You’re walking through the hardware store and spot one of the shiny new Philips LED light bulbs and think to yourself: “FORTY DOLLARS!?! Was this forged by Thor in the fire of the Vestal Virgins to contain Zeus’s blindingly bright lightening brilliance?” (For some reason, you like to mix your Greek and Roman mythologies. Go figure.)
So, you happily pay a buck for red-blooded American incandescent bulb and go on your way. In a few months you buy another. Then another. And all the while, you’re sucking 60 watts of power off the grid, or about 90 kWh in a year at a price of $9.
These small and imperceptible costs lead to death by a thousand cuts. For every 1,000 hours of lighting time, that LED bulb costs you $2.80. The incandescent costs $7.00.
Tom Harrison, over at the 5% Blog, breaks out the numbers for us:
So let’s think about lifetime cost. There are two parts to this: store price and electricity price. Assuming the current average price of electricity in the US stays about $0.10/kWh we can calculate cost per 1000 hours (kh). 60W is .06kW.
- Inc: ($1.00/1kh) + (0.060kW * 1000h * $0.10/kWh) == $1.00/kh + $6.00/kh == $7.00/kh
- LED: ($40./25kh) + (0.012kW * 1000h * $0.10/kWh) == $1.60/kh + $1.20/kh == $2.80/kh
- CFL: ($1.25/8kh) + (0.013kW * 1000h * $0.10/kWh) == $0.16/kh + $1.30/kh == $1.46/kh
So, this Philips LED would cost less (a lot) than the incandescent it replaces. And the CFL is still big winner on price.
It’s a helpful analysis, and the cost per thousand hours (kh) is a good basis for comparison, but let’s take it one step further. What is the break even purchase price that makes an LED as favorable as that CFL? I know you haven’t had algebra in awhile, so we’re going to make this visual:
A CFL uses 13 watts, lasts 8,000 hours, and costs about $1.25. You can either drag the sliders on each graph, or type them in to get a cost per thousand hours of $1.46. Now change the hours to 25,000, the wattage to 13, and find out what initial cost you’d need to beat the CFL.
To my eye, the LED and CFL become about even when the LED costs $6.38 - a long way from the current $40 price Home Depot is asking.
Loyal readers of my blog (hi mom!) will remember the LED deal I got this spring – a 60 watt equivalent LED bulb that only consumes 7 watts and was on sale for just $25 from a company called EarthLED. It wasn’t $6.38, but notice it’s about half the wattage of the Phillips bulb. What does that do to our little competition?
Looks like I got my LEDs at about $1.70 per thousand hours, still not what the CFL advertises, but in fact, my CFL’s burn out long before their stated 8,000 hour shelf life. I’m told it has something to do with mounting them upside down in can lights.
In any case, you can use the sliders to assess your own stock of lighting, or try to answer some important questions:
- How does the cost of electricity in my area affect the break-even point?
- What would the bulb life have to be to justify a $40 price tag?
- Which is more important: wattage or bulb life or initial cost?
For me, LED’s are the answer for the fixtures I have a hard time reaching (in the stairwell), the ones I use frequently (in the kitchen) or the ones where color rendering and light quality are important (task lights). For everything else, there’s CFLs, and Duke Energy Customers can get a box of them for free right now.
For zero initial cost, they’re pretty tough to beat!