Gavitas are commercial equipment. If you have the means to be commercial, you shouldnt be using vented hoods. Vented hoods are for smaller grows to manage heat. They have their place, its just more specific than people think. Just my 2 cents.
With a well designed reflector it is more like 5%
If my memory is correct, the Gavitas aren't cooled on purpose. They need to run at a certain temp to get the correct output spectrum and cooling drops them below the optimal temps. They are also usually run much higher above the canopy so direct heat from lamps isn't as much as an issue. I believe they spec a 10' ceiling height, but it's been awhile since I looked into therm.
