.... what's the best method to lighting such a large space without using the overhead florescent lighting?
You may want to consider using a combination of hard and soft light to create contrast in a situation where the overhead fluorescent lighting is usually very flat as we did in a short film called "Act Your Age" that takes place in a senior center (see the production stills attached.) However to hang anything larger than a 650 or to hang kino banks you will need something like the hangers pictured below:
One of the biggest challenges in situations like this is getting light into the eyes of your talent. If you don't, your talent's eye will look dark and bruised because the very toppy light of the overhead fluorescents won't dig into their eyes.
You may want to consider the approach we took in the production stills above, where we hung 4'-4 Bank kinos with Opal coved below the fixture to make a "Bay Light." Coving the Opal under the light, redirects it horizontally so that it will dig into the talents eyes.
As you can see here, with the right rigging equipment, you can use drop ceilings like a studio grid. Use this link for
more pictures of productions that used drop ceilings on location as if they were a studio grid.
2.5s would be fine, but you'd need to think about how you're going to power them-- they'll need a genny. And as for opal, tht's a personal thing I put most thing through it because I lvoe it.
You can run a 2.5 HMI off of common wall outlets. Most offices have a 240V receptacle of some kind. Common 240V circuits in offices include, Copier receptacles, range receptacles, and special receptacles installed for coffee makers. The latest generation of 2.5/4k HMI ballasts will operate on either 120V or 208-240V and fit comfortably in these circuits. If you are using an older ballast that runs only on 120V, you can step-down a 240V circuit to 120V with a transformer. A step down transformer will convert the 240 volts supplied by 240V receptacles to 120 volts in a single circuit that is the sum of the two single-phase legs of 30/50 amps each (60A usually). Now that you have a larger 120V circuit, you can operate larger lights like 2.5 or even 4k HMIs, or more smaller lights, than you could otherwise. A step-down transformer can do the same with the enhanced 7500W/240V output of a Honda EU6500is Generator. By giving you access to more "house power" through common 240V household outlets, a Transformer/Distro can eliminate the need for dangerous tie-ins or expensive tow generators (use this linik for details.)
Guy Holt, Gaffer, ScreenLight & Grip, Lightng & Grip Rental in Boston