Sawmill House

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The Sawmill House

Annual Heat Budget vs Window Insulation.

The following table presents estimates of the annual heat budget for various windows insulation values.

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

  0.50   9.32    80.98     6.19    11.62     0.79     9.31  118.22  10.37    15.28   102.94     9.03  2008.89
  1.00   9.32    40.49     6.19    11.62     0.79     9.31   77.73   6.82    15.28    62.44     5.48  1218.67
  1.50   9.32    26.99     6.19    11.62     0.79     9.31   64.23   5.63    15.28    48.95     4.29   955.26
  2.00   9.32    20.25     6.19    11.62     0.79     9.31   57.48   5.04    15.28    42.20     3.70   823.56
          *** 50 percent more auxiliary annual heating needed per year
  2.50   9.32    16.20     6.19    11.62     0.79     9.31   53.43   4.69    15.28    38.15     3.35   744.54
          *** 40 percent more auxiliary annual heating needed per year
  3.00   9.32    13.50     6.19    11.62     0.79     9.31   50.73   4.45    15.28    35.45     3.11   691.86
          *** 30 percent more auxiliary annual heating needed per year
  3.50   9.32    11.57     6.19    11.62     0.79     9.31   48.81   4.28    15.28    33.52     2.94   654.23
  4.00   9.32    10.12     6.19    11.62     0.79     9.31   47.36   4.15    15.28    32.08     2.81   626.01
          *** 20 percent more auxiliary annual heating needed per year
  4.50   9.32     9.00     6.19    11.62     0.79     9.31   46.23   4.06    15.28    30.95     2.72   604.06
  5.00   9.32     8.10     6.19    11.62     0.79     9.31   45.33   3.98    15.28    30.05     2.64   586.50
  5.50   9.32     7.36     6.19    11.62     0.79     9.31   44.60   3.91    15.28    29.32     2.57   572.13
  6.00   9.32     6.75     6.19    11.62     0.79     9.31   43.98   3.86    15.28    28.70     2.52   560.15
          *** 10 percent more auxiliary annual heating needed per year
  6.50   9.32     6.23     6.19    11.62     0.79     9.31   43.47   3.81    15.28    28.18     2.47   550.02
  7.00   9.32     5.78     6.19    11.62     0.79     9.31   43.02   3.77    15.28    27.74     2.43   541.34
  7.50   9.32     5.40     6.19    11.62     0.79     9.31   42.64   3.74    15.28    27.35     2.40   533.81
  8.00   9.32     5.06     6.19    11.62     0.79     9.31   42.30   3.71    15.28    27.02     2.37   527.23
  8.50   9.32     4.76     6.19    11.62     0.79     9.31   42.00   3.68    15.28    26.72     2.34   521.42
  9.00   9.32     4.50     6.19    11.62     0.79     9.31   41.74   3.66    15.28    26.45     2.32   516.25
  9.50   9.32     4.26     6.19    11.62     0.79     9.31   41.50   3.64    15.28    26.22     2.30   511.63
 10.00   9.32     4.05     6.19    11.62     0.79     9.31   41.29   3.62    15.28    26.00     2.28   507.47
 10.50   9.32     3.86     6.19    11.62     0.79     9.31   41.09   3.60    15.28    25.81     2.26   503.71
 11.00   9.32     3.68     6.19    11.62     0.79     9.31   40.92   3.59    15.28    25.63     2.25   500.29
          *** Sawmill House
 11.50   9.32     3.52     6.19    11.62     0.79     9.31   40.76   3.58    15.28    25.47     2.23   497.17
 12.00   9.32     3.37     6.19    11.62     0.79     9.31   40.61   3.56    15.28    25.33     2.22   494.30
 12.50   9.32     3.24     6.19    11.62     0.79     9.31   40.48   3.55    15.28    25.19     2.21   491.67
 13.00   9.32     3.11     6.19    11.62     0.79     9.31   40.35   3.54    15.28    25.07     2.20   489.24
 13.50   9.32     3.00     6.19    11.62     0.79     9.31   40.24   3.53    15.28    24.95     2.19   486.99
 14.00   9.32     2.89     6.19    11.62     0.79     9.31   40.13   3.52    15.28    24.85     2.18   484.90
 14.50   9.32     2.79     6.19    11.62     0.79     9.31   40.03   3.51    15.28    24.75     2.17   482.95
 15.00   9.32     2.70     6.19    11.62     0.79     9.31   39.94   3.50    15.28    24.65     2.16   481.13
          ***  5 percent less auxiliary annual heating needed per year

Column Headings -

  WIns   All windows insulation, (F*Hr*Ft**2)/BTU
  Walls  Wall 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 windows, with shades closed at night, amount to the following values -


Window/R-value/Glass/East            9.10 (F*Hr*Ft**2)/BTU
Window/R-value/Glass/North           9.10 (F*Hr*Ft**2)/BTU
Window/R-value/Glass/South           3.00 (F*Hr*Ft**2)/BTU
Window/R-value/Glass/West            9.10 (F*Hr*Ft**2)/BTU
Window/R-value/+Shades/East          5.00 (F*Hr*Ft**2)/BTU
Window/R-value/+Shades/North         5.00 (F*Hr*Ft**2)/BTU
Window/R-value/+Shades/South         5.00 (F*Hr*Ft**2)/BTU
Window/R-value/+Shades/West          5.00 (F*Hr*Ft**2)/BTU

For a net overall building window insulation value of 11.25 (F*Hr*Ft**2)/BTU.

For the shades open at night, the effective window insulation value is 6.25 (F*Hr*Ft**2)/BTU.

As of August 10, 2009

Copyright ©2002, 2009 E. Stiltner.

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Updated '10-Aug-2009,18:34:38'