Setup advice

More air in and out a sealed room the better depending on the size of the room I can imagine with 4 lights its a fairly good sized room you may struggle to get enough air going through it to keep the humidity down obviously depending on how you intend to grow but either way if you fill a room the plant will most likely be large. Large plants give off alot of humidity. Another trouble you may run into would be heat that many lights in a small space which is sealed is going to create hella heat. Your going to need probably atleast a 12 inch extractor if not bigger to suck all that air out and you will need one just as big to pull cool air in also. Having aircon is going to be a must for you but just as a hobby grower and not really industrial i cant give good advice on AC units I will leave that part to my canadian and american brothers who have the good weather lol another thing your gunna need is alot of oscillating fans as the keep the air moving in the room stale air can be a breeding ground for bad bacteria and mould spores. Also your going to want to go round the room and make sure every inch is visible to you and there are no little cracks or crevices that little nasty bugs could hide. WIth the amount of heat thats going to be in the room and the amount of plants i would seriously consider some sort of c02 enrichment too I would not advise it for smaller growers but larger grow spaces with higher temps they can really soak that c02 up.