That's a large space for a grow room. Like suggested you should do a bloom/veg split closet could be used for clones seedlings and grow room material storage. Think about it like this you need a spot to mix water maybe a source depending on grow methods. If it's a true dedicated grow room. Ac in the window insulate the room with foam boards and some panda film to finish off. For a more basic design get some white paint for the walls and ceiling foam around the window frame to ensure no air leaks, you dont want to much temp fluctuation. Need a vent fan for odor control as the room is not air tight and allows for more air exchange especially if you open the door a few times a day. Depending where you live you may not even need the dehumidifier. Before you start go get a humidity/thermometer from walmart or something and get an average of what your temps and humidity look like so you dont over buy and over take space in the grow room unnecessarily. Also another factor to take is power that is needed for your operation, you dont want any fires. Take your time as this is an area that you want to produce for you, you also dont have to spend a billion dollars to do it if you lay it all out before you start spending money because someone here said to do so. It took me about 4 months of planning and analyzing for the right stuff needed for my first grow. I am still using the same setup with minor improvements to my grow room like I ended up adding in a separate clone/seedlings and veg area. When I can I will insulate the walls with foam boards and panda film. Also another word of advice if you are on a concrete floor ("man hole cover") definitely need a buffer between the floor and grow pots or bags. Again the name of the game is clean consistent environment will produce great plants depending on the grower. Look at all factors before laying out any type of capital, just because I can and the next guy say 1000 watt hps or MH doesnt mean your capable of the same things.
