What do 50,000 hour lifespans mean for TLC?

Simply put, the 50,000+ hour lifespan of high quality LED lights means that the initial cost of a light (bulb) is a smaller percentage of the Total Lighting Cost or "TLC" (the total cost of providing lighting to a space.)  But, there is actually more to it.

So, just how long is 50,000 hours, anyway?  As technology advances, it is sometimes difficult to grasp the magnitude of the changes happening.  Here is a quick list with the numbers, as well as some illustrations:

Here's what 50,000 hours (the laboratory-rated lifespan for high quality LED lights such as those from Leading Edge Designs) works out to be, depending on the number of hours the light is operated.  There are 8,760 hours in a year, so a 50,000 hour lamp is laboratory-rated to last this long, given the daily usage listed:

• 24 hrs/day 7 days/week 5.7 years
• 18 hours per day 7.6 years
• 12 hours per day 11.4 years
• 8 hours per day 17.1 years
• 8 hrs/day 5 days/week 24 years
• 3 hrs/day (7 days/ wk) 45.66 years

In comparison, here is how long a traditional incandescent light bulb typically lasts:  According to Wikipedia (linked here), typical incandescent light bulbs last 1000 hours.  However, other sources suggest the range typically is 1000-2000 hours.  So, conservatively, 2000 hours equates to:

• 24 hours a day 83 days (less than 3 months)
• 18 hours per day 111 days (less than 4 months)
• 12 hours per day 167 days (less than 6 months)
• 8 hours per day 250 days (less than 9 months)
• 8 hours / day 5 days / week (about 1 year)
• 3 hours per day 667 days (less than 1.85 years)

 If compared "apples to apples," the LED will last about 25 times longer... 

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So, again, what does this mean?

The LED lights last a little longer (OK, a lot longer) - so what?  Actually, there are many impacts.  Here are a few:

• The incandescent light will need to be purchased (at additional cost) 25 times during the LED life
• The labor to replace the light will have to be purchased / spent 25 times during the LED life
• The equipment to install the light (lift, etc.) will have to be rented 25 times during the LED life
• The relationship between the Total Lighting Cost (TLC) and the cost of the light itself changes

Let's focus on that last bullet for moment...  What is the Total Lighting Cost (TLC) for a given space?  The answer is more than just the cost of a light bulb, and the longer life of high quality LED lights makes this even more apparent.  At a basic level, the Total Lighting Cost or TLC for a space includes:

1. The initial cost of the fixture
   
2. The energy to power it (operating costs), and
   
3. Any maintenance required to keep it working (including replacement fixtures, labor and disposal).

For years, people have equated the cost of a light bulb to its TLC (actually, because light bulbs cost so little, most people just don't think about TLC at all).  However, because high quality LEDs last so much longer, the amount of energy being consumed by a light fixture over its useful life becomes more and more important, particularly in relation to the cost of the bulb / fixture itself.  (Maintenance costs typically increase proportionally over time as well, but that's another discussion...)

Here is an example to illustrate the change in relationship because of longer lasting LEDs.  If an industrial light costs $100 to purchase up front, and costs $50 per year for the energy to produce the light and the light lasts two years, the light (bulb) itself is about 50% of the total lighting cost of providing the lighting over the life of the fixture ($100 bulb + $100 energy [that is 2 x $50 per year]  = $200, so 100/200 = 50% of the TLC is for the bulb).

However, if that same hypothetical light was to last 10 years, the equation stays the same, but the cost of the light becomes only a small portion of the TLC.  If the light costs $100 to purchase and $50/year to run, but lasts 10 years (conservative for an LED that is on 12 hours per day 7 days per week), the light (bulb) itself only represents about 17% of the cost to provide the light.  
($100 bulb + $500 energy cost [50x10] = $600 TLC, so bulb is 100 / 600 or about 17% of the TLC.)

Everyone knows that traditional incandescent light bulbs need TLC (tender loving care) when handling them so they don't break.  Now, even though they are much more durable (learn more about that here), LED's should still make you think of TLC - the Total Lighting Cost - because the long life of high quality LEDs makes the up front cost a much smaller factor in TLC due to their 50,000 hour lifespan.