http://www.packomania.com/
This may be helpful to everyone. All you need is the inside dimensions of the freezer you are considering, or anything really, and the diameter of your corny kegs. For the most part you'll either have 8" or 9" round kegs. Select Circles within a Square. Then choose...
I have 15-20 brews under my belt. My current brew is a Wildflower Wheat made with honey and chamomile. I pitched at around 85-90*. Brew is sitting on my stairwell landing at around 78*. Vigorous fermentation lasted about a day and since then I haven't seen any airlock activity at all. However...
The only items you would have to consider would be the A/C in the house and the fridge. Residual power consumption from "phantom" power sources would most likely not amount to much more than a penny or two over the course of a brewing session.