Halogens burn a lot hotter than an HPS. However, an HPS is a lot larger bulb and gives off more real heat (btu's ?) than a halogen. In other words, it can warm a larger area.

90F is about as high a temp as your average plant can thrive in. That's even too high for some plants. So, any lamp heat over 90F is problematic and needs to be removed from the grow area.

I've never fired up an HPS lamp outside of a cooled hood, so I couldn't tell you what to compare one to.

PC :smokin: