“The finer things in life lights are rigorous test reports”

The last post on solid-state lighting (SSLs, which are also commonly known as LEDs, or light-emitting diodes) explained one of the consequences of the rapid pace of technological improvement: the vastly different quality levels of new products at any given time. The post provided guidelines and shortcuts that consumers can use to help choose the right product from an enormous selection. To help consumers further narrow down their choices to the right kinds of lighting, this post explains how to read and use the product-specific standardized testing results: IESNA’s LM-79 and LM-80.

Don’t be intimidated by their alphanumeric names. The LM-79 standard exists to help consumers know what they’re buying, while the LM-80 standard helps them gauge that they really will get what they’re paying for. Standard “seventy-nine” focuses on how well a product performs electrically. This standard evaluates power, efficacy (lumens per watt delivered), and lighting quality (total output, distribution, and chromaticity). Standard “eighty” demonstrates how a product performs over time. To use a transportation metaphor, think of LM-79 as the MPG sticker rating for a car, and LM-80 as the model’s reliability review. You should look at both before you buy!

The Department of Energy’s Technical Assistance Team recently produced the SSL Playbook to clearly explain these two standards so that readers can understand how significant they are when purchasing lighting. Standard LM-79 measures SSL products’ actual tested performance and places the results in the context of how the product will be used. It also provides detailed testing results so that consumers can interpret and apply specific components to their own particular requirements. Going back to the transportation metaphor, if a person drives exclusively in the city, then a car’s highway MPG is not a critical factor. It can be extremely helpful to see a specific performance type broken out from other types of performance, as in this example. The playbook provides step-by-step instructions of how to navigate this sort of detail.

The LM-80 standard results, such as in this example, highlight any products that suffer significant performance degradation caused by insufficient heat transfer engineering and componentry. It’s important to understand that some products will see fairly large changes in total light output (brightness) and chromaticity (color) over their lifetime. As SSL products are designed to have ever-longer lifetimes, it’s important to pay special attention to these sorts of degradation issues at the time of purchase—the only way to do that is to be familiar with the standards that have been developed.

Fortunately, experts in the field are constantly performing these comprehensive tests and updating the results, which spares the rest of us from the burden of this sort of investigation. Manufacturers of high quality products should be proud to share these test results, so always be sure to request the LM-79 and LM-80 reports for any SSL purchases you intend to make. You’re more likely to make the right choice if you know what to look for, but first you must know how important it is to look!

For an example of how LM-79 and LM-80 reports can be used in actual applications, check out this LED Parking Demo Assessment. Additional information may be viewed at this presentation on LED standards and challenges. If you have questions related to SSLs, please post a comment to this entry or submit a request through the Technical Assistance Center.

Content for this Blog post courtesy of Nick Lange, Vermont Energy Investment Corporation