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What is Energy Efficiency?
Energy efficiency is a measure of how well
a device transfers
energy into the form we want.
What is a Sankey Diagram?
There are many types of
process which transfer energy.
The transfer of energy can be shown by a flow diagram
(also called a Sankey
diagram).
efficiency (%) = (useful energy out ÷ total energy in) x 100.
or
efficiency (%) = (useful power out ÷ total power in) x 100.
When energy is transferred,
some of the energy turns into forms we don't
want.
This energy is called wasted energy.
Wasted energy
takes the form
of heat and
sometimes sound or light.
During any energy
transfer, some energy is changed
into heat.
The heat becomes spread out into
the environment. This dispersed energy
becomes
increasingly difficult to use
in future energy transfers.
In the end, all energy is transferred
into heat.
Efficiency is not the same as cost-effectiveness.
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Energy
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