We Have Met the Future and It Is Green - Sustainable Design: The Science of Sustainability and Green Engineering - page 316

Figure 8.9 Photovoltaic system
in use at the Home Depot Smart
Home at Duke University,
showing reflective glass and
silicon sandwiches. The hollow
areas could be used to transport
heated air.
and stored in the cool tank as a source for radiant floor heating in the home by
circulating it through the panels to heat the water and begin to circulate it through
the house floors. When excess capacity exists or heating is not required in the
home, the water may be diverted for nonpotable uses. In addition to capturing
the waste heat and using this to heat water and the interior of the home, water is
captured in a closed loop and cycled through the system, resulting in significant
savings in potable water use. Using the average statistics for water use in a four-
person household, Hunter arrived at a savings of 114 gallons a day, 3466 gallons
a month, and 41,610 gallons a year.
Rethinking the life cycle of the typical toilet paper roll led Saul, a graduate
student in engineering management, to consider how a product used by millions
everyday might be made more friendly to the environment. Saul began his search
for innovation by collecting data that provided insight into the scale of use of
cardboard rolls. The Charmin Company has gathered data which indicate that
the average American uses 57 sheets of toilet paper a day, translating to 20,805
sheets a year. With the average roll containing 400 sheets, the average person
will use four rolls a month, discarding four cardboard rolls each month based
on a nonscientific survey which suggested that few, if any, Americans actually
recycle the rolls. Taking the current U.S. population and making an allowance
for primary users between the ages of 5 and 86, the four average rolls per month
yields a staggering annual consumption of 1,174,676,430 rolls.
The manufacturing process for paper tubes is very simple. Recycled paper is
pulled out from a paper roll cassette, put in a jar filled with glue, rolled again in
a spiral by a winder, and cut into pieces of a designated length. Saul's goal was to
devise an alternative which would be composed of natural materials of nonwood
and nonsynthetic chemical content and to create a substitute that would have a