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Putting Renewable Energy to Work
in Buildings
Buildings account for about one-third of the
energy consumed in the United States. Heating
and cooling systems use 60 percent of this energy,
while lights and appliances use another 40
percent. Manufacturing and transporting building
materials requires additional energy.
By carefully applying design principles that capture
natural breezes and the sun’s energy and
light, and by using solar water heating systems,
energy use in buildings can be reduced dramatically.
These renewable energy practices save
money, result in more attractive buildings, and
they improve the environment and strengthen the
economy by reducing the need for fossil fuels and
nuclear energy.
In this paper we discuss design considerations for
environmentally responsible buildings and communities.
We emphasize approaches that do not
significantly alter the initial cost of a structure but
that provide substantial long-term savings and a
more comfortable living environment.
Passive Solar Design. Buildings constructed in
the United States today are more energy efficient
than ever before; their energy requirements
can be much further reduced, however. Sunlight,
landscaping, natural breezes, and the choice of
building materials can all reduce the need to use
and pay for fuel and electricity. Passive solar design—the
use of a building’s structure to capture
sunlight and store heat—can alone save up to 50
percent or more of the energy used in a home.
Building orientation and window location. With
little or no extra cost, a building can usually be
oriented with its long face within at least 30
degrees of true South, creating energy savings
without changing the design. (An orientation of
within 15 degrees is optimal; within 30 degrees is
acceptable.)
The next most important design feature is placing
a high percentage of the building’s windows on
the south side. Conventional houses have about
a quarter of their windows on the south side, and
this generally averages about 3 percent of the
house’s total floor area. Ideally, the total area of
south-facing windows should represent about 7
percent of the house’s total floor space. Such a
shift would allow the building to use more of the
sun’s energy by absorbing it into the materials of
the house. This zero-cost option can save up to 25
percent of the house’s conventional heating fuel
and, with protection from a shading overhang,
can help reduce summer cooling bills as well.
In winter, when the sun arcs low in the sky, the
south-facing glass will let in the sunshine to heat
the space. In summer, when the sun is high in
the sky, an overhang can prevent unwanted heat
gain.