Question:
What are the relative pros and cons of LED and Induction lighting?

The TAP team responds: 
For grantees implementing EECBG lighting projects, selecting between LED and Induction options can be a challenge.  Both lighting types have their respective advantages and disadvantages, but there are a few key points of comparison to make:

• Testing -- There are no testing standards for induction lighting.  One manufacturer may rate life based on a single continuous burn, while another manufacturer may turn the test-bulb on and off as part of the test, which is known as “hours per start”.  Be sure to ask for clarification from the supplier.
• Life Span -- Many manufacturers rate their induction systems at 100,000 hours, however it is common for the lumens to drop by 30% or more after 60,000 hours.   When lumens fall below 70% of the initial amount, many experts consider this the end of the useful lamp life.  Likewise with LEDs, you want to make sure the life rating is based on when the system falls to 70% of its initial light output.  This is sometimes referred to as useful life or “L70.”
• Controls -- Most induction lighting units cannot be dimmed, however multiple switching options exist.  For instance, you can have induction lights on at lower light levels for security when the space is vacant, and then be switched to full light output when occupied.  Check with manufacturers for the latest dimming and multiple switching options.
• Color Temperature -- Color temperature refers to the warm or cool appearance of the light source.  Induction lighting comes in 3000K (warm) to 6000K (very cool) colors.  LEDs are also available in a variety of color temps, but note that warmer LEDs are less efficient than cooler temperatures.  To maximize efficiency, select a cool color temp LED. 
• Mercury -- Induction lighting does contain small amounts of mercury, so please dispose of properly.
• Glare -- LEDs are a directional lighting source, which can be an advantage in spot lighting, but can also be glaring if not arranged appropriately.   A fixture needs to be carefully designed and placed to avoid excessive glare while maintaining proper light levels.  Induction is not a point source, particularly compared to LED.
• Directionality -- As noted above, induction lighting is not a point source, making it more difficult to control and direct the light.   The illumination and energy performance of each system is best analyzed by asking the suppliers to provide a layout with photometric results showing the light levels. Reputable lighting suppliers should have the software to do a layout includes the number of poles, spacing, height and other details.   
• Illumination -- You can request that the manufacturer(s) provide photometric layouts showing the average, maximum and minimum illuminance (footcandles) and the avg/min and max/min illuminance ratios.   This can be done for each light source, as well as a variety of layouts, to help evaluate cost, energy savings, and performance. Manufacturers should meet the Illumination Engineering Society of North America recommended practice for the application, and should indicate the IES recommendations in their reports compared to the actual layout. 
• Cost -- Cost will depend on the layout, number of poles, and other site-specific factors.   Some applications will use more poles at lower lumens per pole to reduce glare, but this increases cost which is a concern.  Cost of both induction and LED systems has come down over the past few years.  It is best to get a complete cost for the entire installation after evaluating various layouts, photometric reports, and illuminance results (as opposed to a per pole cost).  

Every situation has its own “best lighting option,” depending on the space, the desired effect and the budget.  If you are an EECBG recipient and would like to speak for free with a lighting expert who can help you determine what option makes most sense for your project, please contact your local Regional Coordinator for Technical Assistance, or make the request directly through DOE’s Technical Assistance Center (TAC).

You can also refer to a recent webinar on lighting, titled “Overcoming Common Pitfalls: Energy Efficient Lighting Projects", which can be found at the Solution Center's Past Webcasts Presentations.  If you have comments or stories that you wish to share about LED vs induction lighting, please comment below.

Content for this blog post were provided courtesy of Jeff Schwartz, ICF International