Purchasing Energy-Efficient Ceiling-Mounted Fluorescent Luminaires

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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.

The Federal Energy Management Program (FEMP) provides acquisition guidance for ceiling-mounted fluorescent luminaires, a product category covered by FEMP efficiency requirements. Federal laws and requirements mandate that agencies purchase ENERGY STAR-qualified products 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 ceiling-mounted fluorescent luminaires that are recessed into suspended ceiling systems or are directly attached to ceiling or roof structures. Ceiling-mounted fluorescent lamps with and specialized luminaires such as recessed linear and round wall washers are excluded. Suspended fluorescent luminaires and industrial (high/low bay) luminaires are covered by separate FEMP-designated product categories. Residential light fixtures and commercial downlights (also known as recessed cans) are covered by the ENERGY STAR program and are excluded from this product category.

This acquisition guidance was updated in July 2017.

Find Product Efficiency Requirements

Federal purchases must meet or exceed the minimum efficiency requirements in Table 1. These requirements are given in luminaire efficacy rating (LER), which is the ratio of lamp lumen output (lumens) to measured electrical power input (watts), and stated in lumens per watt (lm/W). A higher number indicates a more efficient product (i.e., more light output per unit of power input).

Table 1. Efficiency Requirements for Ceiling-Mounted Fluorescent Luminaires
Luminaire Type and SizeOptical ElementLuminaire Efficacy Rating (LER)
T5HOT5T8Twin tubeT8 U-shaped
Recessed 1-foot by 4-footLensed≥56 lm/W≥70 lm/W≥73 lm/W==========
Louvered≥55 lm/W≥68 lm/W≥65 lm/W==========
Other≥69 lm/W≥73 lm/W≥85 lm/W==========
Recessed 2-foot by 4-footLensed≥73 lm/W≥80 lm/W≥89 lm/W==========
Louvered≥66 lm/W≥65 lm/W≥81 lm/W==========
Other≥65 lm/W≥75 lm/W≥88 lm/W==========
Surface-mounted 1-foot by 4-footAny≥66 lm/W≥69 lm/W≥82 lm/W==========
Surface-mounted 2-foot by 4-footAny≥82 lm/W≥78 lm/W≥78 lm/W==========
Strip light 1-foot by 4-foot=====≥73 lm/W≥82 lm/W≥89 lm/W==========
Recessed 2-foot by 2-footLensed≥66 lm/W≥69 lm/W≥72 lm/W≥71 lm/W≥75 lm/W
Louvered≥57 lm/W≥63 lm/W≥64 lm/W≥62 lm/W≥65 lm/W
Other≥57 lm/W≥70 lm/W≥64 lm/W≥63 lm/W=====
Surface-mounted 2-foot by 2-footAny≥66 lm/W≥65 lm/W≥64 lm/W≥67 lm/W≥66 lm/W

Product performance must be determined in accordance with the National Electrical Manufacturers Association (NEMA) LE 5-2001: Procedure for Determining Luminaire Efficacy Ratings Fluorescent Luminaires.

Make a Cost-Effective Purchase: Save $51 by Buying a FEMP-Designated Product

FEMP calculated that the required models below save money if priced no more than $51 above the less-efficient model. The best available model saves up to $101. Federal purchasers can assume products that meet FEMP-designated efficiency requirements are life cycle cost-effective. Table 2 compares three types of product purchases and calculates the lifetime cost savings of purchasing efficient models.

Table 2. Lifetime Savings for Efficient 2-Foot by 4-Foot T8 Recessed Other Luminaire
PerformanceBest AvailableRequired ModelLess Efficient
Light Output7,0007,0007,000
Luminaire Efficacy Rating1048876
Input Power678092
Annual Energy Use242286332
Annual Energy Cost$22$26$30
Lifetime Energy Cost$273$322$373
Lifetime Cost Savings$101$51======

 

View the Performance and Model Assumptions for Table 2

Performance Column

Light Output: A measure of the total amount of visible light emitted by a source, shown in lumens. Seven thousand lumens is typical for this subcategory based on model data.

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 (shown in lm/W).

Input Power: Based on the wattage used by the luminaire with an output of 7,000 lumens.

Annual Energy Use: Based on NEMA’s LE 5-2001 or Illuminating Engineering Society's (IES) LM-79-08 calculations for 4-foot long, lensed luminaires used an average of 3,600 hours per year, which is typical for federal facilities.

