The elephant in the office, invariably, is cost. Thankfully, we can harness the strength of BIM (Building Information Modeling), and extract a trove of data from our virtual model. The tabulation that you see below is the product of over a dozen "schedules" or "take-offs" from the model, which calculate the exact quantity of all materials, from structural framing and concrete, to paint and vapor barriers. Literally every square inch of everything that will go into your house is tabulated across multiple spreadsheets and hundreds of line-items.
When all this information is extracted it can be combined with "RS Means" construction cost data (the industry standard) to estimate expected costs. While actual costs will vary based on regional factors, these numbers still provide you with tremendous leverage when you enter into negotiations with contractors and subcontractors. Not only do you know the actual quantities of materials yourself, instead of accepting the contractors "ballpark estimates." but you also can go line by line and dissect the bid.
This information also helps you make "finish" decisions, by helping you locate where real cost savings are be found. For example, you can easily see how switching from a flooring material at $8/sf to $6sf effects the total cost, and whether it is worthwhile to conserve money there and spend it instead on expensive light fixtures — or vice versa — you get the idea. Or maybe you might learn that the a $2/sf cost in flooring actually doesn't matter that much in the scheme of things (it doesn't.)
Building is expensive, there is no way around it. Even if you cut corners all the time, it would still be expensive, and you'd have a compromised product. The best way to manage cost is first by managing expectations, second, by leveraging data, and third, by beginning with a design that contains the conditions within it for a smooth, efficient construction process. This is where the value of the 5x5 House really begins to shine.
Please note that the figures are taken from Version A. Also note that some GC's will charge their 10% fee on top of their management hours. Also note that prices will vary regionally (a coefficient variable is provided in the RS Means data), and according to global economic conditions.