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Covered Product Category: Industrial Luminaires (High/Low Bay)

The Federal Energy Management Program (FEMP) provides acquisition guidance and Federal efficiency requirements for Industrial Luminaires (High/Low Bay).  Federal laws and requirements mandate that agencies meet these efficiency requirements in all procurement and acquisition actions that are not specifically exempted by law.

Meeting Energy Efficiency Requirements for Industrial Luminaires (High/Low Bay)

Federal purchases must meet or exceed the minimum requirements listed in the following table. The minimum requirement metric is luminaire efficacy rating (LER), which is measured in lumens per Watt (lm/W).

Table 1. Efficiency Requirements for Federal Purchases (Im/W)
High Bay1, Linear, Fluorescent
Distribution Patterna

 

Luminaire Size Required LER (lm/W)
F32T8 F54T5HO
Direct 1’ x 4’ ≥ 92 ≥ 75
2’ x 4’ ≥ 73
Semi-Direct 2’ x 4’ ≥ 70
Low Bay2, Linear, Fluorescent
Direct and Semi-Direct 1’ x 4’ ≥ 86
2’ x 4’ ≥ 85
1’ x 8’ ≥ 88
High Bay, Non-Linear, Metal Halide
Distribution Pattern Input Watts (W) Required LER (lm/W)
Closed Open
Direct 150 - 399 ≥ 57 ≥ 67
400 - 999 ≥ 65 ≥ 70
≥ 1000 ≥ 80 ≥ 81
Semi-Direct 150 - 399 ≥ 63 ≥ 67
400 - 999 ≥ 73 ≥ 79
≥ 1000 NA3 NA
Low Bay, Non-Linear, Metal Halide
Direct and Semi-Direct 150 - 399 ≥ 62 ≥ 67
400 - 999 ≥ 71 ≥ 74
≥ 1000 NA ≥ 81

a Suspended luminaires are designated into categories that differ by the percentage of light emitted in a direction above the horizontal plane of the luminaire. The categories used in this efficiency requirement include direct (0 – 10% upward component) and semi-direct (10 – 40% upward component).

 

Defining the Covered Product

This product overview applies to interior luminaires defined by NEMA LE-64 as either high bay linear, linear industrial (referred to as “low bay linear” in this product overview), high bay non-linear, or low bay non-linear. Fluorescent luminaires (including recessed, surface mounted, and strip lights), suspended fluorescent luminaires, and exterior lighting are each covered by separate FEMP product overviews and efficiency requirements. Commercial downlight luminaires, residential luminaires, and some other commercial luminaire products are covered by ENERGY STAR specifications.

Industrial luminaires are used to light large, open interior spaces with high ceilings. In the Federal sector, these spaces include warehouses, commissaries, maintenance facilities, gymnasiums, and aircraft hangars. Depending on the mounting height of the luminaires used in these spaces, they are considered either high bay or low bay. The efficiency requirements in Table 1 apply to linear fluorescent and non-linear metal halide industrial luminaires. Product performance for luminaires using fluorescent lamps must be measured in accordance with NEMA Standard LE 55, while those using high-intensity discharge lamps must be measured in accordance with NEMA LE 5B6.

Reducing Energy Costs: Save Between $50 and $570 by Purchasing Products That Meet or Exceed FEMP-Designated Efficiency Requirements

FEMP calculated that a product meeting FEMP-designated efficiency requirements is cost effective if it is priced no more than the lifetime energy cost savings resulting from the substitution of that model for the less-efficient alternative. In first example below for a high bay, non-linear, direct, open luminaire using a 400-Watt metal halide lamp, the more efficient options provide sufficient light output to allow the use of luminaires with a 350-Watt lamp. Luminaires would be directly substituted with no adjustment made for spacing due to differences in light output with the less efficient model. The estimated savings over the luminaire lifetime would be $242 for luminaires meeting the FEMP-designated level. Therefore, a high bay, non-linear, direct, open luminaire using a 350-Watt metal halide lamp meeting the efficiency requirements is cost-effective if priced at $242 or less above the less efficient 400-Watt model. The best available level saves the average user more money. The most efficient high bay, non-linear, direct, open luminaire using a 350-Watt metal halide lamp available is cost-effective if priced at $312 or less above the baseline model. The complete cost effectiveness example and associated assumptions are provided in Table 2.

