With LED technology quickly taking over the lighting industry, we thought it might be beneficial to have a quick overview of the commercial and industrial lighting industry. Most of our readers are already well versed in this topic, but for some this might be a helpful introduction to lighting and the benefits of LED.
Just like car efficiency is measured in miles per gallon, lighting efficiency is measured in lumens per watt.
The lighting technologies in use today are, in order of efficacy:
- Fluorescent Lighting
- HID (High Intensity Discharge)
- Metal Halide
- High Pressure Sodium
What follows is a brief explanation of each lighting technology.
Metal Halide Bulb
Most of us are familiar with HID technology, it is still one of the more common technologies in use. NFL stadiums use HID because of its "camera friendly" high color rendition, but there are many drawbacks to this technology. To begin with it is very inefficient, on average metal halide bulbs emit 75 lumens per watt - compared to the 130 lumens per watt in LED - and this is before taking lumen depreciation into consideration. Another major consideration is that advancements in LED technology have helped to close the color rendition gap making them a viable and efficient alternative even in professional sports arenas. Another major drawback of HID is that they don't turn on instantly, they have to warm up before they start emitting light - who can forget the power outage during Super Bowl XLVII?
An improvement to HID was Induction lighting. With its origins in the work of Nikola Tesla (much beloved by the internet) induction lighting became a viable lighting solution in the 1960s and quickly became popular overseas, domestically, however, the technology has never really taken hold because of relatively low energy costs, high initial implementation costs, and a lack of government incentives. Induction lighting is very similar to the fluorescent lighting we see most commonly in commercial applications.
As early as the 1930s we have had the familiar fluorescent linear tubes. There are many styles of fluorescent bulbs (spiral and quads to name two) but for our purposes we will limit ourselves to three generations:
- T12 - 1930s
- T8 - 1980s
- T5 - 2000
Fluorescent Tube Sizes
The letter T refers to the shape of the bulb while the number refers to the diameter of the bulb in eighths of an inch. So a T12 bulb is a tubular fluorescent bulb that measures 12/8 of an inch (or 1.5 inches) in diameter, a T8 measures 8/8 (or 1) inch in diameter, and a T5 measures 5/8 of an inch - 0.625 inches. There are still many T12 in use today, but they are quickly being replaced by more efficient technology. As general rule, T8 bulbs are used in low-bay applications while T5 are used in high-bay applications. Counter-intuitively the smaller bulbs emit more lumens and are more efficient than the larger bulbs. Fluorescent lighting is an excellent lighting solution for many applications. You'll see fluorescent lighting in large retail center, in offices, hospitals, and even at home. Linear fluorescents have relatively low upfront costs and fairly high lumen per watt efficiency. The drawbacks of fluorescent lighting are that, while they do last much longer than HID bulbs, they still don't last nearly as long as LED lights; they have to be replaced every 20,000 hours which translates to material and labor costs; and they contain mercury which is toxic and requires special disposal.
Now we come to what we really want to talk about: LED lighting. Up until about 1-2 years ago LED technology was not efficient at all, there were serious heat management problems considerably shortening lifespan, and development costs were very high. Recent developments in LED technology have solved those problems and present a most efficient lighting solution to date. Up until now we've been dealing with between 70 and 95 lumens per watt, a maximum of 20,000 burn hours, and very high maintenance costs (it takes more than an electrician to replace a bulb - you'll need to rent a ladder, buy the material, in some instances you'll have to replace the ballasts, not to mention temporarily shutting down operations). LED takes care of those problems too:
LED High Bay
- 130 lumens per watt
- 200,000 burn hours
- Virtually no maintenance costs
The only drawback to LED is a considerable upfront investment. However, with energy savings the average return on investment is 2-3 years. There are also incentives from electric companies and the federal and local governments that may even cover your retrofit costs. LED lights come as bulbs or as a self-contained fixture. In general self-contained fixtures are significantly more efficient than bulbs - but that is a topic for another day!
Let us know if you found this article helpful, or if you have any questions!