Henderson Engineers — LED Upgrades That Succeed by Andrea Mulvany

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LED UPGRADES THAT SUCCEED CAR E F U L CO N SIDE R ATIO N O F SAVI NGS, COMPATI BI LI TY AND OUT P U T CAN H E L P M A N AG E R S P LA N A ND COMPLETE EFFECTI VE PROJECTS .

Authored by: Andrea Mulvany | June 21, 2018 While LED technology is rapidly changing the lighting industry, fluorescent lighting is still the most common lighting source in institutional and commercial buildings. Many facilities have upgraded to LED lighting as part of retrofit projects. Some have even carried out these updates as part of a facility upgrade.

Managers must make the decision to upgrade existing lighting only after careful evaluation. Whether operating a health care facility, commercial office building, or education institution, managers have many factors to consider.

WHY UPGRADE Updating lighting is essential to maintaining a modern facility in both appearance and performance. When determining if the change from fluorescent to LED lighting is right for a facility, the efficiency and longevity of the use and appearance of the lighting is essential.

One key factor in upgrading to LED lighting is energy efficiency.

Lighting is the largest user of electricity in these facilities, according to data from the U.S. Energy Information Administration. Lighting accounted for about 17 percent of electricity consumed in commercial buildings in 2012, which is consistent across buildings of different sizes.

Managers often consider upgrading to energy-efficient HVAC systems, but they are not always aware of the potential savings that could be attributed to replacing existing fluorescent tube lights with more modern LED options.

Consider a 4-foot, 32 Watt (W) T8 fluorescent lamp that uses 34 W when in use due to typical inefficiencies with the ballast. A ballast regulates the current and makes sure fluorescent lamps have sufficient voltage to start. If this lamp were to operate continuously throughout the day for a full week, the annual consumption would be 297.8 kilowatt hour (kWh). The equivalent LED tube uses 16 watts. If operated in the same manner, it would consume 140.1 kWh in a year of continual use.

Using an energy cost of $0.12 per kWh, this is a savings of about $19 per year for one lamp, or $57 per year for a three-lamp fixture. Replacing 100 of these fixtures would equate to an annual savings of $5,700.

When considering the lamp life of fluorescent lights versus LEDs, the difference is astronomical. The average lamp life for a 4-foot, 32W T8 fluorescent tube is about 20,000 hours. The average L70 rating — which represents the point at which a fixture’s light output has regressed to 70 percent of its original installed output — for a comparable 16W LED is 50,000 hours. Some LED fixtures even have a projected life of about 225,000 hours.

LED UPGRADES THAT SUCCEED When considering the differences between LED and fluorescent lamp fixture life expectancies, managers need to understand one key to make a fair comparison between the two light sources. Fluorescent lamps possess a visible indication of failure that often presents itself through flickering — otherwise known as strobing — or by just completely shutting off. Unlike fluorescent light sources, the light output from an LED source continually lessens over the life of the fixture rather than burning out.

When planning lighting in a space that will use LED fixtures, designers base their models around L70, the minimum usable light value. The lighting community developed the lifespan rating standards for LEDs and based them on the amount of time it takes for the light output to fall below usable levels.

If an LED lamp fully fails, it is a sign of a production defect rather than a sign of the fixture reaching the end of its true, full designed life. If an LED fixture does fail in this manner, it will often occur in the first few years of use and is generally covered by a manufacturer warranty. If managers make the decision to upgrade lighting, this detail is an important reminder to always consider reputable manufacturers in selecting new LED lamps or fixtures.

CONSIDERATIO NS & CHALLENGES The fundamental components managers need to consider when upgrading a facility’s lighting include lumen output and ballast compatibility, along with controls and dimming needs.

