Heating Houses (P1)
Enery flows from a warmer to a colder body.
A thermogram uses colour to show temperature. Hot: white/yellow and cold: black/dark blue/purple.
Temperature is a measure of hotness = arbitrary scale. Temp increases, average KE of particles increases.
Heat is a measurement of internal energy: absolute scale
Specific heat capacity
- energy needed to raise the temp of 1 kg by 1C
- measured in joules per kg (J/Kg C)
Specific latent heat
- energy needed to melt or boil 1 kg of material (J/Kg)
Practical Insulation (P1)
Double glazing: reduces energy loss by conduction
- Makes it difficult to transfer energy in the gap and there are no particles in a vacuum
Loft insulation: reduces energy loss by conduction and convection
with: warm air rises, energy is transferred through ceiling by conduction and is trapped by loft insulation (both sides of ceiling are the same temp = no energy transferred)
without: warm air can move by convection and energy is transferred to outside by conduction.
Cavity wall inslation: reduces energy loss by conduction and convection
- Air in foam is a good insulator and cannot move by convection = foam traps it.
Insulation blocks (shiny foil on both sides)
- energy from sun is relected back = house cool in summer
- energy from home is reflected back = warm in winter