Fig. 4 shows the variation of the SHGCD and ShW SHGCD of the fenestration system (clear glass window with blind) with the solar profile angle when the slat angle is set at 0, 45 and 45 compared with the SHGCD of the plain clear glass window.
The 0 slat angle refers to the position that the slat is parallel to the ground.
The 45 slat angle refers to the position that the slat edge facing the inner glass window surface is pointing down to the ground making an angle of 45 to the horizontal direction.
The 45 slat angle refers to the position that the slat edge facing the inner glass window surface is pointing up to the sky making an angle of 45 to the horizontal direction.
It can be clearly seen that the SHGCD and ShW SHGCD of the glass window with blind and the SHGCD of the plain glass window are also dependent on the solar profile angle.
The curve with solid line in the figure represents the SHGCD.
The curve with dotted line in the figure represents the ShW SHGCD.
Therefore the difference between the curve with solid line and curve with dotted line represents the LoW SHGCD.
The SHGCD of the plain clear glass window is decreased as the solar profile angle is increased.
Then it is sharply decreased as the solar profile angle is in the range of 60–90.
When the blind is installed behind the glass window the value of SHGCD of the fenestration system is decreased compared to the value of SHGCD of the plain clear glass window.
The variations of the SHGCD of the fenestration system are dependent on the slat angle.
For 0 slat angle, the value of SHGCD is 0.8044 at 0 solar profile angle.
The value of SHGCD is continuously decreasing when the solar profile angle is increasing. For 45 slat angle, the value of SHGCD is 0.4956 at 0 solar profile angle.
The value of SHGCD is continuously decreasing when the solar profile angle is increasing.