LEDs MAGAZINE Feature Article on LED Tubes T8 Technology
LED tubes approach mainstream adoption despite complexities
explains that 2015 will be the year when LED retrofit tubes hit the mainstream market, despite the myriad approaches to the fluorescent-replacement concept and complexities in the designs.
Over the past five years, LED tubes intended as fluorescent replacements have improved dramatically. Indeed, efficiency, lumen output, and uniformity have improved while costs have decreased significantly. Still, there are many choices in LED tube types and the landscape has been constantly changing, leading many lighting professionals and buyers to take a wait-and-see approach. The range of technology, cost, and service options are at the root of the complexity. But a clear understanding of the options can lead to successful small- and large-scale deployments.
Much of the complexity behind tubes is related to heat. Heat is the enemy of the LEDs, and of the power supplies, commonly called drivers. Drivers and LEDs both generate heat. Moreover, the driver implementation in LED tubes is perhaps the key differentiating factor in products from different vendors (Fig. 1). In this article, we will offer some perspective on the range of driver category choices to help define the right match for any given project or application scenario.
|FIG. 1. Replaceable-driver system LED tubes afford a low total cost-of-ownership (TCO) for specific lighting-user scenarios.|
There are six primary options for driver implementation in LED tubes:
1. Internal driver – Parallel driver
2. Internal driver – Thermal isolation end-cap driver
3. Internal driver – Thermal isolation and replaceable driver system
4. Internal driver – Ballast-compatible driver
5. External driver – Thermal isolation with driver direct power to pins
6. External driver – Thermal isolation with driver direct power to tubes
Internal LED driver integration
Let’s begin by discussing the four options for integration of the driver internal to the tube form factor. Typical good application matches for such tubes include single-shift commercial properties such as offices, retail, schools, etc.
Internal driver – Parallel driver. The internal driver that is mounted in a parallel fashion along the length of the tube is the most common architecture (Fig. 2). Advantages include familiarity in the market and the fact that the prices have come down dramatically.
But there are disadvantages to the approach. Heat generated from the LED driver, which runs parallel behind the printed circuit board (PCB), will damage the LEDs in some cases. The result can be degraded color, efficiency, and/or longevity. Indeed, the product may not fail completely but in a way that is still unacceptable. In the areas over the driver, the heat generated from the parallel driver adversely impacts the phosphor coating on the LEDs. The change in color creates an inconsistent fixture and overall ceiling illumination aesthetic that has deterred many buyers to date.
There are other disadvantages as well. When the driver fails in an integrated parallel driver, the tube itself fails, resulting in the need to discard and replace the whole product. Dimming is not always available in such designs. And an electrician is typically required to bypass the ballast for installation. Light output quality failure will most likely occur. These first-generation tube designs have become largely outdated by the latest advancements in thermal isolation in tubes.
Thermal isolation end-cap driver. One approach to thermal isolation places the driver in the end cap of the tube away from the LEDs (Fig. 3). Such designs offer the obvious thermal advantage over the parallel-driver tube, and the prices have also come down.
Still, while the heat generated from the driver is isolated, designs with a fixed integrated driver suffer catastrophic failure with driver failure. Moreover, as with the parallel products, dimming is not always available, and an electrician is also typically required to bypass the ballast for installation.
Thermal isolation and replaceable driver. The early end-cap driver tubes face a new challenger with modular replaceable driver systems in the end caps (Fig. 4). The advantage over the first two options is the ability for a building owner to repair rather than replace failed tubes. Indeed, when the driver fails, it can be replaced easily – in some cases without even cutting wires for some products. This results in discarding only the driver and not the whole tube with the LEDs.
|FIG. 3. Placing the internal LED driver in the end cap of the tube, away from the LEDs, offers a thermal isolation advantage over the parallel-drive tube.|
Prices for the tubes with replaceable drivers are competitive with predecessors. Buyers understand that LEDs are increasing in efficiency as the prices come down, so this category presents an opportunity to upgrade to more efficient drivers as well as LEDs on replaceable-strip PCBs. This modular approach may become a new standard for internal-driver LED tubes, given the flexibility and lower long-term total cost of ownership (TCO). Disadvantages are the same as in the prior two options.
