How much ScrOG coverage from a 1000W MH/HPS?

I'm planning a ScrOG grow with hypothetically infinite space. How much space would a 1000W MH/HPS light cover effectively in a ScrOG-type setup?
Also... okay, let's come clean, it's a massive space. I need to heat it. Any suggestions as to how I could save on energy here? I was thinking just split off a large part of the place by using emergency blankets as a wall.

Some brief anecdotal reading is telling me that I could potentially cover 20 sq. ft., whereas a lights supplier suggests their 1000W HPS to cover only 5 sq. ft. primary. That's a big discrepancy so PLEASE HELP ME, my Rollitup homies!

20sqft is a bit much man, the truth is the more light u have the better your buds will be, i would say you will get the most with space by using one of the large umbrella reflectors. 10ft sq would be good for 1000w, if u can afford another 1000w you should get it.

your best off doing the whole thing in a tent, i would suggest the secret jardin tents. Secret Jardin - they are the best with insulation and everything, because keeping your area clean is very important, and this will create a cleanroom for you. and make your shit the bestest =)

good luck man

well this is what i've read. 20watts per sqft is the min you want so : LxW=sqft then sqft devided by watts = watts per sqft...ok stay with me...so if you have a 1000watts you can do a room of some 50sqft and get 20watts per sqft...but IMO thats the min you want...i try to go for 50watt/sqft....thats a 5x5...fdd said a 1000 covers a 4x4..thats 62.50watts per sqft..more light that is focused on the plants = bigger budds!!!! but thats just me..hope i helped good luck and peace

Alright, guys, thanks alot! Now my focus is on the matter of insulation. I'm afraid those tents are outside my budget, although they look beautiful for another time. Remember that we're talking about a warehouse-sized shed, and I'm trying to isolate about 90 sq. ft. of it.
I was thinking about buying a 250-pack of 2X7 mylar emergency blankets, to serve as both a reflective surface and insulation. It would contain roughly 600 cubic feet of space. Does this make sense to jah?

that should work fine, just scrub your shed clean from head to toe- you can also look up George Cervente's Ultimate Grow video, he teaches you how to make a mylar room out of some 2x4's and mylar. its a much cheaper solution to the tent, just make a square box with your 2x4's and cover the walls of it with mylar, this will give you something to hang your fans and lights on anyway. good solution, then you can cover the outside of your structure with insulation of your choice.

good luck

After you seal your room off check what the temp is in the room with your lights on and if it needs to be higher get an electric heater and put it on a timer. That'll help combat the cold.

There is now a wood furnace in there, and I've decided that each 1000W light will reign over 16 square feet of ScrOG space, at a rate of 1 plant per square foot. At 62.5 lumens I expect (no... demand!) 2 ounces of dry weight for every square foot.