Formula regarding insulator thickness, and surface area covered?

[paperdoll]

Is there a general formula to measure the amount of heat lost per second (Joules per second) given the surface area which the water covers and the width of the insulator material surrounding it?

 

[I like Serena]

Hi paperdoll!

Yes, there is.

Intuitively you might be able to realize that it increases linearly with the surface, that it decreases linearly with the thickness, and that it increases linearly with the temperature difference.
And of course it depends on the material being used.

As you can see here:
http://en.wikipedia.org/wiki/Thermal_conductivity#Equations
the formula is:
$$H = {\Delta Q \over \Delta t} = k A {\Delta T \over x}$$