ok so far loads of good stuff but I still after reading many of the post suggested to me not found the one question answered I was really looking for. Maybe I am just old blind and senile or simply seen the answer and it did not lodge in my brain pan correctly.

I am transforming my old terrarium into a hydroponics set up.
Privacy 100%
Water availability 100%
Others wandering in or out, no prob it is a terrarium and stood workin in this same spot for 5 years.
I plan to put an external covering of plywood simulated sticky paper on the external side of the walls, this is not glass but made from reinforced 2CM thick plexiglass. My friends use to call it the Iguana mobile (pope Mobile) as it is umm Stable and HEAVY built.

Nice part about this is unlike glass I can simply use a drill or cutter to make needed holes mounts or such wth no worries of broken glass.

Humidity no prob, adjustable even with humidifier intakes on the top for a downward flow of water particles if needed, Lighting set up is two slidable adjustable lamp sets which run from top of the back wall to 1/3rd down the full heigth. with secondary inlets for the sides halfway down the side walls towards the front if needed.

So by the time we cover the outside with the imitaiton wood paper it will look like any of the other large "shrunks" Portable closets, in the house, also making it light tight and easier to clean from the inside when needed.

Question is though, this monster is 6.5 feet long, 6 feet high, and just over 3 feet front to back.

Gives an average size if 117 Cubic Feet or 19.5 Square feet of space. Which do I use to calculate for the Watt of light I need for this?
Cubic feet says I need 234000 Lumins
Square feet calculations say 39000

As I can run 1 or 2 lamps from the upper back wall, or smaller lamps one on each side half way up the side walls, or should I best go with an all around approach and run 4 smaller watt lamps from each socket for a combined lumin output overall?

Plan to use high pressure Sodiums off set with Metal Halide between vegative and flower periods.
And yes, the inside of the upper 1/3rd of the structures walls and full ceiling will have reflectice foil applied as well.

Only real problem I see to date with the entire location not being optimum by the questionair to date is the ventilation issue (Good tips on that also by the way), still trying to figure how to work that since German windows do not rise up and down like american windows but tilt from the top inward with the bottom of the window still staying flush with the base of the window opening, or they can swing open like a door inward giving no real option for a partial ventelation.

The window in question however looks out onto our back yard (All 5 acres or so of it) So will not be a real eyepopper if I simply open the window during days and lay the vent tube out the edge then close it off at night, EXCEPT for winters which can be bitterly cold here. As I said, still working on the vent issue for now, house walls are 3 foot thick soild stone and morter so no otption to drill or make a seperate vent hole for this operation through the wall.

Also private growing is frowned upon in my part of Germany but not illegal so long as I do not trade brater sell or transport what I grow. So a small amount of fragrance is also not a big problem I just do not want the entire house smelling sickly sweet or some such.

Still reading maybe will find the answer as I go on, but any ideas and suggestions are helpful. If someone can explain how I can also maybe post some pics of the terrarium so folks have a better idea of that which therof I speaketh, HUmm not good at fancy smancy words