Dear Solar Guy,

         Could you give me some advice on the location of windows for
lighting, while still not causing large costs for air conditioning ?   

A. Fenettre, Kerville.

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Dear Mr. Fenettre,

        For window location there are some pretty good rules of thumb, and
some of these are interrelated with other aspects of the building design
and environment.  First, it is usually preferred to have the building's
longest axis aligned east-west, to have significant overhang on the south,
and to have shading on the west.  It is generally preferred to concentrate
glazing (windows) on the south wall and have a sufficient roof overhang
shade the windows during the summer and allow sunlight to be incident in
the fall, spring and winter months. This reduces direct gain through the
windows during the summer (reduces a/c load), but provides some heating
through direct gain in the other-than-summer months.  Moderate glazing on
the east wall is satisfactory as some early morning direct gain is
acceptable, even in the summer.  One should be particularly careful about
glazing on west walls.  It shouldn't be excessive and it is preferred that
it be partially shaded.  Windows on the north cause no particular concern,
however, one doesn't have the opportunity for direct gain there in the
winter, as is the case for a south wall.  Design to integrate either
natural shading or architectural shading devices with window location.

The Solar Guy.