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Chapter 11 Designing for Sustainability
added to building materials to increase water
resistance or as fl ame retardants.
Pressure-treated lumber is chemically treated
to protect it against decay due to moisture or bugs.
Traditionally, pressure-treated lumber contained
chemicals, including a type of arsenic, considered
both carcinogenic in humans and harmful to the
environment. However, this chemical was phased
out in 2004 for residential use. It is still a good idea
to fi nd out what chemicals were used to treat the
wood before using it.
Greenwashing
Many companies are fi nding that “being
green” is an excellent sales tool because green
building is currently in fashion. People want to
be able to say they have “gone green.” Unfor-
tunately, this has led to many false claims that
advertise a product as green or environmentally
friendly when in fact, it is not. In some cases, the
product may even be environmentally harmful.
This practice is known as greenwashing. When
looking for green alternatives, both for building
materials and for household products, be sure to
read the label carefully. Look at the contents or
ingredients. If you have any doubt, research the
product or its ingredients before purchasing it.
Energy Choices
From an energy perspective, a home is sus-
tainable if it uses net zero energy. A net zero
energy building is one that produces as much
energy per year as it consumes, or one for
which the net energy cost for a year is $0. This
is not science fi ction; a few net zero buildings
exist now, and both government and private
builders are planning to increase that number
signifi cantly within the next few decades.
One of the basic principles of designing a net
zero building is relying completely on renew-
able energy sources. A renewable energy source
is one that can supply electricity or other forms
of energy from continually replenished sources.
Today, many alternatives exist for reducing our
dependence on nonrenewable energy sources.
Some of them are still in their infancy. Others,
although well established, are not quite as effi -
cient as we would like them to be. Here again,
we can plan to be “green” as we work toward
sustainability. Renewable energy sources include
solar, geothermal, wind, hydropower, and some
forms of biomass energy. Of these, both solar and
geothermal energy are suitable for direct use in
carefully designed residential homes.
Solar Energy
Solar energy, or energy harvested from the
sun, can be a completely renewable source of
energy. Even when nonrenewable materials are
used to create the photovoltaic cells (cells that
convert sunlight into electrical energy), solar
energy can be a green alternative to petroleum-
based energy sources. See Figure 11-10.
Figure 11-10. This home is powered by solar energy. The solar panels and other solar features, such as
large expanses of glass on the southern face of the house, were included in the original design of the
home. (Federico Rostagno/Shutterstock.com)