rh1zome is on the right track, however you could go the less expensive / noisy route and get a heat extraction fan for removing heat from your light only. If your light has a duct attachment you should get that (or put it on) and get a good strong 4" or 6" fan to vent out all the hot air from the light right away. This alone should keep your temps down near the acceptable range depending on your other environmental factors. You could get a bigger fan to handle the heat from the light and the ambient heat in the grow space, but having them independent I think is a good idea.