Concept about double glazed windows

[mizzy]

Homework Statement

Double glazed windows are usually made of two glass panes with a thin layer of air sealed between the panes.
a) Why do these windows reduce heat loss to a much great extent than occurs if the double glazing is replaced by a thicker glass instead?
b) Why does the insulating effect of the double glazing decrease if the two glass panes are too far apart?

Homework Equations

P = kA(ti - to)/ l

The Attempt at a Solution

I know that double glazed windows are used for insulation and to reduce heat transfer.

a) is the answer to this because of the medium between the panes? when it's double glazed it's air and the other example is glass.

b) if the distance is increased, the rate of energy transfer is decreased.

can someone help me understand this concept relating it to energy transfer?

 

[merryjman]

a) Glass has a thermal conductivity which is about 50 times that of air.

b) When you have a larger volume of air there is more room for the air to circulate.

I'll leave it to you to explain what this implies.