Another LED indoor light thread - how much heat?

[ultrarunner]

I have not made the change in Olympia where I have a lot of recessed lighting and a lot of lighting overall.

In winter... leaving 4 75W canned lights on made the roomer warmer... thinking this will not be the case when I switch.

The change will have to wait for when/if I move back.

 

[techman]

What the article did not elaborate is that a majority of the infrared from and incandescent bulb ends up heating the area surrounding the bulb. If you note, only 8% of the energy ends up as visible light, compared to 25% for an LED. Greatly reduced radiant heating with an LED is the largest factor of reduced heating. As a comparison LED = 75% of 13 watts, or about 9 watts of heat. Incandescent = 75% of 100 watts is about 75 watts of heat. The LED is about 1/8 of the total heat. So yes they are safe in a can.

paul

 

[Raspy]

tech,

I can't make those numbers work. I have some 60 watt "equivalent" LEDs here to compare with incandescents.

If 8% of 60 watts (4.8 watts) = a number of lumens from a 60 watt incandescent. How can a 60 watt "equivalent" LED produce the same number of lumens with 25% of 8.5 watts? That equals .25 X 8.5 watts = 2.125 watts. Less than half the watts. It seems the visible light per watt numbers don't work as the watts used by the LED per lumen is about half based on 8% and 25% numbers for watts per visible light, or lumens.

Is there a discrepancy in the power supply between different manufacturers? Are they not really equivalent? Or are my numbers way off?

Interestingly, I have two 60 watt equivalent LEDs here. One uses 8.5 watts and the other 10 watts. Cree has just introduced a new bulb that appears WAY cheaper to make. But I don't have the figures on it's performance.

 

[dragoneggs]

LED 'bulbs' are now designed to passively dissipate heat decently enough to cover the their output. For normal household applications you don't need a fan. Active cooling of LED's becomes necessary when you start concentrating light such as for a reef aquarium or other needs requiring high PAR lighting.