WHY USE LED LIGHT BULBS
ANYWAY?
LED stands for Light
Emitting Diode. Diodes are a small solid-state electronic device that only let
electrons pass in one direction. They are used in many electronic devices like
radios and TVs.
Some diodes are designed
to give off light when electrons pass through them. The amount of light given
off is very high compared to the amount of power used.
The photo at the right is an enlarged shot of a single LED before it is wired up and put in a housing.
Several readers have been asking me about the
very energy efficient LED light bulbs that are designed for home use. I have
been putting it off because the very high purchase cost of LED bulbs seems to
rule out any money savings.
I ordered an EvoLux warm
white LED Bulb to try it out. The delivered cost from Amazon was a couple
pennies less than $90. That is for one light bulb!
For testing, I took the
shade off a table lamp and tried several different light bulbs to see the pros
and cons of each. The testing was done with all other room lights out and the
shades drawn.
HOW MUCH LIGHT WAS THERE
The EvoLux literature
offers it as a replacement for a 100-Watt old fashion light bulb. Based on the rated light out put of 1,000 lumens it is more like a 75-Watt incandescent. Unfortunately, I did not have 75-Watt bulb
on hand to measure.
I was curious how
directional the light from the LED bulb was so I measured the light out put
using my light meter at a distance of 3 feet above and 3 feet to the side of the
different bulbs.
My meter reads in foot-candles.
A foot-candle is light the light your eye would see one foot from a single wax
candle.
Foot-candles are the unit
of light intensity that many engineers use in designing installations and
checking existing lighting for commercial and industrial applications. Any way
I used the meter that I had on hand.
Light intensity is very
dependent on how far from the light source the measurement is taken. I used a
common wood yardstick to get the meter the same distance away from each bulb.
As I expected the light
from the old fashion, 100-Watt bulb was close to the same in both the upward
and sideways directions. Since they send light out well in all directions, they
make a good all around light source. That is why we have used them everywhere.
A 23-Watt Compact Fluorescent
Lamp sent more of its light out sideways than it did upward. Because of the
high amount of light going out sideways, they are a good light source for table
lamps.
The EvoLux LED bulb sent
very little light out to the side but did send a lot of usable light upward. In
the up direction, it actually put out more light than the 100-Watt incandescent
bulb.
LED’s make very good spotlights.
Using them in recessed fixtures build into the ceiling would be a good choice.
They are also good for reading lamps where a gooseneck fixture allows you to
aim the light where you need it.
HOW ABOUT THE QUALITY OF
THE LIGHT
I had my resident color
expert look at a variety of quilting fabrics using the three different light
sources. According to her color sensitive eyes, the light from the LED bulb did
not show the colors well. She gave it a POOR rating. To me, the light was gray
not white.
The CFL got a FAIR rating
and the incandescent a GOOD rating.
THE UNEXPECTED PROBLEM
I sent the EvoLux LED bulb
on to one of my readers, Mike in California, to get another opinion. He pointed out something
with the LED bulb that I had not noticed.
It makes noise!
According to my friend
Mike, “the noise is a bit like a computer fan although not as
loud. It's a medium pitched whine along with the whir of a small high
speed fan moving air.”
Here are the rest of his
comments about the EvoLux LED light bulb.
I really wanted to like this light. And while the light
output was quite good for an LED (it seems about the same as a 75 watt incandescent)
I was a disappointed in several important ways.
First, it makes a noise that is not acceptable for most indoor applications for
my wife and I. I believe it has a fan in the base of the bulb to keep it
cool. However, this makes a hum which is very distracting for reading
etc. So, it limits the number of applications to noisy locations, little
used locations or outside (including the garage). Some people may be able to
overlook this, but it was very distracting for me. I even tried it in a
light fixture with a glass enclosure, but I could still hear the noise.
