First post here, so much to learn -- About Heat & Power I would first like to thank those who participate on this forum, I have referred to it several times in the past and have found it highly informative. I am not a teacher, just an old man intrigued by learning, I am mostly retired and have a few hobbies to keep me off the streets. :D I have a large group of friends who also enjoy discussing things we know little about but relish the exchange of ideas, it keeps our geriatric minds working. There is one topic we have beat to death, wattage and heat. I have searched this forum on this topic and did not really find a direct answer to the question. I have hopes that we can settle it with the combined knowledge here and that will allow us to move on to more helpful topics in our group. In this example we have two lights, a 100 watt metal halide and a 100 watt LED. Assuming both lights are pulling the same 100 watts of energy from the wall in a one hour period (measured with a killawatt meter) is it reasonable that both fixtures are also creating 100 watts of heat as the eventual outcome of the energy consumed and the work done? I understand that the LED is more efficient at creating light than the halide and will produce more light but will both units end up producing the same amount of heat?