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Illumination Depreciation - June 15, 2018

Now, with longer, hotter days of summer, I changed my 45-watt CFL bulb to a 35-watt one and, to my surprise, the 35-watt one was brighter! I had suspected that the 45-watt bulb had dimmed a bit but never expected to be able to see it so drastically. (if you care to know, it is a photography bulb since I needed my one-fixture living room to be super bright)

I almost felt like changing back to the dim 45-watt bulb because maybe I don’t need it that bright anyway and thought I would also save energy. Just to be sure, I started researching and learned of a lighting phenomenon known as lumen depreciation. It is the degradation of luminous output that occurs as a light source ages. Another disappointing aspect of this is that as the bulb produces less light it doesn’t consume less energy, it simply dissipates a greater percentage of that energy as heat. Thank goodness for me this happened in the winter.

For an even darker outlook, don’t think that swapping to LED’s is any kind of remedy. Lumen depreciation happens to them too. In fact it happens to all light sources to varying extents. Even to incandescent bulbs. The brightest idea with CFL’s may be to change them before they reach 30% depreciation, that is, when the coil at the base is blackened, rather than waiting for them to burn out!

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