I'm in the early planning stages of a future gasifier setup so I am starting with the heat loss calculation for the home. It is an 1800 sq ft ranch built in 1957 over 1300 sq ft of full basement and 500 sq ft of crawl space. The house has a fair amount of windows, all original, mostly aluminum, single pane with storm windows. As best I can tell there is no insulation behind the plaster-on-sheetrock walls. Last year I added R30 fiberglass batts to 1/2 of the attic and plan to finish the rest this year. There was some old fiberglass in there before so I'm guessing maybe R40 total now. I've also done some air sealing up there but have some more to finish, before the rest of the insulation goes in the attic. I put everything into this heat loss calculator and came up with a design loss of 75k BTU/hr at 20 degree outdoor temp. The info I used is below but not sure I did it correctly, especially with respect to the floors. This seems high but also consistent with what I experienced last year, where my 75k BTU insert would not keep the house warm enough when it dropped into the 20s. Ceilings - 900 sq ft R40, 900 sq ft R10 Walls - 1272 sq ft R3.4 Windows/Doors - 71 sq ft R1.8, 256 R.75 Floors - 1800 R5 Slabs - 0 Infiltration - 1440 cu ft, 1 air change/hr How does this look in terms of accuracy?