Annual Energy Cost: Calculated based on an assumed electricity price of $0.09/kWh, which is the average electricity price at federal facilities. (Source: U.S. Department of Energy. 2016. Federal Government Energy/Water Use and Emissions in 2015. In Comprehensive Annual Energy Data and Sustainability Performance.)

Lifetime Energy Cost: Calculated as the sum of the discounted value of the annual energy cost and assumed product life of 15 years. Future electricity price trends and a 3% discount rate are based on federal guidelines (NISTIR 85-3273-31) and are from the Annual Supplement to NIST Handbook 135 and NBS Special Publication 709, Energy Price Indices and Discount Factors for Life Cycle Cost Analysis – 2016.

Lifetime 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 (shown in kWh).

Best Available Model Column

Calculated based on the most efficient model on the market as of February 2017. More efficient models may be introduced to the market after FEMP's acquisition guidance is posted.

Required Model Column

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

Less Efficient Model Column

Calculated based on the previous FEMP recommended level 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 FEMP-designated products 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 (e.g., the best available model).

Claim an Exception to Federal Purchasing Requirements

Products meeting 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 product is available to meet functional requirements, or that no such product is life cycle cost-effective for the specific application. Get additional information on 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 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 and energy performance requirements into both the technical specification and evaluation sections of solicitations.

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 FedMall (formerly DOD EMALL). Products sold through DLA are codified with 13-digit National Stock Numbers 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.

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 codes.

Ceiling-Mounted Fluorescent Luminaires Schedules and Product Codes

GSA offers fluorescent lamps through Schedule 56 (Buildings and Building Materials/Industrial Services and Supplies).

DLA offers ceiling-mounted fluorescent luminaire models with the ENAC "GN" at the end of the NSN.

The UNSPSC for ceiling-mounted fluorescent luminaires are shown in Table 3.

Table 3. Product Codes for Ceiling-Mounted Fluorescent Luminaires
FEMP Product CategoryUNSPSC
Fluorescent Fixtures39111501
Recessed Lighting39111505
Fluorescent Strip39111533
Lensed Troffer39111534
Parabolic Fixture39111535

Buyer Tips: Make Informed Product Purchases

Buyers are advised to compare efficiencies (i.e., LER or LE) only within each luminaire subcategory, rather than choosing a luminaire for its LER value alone. Luminaire size, luminaire 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)

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

The luminaire market is continuously evolving. Luminaire optical elements have become more varied and more efficient. For the past several years, luminaires using T5HO lamps have proliferated, and a modest number of T5 models have emerged. The market for electronic ballasts driving T8 fluorescent lamps has continued to shift toward subsequently more-efficient generations of high-performance ballasts and lamps, which increases the efficacy of the luminaires where they are incorporated. The most recent additions to the luminaire market are products using LED light sources that offer both higher efficiency and longer life.

Some recessed luminaires can be configured with a more attractive outer housing and surface mounted. In these situations, use the efficiency requirements associated with the recessed version of the luminaire.

Design and Installation Tips

Luminaires are categorized by their optical elements (i.e., lensed, louvered, and other). Buyers should first choose the optical element(s) that meet their lighting application and then compare efficacies within that subcategory.

Efficient design includes the provision of adequate lighting for the application and tasks, using the lighting levels recommended by the Illuminating Engineering Society of North America. Designers should follow building code requirements, which may have limits to watts per square foot as well as prescriptive requirements, and take care not to over light a space. FEMP-designated or best available luminaires may reduce energy use and costs, as well as purchase and installation costs, in comparison to less-efficient luminaires. For example, fewer efficient luminaires with higher light output may be required to light a space, or luminaires with fewer numbers of lamps may be used to provide equivalent light output to that of less-efficient models using more lamps.

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. Higher-efficiency lamps may maintain lumen output better than standard efficiency models, allowing for longer group relamping periods.

General service fluorescent lamps (GSFL), including 4-foot linear T8s, T5s, T5HOs and 2-foot U-Shaped T8s, 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, fluorescent luminaires are often retrofitted with new lamps and ballasts at the same time. This is an opportunity for federal energy managers and facilities engineers to greatly improve the efficiency of these luminaires by selecting lamps and ballasts that are optimized to work together.

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