Ballast-compatible driver. The need for ballast bypass has been the most commonly mentioned disadvantage of tubes thus far. Ballast-compatible drivers, also referred to as “plug and play” or “instant fit,” solve the problem (Fig. 5). Such tubes just clip into the fluorescent tombstone connectors, and no electrician is required for installation. Tenants as opposed to property owners may see this driver type as a key benefit.
Again, however, there are disadvantages. When the original fluorescent ballast fails, the end user needs to purchase another ballast, which typically requires installation by an electrician. The tube wattage is often higher – meaning efficacy is lower – than other LED tubes, because of the pass-through burden on the ballast.
External LED driver integration
Now let’s discuss tubes in which the driver functionality is located externally to the actual tube and LEDs. Typical applications in which such products are being installed include double- and triple-shift industrial and warehouse facilities, 24×7 hospitals, parking garages, fire and rescue centers, and long-runtime areas of any property such as emergency exit stairs, egress hallways, etc.
External driver with power to pins. The first type of external-driver topology still involves wiring the DC power output directly to the tombstones (Fig. 6). Advantages include maximum driver thermal advantage. Moreover, the driver is not space constrained and manufacturers have more options in adding dimming and other smart control benefits. And if the driver fails, it can be replaced; the end user does not have to discard the whole tube with the LEDs.
Disadvantages include the fact that an electrician is required to replace the ballast with the driver. Furthermore, tubes with external drivers typically cost more than internal-driver tubes. If the tombstones are damaged, they need to be replaced, as they would with any of the internal-driver tubes.
External drivers connected directly to tubes. Some manufacturers use external drivers that connect directly to the tubes (Fig. 7). Advantages again include maximum driver thermal benefits with optional dimming and other smart controls. The driver can still be replaced and the end user does not have to discard the whole tube with the LEDs.
|FIG. 5. Ballast-compatible or plug-and-play internal LED drivers require no electrician for installation and may benefit tenants as opposed to property owners from a cost and maintenance viewpoint.|
|FIG. 6. With an external LED driver providing direct power to the tube pins, users gain thermal isolation, plus options for dimming and other smart control implementations while maintaining driver replaceability.|
|FIG. 7. External LED drivers that connect directly to the tubes provide thermal benefits, control options, and replaceability while adding placement flexibility within the fixture for delamping.|
With power bypassing the tombstones and connection directly to the tubes, this category also offers placement flexibility within the fixture for delamping. Plus, if the tombstones are damaged, they do not need to be replaced. For rebates, some utility companies also favor the direct connection between drivers and LED tubes or modules rather than running line voltage directly into the existing fixture tombstones with internal-driver tubes that are not ballast compatible.
Disadvantages primarily come down to cost. An electrician is required to replace the ballast with the driver. The installation typically requires the installer to mount some holder for the tubes. And the products typically cost more than internal-driver tubes.
Cost – Protect your cash
As you can easily discern, cost is a common theme when companies contemplate an LED tube retrofit. Cash is king, and spending dollars on LEDs is often not a priority for building owners and managers that have viewed lighting as more of cost center than an opportunity to create short- and long-term economic advantages.
Prices are dropping, as mentioned upfront. Since 2010, LED tube cost has come down from more than $75 for some 4-ft external-driver LED tubes to less than $20 for some internal-driver LED tubes. Over the same period that the costs have dropped by more than 70%, LED tube efficiency has increased by more than 50%.
Five years ago, LED tubes delivered 80 lm/W in efficacy, and now they deliver more than 120 lm/W in certain cases. Actual efficacy depends on factors such as color rendering index (CRI) and variables such as clear versus frosted lenses. Spending cash on LEDs today may be the best use of a company’s resources. The following considerations can help focus the allocation of dollars by building owners or facility managers who choose to embrace LED linear technology.
Return on investment. The combination of lower unit costs and higher efficiency often yields return on investment (ROI) above 33% and payback inside of three years. Now the advantage of waiting on a retrofit project is decreasing, providing strong motivation to retrofit with LED tubes. Costs will continue to come down and the efficiency will continue to increase, but the delta of annual change is not moving as far forward as it has been over the past five years. In short, the largest strides in cost reduction and technological improvements have already occurred. Waiting for a few more dollars of cost reduction and a few more lumens per watt of output does not make financial sense when the savings per tube is already between $5 and $10 per year in a 12-hour-per-weekday application and more than $20 per tube in certain 24×7 areas, subject to different costs per kWh.
