Monday, February 08, 2010

Looking At Light

Anthony Watts has a great article up on how he changed out a fixture that used a CFL Flood Lamp to one using an LED lamp. Anthony bought 5 LED fixtures and got a deal. He paid $80.00 each for them. So let us run some numbers.

Cree LED Lighting LR6-GU24 White 6$80.0050,00012
GE 47478 15 Watt (65 Watt equivalent) Energy Smart Floodlight 6 Year Life R30 Light Bulb
5 CFLs$31.2550,00015

For 50,000 hours You pay $31.25 capital

In 50,000 hours you save 150,000 Wh or 150KWh with the LED fixture. The LED fixture costs $48.75 more than 5 CFLs . If your electricity costs less than 32.5¢ a KWh The CFLs are a better deal.

On new construction or when replacing a fixture the cost of the fixture enters the picture. Don't forget to figure out what it is worth in time and hassle changing bulbs more often vs installing a fixture. Another point is that you can dim the LEDs and the CFLs do not dim. Dimming the LEDs should add to their life since ordinary LED lifetime is roughly proportional to current. Not only that: light output per watt goes up at lower currents.

My advice to cheapskates? At 10¢ a KWh wait until you can buy one for $45 or less. A couple of CFLs should see you through.

Those are the economic issues - roughly. As Anthony points out there are other considerations. And thank you Antony for being an early adopter. It will help bring the price down to one I can afford.

Cross Posted at Classical Values


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Pastorius said...

It seems to me Fluorescent light and LED light are far from aesthetically pleasing. I attribute this to the fact that they create "full-spectrum" light by combining primary colors into a full-spectrum. A spectrometer reading of fluorescent light shows spikes at the primary colors. By contrast a spectrometer reading of real sunlight, or of Incandescent light, shows a cloudy spectrum with no spikes.

LED light is highly directional and almost laser-like aesthetically, from what I've seen.

Now, there could have been some improvements that I am not aware of, but I do believe the aesthetically displeasing aspect of fluorescent and LED light comes from the fact they do not feed a full spectrum to the eye.

The pupil actually dilates under fluorescent light, for instance. Why would it do this when there is so much glare associated with fluorescent light. It's almost as if the pupil is searching for the missing parts of the spectrum.

Additionally, fluorescent light showers UV rays which break down DNA cells in living organisms. They also break down fabrics, photographs, and plastics.

If I am not mistaken, LED light also pours out UV rays.

How could these two forms of light be preferable to light which delivers an actual spectrum without UV rays?

M. Simon said...

I actually take advantage of that UV by blogging naked. I get the Vitamin D I need. I can tell the difference.