Light, light, who's got a light?
Lets see, 130 years ago Edison electrically heated a filament of carbon, beating out candles and kerosene lanterns and it was good... for about 20 hours. But switching to Tungsten and using Argon gas boosted the lifetime to 1000 hours and an output of about 17 lumens per watt in a 100 watt 1700 lumen bulb. Cost per bulb, $1. Bulbs per 25,000 hours = 25. So $25 in bulb costs. Energy used in 25,000 hours = 2500 kilowatt hours. At $0.10 per kwh, that's $250 plus $25 for bulbs giving $275 cost to operate for 25,000 hours. (Doesn't include impact of the heat produced on increased air-conditioning energy costs.) About 150,000 lumen-hours per dollar.
Then 80 years ago, mercury vapor lamps hit the scene and there was more light, for longer. Today a 28 watt T5 produces about 92 lumens per watt for 2600 lumens and lasts 15,000 hours. Cost per bulb is $9. For 25,000 hours we get $15 for bulb costs and 700 kwh energy consumption for $70 power cost, so that's $95 total. We get about 680,000 lumen-hours per dollar.
Compact florescent bulbs have been commonly available for about 25 years. Cost per bulb is $3. Light output for a 23 watt unit is 1600 lumens giving 70 lumens per watt, lifetime is 20,000 hours. So total cost for the bulbs is $3.75 and energy used is 575 kwh for $57.50 energy costs and a grand total of $61.25. And that figures out to around 650,000 lumen-hours per dollar. Very comparable to the ordinary florescent.
Finally we get to the latest craze, LED lights. These things have been problematic since day one. Initially they used common white LEDs in huge numbers to get usable levels of light. The reliability was rotten though. The LEDs were wired in series and the poor current limiting circuitry was prone to transforming ordinary line voltage spikes into huge over current pulses that destroyed the weakest LED in the chain, ruining the whole lamp. But they were cheap! $5 for one that made about 100 lumens output, in one direction only and used about 2.5 watts of power. Totally unusable as far as I'm concerned.
But, Philips has been working on an improved design, the EnduraLED. A 12 watt model puts out 800 lumens, costs $35 each and lasts 25,000 hours. So that's $35 in bulb costs, plus 300kwh at $0.10 for $30 power cost, total of $65. But the lumen-hours per dollar? 307,000. less that half the CFL number. To get this LED lamp comparable to the CFL, the unit cost must drop to a paltry $0.77. It ain't gonna happen.
My final analysis, florescent is still king and will be for a long time to come. CFL is a viable substitute though.
Oops. I knew I should have used a spreadsheet. I got the florescent light lumen-hours/dollar number wrong. It's 765,000 not 680,000. Even better!
Then 80 years ago, mercury vapor lamps hit the scene and there was more light, for longer. Today a 28 watt T5 produces about 92 lumens per watt for 2600 lumens and lasts 15,000 hours. Cost per bulb is $9. For 25,000 hours we get $15 for bulb costs and 700 kwh energy consumption for $70 power cost, so that's $95 total. We get about 680,000 lumen-hours per dollar.
Compact florescent bulbs have been commonly available for about 25 years. Cost per bulb is $3. Light output for a 23 watt unit is 1600 lumens giving 70 lumens per watt, lifetime is 20,000 hours. So total cost for the bulbs is $3.75 and energy used is 575 kwh for $57.50 energy costs and a grand total of $61.25. And that figures out to around 650,000 lumen-hours per dollar. Very comparable to the ordinary florescent.
Finally we get to the latest craze, LED lights. These things have been problematic since day one. Initially they used common white LEDs in huge numbers to get usable levels of light. The reliability was rotten though. The LEDs were wired in series and the poor current limiting circuitry was prone to transforming ordinary line voltage spikes into huge over current pulses that destroyed the weakest LED in the chain, ruining the whole lamp. But they were cheap! $5 for one that made about 100 lumens output, in one direction only and used about 2.5 watts of power. Totally unusable as far as I'm concerned.
But, Philips has been working on an improved design, the EnduraLED. A 12 watt model puts out 800 lumens, costs $35 each and lasts 25,000 hours. So that's $35 in bulb costs, plus 300kwh at $0.10 for $30 power cost, total of $65. But the lumen-hours per dollar? 307,000. less that half the CFL number. To get this LED lamp comparable to the CFL, the unit cost must drop to a paltry $0.77. It ain't gonna happen.
My final analysis, florescent is still king and will be for a long time to come. CFL is a viable substitute though.
Oops. I knew I should have used a spreadsheet. I got the florescent light lumen-hours/dollar number wrong. It's 765,000 not 680,000. Even better!