You are here

Purchasing Energy-Efficient Suspended Fluorescent Luminaires

The Federal Energy Management Program (FEMP) provides acquisition guidance for suspended fluorescent luminaires, a product category covered by FEMP efficiency requirements. Federal laws and requirements mandate that agencies purchase ENERGY STAR-qualified or FEMP-designated products in all product categories covered by these programs and in any acquisition actions that are not specifically exempted by law.

FEMP’s acquisition guidance and efficiency requirements apply to suspended 4-foot-long luminaires with linear fluorescent lamps that are used in commercial and institutional buildings. Product performance must be measured in accordance with National Electrical Manufacturers Association (NEMA) LE 5-2001: Procedure for Determining Luminaire Efficacy Ratings for Fluorescent Luminaires.

Recessed, surface-mounted, and industrial luminaires are covered by separate FEMP-designated efficiency requirements and are excluded from this product category. Residential pendant-mounted fixtures are covered by the ENERGY STAR program and are excluded from this product category. 

Find Product Efficiency Requirements

Federal purchases must meet or exceed the minimum efficiency requirements in Table 1.

Table 1. Efficiency Requirements for Suspended Fluorescent Luminaires
Optical Element Distribution Pattern Luminaire Efficacy Rating (LER)
Lensed Semi-indirect ≥ 92 lm/W ≥ 72 lm/W
Indirect ≥ 80 lm/W ≥ 71 lm/W
Louvered Direct ≥ 57 lm/W ≥ 50 lm/W
Semi-direct ≥ 61 lm/W ≥ 54 lm/W
Direct-indirect ≥ 69 lm/W ≥ 59 lm/W
Semi-indirect ≥ 87 lm/W ≥ 70 lm/W
Indirect ≥ 70 lm/W ≥ 53 lm/W
Other Direct ≥ 64 lm/W ≥ 61 lm/W
Semi-direct ≥ 64 lm/W ≥ 58 lm/W
Direct-indirect ≥ 73 lm/W ========
Semi-indirect ≥ 86 lm/W ≥ 71 lm/W
Indirect ≥ 84 lm/W ≥ 73 lm/W


Make a Cost-Effective Purchase: Save More Than $20 Per Fixture By Buying a FEMP-Designated Product

FEMP calculated the cost savings for a 1-foot by 4-foot other direct-indirect suspended luminaire with two F32T8 fluorescent lamps. The required model is cost-effective if priced no more than $20 above the less efficient model. The best available model saves the average user more: $24 above the less efficient model. The lumen output of the less efficient model and required model are comparable; however, the lumen output of the best available model is 15% greater than the less efficient model. In rooms that are under-lit, more efficient luminaires could increase illumination levels in addition to saving energy and operating costs.

Table 2 compares three types of product purchases and calculates the lifetime cost savings of purchasing efficient models. Federal purchasers can assume products that meet FEMP-designated efficiency requirements are life cycle cost-effective.

Table 2. Lifetime Savings for Efficient Lensed Semi-Direct Luminaires
Performance Best Available Required Model Less Efficient
Light Output 4,939 lm 4,259 lm 4,285 lm
Luminaire Efficacy Rating (LER) 85 lm/W 73 lm/W 67 lm/W
Required Input Power 58 W 59 W 64 W
Annual Energy Use 209 kWh 212 kWh 230 kWh
Annual Energy Cost $18 $19 $21
Lifetime Energy Cost $238 $242 $262
Lifetime Energy Cost Savings $24 $20 ======
View the Performance and Model Assumptions for Table 2
Performance Column

Light Output: Shown in lumens, a measure of the total amount of visible light emitted by a source.

Luminaire Efficacy Rating: Calculated by multiplying the luminaire efficiency by the total rated lamp lumens by the ballast factor, and dividing by the luminaire watts input.

Input Power: Based on the wattage used by a 1-foot by 4-foot direct-indirect suspended luminaire.

Annual Energy Use: Based on NEMA's LE 5-2001 or Illuminating Engineering Society's (IES) LM-79-08 calculations for luminaires that are operated 3,600 hours per year.

Annual Energy Cost: Calculated based on an assumed electricity price of $0.09/kWh, which is the average electricity price at federal facilities in the United States.

Lifetime Energy Cost: The sum of the discounted value of annual energy cost and an average luminaire life of 15 years or 50,000 hours. Future utility price trends and a 3% discount rate are from Energy Price Indices and Discount Factors for Life-Cycle Cost Analysis – 2015: Annual Supplement to NIST Handbook 135 and NBS Special Publication 709 (NISTIR 85-3273-30).

Lifetime Energy Cost Savings: The difference between the lifetime energy cost of the less efficient model and the lifetime energy cost of the required model or best available model.

Best Available Model Column

Calculated based on the most efficient model on the market. More efficient models may be introduced to the market after FEMP's acquisition guidance is posted.

Required Model Column

Calculated based on FEMP designated efficiency requirements. Federal agencies must purchase products that meet or exceed FEMP designated efficiency levels.

Less Efficient Model Column

Calculated based on the bottom 25% in terms of efficiency for this product type.


