This is my first experience with my 150W HPS. Switching from CFL only to the HPS for flower was a big change. I did not realize how much extra heat it would create. My grow space is a custom built box that I keep in a walk-in closet and not easily vented. While my box is vented and has great airflow, the hot exhaust had nowhere to go being inside the closet. Even with the closet door open 24/7 heat was a constant issue (for the plant and me)