temp sensor location

Could anyone tell me where to put the temp sensor? In the middle of the room, or at the canopy under the light?

Middle of the room at canopy level out of the direct light,make a "shader" out of paper or cardboard you just don't want the light shining directly on to it or you'll get a higher reading than the actual ambient temp.I started using a lazer thermometer after awhile you can shoot the walls at canopy level surrounding the grow and actual canopy temps.It's the most accurate way to get ambient temperature which is what you're looking for

I agree with Floridian.

I hang my sensor in the middle of a 3x3x6 and it usually keeps things ambient.
The set up I have controls 2 exhaust fans, so at times its difficult w/ 1 sensor.
I check it everyday, but love stressing out my genetics in my garden.