Guidelines for Switching to Linear LED Lighting
May 6, 2016 - Lighting
By Kevin Youngquist
LED technology recently significantly eclipsed the high efficiency bar set by linear fluorescent products. New LED linear lighting is delivering on the promise of long performance life, high efficiency and improved color characteristics over traditional fluorescent lighting products.
And, there is no lack of excellent quality products on the market to choose from when retrofitting a facility with LED lighting. However, there are several factors that need to be addressed before making the switch:
- • Will the T8 LED perform well in the existing fixture?
- • Is the return on investment worthwhile?
- • What life expectancy is reasonable from the LED in the retrofit project?
Existing Fixtures. While T8 LEDs come in a variety of configurations, the LED should function in the fixture as well or better than the fluorescent being replaced. The typical 2-by-4 foot troffer fixture utilizes one of three basic designs: a prismatic lens, a parabolic reflector or indirect with a styled lens. The typical fixture for the fluorescent T8 takes advantage of its full 360 degree radial illumination. When selecting an LED T8 product, consider the beam angle it produces. T8 LED can be grouped into three basic beam angle categories — narrow, medium or wide. Narrow or medium beam angles may work well with a prismatic lens in delivering more light down to the work surfaces and tasks than fluorescent lamps. However, an architectural indirect fluorescent system may require a beam angle as wide as possible.
Lamp Operation. UL has categorized linear lamps into three groups. Type A lamps are specified for use on existing ballasts, meaning the LED lamp can simply be installed in place of the fluorescent. Type B lamps are for use without a ballast, meaning the lamp will be direct wired to the power supply. Type C lamps are more complex. They require replacing both the fluorescent ballast with an LED driver and then matching a correct LED tube with it. With technology advances, Type B lamps are quickly overtaking Type C systems in popularity when converting fixtures. The first decision point is the easiest. If the existing T8 fluorescent system is still relatively young, perhaps only four-six years old, simply choose a Type A LED lamp. The retrofit is easy to accomplish – just change the lamp. If the lighting system is a little older, eliminate the ballast from the circuit and use the Type B LED lamp. A certified contractor will know how to rewire and retrofit the fixture quickly.
The Type B retrofit has an added benefit of slightly better energy utilization, because the ballast is removed from the equation. No matter the choice, consider the emergency lighting function that these fixtures may be performing. Many commercial buildings utilize an emergency backup ballast within some of the 2-by-4 and 2-by-2 troffer fixtures to comply with emergency lighting requirements in the event of a power outage. Be careful not to disrupt this system without a plan in place. Recently introduced Type A lamps options are designed to work perfectly with emergency backup ballast systems. This technology now allows the opportunity to retrofit the entire office to LED linear lamps. A review with a contractor on how these lamps will operate in the fixtures is imperative to a successful retrofit project.
Return on Investment. Perhaps the main reason for building owners and managers to consider a lighting retrofit is the return on investment (ROI). Linear T8 LED products have been on the market for several years now. Early LED products sometimes lacked the efficiency to provide a solid return. “De-lamping” became the only way to provide energy saving on the project and typically led to a compromise in available light levels (lumens) or light quality. Lumens is the light a lamp creates and together with the fixture can be measured for fixture efficiency. Retrofit of existing systems is just that — a retrofit. The design that went into the illuminated space requires a specific lumen level within the fixture to deliver the light required. By reducing lamps or lumens within the fixture, there is always a compromise.
So, here’s the simple answer to the ROI question. The linear LEDs should be 40 percent more efficient than fluorescent tubes to provide good ROI, and the lamps should be replaced one for one without cutting corners. A standard T8 fluorescent tube is 32 watts. Replace that with an 18 watt LED lamp. Over its 50,000 hour life, at just 11 cents per kilowatts per hour energy cost, the lamp life savings is $70 per tube. By knowing your projected installed cost per lamp, energy savings can be calculated to determine if the ROI meets expectation. Often, the switch to linear LEDs will provide an ROI of just two years or less.
Performance Life. Life expectancy of the product in specific applications determines the successful outcome. A good resource in understanding lamp life and operating characteristics is a product list maintained by The DesignLights Consortium (designlights.org). The lighting options can be overwhelming, so the qualified product list may be best utilized to check lamps under consideration. Linear LED product life is determined by the quality of the electronics and the ability of the lamp to operate cool. A highly efficient T8 LED lamp that is producing 2,200 lumens and consuming just 15 watts (146 lumen per watt) will operate cooler than a lamp consuming 19 or 20 watts and producing 2,200 lumens (about 110-120 lumens per watt).
Starting with a highly efficient lamp from a reputable supplier is the best way to ensure a good, long service life. Lumen maintenance over life is important, and fortunately there are several good lamp choices that utilize glass tubes that won’t discolor over time and dissipate heat very well. Watching these two aspects — efficiency and tube construction, combined with a knowledgeable supplier, is the best way to satisfy any concerns of performance life. A minimum five-year warranty should accompany any linear LED lamp. Extended warranties may be available based on your hours of use.
The time is now to retrofit linear lamp systems to LED. Products on the market are becoming better quickly. Options are available to replace 8 foot lamps, T12 lamps, U-bend lamps as well as 24- and 36-inch lamps. This product category has finally grown into the market expectation for LED lamps. They really do have the ability to provide excellent energy savings over a long product life, increased light output and great color characteristics. Following these common sense guidelines could free up operating expenses, and saving energy is always a good investment for the environment and for our children’s future.
Kevin Youngquist, an Executive Vice President for EarthTronics, is responsible for the sales, marketing and business operations in North America for EarthTronics. He has more than 30 years of lighting experience. This includes developing lighting specifications, as well as energy audits for hotels, long-term care and commercial buildings.