Last summer I bought some facade lights for my home, so called up-down lights. I mounted two of them on my garage and two more on my house. The result was nice. I didn’t want to change the light bulbs all the time, so I decided to buy LED lights. I was convinced by this by the information text that accompanied the lights. LED bulbs – life time approximately 30’000 hours.
Well, I do have to admit. I didn’t buy the fancy ones. I bought them on Harald Nyborg, a cheap danish DIY store located in our town. Maybe I have to suit myself for buying my bulbs in a cheap store. For some reason you can not expect a cheap store to deliver what the promise, right? One annoying fact remains, though.
One and a half year later, four out of eight bulbs are broken.
A calculation example
Let my try to clarify why I am annoyed. I mounted my lights under the late sprint of 2016. For the sake of this story we can say that it was in April. This means that the lights have been hanging there for a total of 21 months. In 21 months there are around 15’000 hours. You have to believe me when I say that the lights aren’t always on.
Two of the lights are connected to one of our switches. This is the main outdoor switch which we activate almost every night. We switch it on when darkness comes, and we switch it off when we go to bed. In 21 months I would say that the lights have been on for a maximum of 3’000 hours. The other lights are connected to a different switch which we almost never remember to turn on. I would be surprised if they have been used for more than 500 hours. Even so, two lamps on each switch have been replaced.
The Light Emitting Diode (LED) is a form of semiconducting diode, an electronic component which for example can be used to make direct current out of alternating current. Diodes are made out of semiconducting materials that are doped with impurities, atoms with a different amount of valence electrons. Like magnets that have different polarities, the halves of the diode only want the current to pass from one end to the other. If the right semiconducting material is chosen, there will be a small glitch in the current that flows in the diode. This glitch makes the energy in the diode to start leaking and this leaking energy produces visible light. Different materials produces different wavelengths, which means different colors.
To achieve the white colored LED it is possible to mix a red, a blue and a green or yellow LED. Those three colors generate the color white. This is what is going on in your screen right now, where every pixel in the screen corresponds to a RGB (Red Green Blue) combination of lights. Another way to get the white colored LED is to filter blue light through a layer of phosphor, which produces the white light. This is the most common way to create a white LED light bulb today.
The Emperor’s New Clothes
The LED light bulbs takes more shares of the light bulb industry every day. Since you need less energy to produce a given amount of light, the light is cheaper per hour. Besides, the estimated life time for the LED is longer than for an ordinary light bulb. This means that the economical gain is great if you see to the full life of the light bulb, even though it’s a bit more expensive to buy. But what if one of the factors of this equation is removed – will it still be profitable?
I get a feeling of being inside the old fairy tale “The Emperor’s New Clothes”. Hey! The Emperor has no clothes on! He doesn’t have a life time of thirty thousand hours. He only lives for a couple of hundred hours!
Or is it just me having bad luck?