Double glazing
reduces energy loss
by conduction. The
gap between the two
pieces of glass is
filled with a gas or
contains a vacuum
Particle in a gas are far apart. It is very difficult to
transfer energy. There are no particles in a vacuum so it is
impossible to transfer energy by conduction
Loft Insulation
reduces energy
loss by
conduction and
convection
Warm air in the home rises
Energy is transferred through the ceilling by conduction
Air in the loft is warmed by
the top of the ceiling and is
trapped in the loft insulation
Both sides of the ceiling are at
the same temperature so no
energy is lost
Without loft insulation, the warm air in the loft
can move by convection and heat the roof tiles
Energy is transferred to
the outside by conduction
Cavity Wall insulation reduces energy loss by convection and conduction
The air in the foam is a good insulator
the air cannot move by
convection because it is
trapped in the foam
Insulation blocks
used to build new
home have shiny
foil on both sides to
reduce energy
transfer by radiation
energy from the sun is reflected back to keep
the home cool in the summer
energy from the home
is reflected back in the
winter
Conduction, Convection and Radiation
Energy can be transferred by:
Conduction - due to the transfer of
Kinetic Energy
Convection - a gas expands when it is
heated. This make its less dense so it rises
Radiation does not need
a material to transfer
energy. It can be done by
a vacuum
Energy Efficency
Energy Transformations can be shown
in Sankey Diagrams
Energy from the source can be lost to the sink
Different types of insulation cost different prices
Everything that transfers energy will waste
some of the energy as heat to the
surroundings