Question for the EEs: Which type of light bulb generates the least amount of heat?

[Nobody Famous]

Background: I have a seasonal place that I use, think small cabin sized. The main room has two table lamps in it, each lamp has a three-way 50/100/150 light bulb.

In the warm season, those two lamps can raise the temperature in the room 12 to 15 degrees, bad when the outside temp is in the 80s, but a good thing during the winter months. To cool the room in the summer, we use a window air conditioner, which will easily raise the electric bill by an additional $60 to $80 per month.

I’ve tried compact fluorescent bulbs, ones that throw an equivalent amount of light. They also raise the temp in the room, and are hot to the touch, but not as hot as much as the incandescent bulbs.
LED bulbs, even at $35 apiece, will pay for themselves in on one two months, if they give off no heat.

On the LED bulb demo displays in the stores – Home Depot and Ikea – you can touch the bulbs and they are definitely cool to the touch. However they are the low wattage/low light output bulbs. How do you know if the high powered LED bulbs will give off a lot of heat?

An example from Home Depot: http://www.homedepot.com/Electrical-...specifications

[whippersnapper]

Wattage. Not *Equivalent Wattage," just wattage. You can ignore the power that goes to emitting light, because most of that is converted to heat after being absorbed by successive room surfaces. Also consider the high infrared output of incandescent lights, it is directional (of course) and quite bothersome after you've been accustomed to either LED or CF lights. The latter are 4-5 times more efficient in lumens/watt than incandescents. LEDs vary greatly in visible light output/energy and color temperature, some beat CFLs and some don't. I use CFLs but always at a color temp of 2700K, which is a warm yellow-white light like incandescent bulbs make.

I haven't bought LEDs because the tech is changing so fast, I expect great choices to be available soon. They do last a lifetime, though.

[hafilax]

Look for high lumens per watt in the light output you are interested in. Go for the lowest lumens that give you enough light.

Sent from my GT-I9000M using TGR Forums

[nickinbc]

The wattage of the light is the amount of heat given out (since for any light most of the power goes into waste heat).

The only things significantly more efficient than white LEDs or fluorescent lights are sodium lights (i.e. yellow streetlights) and monochromatic LEDs. I wouldn't want to live in a cabin lit by either.

Oh and you might try comparing the temperature in the cabin with the light on but no one in it with the temperature with the light on and you in it. Your body puts out significantly more heat than a compact fluorescent light!

[Nobody Famous]

Wow, three answers in under 30 minutes. Impressive.

[Hugh Conway]

Look for high lumens/watt and, as said above, low watt usage.