The old tent was 4'X4'X~7'. That works out to ~112cf of volume. The new tent is 5'X5'X~8' giving ~200cf of volume. My expectations was for not much difference, just a little extra room to work around what I expected to be pretty much the same number of plants in a grow and a little more head room so I could move some of the air handling inside the tent vs. outside. What I didn't expect was the difference the extra volume makes in temperature control.
The last grow had all the fans working close to 100% all the time and they still did not keep the temp in control. Even with drawing in night air the tent stayed in the high 80'sF to low 90'sF. Much too hot for optimum Cannabis flower even with extra CO2. The crop came in with close to 28g/plant, all loose air buds with mid teen or lower THC content. That's the bad news, not worth a damn for smoking but the OK news they will make FECO that works.
When I first turned the lights and fans on I spent a little time scratching my butt because with the fans running on low the tent temp stayed in the mid to upper 70'sF. Then que flat head syndrome, as per above the new tent has almost twice the volume as the old tent and the lights are hanging almost a foot higher. Bottom line volume makes a big difference. I have an AC unit in the tent now for use if/when the temps increase but it may be used very little.
ken