1 Watt = 3.4 BTU heat (other added variables such as hotter summer months, let's use 4BTU per watt)
Bare bulbs hung vertically are actually pretty efficient, add a fan blowing up under it and it becomes even better. Heat rises, so with no hood to trap that heat and create even more heat, the air is constantly circulating.
Hot summer months (100+ degree's), it's actually the a/c that is taking the hit, the lights are Not going to produce more heat in a sealed room. The air temp within the room is a constant, I'm sure with CO2 your room is going to be somewhere in the low 80s during lights on.
4 (BTU) x 30,000 (Watts) = 120,000 btu worth of heat
10 (Tons) x 12,000 (btu per Ton) = 120,000 btu worth of cooling
They'll be working hard but getting the job done. Add fans in with constant circulation and only trying to keep the room in the low to mid 80s, shouldn't be an issue.
-ALLegal420