Quote Originally Posted by vannewb
Anyone who claims they have seen a significant temperature difference with the same wattage is either mis-measuring, or not using similar wattage.
There's a *MASSIVE* difference between a 1000w LED panel, which does NOT have a glass casing that reaches 1000+F while in operation nor does it have burning electrodes, and a 1000w HID, which DOES. There's a difference between the heat output from a light that uses an open electrical arc (fluorescent, HID) and a light that uses quantum wells.

I compare watt-for-watt lighting (as close as possible) all day long for my job. In the same space (A PC case) even 50w LED runs much, MUCH cooler than 54w T5HO. Reason being, no electrodes as a spark gap emitter for a source of energy loss and heat generation.

I think you're also forgetting that entropy differs in different electrical system configurations. That in itself is a basic tenant of thermodynamics.