U.S. Department of Energy - Energy Efficiency and Renewable Energy

Building Technologies Program

Spectrally Enhanced Lighting

DOE Response to IES PS-02-09

The IES Position Statement, PS-02-09 (PS), "Use of Spectral Weighting Functions for Compliance with IES Recommendations" has prompted numerous inquiries to DOE regarding apparent contradictions between the PS and the DOE Spectrally Enhanced Lighting program. As a result, DOE has issued a response to clarify how SEL fits within the context and wording of the PS.

The U.S. Department of Energy (DOE) conducts studies on spectrally enhanced lighting (SEL) as part of its lighting activities. Here you'll learn about spectrally enhanced lighting and find information about studies and implementation.

SEL is a simple strategy that uses existing products and technology to significantly reduce energy use from lighting in commercial buildings. This low-risk, high-return strategy can provide energy savings of more than 20-40% at no additional cost, according to results of the DOE study, Spectrally Enhanced Lighting Program Implementation for Energy Savings, Field Evaluation (August 2006).

A graphic image with an eye on the left side of the image. The pupil of the eye is small. On the right side of the image is a photo of a desktop with a phone and computer monitor on top. There are lines drawn from the pupil of the eye in a V-shape with the opening of the V centered on the objects on the desktop. The graphic is demonstrating that the items on the desk appear brighter and crisper even with lower levels of light if the lighting is spectrally enhanced.

Recent findings show that the color of lighting can affect the energy efficiency of lighting systems. When the spectral properties of ambient lighting are shifted to be more like the color of daylight (more white), our eyes respond the same as if lighting levels were increased — the pupils of our eyes get smaller, spaces seem brighter, and we see things more clearly.

The concept behind SEL is that a significant amount of energy can be saved by using lamps that have less light output, but higher correlated color temperature (CCT). Lamps with higher CCT appear brighter than those with lower CCT, so the actual light output of higher CCT lamps can be decreased, while maintaining equivalent perceived brightness and visual acuity. Unlike other energy efficiency strategies, SEL is not a technology — it's a different way to quantify light that can be used with any type of lighting design to improve energy performance. Energy savings are achieved by using high performance and high CCT lamps coupled with lower ballast factor, extra efficient electronic ballasts. SEL is a market-ready, cost effective solution for quick energy savings.

Learn more about SEL by viewing the following:

2004 Feasibility Study: University of California, Office of the President
2006 Economics Validation Study: Three-Building Field Assessment
Implementing Spectrally Enhanced Lighting Solutions

If you would like additional resources, see the bibliography of SEL-related publications.