direct sunshine

Greetings. I expect that the information I seek is either available in a
table somewhere or can be easily calculated with the right set of
equations. I would be grateful if anyone could point me to one or the
other of these solutions.

Assume a square house, with each side directly facing a cardinal point.
Assume further no obstructions to the horizon. For a particular latitude
and longitude, how can I determine start-time and stop-time for direct
sunlight entering east windows and west windows, for any given day of
the year?

Thanks in advance.

cheers,

Henry

"Henry" wrote in message
...

Assume a square house, with each side directly facing a cardinal point.
Assume further no obstructions to the horizon. For a particular latitude
and longitude, how can I determine start-time and stop-time for direct
sunlight entering east windows and west windows, for any given day of
the year?

A computer program can give you the Altitude and Azimuth
of the Sun for any given time for a given location. I
provided such a program in issue #41 of The Orrery
newsletter, for example. Some info on The Orrery can be
found at:

http://members.allstream.net/~gneill/orrery.html

The program probably would provide far more positional accuracy
than you could need for your application, and you'd have to
contact me to order the back issue, get the program running,
and so on.

Alternatively, you might wish to make due with an on-line service
which can generate a table for a given location. In this case, I
suggest the U.S. Naval Observatory site:

http://aa.usno.navy.mil/data/

Choose the link for Altitude and Azimuth under the Positions
of the Sun and Moon heading.

You can enter a location by (U.S.) city name, or by longitude and
latitude. So, for example, here's an extract of a table generated
for Colorado Springs for today, January 1st 2003:

----------------------------------------
Astronomical Applications Dept.
U.S. Naval Observatory
Washington, DC 20392-5420

COLORADO SPRINGS, COLORADO
o , o ,
W104 48, N38 51

Altitude and Azimuth of the Sun
Jan 1, 2004
Mountain Standard Time

Altitude Azimuth
(E of N)

h m o o
06:20 -11.0 110.8
06:30 -9.2 112.2
06:40 -7.4 113.7
06:50 -5.6 115.2
07:00 -3.9 116.7
07:10 -2.1 118.2
07:20 0.1 119.7

----------------------------------------

The rest is geometry which depends upon the details of your
building.