A new study by the University of Michigan School for Environment and Sustainability Center for Sustainable Systems in Ann Arbor shows LED lighting is up to 44 percent more efficient than four-foot fluorescent tubes.
The study compared the costs of six replacement options (one fluorescent and five LED) for linear recessed lighting systems and found that LED products were between 18 percent and 44 percent more efficient than most standard tube fluorescent lamps.
Lighting is responsible for 11 percent of electricity use in commercial buildings and residential basements, garages, and shops. The study states that linear recessed lighting systems, which are also called linear fixtures or troffer lights, are among the largest opportunities for energy efficiency improvement, given their long operating hours.
The study’s key takeaway is that switching to LEDs can save money and energy and reduce one’s carbon footprint, according to senior study author Greg Keoleian, co-director of the Center for Sustainable Systems.
“It’s definitely better to replace your fluorescent lamps with LEDs rather than replace them with new fluorescent lamps,” says Keoleian. “Our finding is consistent with the U.S. Department of Energy’s indication that LED systems are 25 percent more energy-efficient than fluorescents.”
LED lamps outperform fluorescent lamps in numerous ways. They produce light without flickering, have higher energy efficiency, and last longer, which leads to improved ambiance, less maintenance, and energy cost savings.
LEDs also offer better dimming performance than fluorescent lamps. They have faster ramp-up to full brightness and are more energy-efficient at low dimming levels. In addition, LEDs do not contain mercury, making them safer for indoor use and at end-of-life.
Keoleian and his team surveyed more than 160 LED replacement options, which included lamp replacements, retrofits, and luminaire replacements. A lamp replacement is a change-out of the lamps only and does not require any electrical modification, while a retrofit involves modifying the existing fixture to accommodate a new light source and/or electronics. A luminaire replacement is a full change-out of the lighting system, including the mechanical structure.
The study authors compared the costs of six replacement options:
- Replacing a burnt-out fluorescent lamp with a new fluorescent lamp (not recommended).
- Replacing a fluorescent lamp with a plug and play Type A LED lamp (this requires no modification with the current unit and is compatible with electronic or magnetic ballasts).
- Hiring an electrician to retrofit an existing fixture and using a ballast bypass or direct-wire Type B LED lamp.
- Using a hybrid Type AB LED lamp that works in an existing fixture or one where the ballast has been removed.
- Buying a whole new recessed unit (luminaire) that uses an LED lamp that allows you to change the style and eliminates the need for a ballast replacement.
- Buying a whole new recessed unit (luminaire) that uses an integrated non-replaceable LED lamp.
Among their key findings:
- Plug and play, direct wire and hybrid LEDs are all more cost-effective and energy-efficient options for replacing fluorescent lamps.
- Plug and play LEDs (Type A) work in existing fixtures but ballasts may fail before the lamp. Their ease of installation can help spur LED adoption.
- Hybrid LEDs (Type AB) have the lowest upfront cost when an existing ballast is still usable.
- Direct-wire LEDs (Type B) are the lowest-cost option in terms of operation and maintenance costs and life cycle costs. They have relatively high installation costs.
- LED luminaires with replaceable lamps cost less than those with integrated non-replaceable lamps, though they offer fewer design options.
“These findings highlight tradeoffs when deciding between LED options and can help guide commercial building owners and managers who are considering lighting replacement,” says Keoleian.
The exact savings depend on lamp costs, electricity rates and labor costs for an electrician if you are retrofitting or replacing the recessed fixture. The LED options—except where you purchase a whole new lighting system (luminaire)—all result in cost savings over time. A whole new luminaire means a higher life cycle cost because of the higher upfront cost of a new unit.
The results are also applicable to residential buildings where T8 lamps and troffers are commonly used, particularly in workshops, basements, and garages.
The study was published online Nov. 10 in the journal Lighting Research and Technology. Lixi Liu of the Center for Sustainable Systems and the U-M Department of Mechanical Engineering and Geoff Lewis of the Center for Sustainable Systems are co-authors.
The research was supported by the National Science Foundation Graduate Research Fellows Program and the University of Michigan Rackham Merit Fellowship.
