you need ventilation weather led, t5, hps, ect even when heat is low a full canopy resperates a huge amount and you still need to exchange the air for that reason alone not to mention you need the inline fan already for a carbon filter. the low heat of the cob makes the biggest difference in a sealed grow room with dehumidifiers and ac. the ac wont have to work as hard and the dehumidifiers take care of respiration.