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Copyright ©2013 Sefaira Ltd.
F O U R RU L E S O F TH U M B TH AT CO U L D L E A D YO U A S TR AY
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Rule 1: East-West Orientation
The Rule
One of the most common rules of thumb related to sustainable design is that the ideal alignment
for most buildings is for its long axis to run east-west. This allows the building to have a majority of
its glazing on the north and south, where sunlight can be most easily harvested and controlled for
daylight and passive solar gain.
WHEN IT WORKS
A simple rectangular building
(optimal orientation is within
10° of due south)
WHEN IT MISSES
A building with self-shading
or overshading (here, optimal
orientation is 42° east of
south)
When it Works
This rule generally works for buildings with a simple rectangular shape, relatively symmetrical
glazing, and no significant obstructions to sunlight, such as neighboring buildings or trees. Our
example is a roughly rectangular office building located in Pittsburgh, PA. In this case, analysis
revealed that the ideal orientation is 10 degrees east of south — not precisely what the rule of
thumb suggested, but relatively close.
When it Misses
For sites with some amount of shading and/or non-rectangular shapes — particularly forms with
some amount of self-shading like the L-shape building shown above — this rule can fall apart
entirely. In the case we studied, the orientation that minimized energy use was nearly 45 degrees
east of south.
