
555Passive Solar Heating, Cooling, and Daylighting
© 2008 Taylor & Francis Group, LLC
9.7.3.1 Solar Altitude Angle (α)
The solar altitude angle is the angle swept out by a person’s arm when pointing to the
horizon directly below the sun and then raising the arm to point at the sun. The equation
to calculate solar altitude, α, is
sin cos cos cos sin sin αδ δ=+LHL
(9.22)
where
L is the local latitude (degrees)
δ is the earth–sun declination (degrees) given by δ = 23.45 sin [360 (n − 81)/365]
n is the day number of the year
H is the hour angle (degrees) given by
H =
−
;
(+morning, afternoon) (9.23)
9.7.3.2 Sun–Window Azimuth ...