Good design? Yay or nay?

Contructing a 6x8x8f grow room in attic. Attic stays around 50 degrees F. Making a totally sealed room made of 1/2 inch plywood. I'm pulling air from basement (68 degrees F) into grow room. Pushing air out of how room to outside with a squirrel cage fan. 100 Cfm. The same fan will also be pulling hot air from my 600 watt hps air cooled hood. I will also have a 150 watt hps in the same room. Does this design sound good? Will my room be too cold because if the cold air in the attic? I have a small heater invade I that.

What kind of light are you planning to use? If you are going 1000 W, I wouldn't worry about the temps being too cool, on the contrary, you might want to move more air than that to keep your temps low enough. I might go two 600 W hps, to keep the lights cooler and closer to the canopy.

Im going to have a 600w hps and a 150w hps. I'm not worried about the temps when the lights are on. I'm worried abou temps being too cold when the lights are off

ah, let us know how that works out for you. a max/min thermometer will be your best friend!

sounds good to me...

I like the avatar pic rollinbud. Also, looks good. Buy a giant grow tent.

Your attic isn't gonna stay 50°F for very long. Much better to grow in the basement. Unless this is for winter only.