Yes, I agree w/Dr Home, that from a pure, concrete perspective, a straight concrete home is NOT energy efficient.
(Rhetorically asking ...) Should you insulate the concrete home, inside and/or out? And don't forget about moisture-prevention too. I'm no expert but do you have to put up 'sticks' anyway? I can't imagine running wires and plumbing 'through' concrete?!
So, the question is, how do you justify the costs of building a concrete home over that of a conventional home? Questions along that line must be asked of both types of builders, et al.. As previously mentioned, you'll get a good sell from both types of builders et al.. In short, you (Jen) should ask away of the builders of the +'s and -'s to justify the expense/savings.