While not always recommended, the simplest upgrade for many facilities is a one-for-one replacement of existing fluorescent lamps with new LED replacement tubes. Considering lumen output is essential when choosing the most appropriate replacement lamps, especially when working with existing, non-dimming fixtures. A lumen is the standard unit of measurement for luminous flux, the measure of the perceived power of light. LED sources rank above fluorescent lamps in their system efficiency, or the amount of light that actually reaches a targeted area after all losses are accounted for.

In terms of directionality, fluorescent lights are omnidirectional sources that emit light in a 360 degree pattern, meaning the entire circumference of the tube emits light. On the other hand, LED light sources rely on individual diodes to produce light, which means that LED retrofit tubes generally will only emit light in a 180 degree arc originating from the strip of diodes.

In LED tubes, the diodes always point down from the fixture towards the space. This orientation effectively provides more useful lumens and overall system efficiency because the entirety of the light being is directed downward and is not wasted through reflections within the fixture. But it can create a disconnect between the effective lumen output of a fluorescent lamp when compared to an LED replacement lamp.

Consider this example: One facility manager replaced all fluorescent tubes in one department with new LED replacement tubes. But end users considered the resulting lighting level to be too high. As a result, new replacement lamps had to provide a lower lumen output.

To avoid this scenario, managers can use a range of tools to help facilities choose the right replacement source. Many of these tools rely on knowledge of the desired illumination level in lux or footcandles. If managers do not have this information, one easy but not always perfect solution is to have the operator match the lumen output of the existing lamps being replaced.

Carefully measuring the desired lumen output of the replacement lamp also can impact the true energy savings. If managers select an incorrect replacement that emits more lumens than needed, the overall energy savings will be lower.

Managers who are considering the use of replacement LED tubes should understand ballast compatibility.

The chances that an existing ballast is compatible with a replacement LED tube is a potential concern, but the number of replacement tubes on the market that are compatible with existing ballasts is rising.

LED UPGRADES THAT SUCCEED

TECHNOLOGY ADVANCES As LED technology progresses, designs are using circuits that can restrict inrush current transients while at the same time allowing for higher energy efficiencies. The use of an LED driver retrofit kit is one relatively easy, affordable solution that eliminates ballast compatibility issues common with plug-and-play LED lamps.

An LED driver used in the housing within the light fixture bodies themselves or in existing lights might have sufficient independent outputs that eliminate the need for additional wiring or a daughterboard.

Another potential consideration a manager should be aware of is potential operability issues related to existing dimming controls. While LEDs are the preferred source for dimming versatility, they do require a dimming-compatible driver in order to provide dimming control whether using a new fixture or a retrofit lamp. Be sure to coordinate with the manufacturers of both the driver and dimmer to confirm that it is the right product for the application’s needs.

Even if a driver and control device are said to be compatible, managers should test the combination if possible. Many fixture or driver manufacturers can perform this test. The benefits of having LED lamps with proper dimming capabilities include even greater energy efficiency and a prolonged lamp life. They also provide end users with more ability to fine-tune their environments to their needs and preference.

LEDs have become a much more viable and increasingly simple option for replacing fluorescent lights in a variety of facilities, and they often provide considerable energy savings. But it is important for managers to be aware of the potential challenges when upgrading from fluorescent to LEDs before making the purchasing decision.

Understanding the desired light level and the intended use of a space are important first steps in considering whether to pursue one-for-one replacement lamps or invest in a full light fixture replacement. Researching compatibility with dimming controls and ballast types, along with testing proposed combinations, can go a long way in preventing potential post-installation issues. Managers also should consider the assistance of a professional lighting designer or engineer to provide evaluation of the application and guidance through the purchasing process.

ANDREA MULVANY PE Andrea Mulvany is an associate vice president and director of the arts and culture practice for Henderson Engineers, where she helps run operations in the firm’s downtown Kansas City office.

She is a Professional Engineer with an electrical background and is responsible for the design of facility electrical systems that are both innovative and cost-effective, and she specializes in performing arts centers, commercial interiors, retail, healthcare, and educational facilities.