That would be amazing if they had bulbs that actually cooled... It would be a technique that would help turn some strains purple and/or darker in color..the 42w's give off plenty of heat. nobody said those things would stay ice cold. they just don't get hotter than the surface of the sun
Anything that produces energy, especially a light bulb, is going to generate heat. It's not very much but it is enough to burn the plant if put too close.yea that sucks they all give off heat because i think i had them to close to my plant and it burnt so i had to raise them a couple inches