Text and photos by
NORBERT M. LECHNER
Shading is necessary almost every- where in the world. Even countries located fairly far north and having cool weather use shading extensive- ly. One of the world’s main users of
shading is Germany, at 51 degrees north latitude (for comparison, the Canadian border is at
48 degrees latitude). Because shading is useful
almost everywhere, and because shading can go
a long way in reducing the need for air condition-
Figure 1. Horizontal glazing (skylights) and east
and west glazing collect the most sunshine in the
summer and the least in the winter — just the
opposite of what we want.
ing, it is a major solar strategy for saving money,
energy and the planet. It is considered a solar
strategy because it controls solar energy and it
requires knowledge of solar geometry.
Start with Window
Placement, Overhangs
As Ben Franklin said, an ounce of prevention is worth a pound of cure. Likewise,
a building’s design should optimize shading
to minimize cooling requirements. Figure
1 (left) should look familiar to readers of
my January/February issue article, “For
Aggressive Efficiency, Choose Passive Solar”
(see solartoday.org/digital). It is essentially
the same graph, shifted so that summer is in
the center. It clearly illustrates that during the
summer, north and south windows receive the
least sunshine, while skylights (horizontal and
near-horizontal glazing) and east and west
windows receive the most sunshine. Although
the graph is for locations at 32 degrees north
latitude, this situation is true everywhere on
the planet. Consequently, skylights and east
and west windows should be minimized (see
Burton Barr Central Library photos, below).
South windows should be maximized if winter
heating is required, and north windows should
be maximized if winter heating is not required.
Although north and south windows receive
some summer sun, they can be effectively
shaded while still maintaining views to the
Norbert M. Lechner ( lechnnm@auburn.edu) is an
architect, professor emeritus in the College of Architecture, Design, and Construction at Auburn University, LEED-accredited professional and ASES Fellow.
He is an expert in energy-responsive architectural
design with an emphasis on solar-responsive design.
Lechner’s book, Heating, Cooling, Lighting: Design
Methods for Architects, is used by more than a third
of all architecture schools in the United States and in
architecture schools worldwide. He is also a sought-after speaker, giving keynote lectures and workshops
at universities and conferences around the world.
Because an effective
overhang on east and west
windows has to be more
than 100 feet long, many
books recommend vertical
fins for east and west.
That recommendation
turns out to be a fallacy.
Phoenix’s Burton Barr Central Library has no east or west windows, because those orientations cannot be
effectively shaded. The south façade has louvers (left), and the north façade has fins (right).
