New grow room, can a high enough fresh air intake eliminate need for active exhaust??

I just moved all my goodies from a small well ventilated closet to a relatively large room In the basement. I have a very large storage space with a roughly 12x15 room that is about half way sealed off from the other half of the storage closet. My original plan was to finish sealing it off, and to construct an air-tight door to access the room. I have deconstructed a relatively large hepa air filter, which I planed to install into the wall of the room as an active exhaust to create negative pressure which would be relieved through a new wall vent into the air conditioned house that I installed. As I moved everything before sealing the room to anything close to air tight I had to improvise a ventilation system, and attached my fan to the new vent through ducting. The fan is pretty strong and does a good job of bringing in clean and cold air, temps are fine and plants are happy. I have since run into a lot of trouble actually getting the room sealed air-tight and haven't managed to construct a sealing and inconspicuous door, and was wondering if my current situation would lead to an eventual build up in oxygen, or if my fan pulling in fresh air and oscillating fan blowing air away from the plants would suffice long-term until I figure out the last of this construction.. Sorry it's so wordy there's a lot to explain

What kind of lights you using? General rule of thumb is passive intake low to the ground to suck in cool air, active exhaust high near the ceiling to suck out hot air. 12x15 you gonna need active exhaust. I'd go with a 6" or better yet 8" inline fan depending on a lot of things... whether you are using HID or not. Over build your exhaust or else you'll be battling heat issues.

Working in that direction is going to pose a few problems, mainly the fact that any and all leaks will now exhaust plant odors ( bad juju ) If the room is working with an active exhaust and a passive intake, the room operates in a slightly negative pressure ( much easier to control and stealthier as well.) Having any and all air that comes into the grow space have to leave the room via a filter is always a great option.

Peace and Stealthy Grows

Asmallvoice

If you are running a bulb or two in that space the walls will act as a heat sink and absorb most of the heat from the lights and ballasts so long as you do not enclose the bulbs in a more confined space you should not need cooling.The earths temperature and the basement walls will run around 60 degree year around.The more surface area available the more heat it will absorb out of the ballasts and bulbs.Some basements depending on where they are at in the country can get really cold at night and might need a little heat.
It is important to watch humidity .If the basement is sealed up tight it might not get enough humidity.If there is water that comes around the edges and leaks in the basement when it rains.it might get to much humidity.
Most homes with basements have the furnace located in the basement.
If it is a gas furnace it will have a chimney around it.You can knock a hole IN THE CENTER of the chimney and put your exhaust into it and pump air out the chimney with a carbon filter.Make sure it is ducted with metal and mortared into the chimney.This will make a negative pressure but will draw fresh air from everywhere in the home to the basement.
If you have a modern home it will probably have double wall B vent type flue and you wont be able to hook it up.
You could also always run a duct through a closet upstairs into the attic or the attic of a garage.Dry wall and floor is always easy to patch latter.
Get you some orca film and lay it on the floor under where your plants will be.If you can put the grow right in the middle of the floor would be best.Hang curtains made of orca film around the plants .This will make the whole grow easier to work around.The curtains will be short enough to allow air under and around them but reflect the majority of the light back into the plants.Get the curtains hung as close to the plants as you can.The faster and sooner you reflect the light back into them the brighter the area will be and better results you will get.
Most basements is where you will find your power source also.Please be careful when you mess with power.Its not really dangerous so long as you respect it and are careful with it.
There should also be a floor drain or sump pit to pump drain water to and access to water.
Good luck and hope this gives you some ideas.

you need to tell us your set up your goals/ using co2 ? hydro or soil ? ac ?

My medium is soil, and I'm using led panels for the most part, but there's some cfl side lighting. Room high is 81 during the middle of the day, and 70 at night but winter is coming and that will most likely change. As of right now my co2 is all from the fresh air intake, but once I get the room sealed and exhaust set up I may invest in some supplementing, but that's not too high on the list of priorities at the moment. Unfortunately I rushed the move to he new room because I was getting a little worried about the stealth of the old spot, and now I'm battling spider mites while I try to finish the room -_- But hey if it was easy everyone would be doing it right??

Forgot to mention I also have a small section for seedlings in the same room with about 100watts of t5'S