just thought Id throw my two cents in,If its allowed I see every other ass hole can,
props to you first of all on tackling this,Its a pile of work,I know a thing or two about heating and air,
Just to cool 30K watts Just the watts of the lamps will take 8.5 tons of cooling,
a geothermal heat pump system is the cheapest to operate by far concerning electrical costs,it is however the most expensive to install,the outdoor loop as it is called can be buried in the ground either horizontal or vertical ,they can also be dropped into the bottom of a pond,
a package unit would be the cheapest to install,i wish I knew more about your climate,but its all good I don't want to know,
a outdoor unit with a economizer, a economizer will mix the outdoor air with indoor air,causing the compressor to not have to run as much saving energy,lots of it too,someone mentioned not using outdoor air because of problems,these economizers have filters,i think you would want to upgrade the filters and also install cheap UV lights that kill pollen and bacteria,you can run duct up on the outside of the building to each section with control dampers for each section,humidifiers for dry winter months are easy to install in the duct work, along with automatic smoke detectors they should be needed according to most codes in the duct work wired to alarms and shuts the system down at the same time,
The duct work would run along the ceiling with branch runs pointing down into the plants distributing the air evenly under a constant even pressure ,This will save on the amount of fans that are needed in the room,
of course sealing and insulating the building will make temps easier to control and a lot cheaper on the power bill,
A 15 ton system will move 6000 CFM of air,for thirty lamps that would be 200 cfm per light,(wouldn't get the full 6000)
with a velocity of almost 600 fpm on a 8 inch hood,
it would change the air over in a 5x5x5 area about one and half times per min,
im not sure what your local codes are but you could set up a dry well and run waste water to it so long as its not human waste,a dry well is just hole in the ground filled with gravel and water drained to it,you can put dirt back over it and plant grass on it if you want,Also could run waste water through RO and reuse it