Let’s consider some sample scenarios. First we will examine a single-shift commercial property – examples include offices, retail, schools, etc. The key characteristics are:
• 12 hours use per weekday and the US average of $0.11 per kWh
• 32W fluorescent versus 16W LED equals 16W saved
• (16W/1,000)×3,120h = 49.92 annual kWh saved
• (49.92kWh×$0.11)/kWh = $5.49 savings per tube per year
In many cases, utility rebates for this scenario add up to about $5 per tube. A 50,000-hour-life, $20 internal-driver tube nets out to $15. The simple ROI is 36% when you divide the energy savings by the cost of the LED tubes.
Now let’s examine a scenario in which the lamps are used for much longer hours and energy costs are higher than average. Typical application scenarios include triple-shift industrial and warehouse facilities, 24×7 hospitals, parking garages, fire and rescue centers, and long-runtime areas of any property such as emergency exit stairs, egress hallways, etc. The key characteristics are:
• 24×7 usage at above average rates of $0.16 per kWh
• 32W fluorescent versus 16W LED equals 16W saved
• (16W/1,000)×8,760h = 140.16 annual kWh saved
• (49.92kWh × $0.16)/kWh = $22.42 savings per tube per year
In many cases, utility rebates for this scenario add up to about $10 per tube. So, a 100,000-hour-life, $60 external-driver tube nets out to $50. The simple ROI is 45%.
Warranties. Tube reliability is also greatly improved as indicated by warranties offered by manufacturers. Typical warranties have gone from one to three years up to five years for rebate-eligible products recognized through listings such as the DesignLights Consortium (DLC). Some LED tubes now also offer 10-year warranties. However, not all warranties are created equal. Buyers should read the fine print before spending their money.
For example, Philips offers a five-year warranty for its ballast-compatible InstantFit tubes that are sold at Home Depot. But the warranty fine print on the box says, “5 years based on up to 3 hours average usage per day/7 days per week, when used as directed.” Such usage only adds up to coverage on 1,068 hours of annual illumination. The warranty may work for home laundry rooms or garages but not for an office, retail store, or school running eight or more hours per day.
Total cost of ownership. Buyers should also look beyond ROI when considering an LED tube project. ROI is a sprint while TCO is a marathon. With the long life of LEDs, review the total cost of the product along with the electricity cost over a period such as ten years. Seemingly small differences in wattage between LED products may surprise you in the ripple effect over multiple years. The product with the higher ROI may not necessarily generate the lowest TCO. For the most accurate TCO analysis, factor in the replacement of LEDs that have shorter warranties than others and include the burden of replacement labor costs as well.
Potential buyers should further consider net operating income (NOI). A penny saved is a penny earned. If a building owner is considering selling a property in the near future, it may seem counter-intuitive to change the current lights to LEDs. But with capitalization rates of 10% and better, a $100,000 investment in LEDs that saves $36,000 per year would yield a property value increase of $360,000 or more. Saving the $36,000 is equal to generating $36,000 of net profit given the reduced utility obligation. Real estate investors buy properties based on location and other factors; however, the higher the NOI, the better for the seller.
There are also many ways for building owners to finance LED projects. Potential buyers worried about preservation of cash should consider $0 upfront-cost financing options and savings share programs that yield positive cash flow in the very first month. The annual interest rates have come down from the teens to less than 5% in some cases as the LED market has matured and proven itself. Instead of investing $100,000 to save $36,000 per year and $3,000 per month for ten years or longer, you can spend $0 and generate cash today. A 50/50 split on $3,000 per month of savings puts $1,500 in the building owner’s pocket each month.
Service – Protect your time
As you might gather, an LED tube project, or any other solid-state lighting project, is very complex. Time is money. Given the increasing complexity of the lighting market, a potential buyer’s time may be best spent working with a trusted lighting expert rather than navigating through the choppy seas. Here are a few examples of where a quality service provider can add value.
Rebates can complicate a project. Utility companies typically offer prescriptive and custom rebate options for LED tubes and other LED lamps and fixtures. The rebates are structured differently across different types of LEDs and across different utility companies. In many cases, end users can earn higher rebates through custom applications compared to prescriptive incentives. However, the larger rewards often come with more paperwork.
