For fresh water tanks where live plants aren't a concern heat is your biggest expense in most cases. Where I'm at it's cheaper to heat a house with natural gas than electricity. If your place is the same consider running a good size heat duct to that area.
Insulation is always an item that pays for itself in the long run, consider upgrading the insulation of this area if it isn't already well insulated. You will get the best efficiency in a well insulated and sealed room with enough room to work the tanks & that's it.
Lights in a setup where there are no live plants are more for the fishkeeper than anything. Fish get by just fine with room light. This is where you can save, a light on every tank is for show, not breeding or growing out.
Ten 100w heaters will use just as much electricity as one 1,000w heater heating the same tanks in the same area. Having all the tanks in a shop on one common system keeps heaters & filters out of the tank, better looking for sales. It's also easier to do one large water change on the sump they are connected to than to change water on individual tanks. The sump, which contains the heaters & filter media also adds to the water capacity of the system, a 40 gallon tank with 10 gallons of sump has the actual water capacity of a 50 gallon tank, and can be stocked as such.
The problems with several tanks on one system using a sump for filtration are transfer of disease from tank to tank, all the tanks are the same temperature, as well as other water parameters. The ease of maintenance & cleaner look does have its downsides.
Most breeders, including myself, will have the need to have different temperatures and such in tanks, as well as using tanks for quar from time to time. This being the case, the best solution is an air powered filtration system, operating off of one large pump,running pvc with pipe valves around the room. Keeping the room at a warmer temperature with gas forced air keeps run time on each heater to a minimum. Heat rises, keep cooler water species towards the bottom, warmer in the upper tanks.
Another issue is evaporation & condensation in a fishroom. Forget those pre-made hoods with the lights, with the large slot towards the back. You are losing water through evaporation, and heat by exposing the water to cooler air. If you really are packing the tanks in you will have to consider some sort of ventilation, as the humid air will condense on cooler surfaces, creating a mold issue. I’ve seen structural damage in a huge long running operation that didn’t take this into consideration.
Over the years I’ve taken ideas from many other people’s fishrooms, redone mine several times, and still have projects in the works. My fishroom was roughed out at 8’x16’, insulated, drywalled, & painted with a gloss paint. I cut a register into the main trunk of my forced air heat system, this heats the room. When summer comes this register gets pulled, an insulated piece of plywood gets screwed over it, aquatics is usually slow in the summer, tanks get drained.
Filtration is provided by an 85lpm linear air pump, all sponge & box filtration’ pvc with pipe valves run around the room. I use light diffuser panels for tank covers, these seal well, let light in, and are cheap. Light is minimal, a couple of cans with dimmers in the drop ceiling, small flouro fixtures over a couple of tanks. I have a clamp light with an extension for working on tanks. I mentioned evaporation, a bath fan on a timer leading to a dryer vent in one of the glass blocks keeps humidity down.
Another thing to take into consideration is ease of maintenance. Tanks closer together with enough room to work without wasted space means less motion, more efficiency. This in many ways has to be planned around you own physical size & capabilities. Someone who weighs 300 pounds won’t be able to move much in my fishroom, someone who is 5’2” won’t be able to reach the back of most of the tanks. Consider your water supply & waste water removal, keep them as close as possible. I ran hot & cold to my fishroom some time ago, as well as have most of my tanks drilled with overflows for water changes. The drilling & drainage is still a work in progress, several tanks yet to drill, as well as digging through the concrete floor to install an actual sump pump for waste water removal. A large bin & a pump work well enough for now.
Try to integrate work areas into the design as well, a few smaller areas work better than one large area that you constantly have to walk across the room for. Remember that a working fishroom is not a fish showroom, if it looks a bit cluttered but you can turn around & grab what you need it is efficient.
Holy crumb, I wrote a novel! Any more questions feel free to ask!
