Imho the best way to go about light cooling is to have openings on the front and back of the lamp with intake and exhaust ducts running to outside the growroom; often up into the attic. Then have air blowing across the canopy level to cool the parts of the plants closest to the lamp.
This time of year, the outside air can be used to completely cool lamps in most areas. I've had the glass on 430w lamps ice cold when the light's been on all day and cooled with winter air.