How do we ensure SSL product quality? How can we be confident that product test results are reliable?
Lifetime testing is particularly relevant for policy makers and market surveillance authorities who are concerned with lamp lifetime testing and verifying lifetime claims on packaging. The SSL Annex works to synthesize credible findings from lifetime studies (see lifetime study review) and conducts interlaboratory comparisons to improve measurement of SSL products globally.
Testing & Standards Resources
Determining the lifetime of LED products can be challenging and costly. The SSL Annex is working to understand lifetime issues of LED products in support of government measurement, verification and enforcement programmes.
A report was published that looks across the body of literature on lifetime definitions for LEDs and LED products. The report looks at failure mechanisms, accelerated life test and test methods for estimating lifetime, and provides some recommendations. There is currently no agreement as to which test method can best estimate the lifetime of LED lighting products and the report thus addresses a key issue for regulators and industry interested in deployment of LED technologies.
CLICK HERE to download the Literature Summary of LED Lifetime Testing
In 2014, the SSL Annex published a report (2013 IC Final Report) that compared the measurement accuracy of 110 laboratories worldwide testing Light Emitting Diode (LED) lamps and luminaires. That report is intended to help governments and manufacturers ensure that new LED products sold to consumers and companies are of high quality and meet the claimed performance. That work also sought to establish a common proficiency test method for accreditation programmes.
In 2021, the SSL Annex published a report (2017 IC Final Report) that compared goniophotometric measurements of LED luminaires and narrow-beam LED lamps. IC 2017 was designed to be in compliance with ISO/IEC 17043 to serve as a proficiency test for SSL testing accreditation programmes that recognise this comparison. IC 2017 used CIE S 025/E:2015, Test Method for LED Lamps, LED Luminaires and LED Modules as the test method for LED performance measurement.
In 2015, The Commission Internationale de l’Eclairage (CIE) published a new International Standard (CIE S 025/E:2015) called “Test Method for LED Lamps, LED Luminaires and LED Modules”. This standard was developed to be used by regulators and accreditation bodies around the world to harmonise the testing and accreditation of LED products. The SSL Annex conducted a study of this standard, including looking at the coverage of products, the performance metrics measured, the equipment covered and the requirements for testing.
This report prepared by the SSL Annex is titled “Application Study of CIE S 025/E:2015” and it evaluates the international standard for use as a standard by accreditation bodies, government policy makers and other key stakeholders as the basis for measuring quality and performance aspects of LED lighting products and equipment.
CIE S 025/E:2015 specifies the requirements for measurement of electrical, photometric, and colorimetric quantities of LED lamps, LED modules and LED luminaires, for operation with AC or DC supply voltages, possibly with associated LED control gear. LED light engines are assimilated to LED modules and handled accordingly. Photometric and colorimetric quantities covered in this standard include total luminous flux, luminous efficacy, partial luminous flux, luminous intensity distribution, centre-beam intensity, luminance and luminance distribution, chromaticity coordinates, correlated colour temperature (CCT), colour rendering index (CRI) and angular colour uniformity.
The lighting laboratory measurement instruments that are covered by CIE S 025/E:2015 include: sphere-photometer, sphere-spectroradiometer, goniophotometer, gonio-spectroradiometer and luminance meter. The following lighting laboratory measurement instruments are also accepted for use with CIE S 025/E:2015 as long as equivalent results are demonstrated. In other words, these measurement instruments are acceptable if they are demonstrated to produce results equivalent to those of a conventional integrating sphere system or conventional (i.e., far-field) goniophotometer system: integrating hemisphere, near-field goniophotometer and imaging luminance measurement device (ILMD).
This report is a supporting document to the SSL Annex’s Interlaboratory Comparison 2017 (IC 2017) which was launched on 30 June 2017. IC 2017 is using CIE S 025/E:2015 as the test method for testing the lamp and luminaires in this interlaboratory comparison.
CLICK HERE to download the Application of CIE S 025/E Report
This research activity will investigate existing test methods for determining luminous flux maintenance and colour maintenance of SSL products (available from IEC product standards and regional standards on products and their components).
This task will evaluate the latest standards for lifetime testing of LED products. It is linked to and supports our research on the characterisation of product lifetime. However, where that research looks into generic lifetime issues, this activity focuses on testing aspects of SSL product lifetime:
- Investigate test methods for determining luminous flux maintenance and colour maintenance, which was not covered in the previous (2010-2014) work of the SSL Annex. There are several test methods available, such as LM-80 and TM-21 by the Illuminating Engineering Society of North America. The IEC has different approaches in their draft standards.
- Another issue is testing of complete products (LED lamps, luminaries), which is not covered by LM-80 and TM-21 (for LED packages/modules). New standards LM-84 and TM-28 are being developed for complete products and will try to address their lifetime testing. But which of these standards are most suitable for governments to use in their SSL policy programmes?
This task will involve consultation with standards making bodies, but the SSL Annex itself will not be developing test methods. Instead, the Annex would seek to identify and promote any lifetime test standards that were found to address government testing needs. This research will culminate in a report that provides guidance to governments on lifetime testing of SSL products.
This research activity will include a meta-study of papers published by academic researchers, international associations/societies (e.g., IES, CIE, IEC, etc.) and testing laboratories and will result in a synthesis of information to help policy makers make decisions on SSL product lifetime. The Annex will prepare a summary of this research, explaining key features in defining, evaluating and testing for product lifetime in a format that is accessible and will provide policy guidance.
There is a lack of global agreement on SSL test standards and mutual recognition of regional accreditation programmes. This situation creates trade barriers and increases the costs of doing business, slowing down the adoption of LEDs and associated energy savings.
The SSL Annex seeks collaboration with accreditation bodies worldwide in support of mutual recognition of regional accreditation of SSL product testing. Coordination of international accreditation of SSL testing laboratories is important for traceability of SSL products. By comparing 110 LED testing laboratories around the world, the 2013 Interlaboratory Comparison (see Final Report) produced a common proficiency test that:
- Testing laboratories can use to compare their LED product testing performance (integrated sphere) with other laboratories around the world and
- Regional accreditation bodies can use in support of mutual recognition of other accreditation programmes, thereby lowering product testing costs.