What affects the rate of heat transfer?

The rate at which heat is transferred just means how quickly it is transferred.

Heat energy always moves from a hot place to a cold place (unless we force it to do otherwise as we do in a fridge). How quickly it does so depends on a number of factors.

temperature difference	surface area / shape	the materials involved	the colour of the surfaces involved
The greater the temperature difference the quicker heat energy is transferred.	The greater the area the more heat is transferred. African elephants have big ears to help them keep cool.	These space shuttle tiles are excellent thermal insulators. They need to be on re-entry.	We have seen how dark surfaces are good emitters and absorbers of heat radiation. Being black helps this chip keep cool.

 

Imagine you were given the job of designing a room heater. How would you design it so that it gave off lots of heat quickly?

Imagine you were designing a house. How would you design it so that it doesn't lose lots of heat energy in winter?