According to Gigantic Signs & Prints , LED lighting long ago have surpassed incandescent efficiency and is now approaching the efficiency of linear fluorescent and metal halide. However, there are many other benefits to LEDs including lasting 5 to 10 times longer than fluorescents, consuming less energy while on, are fully dimmable, contain no hazardous mercury, are unbreakable, are free of flicker and buzz and are safer. LEDs operate on low voltage DC with no glass or vacuum.
LEDs are no longer just for task or accent lighting or colour-changing architectural effects, but are now being built into fixtures that are tackling some of the most challenging applications in general lighting, and they are competing with efficient linear fluorescent and bright HID. Some LED performance examples include parking garage fixtures from multiple suppliers that deliver more than 6,400 effective lumens while consuming 77W, high bay fixtures with 18,000 usable lumens that consume about 190W and troffers with 5,000 effective lumens that consume over 50W.
Though the LED fixture performance is attractive, the key characteristic of LEDs that has the biggest impact on the business case for LED lighting is not efficiency, but their impact on maintenance costs, especially in lighting retrofit applications.
There are several aspects to consider when looking at lighting maintenance economic including lifetime, revenue-generating down time, fragility and toxicity.
High brightness white LEDs are commonly specified to last 50,000 to 60,000 hours at maximum operating conditions. When operated below these maximum conditions, they can last well in excess of 70,000 hours. Well-designed fixtures that minimise the lifetime limitations of other system components can take advantage of LED longevity to deliver reliability.
In order to understand the value that this lifetime delivers to lighting users, one must understand lifetime as defined by LEDs versus traditional light fixtures. LED fixture manufacturers define fixture end of life as a 30% reduction in output. This is contrasted with traditional lighting like fluorescent, which suffers complete lamp failure. Since fluorescent lamp’s lifetime is defined as an MTBF, half of the lamps are dead and require replacement by the lifetime rating.
Fluorescent has the least amount of lumen degradation over time at about 5%, followed by high-power LED. Both of them are significantly superior to any other lamp type.
In the lifetime of the LED fixture, a fluorescent fixture will probably have required many complete relampings. This hits lighting operators particularly hard if replacing lamps impacts other aspects of their operations. Examples include lighting over operating machinery, lighting in difficult-to-reach or public areas.
For many companies, the cost of maintaining their lighting weighs more heavily on their P&L than does the cost of the associated energy. LEDs' dramatic lifetime advantage can have greater impact on these companies.
In a typical convention centre, many light fixtures are in public areas and installed in locations that are difficult to reach. Some lamps are 40 feet or 90 feet in the air, requiring a tall scissor lift and a two-man crew to service, making them expensive to replace. These relampings frequently cost more per lamp. Not only is it difficult to reach those lamps, but they cannot be replaced when the facility is being used, so scheduling maintenance can be difficult.
On the other hand, a convention centre cannot afford to have burned-out lamps. If the facility does not look pristine, their trade show and conference business will go to another venue.
According to a carpet manufacturer, to change a lamp over one of their looms, they have to shut down the revenue-generating loom. When the electrical maintenance crew is doing that, they are not fixing the broken looms, so lighting maintenance is not only a cost impact, but it reduces capacity utilisation and revenue.
In addition to the convention centre and heavy manufacturing examples discussed above, there are several other commercial and industrial segments that face high lighting maintenance costs.
Offshore drilling platforms: The harsh and hazardous environment of drilling rigs where vibration is the major cause of failure for traditional light sources is a perfect fit for LEDs, which contain no filaments or glass to break. In addition, all goods must be brought to the platform by sea or air, and the lightweight bulkiness of fluorescent lamps makes that transport uneconomical.
Hazardous chemical plants: Fluorescent lighting fixtures in some chemical plants are sealed in cases to prevent sparks from being exposed to volatile chemicals in the air. This makes both their purchase and maintenance expensive.
Nuclear power plants: Nuclear plants typically ensure radiation safety from the floor up to seven feet. Above that (where the fluorescents reside) a radiation survey crew must first test the environment before an electrical maintenance crew can change a lamp. Also, post-September 11, security requirements have increased the cost of bringing any material into, or removing any material from, a nuclear plant. Finally, the hazardous material disposal activities nuclear plants are subject to heavy scrutiny, so discarded fluorescents are not deposited in landfills.
Underground mines: Similar to chemical plants, fluorescent fixtures are made explosion-proof. Also, all new lamps must be brought down into the mine from the surface and the old lamps taken back out, making lamp replacement expensive.
Shopping malls and airports : Large commercial or municipal facilities with heavy foot traffic and high ceilings present a challenge for lighting maintenance. Maintenance staff must typically use a lift to reach open area light fixtures. This forces them to either perform lighting maintenance only at night and incur the added expense of higher labour rates, or to disrupt business during the day.
All traditional forms of energy-efficient lighting use mercury. When these lamps are thrown away, they introduce that mercury into landfills and ultimately into the water supply. This growing mercury contamination problem has led to new government regulation. LEDs contain no mercury. In fact, as a result of recent global efforts in the electronics industry, LED fixtures also contain no lead and dramatically reduced amounts of other hazardous materials. They are inherently greener than any other form of lighting in terms of all hazardous materials. Since LEDs have no filaments and glass to break, there is no waste due to breakage, and valuable machinery lit from above is not at risk.
- Incandescent: 750 to 2,000 (Typical Rated Life Estimated Useful Life (hours)
- Halogen Incandescent: 3,000 to 4,000 (Typical Rated Life Estimated Useful Life (hours)
- Compact Fluorescent: 8,000 to 10,000 (Typical Rated Life Estimated Useful Life (hours)
- Metal Halide: 7,500 to 20,000 (Typical Rated Life Estimated Useful Life (hours)
- Linear Fluorescent: 20,000 to 30,000 (Typical Rated Life Estimated Useful Life (hours)
- High-Power White LED: 50,000-60,000 component >70,000 fixture (Estimated Useful Life) (hours)