Determine When FEMP-Designated Products Are Cost-Effective

An efficient product is cost-effective when the lifetime energy savings (from avoided energy costs over the life of the product, discounted to present value) exceed the additional up-front cost (if any) compared to a less efficient option. FEMP considers up-front costs and lifetime energy savings when setting required efficiency levels. Federal purchasers can assume that ENERGY STAR-qualified products and products that meet FEMP-designated efficiency requirements are life cycle cost-effective. In high-use applications or when energy rates are above the federal average, purchasers may save more if they specify products that exceed federal efficiency requirements, as shown in the Best Available column above.

Claim an Exception to Federal Purchasing Requirements

Products meeting ENERGY STAR or FEMP-designated efficiency requirements may not be life cycle cost-effective in certain low-use applications or in locations with very low rates for electricity or natural gas. However, for most applications, purchasers will find that energy-efficient products have the lowest life cycle cost.

Agencies may claim an exception to federal purchasing requirements through a written finding that no FEMP-designated or ENERGY STAR-qualified product is available to meet functional requirements, or that no such product is life cycle cost-effective for the specific application. Learn more about federal product purchasing requirements.

Incorporate Federal Acquisition Regulation Language in Contracts

These mandatory requirements apply to all forms of procurement, including construction guide and project specifications; renovation, repair, energy service, and operation and maintenance (O&M) contracts; lease agreements; acquisitions made using purchase cards; and solicitations for offers. Federal Acquisition Regulation (FAR) Part 23.206 requires agencies to insert the clause at FAR section 52.223-15 into contracts and solicitations that deliver, acquire, furnish, or specify energy-consuming products for use in federal government facilities. To comply with FAR requirements, FEMP recommends that agencies incorporate efficiency requirements into technical specifications, the evaluation criteria of solicitations, and the evaluations of solicitation responses.

Find Federal Supply Sources

The federal supply sources for energy-efficient products are the General Services Administration (GSA) and the Defense Logistics Agency (DLA). GSA sells products through its Multiple Awards Schedules program and online shopping network, GSA Advantage!. DLA offers products through the Defense Supply Center Philadelphia and online through DOD EMALL. Products sold through DLA are codified with a 13-digit National Stock Number (NSN) and, in some cases, a two-letter Environmental Attribute Code (ENAC). The ENAC identifies items that have positive environmental characteristics and meet standards set by an approved third party, such as FEMP and ENERGY STAR.

The United Nations Standard Products and Services Code (UNSPSC) is a worldwide classification system for e-commerce. It contains more than 50,000 commodities, including many used in the federal sector, each with a unique eight-digit, four-level identification code. Manufacturers and vendors are beginning to adopt the UNSPSC classification convention and electronic procurement systems are beginning to include UNSPSC tracking in their software packages. UNSPSCs can help the federal acquisition community identify product categories covered by sustainable acquisition requirements, track purchases of products within those categories, and report on progress toward meeting sustainable acquisition goals. FEMP has developed a table of ENERGY STAR and FEMP-designated covered product categories and related UNSPSC numbers.

Commercial Suspended Fluorescent Luminaire Schedules and Product Codes

GSA offers energy-efficient lighting products through Schedule 51 V (Hardware Superstore) and Schedule 56 (Buildings and Building Materials/Industrial Services and Supplies).

DLA's ENAC for ceiling-mounted fluorescent luminaires is "HK."

The UNSPSC for suspended luminaires is 39111522.

Buyer Tips: Make Informed Product Purchases

Buyers are advised to compare models within each luminaire subcategory, rather than choosing a luminaire for its efficiency (i.e., luminaire efficacy rating [LER]) value alone. Luminaire size, type, optical element, and lamp type may be selected for a variety of reasons based on the application—including color temperature, color rendition, light output, light distribution, rated lifetime, and cost.

LERs should be readily available in manufacturers' literature. If they are not, ask your supplier for these values, or calculate them using this equation:

LER = (Luminaire Efficiency  x Total Rated Lamp Lumens x Ballast Factor) / (Luminaire Watts Input)

Luminaire efficiency, total rated lamp lumens, ballast factor, and luminaire watts input are typically found in manufacturers' product specification sheets and photometric reports.

User Tips: Use Products More Efficiently

In addition to selecting the optimal luminaire for the application, building operators should operate lighting only when needed. Buyers should consider using lighting controls such as occupancy sensors, task tuning, and dimming when daylight is present (where applicable) to facilitate further energy savings.

Fluorescent luminaires should be maintained to retain their light levels. This includes periodically cleaning lenses and reflectors, and replacing lamps and ballasts. Changing lamps as they burn out is very labor intensive. Group relamping (changing all lamps in an area at a certain point in their average lives) is a more cost-effective maintenance practice than individual lamp replacement due to failure.

General service fluorescent lamps (GSFL), including 4-foot linear T8s, T5s, and T5HOs, are a product category covered by FEMP. When relamping luminaires with these products, the new lamps must meet the efficiency requirements set in FEMP’s product overview for general service fluorescent lamps.

Fluorescent ballasts are also a product category covered by FEMP. When replacing these products in federal facilities, the new models must meet the efficiency requirements set in FEMP’s product overview for fluorescent ballasts.

Due to their long service lives, some fluorescent luminaires are retrofitted with new lamps and ballasts at the same time. This is an opportunity for federal energy managers and facilities engineers to greatly improve luminaire efficiency by selecting lamps and ballasts that are optimized to work together.

Lawrence Berkeley National Laboratory provided supporting analysis for this acquisition guidance.