The type of window and the installation method used depends on the problem that is being overcome and the construction characteristics of the house. The following problem areas are presented and explained to help you understand the various directions your new window installations might take.
INSULATION
Windows and doors are among the weakest components in your home's insulation.  PG&E states that the areas with the largest return for dollars spent on insulation are (in order of importance):
  • Attics
  • Windows and Doors
  • Exterior Walls
  • Under Floor
U-VALUE
The U-Value is a rating of a window's insulation quality that takes everything in that window into consideration. The lower the U-Value the better the insulation properties. Coating or tints on the glass surface further increases the insulation factor.
  • Frame Material
  • Style of Window
  • Manufacturer’s Design of the Window
  • Glass Treatment
  • Space Between the Glass
  • Spacer Technology
  • Argon Gas
BOTTOM LINE, THE U-VALUE IS THE SUMMATION OF ALL THE FACTORS THAT EFFECT INSULATION.