Table 2. Cost-Effectiveness Example for High-Bay, Non-Linear Luminaries7

Performance

Best Available, 350 W MHa FEMP-Designated, 350 W MHb Less Efficient, 400 W MHc

LER (lm/W)

83 70 61

Power Input (W)

382 400 463

Initial Luminaire Light Outputd (lm)

31579 29151 28197

Annual Energy Use (kWh)

1375 1440 1667

Annual Energy Cost

$124 $130 $150

Lifetime Energy Cost

$1,469 $1,538 $1,781

Lifetime Energy Cost Savingse

$312 $242 ======

a The efficiency of the Best Available models was obtained during FEMP’s market analysis. More efficient products may have been introduced to the market since this information was obtained.
b Federal purchases must be of products that meet or exceed FEMP-designated efficiency requirements.
c Less Efficient represents low efficiency (bottom quartile) fluorescent luminaires in this category.
d Initial luminaire light output = initial lamp lumens * number of lamps * ballast factor * luminaire efficiency.
e Luminaires are directly substituted with no adjustment made for luminaire spacing due to differences in light output with the less efficient model.

 

The next example, shown in Table 3, compares low bay, linear, direct, 1-foot x 4-foot luminaires using two F32T8 lamps. This example assumes that because the FEMP-designated model or the best available model provides higher light output than the less efficient model, specifiers could potentially use fewer luminaires per square foot in a renovation or new installation. The estimated savings over the luminaire lifetime would be $50 for luminaires meeting the FEMP-designated level and $77 for luminaires meeting the best available level.

Table 3. Cost-Effectiveness Example for Low-Bay, Linear, 1-Foot by 4-Foot Luminaries Using Two F32T8 Lamps

Performance

Best Available FEMP-designated Less Efficient

LER (lm/W)

102 86 67

Power Input (W)

57 59 61

Initial Luminaire Light Output (lm)

5826 5143 4144

Annual Energy Use (kWh)

205 212 218

Adjusted Annual Energy Usea,b (kWh)

146 171 218

Adjusted Annual Energy Cost

$13 $15 $20

Lifetime Adjusted Energy Cost

$156 $183 $233

Lifetime Energy Cost Savings

$77 $50 ======

a Annual adjusted energy use is adjusted by the ratio of the initial luminaire light output of the less efficient model to the initial luminaire light output of the FEMP-designated, or best available, luminaire. Annual energy cost and lifetime energy cost are also adjusted accordingly.
b Assumes that for FEMP-designated or best available luminaires, fewer luminaires or can be used to provide equivalent light output.

 

The final example, shown in Tables 4 and 5, compares high bay, non-linear, semi-direct, closed luminaires using 250-Watt metal halide lamps with high bay, linear, semi-direct fluorescent 2-foot x 4-foot luminaires using four F54T5HO fluorescent lamps and six F32T8 fluorescent lamps. This calculation also adjusts annual energy use using ratios of luminaire light output, assuming that luminaire spacing could be adjusted to provide equivalent light output to the less-efficient model. For this comparison, the adjustments in luminaire light output are made using mean (maintained) lumens, which are lumens produced by the lamp at 40% of rated life for these lamp types, rather than initial lumens.

Fluorescent systems have higher maintained lumens during their lifetime than metal halide systems, and metal halide systems using electronic ballasts have higher lumen maintenance than those using magnetic ballasts, which should be considered in the comparison of the two system types. For luminaires meeting the FEMP-designated level the estimated savings over the luminaire lifetime would be $125 for luminaires using 250-Watt metal halide lamps, $371 for luminaires using four F54T5HO lamps and $553 for luminaires using six F32T8 lamps.