Second, even though the light has a bulb like enclosure, the light mainly comes
out in one direction. For example, when I put it in a desk lamp, most of
the light when up to the ceiling. Even when I tried it in a downward
hanging ceiling light fixture with a 2 foot broad reflector designed to light a
table area, it didn't produce a broad enough light to feel comfortable. The
light output was acceptable in the ceiling light fixture with a glass enclosure
and a downward focusing reflector, although the noise made this application
unacceptable overall. I did try it as a replacement for a floodlight outside
and that works pretty well.
Third, the quality of the light was not as warm as the CFLs or incandescent
bulbs. It was not a blue light, but it was not as warm as we prefer. Also, the
light is quite bright if you look directly into the bulb. This is worse than a
CFL or incandescent as well. For most applications, this isn't an issue, but
it's worth noting. For example, the hanging ceiling fixture mentioned above has
no cover etc, so it can be annoying since you occasionally glace at the light.
So as I said, I really really wanted to like the EvoLux, but at this point, it
will be relegated to the garage or used outside. One other great application
will be when we are out of the house on a trip, I put lights on a timer to give
that lived in look. Because of the energy efficiency, this will work great for
that application. In fact, we have a second home that could benefit as well.
Here is a link to a video
review that comments on the sound and puts the microphone by the bulb, so you
might be able to hear it. EvoLux review at ecogeek.org
I missed the noise because
I don’t hear so good. I wear hearing aids to help my explosion battered ears,
but often miss hearing things. Mike has very good hearing and found that the
noise from the LED bulb was irritating to him.
The LED bulb has a very
long life expectancy, (50,000 plus hours of rated life) but needs to be cooled
to last that long. The very small diode has to be hit with a large amount of
power to give off the amount of light needed to be useful in home applications.
12-Watts isn’t all that much power, but because of the very small pathway, that it
needs to squeeze through, it gets hot right where the action is.
The EvoLux LED bulbs have
a built in fan to cool them. The outside of the plastic bulb housing stays cool
to the touch.
I wonder how many Watts the cooling fan uses.
DOES IT SAVE MONEY?
The LED bulb used about one-eighth the amount of power that a 100-Watt Edison lamp uses. It
used about one-half the amount of power used by the CFL so it really is
efficient for light it gives out.
It has a very long life
that helps it to overcome the high price. It lasts at least 8 times longer than
a CFL and 80 times longer than that old Edison bulb.
It is made of durable
plastic, not glass. It will take a lot of abuse without breaking and wasting
your investment in it.
The answer is yes it will
save you some money over the long haul of its long life. If you can tolerate
the noise and if you have a place to use it where the color quality is not an
issue it will pay for itself. Most homes do have such places.
Here is a chart to compare
the numbers. The cost numbers show that CFLs and LEDs are money savers.
|
|
23 Watt CFL
|
EvoLux LED
|
Incandescent
|
|
Ligh Bulb Measurements
|
Cool White
|
Warm White
|
Cool White
|
|
|
|
|
|
|
Measured Watts
|
23
|
12
|
101
|
|
Foot Candles at 3 ft above
|
9.0
|
19.0
|
14.4
|
|
Foot Candles at 3 ft
sideway
|
13.0
|
2.2
|
19.7
|
|
color perception
|
fair
|
poor
|
good
|
|
relative purchase cost
|
$4
|
$90
|
$1
|
|
rated life hours
|
7,000
|
60,000
|
750
|
|
Rated Lumens
|
?
|
1,000
|
1,600
|
|
burn outs in 60,000 hours
|
8
|
1
|
80
|
|
replacement cost
|
$32
|
$90
|
$80
|
|
energy kWh in 60,000 hrs
|
1,380
|
720
|
6,060
|
|
energy cost at 12 cent /
kWh
|
$165.60
|
$86.40
|
$727.20
|
|
Total cost
|
$197.60
|
$176.40
|
$807.20
|
It is my hope that the
science and engineering of LED light bulbs will continue to improve so that
they will soon give better light and be available at a substantially lower
cost.
LEDs have a bright future.
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