Handbook of air conditioning and refrigeration / Shan K

3.44 CHAPTER THREE
FIGURE 3.16 Shading from adjacent building.
where H B � height of building B, ft (m)
W B � width of building B, ft (m)
L AB � distance between two buildings along X axis, ft (m)
W OB � distance between X axis and building B, ft (m)
Subscript A indicates the shaded building and B the shading building.
Because of the sun’s varying position, the solar altitude � and the surface solar azimuth � change
their values from time to time. Table 3.10 lists the solar altitude � and solar azimuth � at north
latitudes 32° and 40°. To evaluate the shaded area of the outer surface of a building, a computer program
can determine which of several hundred representative points on this outer surface are sunlit or
shaded at specific times of the day. Then a ratio of shaded area to total area can be calculated.
At a certain time instant, a window glass area can be shaded due to the effect of the overhang
and vertical fins, or the effect of the adjacent building, or both. For the calculation of the combined
shading effect of overhangs, vertical fins, and adjacent building, it is recommended that the number
of sunlit and shaded windows of an outer surface of a building under the effect of the adjacent
building be calculated first. According to Eq. (3.88a), the total sunlit area can be calculated as the
product of the net sunlit area for each window because of the overhang and vertical fins and the
number of windows in the sunlit area of that outer surface.