For luminaires meeting the best available level the estimated savings over the luminaire lifetime would be $364 for luminaires using 250-Watt metal halide lamps, $386 for luminaires using four F54T5HO lamps and $570 for luminaires using six F32T8 lamps. In general when considering the choice of luminaires using T8 or T5HO lamps, in addition to maintained light output and input watts, buyers should consider light distribution and quality issues.

Table 4. Cost-Effectiveness Example for High-Bay, Semi-Direct, Closed Luminaire Using 250 Watt Metal Halide Lamp (FEMP-Desingated Options)7

Performance

FEMP-Designated

F32T8, 6-Lamp

FEMP-Designated

F54T5HO, 4-Lamp

FEMP-Designated

250 W MH

Less Efficient

250 W MH

LER (lm/W)

93 71 63 59

Power Input (W)

174 230 300 300

Initial Luminaire Light Output (lm)

16181 16419 18880 17690

Maintained Luminaire Light Outputa (lm)

15372 15598 15482 13798

Annual Energy Use (kWh)

626 828 1080 1080

Adjusted Annual Energy Useb,c (kWh)

562 732 963 1,080

Adjusted Annual Energy Cost

$51 $66 $87 $97

Lifetime Adjusted Energy Cost

$601 $782 $1,028 $1,154

Lifetime Energy Cost Savings

$553 $371 $125 ======

a Maintained lumen adjustment factors are from manufacturers literature.
b Annual adjusted energy use is adjusted by the ratio of the maintained light output of the less efficient model to the maintained light output of the FEMP-designated luminaire. Annual energy cost and lifetime energy cost are also adjusted accordingly. For metal halide luminaires, the lumen maintenance factor for the less efficient model is that of a magnetic ballast, for the FEMP-designated model is the average between magnetic and electronic ballast, and for the best available model is that of an electronic ballast.
c Assumes that for FEMP-designated luminaires fewer luminaires can be used to provide equivalent light output.

 

Table 5. Cost-Effectiveness Example for High-Bay, Semi-Direct, Closed Luminaire using 250 Watt Metal Halide Lamp (Best Available Options)7

Performance

Best Available
F32T8, 6-lamp

 

Best Available

F54T5HO, 4-lamp

Best  Available

250 W MH

Less Efficient

250 W MH

LER (lm/W)

96 73 78 59

Power Input (W)

175 240 288 300

Initial Luminaire Light Output (lm)

16735 17453 22498 17690

Maintained Luminaire Light Outputa (lm)

15899 16580 19348 13798

Annual Energy Use (kWh)

630 864 1037 1080

Adjusted Annual Energy Useb,c (kWh)

547 719 739 1,080

Adjusted Annual Energy Cost

$49 $65 $67 $97

Lifetime Adjusted Energy Cost

$584 $768 $790 $1,154

Lifetime Energy Cost Savings

$570 $386 $364 ======

aMaintained lumen adjustment factors are from manufacturers literature.
b Annual adjusted energy use is adjusted by the ratio of the maintained light output of the less efficient model to the maintained light output of the FEMP-designated luminaire. Annual energy cost and lifetime energy cost are also adjusted accordingly. For metal halide luminaires, the lumen maintenance factor for the less efficient model is that of a magnetic ballast, for the FEMP-designated model is the average between magnetic and electronic ballast, and for the best available model is that of an electronic ballast.
c Assumes that for FEMP-designated luminaires fewer luminaires can be used to provide equivalent light output.

 

Exceptions

Products meeting FEMP-designated efficiency requirements or ENERGY STAR performance specifications may not be life cycle cost effective in certain low-use applications. For most other average or high-use applications, purchasers will find that energy-efficient products have the lowest life cycle cost.

Operating conditions vary from facility to facility. To help determine cost effectiveness for operating hours different from the example, multiply savings by this ratio:

(Your Annual Hours of Use) ÷ (3,600 Annual Hours of Use)

Complying with Contracting Requirements

Legislation and the Federal Acquisition Regulations (FAR) require Federal agencies to specify and buy ENERGY STAR® qualified products or, in categories not included in the ENERGY STAR program, products that meet or exceed FEMP-designated efficiency requirements. Agencies that follow requirements to buy efficient products can realize substantial operating cost savings and help prevent pollution. As the world's largest consumer, the Federal Government can help pull the entire U.S. market toward greater energy efficiency, while saving taxpayer dollars.

