Page 42 - Alternative Energy Systems in Building Design

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ENERGY SYSTEMS

The following is a summarized narrative from Wikipedia, the Web encyclopedia. For
broader details, refer to www.wikipedia.com. In order to differentiate alternative energy
sources, it is important to understand the various definitions of energy. Energy in
physics, chemistry, and nature occurs in numerous forms, all of which imply similar
connotations as the ability to perform work. In physics and other sciences, energy is a
scalar quantity that is a property of objects and systems and is conserved by nature.
Several different forms of energy exist, including kinetic energy, potential energy,
thermal energy, gravitational energy, electromagnetic radiation energy, chemical energy,
and nuclear energy. These have been defined to explain all known natural phenomena.

Conservation of Energy

Energy is transformation from one form to another, but it is never created or destroyed.
This principle, the law of conservation of energy, was first postulated in the early nine-
teenth century and applies to any isolated system. The total energy of a system does
not change over time, but its value may depend on the frame of reference. For example,
a seated passenger in a moving vehicle has zero kinetic energy relative to the vehicle
but does indeed have kinetic energy relative to the earth.

The Concept of Energy in

Various Scientific Fields

■ In chemistry, the energy differences between chemical substances determine whether
and to what extent they can be converted into or react with other substances.
■ In biology, chemical bonds are often broken and made during metabolism. Energy
is often stored by the body in the form of carbohydrates and lipids, both of which
release energy when reacting with oxygen.

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