My cheapo Chinese LED lights do not put off any heat to speak of. CFLs will put off almost no heat as well. I use two 4 ft florescent tubes (one grow one normal) for clones and early veg in a small enclosure. I use one LED light (114 LEDS) per plant in another small but tall space. My biggest problem now is the cold which has slowed flowering tremendously. The florescent lights put off enough heat to keep the top of the small enclosure warmer than the LED closet.
So in short both do not put off enough heat to be of concern. In the summer temps rise unless I keep the circulation fans going but is not really from the LEDs or Flouros, it is simply the ambient temps.
So either LEDs, CFLs or tubes would be a good choice to beat the heat.
I am having way better results under LEDs than I ever expected but keep in mind I am using one per plant (they were given to me by a non-believer) and I can only house two mature flowering plants. I am convinced they are better than florescent simply for the more appropriate wave lengths (72 red/42 blue).
Using LEDs have allowed me to realize my potential as a cheap bastard. I have experienced $2000 a month electric bills when doing Hydro drip with 8 MH 1000 Watt lights. We had to vent the light heat out via many yards of venting and 4 fans.
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