First Principles - Sustainable Design: The Science of Sustainability and Green Engineering - page 73

and

P = P 1 − P 2 = I v R (2.21)

where I v is the volume flow rate and R is the proportionality constant, representing
the resistance to the flow. R depends on the length L of the pipe section, the
pipe's radius, and the fluid's viscosity.

Bioenergetics

Energy is stored and used in organisms. The manner in which energy is transfered
and transformed in living organism is known as bioenergetics. The thermody-
namics involved as the energy is transformed and released in the environment will
determine the efficiency and health of microbes as they help us treat contami-
nants, how ecosystems transform the sun's energy throughout the food chain, and
which chemical reactions will break down contaminants, metabolize substances,
and ultimately participate in the toxicological response of organisms, including
humans. In addition, bioenergetics can be a resource for energy needs in buildings
and devices, such as heat produced by microbial metabolism. It is also a measure of
efficiency. For example, using biomass from lower trophic states (e.g., producers)
is more energy efficient than that from higher trophic states (e.g., consumers).

Systematic Design and the Status Quo

Interestingly, thermodynamic terms are frequently used in design. We must know
the system, the boundary, the surroundings, the constraints, and the drivers. These
must all be incorporated into the design. So the concept of systems is important
in another way: It is a mental construct that influences the way that designers
think. Designing to improve a process or to solve a problem requires that we keep
in mind how best to measure success “systematically.” The two most common
design metrics are efficiency and effectiveness. The first is a thermodynamics
term. The second is a design term. Efficiency and effectiveness refer to whether a
design is conducive to the purpose for which it was created, and whether the
design function performs some task, respectively. Unlike mathematics, engineer-
ing and architecture are not exclusively deductive endeavors. Designers also base
knowledge on experience and observation. Design professions first generate rules
based on observations (i.e., the laws of nature: chemistry, physics, biology, etc.) of
the world around them: the way things work. Once they have this understand-
ing, they may apply it by using the rules to create something, some technology,
designed to reach some end: from keeping food cold to delivering nutrition to