These requirements apply to all forms of procurement, including construction guide specifications and project specifications; renovation, repair, maintenance, and energy service contracts; lease agreements; acquisitions made using purchase cards; and solicitations for offers. Energy efficiency requirements should be included in both the evaluation criteria of solicitations and the evaluations of solicitation responses.

Federal Acquisition Regulation (FAR) Part 23.206 requires Federal agencies to insert the clause at FAR section 52.223-15 in solicitations and contracts that deliver, acquire, furnish, or specify energy-consuming products. FEMP recommends that agencies incorporate efficiency requirements into both the technical specification and evaluation sections of solicitations. Agencies may 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.

Designing an Industrial Luminaire Installation: Special Considerations

Once the designer determines whether an application requires high bay or low bay luminaires, the next decision is whether to use a linear or a non-linear luminaire. The light source types for the luminaires covered by this product overview are fluorescent for linear luminaires and non-linear metal halide for non-linear luminaires.

Luminaires using fluorescent lamps and ballasts have the following advantages in comparison with those using metal halide: longer life, higher lumen maintenance, shorter warm-up and restrike times, more controllable in terms of wider dimming range and usage with occupancy sensors, better color rendering index, and better color consistency (less color shift over time). As a linear source, they also tend to have less glare than a metal halide luminaire using a point source, although T5HO luminaires may cause glare at lower mounting heights.

Luminaires using T5HO lamps can provide quality light output and higher fixture efficiency in high bay applications than luminaires using T8 lamps. A T5HO system is not as efficacious as a T8 system but produces more light output from the same number of lamps. Also, T5HO lamp operation is optimized at a higher ambient temperature than it is for T8s; this may be a factor in some locations. With more light produced from a smaller diameter lamp, T5HO lamps are much brighter than T8 lamps. This may produce glare in low bay applications, where luminaires using T8 lamps may be more appropriate. However, depending on the application, either lamp type may be used.

Metal halide systems may be the preferred option when it is desirable to have a point source rather than a linear light source. One main advantage of metal halide luminaires is lower maintenance costs, since these systems usually use one lamp in contrast to fluorescent luminaires using several lamps to provide sufficient light output. Other advantages include better operation in spaces with wide temperature range or low ambient temperature, availability of more closed luminaires for hazardous or corrosive environments, and availability of higher-wattage luminaires available for very high mounting heights.

When specifying metal halide luminaires, buyers are advised to select those using pulse start lamps and ballasts.8 The advantages of pulse start over probe start operation include longer lamp life, higher efficacy, increased lumen maintenance, better color rendition, better starting at low temperatures, faster starting and warm-up times, shorter re-strike times, and better color shift control. In addition, buyers are advised to consider electronic metal halide ballasts, which provide higher efficacy, better lumen maintenance, and better control of color shift over the lamp life than do magnetic ballasts. For applications where high color rendition is desired, luminaires using ceramic metal halide lamps provide superior color rendering indices (CRI) as well as high lumen maintenance, especially when used with an electronic ballast.

Metal halide systems using pulse start electronic ballasts may have higher efficacy in terms of initial lumens than fluorescent systems. However, comparison of luminaires using these two different light sources should consider efficacy in terms of maintained or mean lumens. For new designs or substantial lighting renovations, by using higher-efficiency luminaires that provide sufficient lumen maintenance over the lifetime of the installation, designers may be able to use fewer luminaires per unit area, lower lamp wattage, or fewer lamps per luminaire to provide the desired light output. See the discussion in the third cost-effectiveness example above for more details.

