LED Commercial Office Lighting (2 ft x 2 ft troffer)
General Office Lighting: Linear LED vs. Linear Fluorescent
Open area recessed, suspended or surface-mounted fixtures for office lighting, typically in place of fluorescent troffers.
Item ID: 401
Technical Advisory Group: 2012 LED Lighting TAG (#5)
Average TAG Rating: 3 out of 5
TAG Ranking Date: 04/05/2012
LED products are becoming broadly available for general office area lighting applications. Products are available in 2’x4’, 2’x2’ and 1’x4’ sizes to replace typical fluorescent troffers. The DesignLights™ Consortium Qualified Products List includes categories for 2’x2’ and 2’x4’ LED panels. The efficacy of LED linear panels can rival or exceed the efficacy of a high-efficiency fluorescent system, with some systems exhibiting overall luminaire efficacy as high as 100 lumens/watt. However, their overall performance may not exceed the best fluorescent systems and the first cost continues to be high.
Energy savings over traditional fluorescents may be possible, depending on design light levels and fixture efficiency. Lamp life could be significantly longer than for most fluorescent lamps, potentially providing maintenance savings that can be significant for commercial applications. The white light is available in a range of color temperatures and high color-rendering index (CRI) suitable for office lighting uses. Additionally, the DOE predicts continued improvement in efficacy and decline in price for LED lighting.
One potential advantage of LED lighting over fluorescent is that they have some features that are difficult to achieve with fluorescent technology. For instance, LEDs are inherently dimmable, though it is important to make sure the controls are compatible with the LED system. Another feature that is emerging is systems with the ability to control the correlated color temperature (CCT). This allows end users to control the light to have different color of light at different times of day, or to adjust for personal preferences in individual offices.
Baseline Description: Standard 2 ft U-Shaped Lamp
Baseline Energy Use: 233.8 kWh per year per unit
A troffer fixture is an inverted metal trough that houses and serves as a reflector for a fluorescent lamp/ballast system. These fixtures are widely used in commercial and industrial establishments ( Navigant Consulting Inc, 01/11/2011). This analysis considers the potential for LED 2 ft x 2 ft troffers as replacements for T-12 and T-8 lamps (Note that T-5 lamps are another energy savings choice). Navigant estimates a nationwide population of 9,200,000 2-foot U-shaped T-12 lamps and 39,300,000 2-foot U-shaped T-8 lamps in 2010. These lamps draw 70 W and 59 W, respectively and operate for 3,833 hours per year. The baseline energy use is thus 61 W (weighted average lamp wattage) x 3,833 hours per year/1000 = 233.8 kWh/year.
Manufacturer's Energy Savings Claims:
Currently no data available.
Best Estimate of Energy Savings:
"Typical" Savings: 25%
Energy Savings Reliability: 3 - Limited Assessment
An LED replacement for a T-12 or T-8 2 ft x 2 ft troffer requires about 46 Watts (Navigant Consulting Inc, 2011). As the average power required by the population of existing fluorescent units is 61 Watts, the estimated savings is 24.6%
Selecting an appropriate LED lighting system is not a matter of simply matching lumen output; because of the directional nature of LED sources, LED luminaires can often provide equivalent lighting performance using fewer lumens than conventional sources. Energy savings will be maximized by specifying an LED lighting system that delivers the necessary illuminance in the target area, with appropriate lighting quality, for the lowest power density. Energy savings will also depend on LED luminaire quality, longevity and proper installation of the LED lighting system, and whether controls are included in the system and what kind of controls are used.
Energy Use of Emerging Technology:
175.4 kWh per unit per year
Energy Use of an Emerging Technology is based upon the following algorithm.
Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))
Potential number of units replaced by this technology:
Navigant estimates that the nationwide installed base of T-12 and T-8 2-ft x 2-ft troffer fixtures is 48,500,000 units as of 2010 (Table 2.10) (Navigant Consulting Inc, 2011). Assuming that 4% of the installed base is in the Northwest (prorating by population) yields 1,940,000 potentially replaceable units.
Regional Technical Potential:
0.11 TWh per year
Regional Technical Potential of an Emerging Technology is calculated as follows:
Baseline Energy Use * Estimate of Energy Savings (either Typical savings OR the high range of savings) * Technical Potential (potential number of units replaced by the Emerging Technology)
Installed first cost per: unit
LED options are now available at prices on par with high quality architectural fluorescent lighting, making them particularly competitive in major remodel and new construction situations. Additionally, the DOE predicts continued improvement in efficacy (L/W) and associated energy savings and continued decline in first cost for LED lighting.
Based on information developed by Stan Walerczyk for the LED Linear Commercial Lighting TAG Working Group, the installed cost of high-performance LED troffer systems is approximately $325 per luminaire. The installed cost of high-performance fluorescent lighting systems is approximately $250 per luminaire. For a retrofit situation, the incremental cost will be the installed cost of the new LED lighting system plus the cost of removing and disposing of the previous luminaire ($20), or approximately $345 per luminaire. For a new construction situation, the incremental cost will be the cost of the new LED luminaire less the cost of the conventional option, or approximately $75 (assuming equivalent installation labor cost).
