Fluorescent vs Recessed LED - Is my math wrong?

trouperDecember 5, 2012

Like a lot of people I have a fluorescent fixture as the main source of light in my kitchen. It consists of 4 (T-8?) 48 inch linear tubes in the center of the room. Was considering modernizing somewhat to recessed LED cans, and actually hoping to get more light output out of it.

room = essentially 10 x 13 feet so it's not that big, and with upper cabinets, the available surface area is even smaller.

Calculating what I currently have:

4 x ~2700 lumens = ~11k lumens

I've read 35 lumens/ft2 is ideal for kitchens
this equates to 10 * 13 * 35 = 4550 lumens

This is half of what I currently have.

Using HD/Cree (575 lumens) would be 8 light to get half of what I have. Would be alot of light.

To equal what I have would take 19/20 LEDS.

Is something wrong with my math? Have I forgotten something? Or is the ugly fluorescent the best light I'm going to get?

Any thoughts? Thanks.

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One thing to consider is that a lot of light from those fluorescent tubes never goes downward, so is wasted. Depending on the fixture, it is plausible that half or more of the light is lost. With LED downlights, all the light is emitted downwards with little waste.

    Bookmark   December 6, 2012 at 10:23AM
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Fluorescents are currently the king of the lowest initial cost, high output, long running time category.

Like wws944 said, the typical fixture/ enclosure used could dramatically cut the actual usable output.

I was initially loath to give up my recessed fluorescent light box, but the benefits of having a higher ceiling forced the decision. In the end, the Lr6 downlights worked out far better than the original.

    Bookmark   December 6, 2012 at 10:35PM
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"I've read 35 lumens/ft2 is ideal for kitchens "

That is a general lighting number, not a task lighting number.

Task lighting is in addition to general lighting.

Cans tend to be more directional.

This post was edited by brickeyee on Fri, Dec 7, 12 at 15:20

    Bookmark   December 7, 2012 at 3:19PM
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