I think I need some help. I have a house where, when I run the computation for the HERS rating it comes out as an 83. When I run it as HERS IAF it comes out at 107. 24 seems like a HUGE adjustment for the size of the home. I've run HERS vs HERS IAF on a few other projects and they were typically pretty close to one another. Within just a few points. Granted, this is one of the bigger homes I see (its 3716 sq ft) but the difference in 24 points seems way out of proportion. Any ideas, suggestions?