Sawmill House

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The Sawmill House

Annual Heat Budget vs South Window Size.

The following table presents estimates of the annual heat budget for various south windows sizes, expressed as a function of fraction of the floor.

 SWSz   Walls   Wndws    Ceilng   Floor    Doors   Inflt    LSum1  HIndx1   SGain    LSum2   HIndx2   NGals

  0.00   9.95    1.53     6.19    11.62     0.79     9.31   39.40   3.46     2.08    37.32     3.27   728.30
  0.01   9.84    1.93     6.19    11.62     0.79     9.31   39.69   3.48     4.31    35.38     3.10   690.42
  0.02   9.74    2.33     6.19    11.62     0.79     9.31   39.98   3.51     6.55    33.44     2.93   652.55
  0.03   9.63    2.73     6.19    11.62     0.79     9.31   40.28   3.53     8.78    31.50     2.76   614.67
          *** 20 percent more auxiliary annual heating needed per year
  0.04   9.52    3.13     6.19    11.62     0.79     9.31   40.57   3.56    11.02    29.56     2.59   576.80
          *** 10 percent more auxiliary annual heating needed per year
  0.05   9.42    3.53     6.19    11.62     0.79     9.31   40.86   3.58    13.25    27.61     2.42   538.92
          *** Sawmill House
  0.06   9.31    3.93     6.19    11.62     0.79     9.31   41.16   3.61    15.48    25.67     2.25   501.05
  0.07   9.20    4.33     6.19    11.62     0.79     9.31   41.45   3.64    17.72    23.73     2.08   463.18
          *** 10 percent less auxiliary annual heating needed per year
  0.08   9.10    4.73     6.19    11.62     0.79     9.31   41.74   3.66    19.95    21.79     1.91   425.30
          *** 20 percent less auxiliary annual heating needed per year
  0.09   8.99    5.13     6.19    11.62     0.79     9.31   42.04   3.69    22.19    19.85     1.74   387.43
          *** 30 percent less auxiliary annual heating needed per year
  0.10   8.88    5.53     6.19    11.62     0.79     9.31   42.33   3.71    24.42    17.91     1.57   349.55
  0.11   8.78    5.93     6.19    11.62     0.79     9.31   42.62   3.74    26.65    15.97     1.40   311.68
          *** 40 percent less auxiliary annual heating needed per year
  0.12   8.67    6.33     6.19    11.62     0.79     9.31   42.92   3.77    28.89    14.03     1.23   273.81
          *** 50 percent less auxiliary annual heating needed per year
  0.13   8.56    6.73     6.19    11.62     0.79     9.31   43.21   3.79    31.12    12.09     1.06   235.93
  0.14   8.46    7.13     6.19    11.62     0.79     9.31   43.50   3.82    33.36    10.15     0.89   198.06
  0.15   8.35    7.53     6.19    11.62     0.79     9.31   43.80   3.84    35.59     8.21     0.72   160.18
  0.16   8.24    7.93     6.19    11.62     0.79     9.31   44.09   3.87    37.82     6.27     0.55   122.31
  0.17   8.14    8.33     6.19    11.62     0.79     9.31   44.38   3.89    40.06     4.33     0.38    84.43
  0.18   8.03    8.73     6.19    11.62     0.79     9.31   44.68   3.92    42.29     2.39     0.21    46.56
  0.19   7.92    9.13     6.19    11.62     0.79     9.31   44.97   3.95    44.53     0.45     0.04     8.69
  0.20   7.82    9.53     6.19    11.62     0.79     9.31   45.26   3.97    46.76    -1.50    -0.13   -29.19

Column Headings -

  SWSz   South windows size, as a fraction  of the floor size
  Walls  Walls annual heat loss, MBTU/year
  Wndws  Windows annual heat loss, MBTU/year
  Clng   Ceiling annual heat loss, MBTU/year
  Floor  Floor annual heat loss, MBTU/year
  Doors  Doors annual heat loss, MBTU/year
  Iflt   Infiltration annual heat loss, MBTU/year
  LSum1  Sum of annual (walls ... infiltration) losses, no solar Gain
  HIndx1 Heating Index, BTU/DD/Ft**2, No solar gain
  SGain  Annual solar gain, MBTU/year
  LSum2  Net sum of Heat Losses, including solar gain, MBTU/year
  HIndx2 Heating Index, BTU/DD/Ft**2, with solar gain
  NGals  Estimated Annual propane need, gallons/year, exclusive of domestic hot water

Notes - The floor area of the Sawmill House is 1152 ft**2; the south window area is 68.08 ft**2, amounting to a floor fraction of 0.0591.
Architectural guidlelines suggest that the amount of south window glass range from 0.05 to 0.14 percent of floor area.

As of August 27, 2009

Copyright ©2002, 2009 E. Stiltner.

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Updated '27-Aug-2009,16:17:44'