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1.2.2 Reducing Unwanted Energy Transfers, Reducing energy transfer, We…
1.2.2
Reducing Unwanted Energy Transfers
Lubrication
:star:
Lubrication
reduced
frictional forces
:star: A moving force normally has at least one
frictional force
acting against it. This causes some energy to be
dissipated.
:star:
Lubricants
can
reduce
the friction between the surfaces of objects that are rubbing together.
:star:
Lubricants
are normally
liquids
, so they can
flow
easily between objects and
coat
them.
Walls in homes
• We can decrease the rate a house cools by:
◦ Having thicker walls
◦ Having walls made from a material with a lower
thermal conductivity
. The
thicker
the walls and the
lower
their
thermal conductivity
, the
slower
the are of energy transfer will be (so the building will
cool more slowly.
)
• The more heat that a material
conducts
(the higher its
thermal conductivity
is, the
higher
the rate of energy transfer by
conduction
across the material.
Thermal insulation
:star: Heat will be lost through the roof, windoes, walls and floor.
:star: To reduce the energy transfer, we might:
Reducing energy transfer
Fit loft insulation (the roof)
Loft insulation
can reduce
convection
currents ( a
cycle
where air particles are constantly being
heated, rising, cooling
and then
sinking
) being created in lofts
Use double glazing (windows)
Double-glazed windows
work in the same way as cavity walls - they have an air gap between two sheets of glass to prevent energy transfer by
conduction
through the windows**
Use cavity wall insulation (walls).
Cavity walls
are made up of an
inner
and an
outer
wall with an air gap in the middle. The
air gap
reduces the amount of energy transferred by conduction through the walls.
Cavity wall insulation
where the cavity wall air gap is filled with a
foam
, can also reduce energy transder by
convection
in the wall cavity.
Fit carpets (floors)
Draught excluders
around doors and windows reduce energy transfers by
convection
.
We take steps to reduce the amount of energy wasted.