A sealed environment with CO2 enhancement is the highest-performance way to grow. Seal the room, add adequate air conditioning and dehumidification, and pair a CO2 controller with a regulator, solenoid and bottle (warmer climates) or a CO2 burner (cooler ones).
The payoff is serious: veg time drops from around 4 weeks to 3, flowering from 8 weeks to 6.5–7, and yields climb by roughly 30%. A sealed room also keeps pests and fungal problems like grey mould, botrytis and bud rot at bay, and odour control is as simple as a fan with a carbon filter.
Because you're not constantly exhausting conditioned air, a sealed setup can even cut energy costs — your appliances stop fighting the outside world, and your plants get a climate better than nature can supply.