The Future of Light

Posted on March 16th, 2011 by
LED technology is evolving at a rapid pace.  There have been steady breakthroughs in, increases in lumens per watt, thermal management, secondary optics and phosphor technology improvements in CRI (color rendering index).  These leaps in technology have allowed lighting manufacturers to replace traditional lighting products with energy efficient, maintenance-free LED fixtures. You can now see LED products in office buildings, retail stores, warehouses, museums, schools and homes, an application exists for just about everywhere.

Two major advantages of LED lighting products are energy savings and long life. Due to the solid state technology employed by LEDs, they generate far greater lumens per watt of electricity than traditional light bulbs.  For example, incandescent and halogen bulbs produce about 15 lumens per watt and LEDs are in the 80 lumens per watt range (and gaining rapidly).  LEDs are about five times more efficient converting energy to light.  Traditional light bulbs convert most of the electricity to heat, hence they are less efficient.

LEDs last up to 50 times longer than traditional light bulbs. Traditional lighting products use Average Rated Life to define lifetime.  Average Rated Life means that at that time 50% of the bulbs have failed and the other 50% are still working but will need to be replaced soon. LED manufacturers do not use average rated life, but reliability to define lifetime.  LED reliability means at 50,000 hours LEDs still produce 70% of the original light output with no failures.  LEDs operated 12/7 still deliver 70% of their original light output at 11.4 years.  Operating hours/day/years reliability:
137 Years at 1 hour/day

68.5 Years at 2 hours/day

34.2 Years at 4 hours/day

22.8 Years at 6 hours/day

17.1 Years at 8 hours/day

11.4 Years at 12 hours/day

5.7 Years at 24 hours/day
LEDs dim slowly over time, whereas traditional bulbs experience  lumen depreciation and system degradation from the moment they are first turned on.  HID luminaries deliver only approx 40 to 50% of the initial gross lamp lumens due to the lamp’s lumen depreciation and the fixture’s inability to extract and deliver all of the lamp’s light.  LEDs are highly directional so most of light it produces reaches the intended location thus increasing the fixtures efficiency.  HID lamps lose brightness quickly as they age.   HID lamps lose as much as 40 to 50% of their initial brightness (gross lumens) after operating just a few months. For, example the output of a 175W MH Lamp with a 10,000 hr rated life and 13,000 initial lumens declines to just 7,800 lumens after 4000 hrs.

Unlike CFL and other fluorescent bulbs, LED products do not contain the neurotoxin mercury and are RoHS compliant (contain no toxins).  Mercury found in fluorescent bulbs is a hazardous material and Government regulations require CFL and florescent bulbs to be disposed of as HazMat which add disposal fees to the end user cost.  In fact, Target Corporation recently settled in a $22.5 million lawsuit by the state of California for dumping hazardous waste including light bulbs containing mercury into normal disposal containers ending up in landfills.

A return on investment (ROI) financial analysis is extremely important when considering the migration to LED fixtures.  It is important to compare the life cycle cost associated with owning and operating your current system verses a LED lighting system. Cost of power, hour/week usage, current replacement and labor installation costs, HVAC, and bulb disposal fees will give you an understanding of what you pay to own and operate your current system over its useful lifetime.  LED systems have a higher initial cost than a traditional lighting systems, but financial analysis shows that the life cycle cost of LED lighting systems deliver high ROI rates and speedy payback periods.  The impact on your balance sheet is very attractive.

The future of LEDs as a mainstream lighting solution is just beginning. Many governments have already banned incandescent bulbs.  In 2012, the US will phase out incandescent and T12 fluorescent lamps.  China, which accounts for 70 percent of the world’s light bulb production, has agreed to stop the production of incandescent bulbs over the next 10 years.  Europe and Australia have also mandated phasing out these traditional bulbs.

LED lighting systems are being rapidly deployed to retrofit and replace traditional lighting systems.  As LED lighting systems continue to gain acceptance, prove their performance claims and are validated by government and utility support, traditional lighting will continue to decline and be replaced by LED technology using science rather than heat to create light.

Written by Amy Falzone of LED Light Technology.

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2 People have left comments on this post

» RelightDepot said: { Mar 17, 2011 - 01:03:45 }


I agree that LEDs and LED-based fixtures represent a significant opportunity to reduce our country’s energy demand. You point out many dimensions where LEDs excel over older HID technologies and newer linear fluorescent sources. One area that I would like to see more information on is the “Lumens per Dollar” or the cost per lumen for LEDs compared with other sources. I realize that LEDs are earlier in the technology learning curve than others and their costs are bound to go down and that costs in general have to be normalized somehow. Are you familiar with any studies that provide this type of information?

» Amy Falzone said: { Apr 12, 2011 - 02:04:03 }

Hi RelightDepot,

Sorry for the delay. The comments section has been closed and I have been unable to reply.

There are many studies out there that focus on Lumens per Dollar. Most are at about $0.01 per lumen, but in many cases, Cree and other top tier manufacturers are able to get to about 0.005 per lumen. In notice on your website that you sell LED products, your best bet would be to contact whatever LED manufacturer you are using and ask them to furnish you this information, they should be happy to do this for you.

Hope this helps!

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