Simple payback, new construction (years): N/A
Simple payback, retrofit (years): N/A
Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.
No independent evaluations of the cost effectiveness of LED linear commercial lighting in actual installations were found. However, in general, cost effectiveness will vary based on a variety of factors, including the electricity rate, maintenance savings estimates, fixture cost and new construction versus retrofit scenarios.
In retrofit situations, given the high cost of new LED luminaires, replacing fluorescent lighting systems with new LED linear commercial luminaires is not likely to be cost effective compared to simple lamp/ballast replacement. In major remodels or new construction where new fixtures are being installed, the incremental cost of LED linear commercial luminaires compared to high-performance architectural fluorescent is small and declining. In these situations, LED options are likely to be cost-competitive.
In general, the cost effectiveness of LED linear commercial lighting is expected to improve as LED prices continue to decline and performance continues to improve. The estimated cost trajectory for LED lighting is well documented by the DOE. Prices are anticipated to drop by approximately 85% between 2010 and 2020, from $181/klm to $24/klm.
LED products are becoming broadly available for general office area lighting applications. Typically, these are linear products, available in 2’x4’, 2’x2’ and 1’x4’ sizes to replace typical recessed, surface and pendant-mounted fluorescent luminaires. Fixture designs employ a variety of methods to produce appropriate light distribution, pleasing aesthetics and minimal glare. These include uplight, edge lighting and unique lens designs.
The efficacy of LED linear panels can rival or exceed the efficacy of a high-efficiency fluorescent luminaire, with some luminaires exhibiting efficacy as high as 100 lumens/watt. However, their overall performance may not exceed the best fluorescent systems and the first cost continues to be high. The DOE is encouraging research, development and market penetration of the technology and is providing resources for developing objective, updated information about the technology.
The useful life of LED luminaires could be significantly longer than for the most common fluorescent lamps, potentially providing maintenance savings that can be significant for commercial applications. The white light is available in a range of color temperatures and high CRI suitable for office lighting uses.
LED linear commercial office luminaires are widely available from a number of manufacturers. These include CREE, Finelite, Albeo, Lithonia, MaxLite, Peerless, Philips and Lunera. As of April 2012, the DOE LED Lighting Facts program lists almost 150 products and the DesignLights Consortium Qualified Products List includes categories for 1’x4’, 2’x2’ and 2’x4’ LED linear panel luminaires and lists over 115 qualified products as of April 2012.
In addition, manufacturers are taking advantage of the unique aspects of LED lighting to develop a broad range of lighting products for use in office environments. While the focus of these products is not to maximize energy savings, they demonstrate the wide range of lighting design possibilities with LED sources. Many of these design aspects may provide non-energy benefits that may drive customer adoption.
For instance, manufacturers are developing LED office lighting in a wide variety of non-standard form factors. One example is the Philips DayWave, which delivers different light intensities and color temperatures over the course of the day (http://www.design.philips.com/philips/sites/philipsdesign/about/design/designportfolio/product_innovation/daywave.page).
The DayWave product and others like it draw attention to the interesting possibility with LED linear commercial lighting to provide lighting that changes color throughout the day to simulate the natural circadian rhythms of sunlight color change throughout the day. Alternatively, these color-changing products can be adjusted to suit personal preferences in light color. PlanLED's Color Change LED Troffer, shown at the 2012 LightFair is featured in this video: http://www.youtube.com/watch?v=OPaKuOeuMg8&feature=channel.
Another interesting idea possible with LEDs is making the lights look like sky, such as blue sky with cloud scenes. PlanLED's Sky Panel is featured in this video: http://www.youtube.com/watch?v=rYDW7rvbpTY&feature=channel.
Phillips is offering a line of "HealWell" lights that include ceiling lights that change color with the time of day for healthcare patient rooms. They claim that this is "A lighting solution that improves patient satisfaction and supports recovery in patient rooms." For a video and brochure, go to: http://www.lighting.philips.co.uk/application_areas/healthcare/healwell.wpd.
Phillips has also introduced a line of SchoolVision lighting that gives teachers control over the level and color of the light, claiming that it can enhance performance of students and help control the mood of the class during the day. See the Philips video at: http://www.lighting.philips.com/main/application_areas/school/schoolvision/.
Standard practice for office lighting most often focuses on providing an even distribution of light while meeting building and energy codes. Typically this is accomplished through the use of overhead fluorescent fixtures, either recessed or pendant mounted, with 2’ or 4’ linear fluorescent lamps.
Fluorescent lighting system technology has advanced over the years, progressing from T12 lamps and standard magnetic ballasts to high performance T8 and T5 lamps with electronic ballasts.
