Page 242 - Materials Chemistry, Second Edition

ACCOUNTING FOR ECOSYSTEM GOODS AND SERVICES 229

ecological models are used to capture the effect of the ecosystems included in
the design problems. So, at each design iteration, objective function values can
be calculated, despite the fact that the actual functions are unknown. A sim-
ulation-based optimization program, GenOpt (Lawrence Berkeley National
Laboratory) takes in the output of the simulation, determines the objective
function values, and uses a genetic algorithm search method to determine the
next iteration. This is repeated until a fixed number of iterations are reached.
Because of the nature of the problem, the algorithm is not guaranteed to find
the Pareto-optimal solution set, but rather near Pareto-optimal solutions. The
optimization is performed for a time period of 10 years for a Columbus, Ohio,
USA climate.
Upon optimization of the design space, it is shown to be possible to oper-
ate at water neutrality and closer to carbon neutrality while maintaining a net
positive profit compared to a baseline design. Also, ecological and behavioral
design variables have a significant effect on the three objectives, in some cases
rivaling and exceeding the effect of traditional technological design variables.
Also, including ecosystems improves each of the objectives compared to opti-
mization using only technological variables. These results indicate that a rigor-
ous multi-objective optimization of a suburban home that includes ecological
and behavioral design variables may provide more insight and better designs
than traditional design methods. More generally, problems beyond residential
systems such as large scaled industrial process design can benefit from the
application of techno-ecological network optimization.
In addition to considering direct or "process level" effects of design changes,
such as emissions from burning natural gas in the home, the life cycle scale
can also be included in the design problem to draw insight into the difference
between optimal designs when considering direct and life cycle scales. Eco-
LCA methodology is applied to capture indirect water and carbon emissions
associated with the inputs needed in the residential system. However, in this
study, including the life cycle scale does not significantly alter the conclusions
found when considering the process level alone. This result is not generaliz-
able, as the life cycle scale can have a significant effect when comparing alter-
natives at the process scale versus the life cycle scale. This study is currently in
the final stages of completion (Urban & Bakshi, 2011).

9.7 Conclusions

Including ecosystem goods and services in life cycle assessment is crucial for
truly determining the sustainability of a product or process; otherwise, per-
verse decisions may be made that result in the destruction of the natural capital
not accounted for. Ecosystems also serve as a template for sustainable design
due to their robust and resilient structure. Additionally, ecological systems can
replace traditional man-made systems and can integrate with technological
systems to form efficient networks with minimal waste. Because of the vital
role that ecosystem goods and services play in every process, preserving them