FEMP Designated Product: Commercial Downlight Luminaires
Federal agencies are required by the Energy Policy Act of 2005 (P.L. 109-58) and Federal Acquisition Regulations (FAR) Subpart 23.2 to specify and buy ENERGY STAR®-qualified products or, in categories with no ENERGY STAR label, FEMP-designated products which are among the highest 25 percent of equivalent products for energy efficiency.
Information about commercial downlight luminaires in this section includes the following:
- Performance Requirement for Federal Purchases
- Buying Energy-Efficient Commercial Downlight Luminaires
- Calculating LER
- Buyer Tips
- Cost-Effectiveness Example
- Cost-Effectiveness Assumptions
- Using the Cost-Effectiveness Table
- What If My Energy Prices or Operating Hours Are Different?
- For More Information
Also provided is a portable document format version of Purchasing Specifications for Commercial Downlight Luminaires.
|Performance Requirement for Federal Purchases|
|Compact Fluorescent Lamps|
|Luminaire Type||Required Luminaire Efficacy Rating (LER)|
|Open Optics||29 or higher|
|Baffled Optics||21 or higher|
|Lensed Optics||24 or higher|
|Metal Halide Lamps|
|Luminaire Type||Required Luminaire Efficacy Rating (LER)|
|Open Optics||35 or higher|
|Lensed Optics||30 or higher|
Buying Energy-Efficient Commercial Downlight Luminaires
This Specification is for commercial downlight luminaires. ENERGY STAR offers a program for residential fixtures that includes residential CFL downlight luminaires (see For More Information).
When buying a commercial downlight luminaire, specify or select a model with a Luminaire Efficacy Rating (LER) that meets or exceeds those shown in the Performance Requirement table. Commercial downlight luminaires using incandescent lamps will not meet these requirements. Commercial downlight luminaires using halogen lamps, while more efficient than standard incandescents, also will not meet the LER requirements.
Agencies must use ENERGY STAR-qualified and FEMP-designated performance requirements for all procurements of energy-consuming products and systems including guide and project specifications, and construction, renovation and service contracts. These performance requirements should also be used in evaluating responses to solicitations. In contracts and solicitations, agencies must specify that commercial downlight luminaires meet or exceed the performance levels shown in the Performance Requirement table.
Agencies can claim an exception to these requirements through a written finding that no ENERGY STAR-qualified or FEMP-designated product is available to meet the functional requirements, or that no such product is life-cycle cost-effective for the specific application.
LER data may not be available for some manufacturer's products. If an LER is not available, buyers may estimate the LER using this formula:
LER = Luminaire Efficiency x (Lamp Lumens ÷ Lamp-Ballast Input Watts)
Luminaire Efficiency, Lamp Lumens, and Lamp-Ballast (System) Input Watts may typically be found in manufacturers' product catalogs and photometric reports.
The LER formula may be used with generally-available component performance data to determine the minimum performance of other components. For example, a known lamp-ballast efficacy may be used to calculate the lowest luminaire efficiency necessary to meet an LER requirement:
A 50-Watt metal halide lamp with a pulse-start electronic ballast produces 3200 initial lumens with 58 input Watts. What Luminaire Efficiency (LE) is necessary to meet the minimum required LER of 30 for a lensed fixture?
LE = (Lumens ÷ Watts) ÷ LER = (3200 ÷ 58) ÷ 30 = 0.54
For a minimum required LER of 30, a lensed fixture combined with the lamp and ballast values provided must have an LE of at least 54%.
Downlights using incandescent lamps do not meet the performance requirements of this Purchasing Specification. In lighting situations with low lumen output requirements, CFLs with electronic ballasts are recommended as replacements for incandescents downlights. Low-wattage ceramic metal halide (CMH) lamps may also be used where incandescent lamps may have been preferred for their small dimensions and color rendering qualities.
Downlights using halogen lamps do not meet the performance requirements of this Purchasing Specification. Where higher lumen output is required from a small source, pulse-start metal halide (MH) or CMH lamps are recommended as a replacement for higher-wattage incandescent or halogen lamps. Pulse-start MH lamps offer reduced input watts and increased light output (lumens) compared to standard metal halide lamps. Input watts may be reduced by up to 25%, resulting in higher LERs. Pulse-start lamps also provide faster restrike, improved color rendering and stability, and longer lifetimes.
Electronic (rather than magnetic) ballasts are recommended for both CFL and MH downlights. Some CFL electronic ballasts offer dimming capabilities. Electronic ballasts for metal halide lamps offer reduced size and weight, as well as improved color rendering and lumen maintenance, with minor efficiency gains compared with magnetically-ballasted models.
