1.5) Gable height (G): This the height of the gable in
 feet.

 1.6) U factor of single material wall: This is the heat
 transfer coefficient of the wall's material in
 BTU/hr.F ft2. Values of this coefficient for typical
 materials are shown in Table 1.

 1.7) U factor of rafter material: This is the heat transfer
 coefficient of the rafter's material in BTU/hr F ft2.
 Values of this coefficient for typical materials are
 shown in Table 1.

 1.8) U factor of roof material: This is the heat transfer
 coefficient of the roof's material in BTU/hr F ft2.
 Values of this coefficient for typical materials are
 shown in Table 1.

 1.9) U factor of the perimeter: .This is the heat transfer
 coefficient of the perimeter in BTU/hr F ft. Values of
 this coefficient are shown in Table 1.

 1.10) Number of individual bays: This is the number of
 bays that make up the greenhouse.

 1.11) Number of air exchanges per hour: This is the number
 of times that the volume of air in the greenhouse is
 replaced per hour. Typical values can be seen in
 Table 2.

 1.12) Temperature difference: This is the difference between
 the nightime desired inside temperature and the minimum
 expected outside temperature. This value is given in
 degrees Fahrenheit.

2) Gable/curved greenhouse using different material for the
 lower and upper wall.

 The required data to estimate the heat losses in this type
of greenhouse (Figure 2) are:

 2.1) Wall height (H): This is the height of the greenhouse
 wall in feet.

 2.2) Lower wall height (B): This is the height of the lower
 wall in feet.

 2.3) Upper wall height (A): This is the height of the upper
 wall in feet.