In the United States, electric lighting consumes about one fourth
of all the energy generated. According to the Rocky Mountain Institute,
a nonprofit research and educational organization that fosters efficient
use of resources, this usage equals the energy produced by 170 large powerplants.
It only makes sense to take advantage of daylight to provide light and warmth--but
this means planning ahead during building or remodeling.
The daylight that enters a building may shine directly from the sun, bounce
off of bodies of water, streets, buildings, or other surfaces, or come from
the diffuse, day-lit sky. Placing and sizing windows and figuring control
measures, such as roof overhangs, requires a clear understanding of the
sun's path.
The sun's daily east-to-west arc changes throughout the year. At the summer
solstice, June 21, the sun rises and sets farthest to the north, which means
that it is higher during the day. At the winter solstice, December 21, the
sun's arc is at its southern-most position, with a much lower mid-day elevation.
The sun's angle at any given time of the day depends on your latitude. The
further north you live, the lower the winter sun will be in the southern
sky.
Whether a window faces north, east, south or west makes a big difference
in the type of light it receives.
If you want morning sunlight to spray across your breakfast table, your
breakfast room window should face east.
Light from the south is bright and direct; solar houses are oriented to
the south for maximum heat gain. South-facing windows are often located
beneath eaves or roof overhangs that block the high, intense summer sun
but allow the warmth of the lower winter sun.
Western sun can be intense and glaring. Controlling it is more difficult
because, as the sun sets, its low angle dips beneath eaves and overhangs.
Shades, blinds or glare-resistant glazing are generally required. It's also
helpful if deciduous trees are planted on the west side of a house--their
spring-and-summer leaves block unwanted heat, then when the leaves drop
in the fall, the trees allow the sun's warmth and light.
North light, never direct from the sun, has cool, bluish hues because it
comes from the sky. Because it's constant, north light is favored for artists'
studios and the like.
Be sure any architect or builder you hire will take all of this into account
when planning your house's window placement; ask for references and call
previous clients.
--Don Vandervort