Electronic MH ballasts can also provide a variety of lighting control options. Because of the delay in restrike time, it is generally not practical to shut off metal halide systems completely except for extended periods of non-occupancy.
Luminaires that use T5 fluorescent lamps may also be substituted for downlights in some applications. T5 lamps are generally longer than CFLs but only slightly larger in diameter. T5 lamps offer higher efficiencies than either CFLs or low-wattage MH lamps.
In a limited number of commercial applications, recently-adopted energy code requirements may prohibit the use of vented downlights. Unvented downlights may shorten the life and degrade the performance of CFLs. Pacific Northwest National Laboratory has tested and rated air-tight CFL downlights which are designed to prevent these problems (see For More Information).
|Compact Fluorescent Lamp, Open Optics|
|Performance||Base Models||Required Level|
|1 Incandescent 150W PAR lamp||3 CFQ26W lamps, magnetic ballast||2 CFQ26W lamps, electronic ballast|
|Luminaire Efficacy Rating (LER)||9||18||29|
|Initial Luminaire Light Output||1350 lumens||1390 lumens||1474 lumens|
|Lifetime Average Light Output||1282 lumens||1181 lumens||1253 lumens|
|Power Input||150 watts||78 watts||50 watts|
|Annual Energy Use||540 kWh||281 kWh||180 kWh|
|Annual Energy Cost||$32||$17||$11|
|Lifetime Energy Cost||$341||$178||$114|
|Lifetime Energy Cost Savings||—||—||$228 / $64|
|Metal Halide, Lensed Optics|
|Performance||Base Model||Required Level|
|Q150T4 Halogen lamp||Metal Halide lamp, Pulse-Start Electronic Ballast|
|Luminaire Efficacy Rating (LER)||19||30|
|Initial Luminaire Light Output||1596 lumens||1824 lumens|
|Lifetime Average Light Output||1516 lumens||1569 lumens|
|Power Input||150 watts||58 watts|
|Annual Energy Use||540 kWh||209 kWh|
|Annual Energy Cost||$32||$13|
|Lifetime Energy Cost||$341||$132|
|Lifetime Energy Cost Savings||—||$209|
In the CFL example, two Base Models are shown. The Base Model in the first column uses an incandescent reflector lamp. The Base Model in the second column uses a CFL with a magnetic ballast. The Required Level model uses a CFL with an electronic ballast. Over the assumed luminaire lifespan of 15 years, incandescent lamps would be replaced 35 times and CFLs 5 times.
In the Metal Halide example above, the Base Model uses a halogen lamp, while the Required Level model uses a MH lamp with a pulse-start electronic ballast. Over the assumed luminaire lifespan of 15 years, halogen lamps would be replaced 20 times and MH lamps 3 times.
For both examples, Lifetime Energy Cost is the sum of the discounted value of annual energy costs, based on 3,600 operating hours per year and an assumed luminaire life of 15 years. The assumed electricity price is 6¢ per kWh, the federal average electricity price in the U.S. Future electricity price trends and a discount rate of 3.0% are based on federal guidelines effective from April 2006 to March 2007.
Using the Cost-Effectiveness Table
In the first example shown above, the specified CFL commercial downlight luminaire meeting the required LER of 29 or higher is cost-effective if its purchase price is no more than $228 higher than an incandescent luminaire and no more than $64 higher than a CFL luminaire with a magnetic ballast.
In the second example shown above, the specified MH commercial downlight luminaire meeting the required LER of 30 or higher is cost-effective if its purchase price is no more than $209 higher than a halogen luminaire.
The calculations are for energy costs savings only and do not include lamp replacement or labor costs. If lamp replacement and labor cost are included, the savings may be significantly greater.
What If My Energy Prices Or Operating Hours Are Different?
To calculare Lifetime Energy Cost Savings for a different electricity price, multiply the savings in the above table by this ratio: (Your price in ¢/kWh) ÷ (6.0¢/kWh). Longer operating hours will make an efficient commercial downlight luminaire even more cost-effective.
For More Information
- National Electrical Manufacturers Association (NEMA) publishes Standards Publication LE 5A, Procedure for Determining Luminaire Efficacy Ratings for Commercial Non-Residential Downlight Luminaires.
Phone: (800) 854-7179
- The EPA/DOE ENERGY STAR® program provides product listings of residential CFL downlight fixtures.
Phone: (800) 372-7827
- Lawrence Berkeley National Laboratory provided supporting analysis for this recommendation.
Phone: (202) 646-7950