Right now I know I'm doing a 6" thick concrete, rebar-reinforced flooring. On top of all that the floor will be epoxy coated, I'm also going to do the waste oil heating. I've got too many vehicles to worry with taking them in to have the oil changed. I've also got a tractor to keep the oil changed in, can't easily take that one in to have the oil changed. Besides, it only takes me about 10 minutes to change the oil. I also normally check everything too (sometimes even the stuff that the dealership and oil change places don't check), so I'm looking at about 20 minutes of work to keep the fleet running. On the flat floor side of the shop I'm going to primarily do stuff like painting and tune up stuff, anything where the car might even need to be lifted, I'm putting it in on the rack. As far as geothermal, I could do it since I'd only have to dig about four feet down to get do dirt at about 65 degrees in any weather. We thought about doing that in the shop up at my parent's house, but dad just eventually decided that a conventional heating and air system would do the job a heck of a lot easier, and cheaper since we didn't feel like putting the plumbing in to run the system. I'm not sure about the efficiency of the waste oil system, but I do know that one of my shops that my store services uses it and during the winter it definitely keeps the place comfortable (I'm talking about a nine-bay shop running one waste oil system, so I'm pretty sure that it'll more than keep my shop warm.