We have been trying to get more energy efficient, not so much for the environment, but for cost savings. The first thing we did was to get our attic properly insulated. This was done last year, and we noticed a big difference in the winter. However, the summer was not as noticeable. Our first theory was our very old windows. The large windows on the front of our house really got a lot sun and made the AC work harder. The new windows made a big improvement. At night, we did notice the AC was still going a bit. This is where I began to develop my theory. 

The Test

I wanted to see if the additional heat was being generated by the can lights we have in the kitchen and den area.  We have 6 in the den and 4 in the kitchen. They are on the entire evening after work. The den lights are on dimmers, the kitchen are not.  I thought if I replaced the lights with compact fluorescent bulbs, the energy savings would also have a heat saving.

 My first step was to get a temp of the room. I took my wireless cooking thermometer  and let is sit out in the open.   It read 76 degrees. 

I then took the thermometer and put it near the light. Not touching it but in the ambient air around the light.

 I did two tests. A 5 min test and a 30min test.  My findings were surprising. The CFL stayed around 85 to 90 degrees. The incandescent light stayed from 140 to 150 degrees. 
Without getting into a discussion of watts, BTU's and Lumen's. These lights were similar in light output, however the incandescent put out much more heat per bulb.

Here is what the bulb looks like 

 I also did some searching on the web and confirmed my original theory. 

 Here is what GE says about CFL's

How much heat (or infrared radiation) is emitted by regular, halogen, and compact fluorescent light bulbs?
Regular light bulbs, known as incandescent bulbs, create light by heating a filament inside the bulb; the heat makes the filament white-hot, producing the light that you see. Halogen light bulbs create light through the same method. Because incandescent and halogen bulbs create light through heat, about 90% of the energy they emit is in the form of heat (also called infrared radiation). To reduce the heat emitted by regular incandescent and halogen light bulbs, use a lower watt bulb (like 60 watts instead of 100).

Fluorescent light bulbs use an entirely different method to create light. Both compact fluorescent bulbs and fluorescent tubes contain a gas that, when excited by electricity, hits a coating inside the fluorescent bulb and emits light. (This makes them far more energy-efficient than regular incandescent bulbs.) The fluorescent bulbs used in your home emit only around 30% of their energy in heat, making them far cooler.

Here is what the Energy Star Website says on CFL