I was the same way when I started. I made a grow space in my attic during the summer and it got way too hot. Spent a week dragging up materials to make a spot where I could grow.
My next grow space with in a closet. It had no ventilation. Temps again always in the upper 90s with too much humidity.
Third grow space was in another closet in the room next to the second one but I cut a hole in the ceiling to run ventilation out. That kept my temps in the upper 80s, had no cool air intake.
4th grow space was in the basement. I had an extra room down there and did everything the right way. I had plenty of ventilation and temps stayed in the mid to upper 70s. Some of my best grows were in that room. Soon I had kids and wanted to move it out of the house for fear of a fire hazard.
So i bought a house to convert into an office (for my 5th grow space) and finished off the basement. Again I planned it out right so ventilation was my top priority and again had some of the best grows ever for many years.
My current setup is my 6th grow space since starting in 2001. I didn't want to cut holes in my home's interior and i don't have space to have a whole room dedicated to it. That's why I created The Growing Rack. I took the experience I had gained from my previous spaces and condensed them into a mobile (it's on caster wheels) 10 sqft package (20 sqft total canopy). Once assembled, lights & ventilation are added it's ideal for growing cannabis in any room or apartment (brother has one in an apartment complex). Sorry if it sounds like an advertisement, I really don't mean to come off that way. It's just a lot of time, effort, testing and money went into it and i'm rather proud of the end result. If I had to do it all over again the results would be the same. Been using the rack setup now for quite some time (personally) and couldn't imagine a better more optimized grow space.