Framing double windows on your home will both help to keep it warm in the winter yet cool in the summer, whilst also greatly reducing your fuel bills. The simple fact of the matter is that glass is an excellent conductor of heat, allowing the heat in warm air to pass through it.
You can prevent that heat loss by adding a second, inner, pane of glass, creating an air space between the two sheets of glass. This layer of air prevents the heat from being transferred to the outer pane of glass, helping to keep your property warm. Using wood, framing double windows is no different to framing a regular single pane of glass window. However, fitting the glass into the double frame is different.