Last month marked the 25th anniversary of the movie "Ferris Bueller's Day Off". The title of this article has absolutely nothing to do with anything. I just wanted to try to get your attention.
Hope I've got it.
My article concerns the ever changing world of "lamp life" and associated efficacy factors. Efficacy (not efficiency) is from the word efficacious, in this case the overall effect the lighting system has on a particular application. It is measured in usable lumens per watt. The higher the factor, the better the overall effect. For those unfamiliar with the lighting industry, a "lamp" as defined in The Merriam Webster Dictionary is:
- A vessel with a wick for burning a flammable liquid (as oil) to produce light
- A device for producing light or heat
For the purpose of today's lighting industry:
- A light bulb (Incandescent, fluorescent, low and high pressure sodium, metal halide, light emitting diode [LED], etc.) Induction lighting fixtures don't have "lamps"
For those of you readers that are not members of MAPA (Middle Atlantic Parking Association) or other regional parking associations across the country, you are missing out. If it weren't for regional conventions and trade shows especially in my area, like what MAPA puts on, I'd probably be unemployed. How refreshing it was to attend the MAPA Fall Show and the spring PPA (Pennsylvania Parking Association) and PAV (Parking Association of the Virginias) trade shows. The PPA and PAV shows speakers discussed, yes, lighting for the parking industry. Always at the ready to pounce on any misinformation, I typically wait for the presenters to finish while writing down all the many issues with which I disagree. Shockingly, in both cases my pad was empty.
Gib Armstrong of Blue Star Energy spoke about the importance of a uniform distribution of light across the parking structure and how often many of the lighting systems result in spotty distribution resulting in dark areas. He addressed how critical ample ceiling illumination and reflection is to eliminate a cavernous appearance (something that I have been preaching for the last 10 years). He addressed the fact that LED fixtures in general don't have an uplight component but those that do (Philips and GE for instance) cost a fortune. In fact, my manufacturer is presently working on a linear LED fixture that will surpass the light output of their fluorescent system that I have been successfully using all this time. Do you know how much it's going to cost? Right, a fortune. Gib went on to state that LED lamp life was 50,000 hours. Not 80,000, not 100,000, not 110,000 not 150,000 that I (and apparently Gib) continually see published.
Here's an interesting question. If many LED fixtures manufactured today need to be completely replaced at their life's end (let's say five to six years running 24/7), and many are still so expensive that the payback is generally longer than five to six years, is there an actual return on investment (ROI) or payback that can be justified?
The other presenter I saw was Sean Good of Brinjac Engineering. Here again the discussion was directed toward LED lighting, perhaps this was in part due to the garage that was recently built in that city. Our "field trip" revealed that the lighting for the garage had Philips "Wide-Lite" dual level LED fixtures. Despite the expense it's a great looking fixture with a major uplight contribution. Just there is only one row of fixtures down the drive path and because the clearance is very low the fixtures could not take advantage of its uplight component. It's nearly impossible to spread light 30 feet in each direction with only one row of fixtures that are only dropped about one inch below the bottom of the tees. We were told that the energy savings payback of the 50/100w fixtures would be 12 years over the typical metal halide fixtures that are, sadly, still specified in many new facilities. TWELVE YEARS? (See my "question" above). Interestingly, Sean mentioned that rarely do articles on LED "successes" (parking publications or otherwise) mention system cost, ROI, payback, or even what new light levels end up being. I wonder why?
System life is critical to future maintenance costs. The charts attached show lamp life and efficacy factors after the first year and after five years at a 24/7 continuous burn. Note that the metal halide (17,000 hour life) and compact fluorescent (15,000 hour life if you're EXTREMELY lucky) efficacy factors are somewhat misleading, since they need to be replaced every other year. Needless to say, why on earth would anyone ever specify the use of these systems?
As noted above, the LED lamp life is 50,000 hours. Induction system life is rated at 100,000 hours. That's an awfully long time. I hope that's an accurate number. Fluorescent T8 lamps over the last few years have gone from 30,000 hours to 42,000 hours and now up to 55,000 hours and that's at a 12-hour burn cycle. They cost less than $3.00 per lamp. The charts use a three-lamp fixture. $3.00 per lamp x 3 lamp per fixture = $9.00 every 55,000 hours (five to six years) as compared to hundreds of dollars every 50,000 hours for LED replacements. I hope I'm getting this point across.
At the end of the first year the 111-watt fluorescent system has a higher usable lumen output than any of the others except the 165-watt induction. However, the induction wattage is quite high for "energy efficient" lighting. After the fifth year, the fluorescent system's usable lumens are highest of all and nearly double the LED output.
The efficacy factors are defined as usable lumens (lamp quantity x lamp lumen depreciation [LLD] x ballast factor x fixture efficiency) divided by the total watts. The fluorescent system after one year has a 50 percent higher efficacy factor over the metal halide, 19 percent higher than the 100-watt induction, 26 percent higher than the 165-watt induction and 30 percent higher than the LED. The fifth year looks even better, primarily due to the low LLD of the fluorescent lamps.
Note that I skipped over compact fluorescent, which shouldn't even be in the charts to begin with. Pass on them always.
So what does all this tell us?
Just do the math.Peter J. Kelly is the principle of Green Lighting Technologies. He can be reached at firstname.lastname@example.org or 914-299-7509.