High-pressure sodium (HPS) systems have been widely used in industrial and outdoor applications, but they do not meet the visual performance requirements of most interior high bay and low bay applications. The availability of pulse-start metal halide and high-efficiency fluorescent systems has substantially diminished the traditional advantages of long life and high efficacy that HPS systems have compared to standard metal halide or fluorescent systems. In circumstances where it is still desirable to use high-pressure sodium systems, they are required to meet the corresponding metal halide system requirements shown in Table 1. Other high-intensity discharge lamp types, such as mercury-vapor and low-pressure sodium, have very poor color rendition. Mercury-vapor luminaires are much less efficient than those using metal halide or HPS light sources.9

Once the major decisions on luminaire type, lamp type and ballast type have been made, the specifier should determine the light distribution needs of the application and make selections of light distribution, beam distribution and enclosure as appropriate. The choice of an open, closed, or lensed luminaire depends on the degree of protection required for the lamps, as well as glare control considerations.

Comparing Efficacy

Buyers are advised to compare LERs only within each luminaire category and subcategory, rather than choosing a luminaire for its LER value alone. Luminaire type, light source type, light distribution, enclosure type, luminaire size, lamp wattage, number of lamps, and ballast type may be selected for a variety of reasons based on the application—including color temperature, color rendition, light output, rated lifetime and cost.

LERs should be readily available in manufacturers' literature. If not, ask your supplier for LER values. If LER is not available, buyers may calculate LER using this formula:

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

Luminaire efficiency (LE), total rated lamp lumens, ballast factor (BF), and luminaire watts input (input watts) may typically be found in manufacturers' product specification sheets and photometric reports.

Target efficacy rating (TER) is another informative metric for comparing luminaire effectiveness in delivering light to the application target. While LER uses luminaire efficiency (LE, the percentage of total lamp lumens that leaves the luminaire), TER uses energy effectiveness factor (EEF, the percentage of total lamp lumens that reaches the specified target area typical of the luminaire) in its calculation of luminaire efficacy. Since TER is available in some but not all manufacturer literature, this guidance relies on LER as its efficiency metric.

User Tips: Using Products More Efficiently

In addition to selecting the optimal luminaire for the application, building operators should endeavor to operate lighting only when needed. The use of lighting controls such as occupancy sensors, task tuning, and dimming when daylight is present (where applicable) should be considered to facilitate further energy savings. Controls are available for fluorescent systems and, to a more limited extent, for metal halide systems (due to their longer warm-up and restrike times). Industrial luminaires should be cleaned periodically to maintain their rated light output.

Finding More Information

Lawrence Berkeley National Laboratory provided supporting analysis for this product overview.

Updated January 2014

1 “High Bay” refers to a luminaire used at a mounting height greater than 25 feet.

2 “Low Bay” refers to a luminaire used at a mounting height up to and including 25 feet.

3 “NA” indicates that the database contains too few models to propose an ER for this lamp type.

4 National Electrical Manufacturers Association Standard Publication LE 6-2009: Procedure for Determining Target Efficiency Ratings for Commercial, Industrial and Residential Luminaires.

5 National Electrical Manufacturers Association Standard Publication LE 5-2001: Procedure for Determining Luminaire Efficiency Ratings for Fluorescent Luminaires

6 National Electrical Manufacturers Association Standard Publication LE 5B-1998: Procedure for Determining Luminaire Efficiency Ratings for High-Intensity Discharge Industrial Luminaires

7 Based on the following assumptions: The luminaire is used an average of 3,600 hours per year for its lifetime of 15 years. The electricity rate is $0.09 per kWh, the average at U.S. Federal facilities. Future electricity price trends and a 3% discount rate are based on Federal guidelines (NISTIR 85-3273-27).

8 The Energy Independence and Security Act of 2007 (EISA), which took effect in 2009, requires that metal halide fixtures designed to be operated with metal halide lamps from 150 to 500 watts must contain ballasts that meet efficiency requirements that depend on ballast type (pulse start, magnetic probe start or non-pulse start electronic). Since most probe start ballasts do not comply with their higher efficiency requirements, essentially this legislation is driving the market toward pulse start metal halide luminaires.

9 The Energy Policy Act of 2005 eliminated the sale of mercury vapor ballasts as of January 2008. Mercury vapor lamps can be sold for use in existing luminaires, but no new luminaires using mercury vapor lamps can be sold because ballasts are not available for them.