Page 175 - Design for Environment A Guide to Sustainable Product Development

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nonrenewable sources, if one takes into account the energy and
labor-intensive activities required to construct and operate the neces-
sary equipment and facilities (see Figure 9.2).
Not all GHG emissions are due to fossil fuel combustion. There
are many industrial and agricultural processes that emit GHGs;
for example cement calcination (see Chapter 17). Herds of dairy
cows and even landfills generate methane emissions. Therefore GHG
reduction efforts should examine all emission sources and utilize
“green chemistry” either to achieve reductions in GHG releases or to
sequester GHGs so that they cannot enter the atmosphere. Chapter 9
provides additional information about carbon footprint assessment.
Finally, GHG emissions can be reduced by recovering and
reusing waste energy, especially waste heat. It is a fundamental law
of thermodynamics that some energy loss is necessary in order to
create higher-quality energy, such as electricity. However, much of
the energy consumed in our economy is wasted unnecessarily due to
inefficiency and poor practices. Examples of energy recovery technol-
ogies at manufacturing facilities include combined heat-and-power
systems, steam recovery from boilers, and synergistic activities, such
as heating of adjacent fish ponds. One example of a waste heat recov-
ery initiative at an Owens Corning plant is described in Chapter 17.

Water Resource Protection
The importance of water resources has been overshadowed by the
climate change debate, but the global threats to water quality and
availability are arguably more urgent. Over a billion people are with-
out access to clean water, while the rate of depletion in freshwater
resources continues to rise due to agriculture and other demands.
Ironically, the “green revolution” enabled huge increases in crop
yields to feed the world’s population, but the new varieties of high-
yielding crops are much more water-intensive—while food produc-
tion has doubled, the corresponding water consumption has tripled
[8]. Besides agriculture, other major consumers of fresh water are
industrial activities, such as power generation and material process-
ing, and, of course, municipal water supplies. Water is never depleted,
of course, since it eventually returns to the earth, but water quality
can be severely degraded through human or industrial contamina-
tion. Design strategies for protecting water resources include many of
the same approaches used for dematerialization:
• Reduce the water intensity of the supply chain through elim-
ination of water-intensive operations or through closed-loop
recycling of process water. Note that the use of water-based
technologies to reduce solvent emissions conflicts with this
strategy.
• Reduce the water content of products by increasing their con-
centration or delivering them in dehydrated form. Note that