That's because its passively cooled, the unit itself will be warmer than a light that is actively cooled, but that's because the active cooled light is pulling the heat away faster. The heat still ends up in your grow room though, its not a reflection of how hot or not its going to make your room.
The way for it to be cooler is to use a unit that gives the most light out for the power it uses, that spider farmer will be far more efficient and you will be able to use less watts to light the same space in comparison to what you linked. Watts are heat.
After that its about how much airflow you run to keep your temps down, but if your already above your desired grow room temp then AC is needed in the first place. Otherwise , the more air you exchange the closer to ambient temps you will be.