Rebate administrators and some manufacturers with support services that work on performance commissions offer end users a means to generate larger returns without the burden of dedicating their own time. Plus, experts in rebates can steer end users away from pitfalls since the utility companies periodically change their programs. As an example, some utility companies, like ones in Pennsylvania and Maryland, have recently eliminated the rebates on LED tubes unless they are ballast compatible or if they use an external driver and directly power the tubes. The DLC does not currently have a separate category for ballast-override versus ballast-compatible LED tubes. So, buyers could think that they are purchasing rebate-eligible products only to learn that the rebate rules have changed.
Analysis of smart control options is also complicated. Qualified service providers can help end users model the financial advantages to determine the most appropriate use of smart controls. Occupancy sensors, dimming, light harvesting, and demand-response integration are examples of ways to reduce annual energy usage. However, investing in controls may slow the ROI, and it is key to weigh the short-term penalty on cash against the long-term benefits to yield lower TCO.
Experts can also help answer the question as to whether one-for-one replacement of tubes is necessary. The lowest-wattage LED tubes may appear at first to save the most money relative to their fluorescent predecessors. However, two higher-output LEDs may generate equal or greater output than four tube replacements in an application such as an existing four-tube fluorescent troffer, and delamping the fixture by half changes the TCO equation.
Service providers can help determine which areas deserve a complete new-lights retrofit compared to others where a rolling retrofit may be more advantageous. The rolling retrofit concept is simply changing old lights to new LEDs only as the old ones burn out, rather than a one-time lighting retrofit. End users can also work with trusted lighting experts to develop energy-saving plans over several years to optimize facilities with multiple sub-set areas, multiple buildings, or properties in multiple states. Below are six factors to consider. As a rule of thumb, if an owner, property, or area within it has three or more of the six, then it is well positioned for a full LED project:
• Need for lights (new construction, renovation, or lights are due to burn out)
• Long runtime (12 to 24 hours/day)
• Inefficient existing lighting (incandescent, halogen, high-intensity discharge [HID], or T12 fluorescent)
• High cost of electricity (more than $0.14/kWh)
• High rebates (utility incentives more than $0.05/annual kWh saved)
• Green-minded (seeking LEED, Energy Star Points, CO2 reduction policy, etc.)
Recommendations – Manage the complexity
Finally, anyone considering a tube project must manage the inherent complexity in the technology. For architects, lighting designers, sustainability and energy professionals, sales representatives, value-added resellers, and distributors, good advice is to work with manufacturers that have sound technology for thermal management and engineering. The manufacturer should have third-party testing to back up the engineering skills and quality assurance to exceed expectations.
End users should work with quality manufacturers and trusted lighting experts that have a track record of case studies and references as well as perspective on LED thermal management. For both end users and for the range of advisors and influencers, the key to success with LED tubes is to assess the needs of any property or sub-set of the property and match the right technology to the different applications.
External-driver LED tubes may make the most sense for reliability and longevity in 24×7 stairwells. Replaceable driver-system LED tubes may generate the lowest TCO for owner-occupied areas, and ballast-compatible plug-and-play LED tubes may work best for end users that are tenants, given the ease of installation within a lease. Treat the LED tube as an energy tool and not a commodity. One size does not fit all.
With all of the technology improvements and lower prices, 2015 is shaping up as a tipping point for LED tubes. However, the US market is still well behind the European and Asian levels of LED tube adoption, in part because of the confusion over driver options and the other variables ranging from rebates to warranties. The LED industry has an opportunity to seize the day and educate end users with energy solutions and comparative analysis versus the previous commodity approach to selling fluorescent tubes. The American energy revolution is underway. With 2.3 billion inefficient fluorescent tubes in our ceilings, the US market is ripe for a technology that can deliver energy independence and security. Let’s change the dialogue from “if and when” to change the fluorescent tubes to “where and which type of LED tubes” make the most sense to install today.
CHARLIE SZORADI is CEO of Independence LED (IndependenceLED.com).
This LED Tubes T8 Technology Article Source is: http://www.ledsmagazine.com/articles/print/volume-12/issue-4/features/led-tubes/led-tubes-approach-mainstream-adoption-despite-complexities.html
See the Spec Sheets for Independence LED Tubes T8 series
For more details see the LED Tubes T8 White Paper.
For background on internal vs external drivers for LED Tubes T8 Technology see the LED Tube Report.