Most lights come with built-in fans that help them keep their temperatures low. Apart from that there are a number of openings and vents on the grow lights which ensure that there’s enough space for the heat to escape. Even the front panels have holes on the protective screen to make sure that heat exits the light from all directions. Some growers also prefer to use clip-on fans inside the tent which help lower the temperatures by maintaining a steady breeze. If there are too many lights at work you might even have to use an air conditioner to keep the temperatures under control.