Hi Karol,

The standard assumptions we use for Building America research are detailed in the "Building America House Simulation Protocol" which can be downloaded directly from NREL's publications site here:
http://www.nrel.gov/docs/fy11osti/49246.pdf

The document Morgan attached (Building America Benchmark) has been replaced by the above.

We do revise these assumptions periodically based on newer research and you can always check http://www.buildingamerica.gov/ for the latest updates.

Regards,

Dane Christensen, PhD