white light sources only. No RGB white light conversion LED’s were tested in Round 3.

Round 3 Overall Conclusions
Round 3 testing showed that on average, SSL downlights surpass efficacy levels of incandescent reflector lamps and are comparable to CFL luminaire efficacy ratings. The testing also showed that under-cabinet and task light SSL luminaires now perform better than halogen or fluorescent devices and would be further distinguished if off-state power draw was eliminated. Furthermore, several products tested in Round 3 meet ENERGY STAR SSL requirements for luminaire efficacy, luminaire output, and color quality. However, it remains critical to recognize that results under CALiPER testing generate a wide range of performance results such that generalizations (including summaries such as this) should not become the basis for decision-making, and that individual products should be carefully considered on their own merit as purchasing decisions are made.
The complete report from U.S. DOE can be found at: http://www.netl.doe.gov/ssl/PDFs/DOE SSL CALIPER ROUND 3 summary_FNL.pdf