Energy Transfers in a System
Energy can be transferred usefully, stored or dissipated, but cannot be created or destroyed.
Where there are energy transfers in a closed system, that there is no net change to the total energy.
In all system changes energy is dissipated, so that it is stored in less useful ways. This energy is often described as being ‘wasted’
Unwanted energy transfers can be reduced through lubrication and the use of thermal insulation.
The higher the thermal conductivity of a material the higher the rate of energy transfer by conduction across the material.
The rate of cooling of a building is affected by the thickness and thermal conductivity of its walls.