DOE Releases Revised Draft ENERGY STAR Performance Criteria For Outdoor Pole-Mounted & Other Luminaires

July 06, 2009 by Jeff Shepard

The U.S. Department of Energy (DOE) has released the second draft ENERGY STAR® performance criteria for outdoor pole-mounted area and roadway luminaires, outdoor wall-mounted area luminaires ("wall packs"), and parking garage/canopy luminaires. The DOE has developed a new metric, called Fitted Target Efficacy (FTE), for the evaluation of outdoor pole-mounted area and roadway luminaires.

The DOE is providing the second draft ENERGY STAR performance criteria for several lighting applications to be added to Category A: outdoor area pole-mounted and roadway luminaires, outdoor wall-mounted area luminaires ("wall packs"), and parking garage/canopy luminaires. The First draft criteria for these applications were published in August 2008 as part of a larger set of additions to Category A.

These outdoor area lighting applications were removed from the ENERGY STAR Program Requirements for SSL Luminaires version 1.1 (published Dec 19, 2008 and effective Feb 1, 2009) because additional analysis was needed to address issues raised during the first stakeholder comment and review period. In the meantime, DOE has developed a new approach for evaluating the performance of outdoor area and roadway lighting.

Outdoor area and roadway lighting, outdoor wall packs, and parking garage/canopy lighting are being proposed for inclusion in the ENERGY STAR for SSL Luminaires program at this time for several reasons: 1) LED-based luminaires intended for these applications are available through normal market channels, and new products are being introduced regularly. 2) Energy-efficiency programs, municipalities, and other stakeholders have indicated a high level of interest in these applications. 3) CALiPER testing of market-available luminaires in these categories reveals a wide range of performance in terms of luminaire efficacy, total luminous flux, color characteristics, and other attributes. 4) Demonstration projects sponsored by utilities, municipalities, and the DOE GATEWAY program indicate potential for energy savings, but also the need for minimum performance guidelines for these applications.

The DOE is inviting stakeholder review and comments regarding these second draft criteria by July 31, 2009. Depending on the nature of comments received, DOE intends to revise the criteria as necessary, and to add them to the existing ENERGY STAR Program Requirements for SSL Luminaires as version 1.2. This revision provides performance criteria for SSL luminaires for use in several additional lighting applications. These revisions do not change the performance requirements for the Category A applications included in version 1.1.

The DOE has developed a new efficacy metric for outdoor area and roadway luminaires. Fitted-Target Efficacy (FTE) meaningfully gauges a luminaire’s performance independent of a specific application. Two key assumptions underlie the FTE metric. First, relatively rectangular distribution patterns cover most areas more efficiently (with less unnecessary overlap) than rounded distributions. Second, a luminaire’s approximate area of coverage can be defined as the area illuminated to IES-recommended uniformity ratios.

The FTE metric is similar to luminaire efficacy in that its units are luminaire output (lumens) per unit of power (watt). However, FTE differentiates useful lumens from those that may cause glare, wasted light, and/or light trespass. It evaluates the efficacy with which a luminaire delivers light to a rectangular area defined by the luminaire’s own intensity distribution, encouraging luminaires to direct light efficiently to a target area.

This metric is said to have several advantages important to the evaluation of outdoor area luminaires by ENERGY STAR: 1) It is application-independent, i.e., it is not a function of site-specific conditions like required illuminance levels or mounting height. This is essential for product-level qualification. 2) It is applicable to all pole-mounted outdoor luminaires, regardless of IES luminaire classification. 3) Going beyond simple luminaire efficacy, FTE discourages high-angle light that does not contribute to uniform target coverage by not counting those lumens towards the efficacy score. Such luminous flux may cause glare, light pollution, and/or light trespass. 4) It discourages uncontrolled back (house-side) light, but recognizes the potential utility of properly controlled back light that contributes to uniform target coverage. 5) FTE is calculated using standard absolute photometry (IES-format files as per LM-79-08 and LM-63-02). No additional testing is required.

The most efficient lighting design uses the lowest wattage to provide the necessary quantity and quality of illumination for a given application. FTE quantifies luminaire performance to help lighting specifiers and end-users in selecting luminaires for efficient outdoor area and roadway lighting applications.