LED linear commercial lighting has advanced rapidly in recent years, tracking advancements in LED lighting in general. LED linear commercial luminaires are widely available from a significant number of manufacturers, with the number growing especially rapidly over the past two years. As of April 2012, the DOE LED Lighting Facts program lists almost 150 products. Approximately 25% of those have an efficacy of over 90 lumens/watt. The DesignLights Consortium Qualified Products List includes categories for 1’x4’, 2’x2’ and 2’x4’ LED linear panel luminaires and list over 115 qualified products as of April 2012.
The DOE CALiPER program tested LED linear commercial lighting in several rounds. The most recent report (as of April 2012) on the Round 13 tests was issued in October 2011. The CALiPER program also tested baseline traditional fluorescent products. Results show LED troffers tested in Round 13 and previous rounds were more efficacious and produced more light than some, but not all, tested fluorescent luminaires. On average, the 2' × 2' LED troffers had higher efficacies and lower light output than the fluorescent troffers, but there was a wide range of performance for both fluorescent and 2' × 2' LED troffers.
End User Drawbacks:
Long-term performance: Numerous independent assessments of LED lighting performance have been conducted and short-term performance is well documented. However, long-term performance data information does not exist given the early stage of the technology’s development.
Product quality: Studies such as DOE CALiPER reports demonstrate that product performance and application suitability vary widely. Product quality is highly variable and is changing rapidly, so it is important to carefully research and review available information to assess quality, performance, and overall value at the time of purchase. Product qualifications for LED exterior lighting available through organizations such as the DesignLights Consortium can be useful in vetting product quality.
High first cost and cost effectiveness: LED luminaires are currently more expensive than the incumbent lighting technologies. Costs are expected to decline due to technological advances and increased demand, and cost reductions are evident in the marketplace. Evaluating LED luminaires based on total cost of ownership will take into account potential non-energy benefits, such as maintenance savings, which will improve the cost-effectiveness analysis.
Operations and Maintenance Costs:
LED sources promise long life with slow lumen depreciation, which could result in lower maintenance costs and longer intervals between product replacement. Typically, assessments of indoor LED lighting have assumed zero regular maintenance costs over the course of their useful life because the technology is very robust and periodic replacement of light sources is not anticipated.
Typically, LED lights do not fail catastrophically, but rather decrease gradually in lumen output. When they lose 30% of their original output, they are considered to be at the end of their useful life and need replacing. At that point, however, they are still serviceable, even though light output is decreased. This allows for planned and orderly replacement rather than having to replace individual lamps as they fail, as usually happens with fluorescent lighting. This helps to further decrease the relative maintenance costs.
The rated life for conventional light sources is typically calculated as the mean time to failure of a statistically valid sample of lamps. The typical rated lifespans of the most common fluorescent lamps is 20,000 to 36,000 hours. Fluorescent lamps with very long life, up to 60,000 hours, are becoming available. However, they are not in widespread use at this time.
The useful life of LED sources is typically expressed in terms of lumen maintenance, most often as the number of hours until the lumen output has dropped to 70% of the initial light output (commonly referred to as L70). Well-designed LED linear office lighting can be expected to have an L70 life of over 50,000 hours and perhaps much longer. Given an average operation of 3,000 hours/year, this translates to approximately 17 years.
For fluorescent lamps, it is important to note that operating cycles have a large effect on lamp life. In contrast, the life of LED sources will not be degraded by frequent switching. In fact, an LED lamp that is dimmed or switched off frequently will run cooler, which could arguably increase the lamp life.
Also, it is important to note that a fixture may fail before the light source has reached its end of life, due to failure of another component of the fixture, including the electronics, materials, housing, wiring, connectors or seals. This is true for fixtures with conventional sources and fixtures with LED sources, but is likely to be more of an issue for LED fixtures given the very long life of the source. Modular design of LED luminaires is desirable so components that fail can be replaced without having to replace the entire luminaire.
The expected life of LEDs is so long that many LED lamps will need to be replaced long before they have reached the end of their effective (technical) life. A lamp expected to last 17 years will often be in a building that will get a major remodel within the expected lifetime. In addition, end users willing to install LEDs now are likely early adopters, and may be willing to upgrade their lamps to the much higher quality and less expensive lamps that are expected to be on the market in 10 to 15 years, before the original LED lamps have to be replaced. It may be unwise to calculate utility savings of installing LED lighting based on a full 17-year life.
High-performance fluorescent lighting systems are the primary technology competing with LED linear commercial office lighting. These high-performance fluorescent systems offer good color quality, luminaire efficacy up to 90 lumens/watt and relatively long life of up to 50,000 hours at a cost that is currently lower than competing LED systems. In retrofit situations, replacing fluorescent lighting systems with new LED linear commercial luminaires is not likely to be cost effective compared to simple lamp/ballast replacement with high-performance products. In major remodels or new construction where new fixtures are being installed, the incremental cost of LED linear commercial luminaires compared to high-performance architectural fluorescents is small and declining. In these situations, LED options are likely to be cost-competitive.