Restore
  If you have foggy window then restoration may the first option for you to consider before replacement.  Foggy 
  windows can occur when the original factory seal on a double pane window has failed.  This can be due to 
  cracks and damage or the seals have worn out. Restoration involves repairing and reestablishing the seal after 
  removing the moisture.  Restoration can be far less expensive than replacing your windows. 
  Repair
  If your windows have broken glass or damage to the frame you may want to repair the specific problem with 
  your windows.  Glass repair is fairly common and be done without replacing the entire window.  As your 
  windows age, you may have damage to the window frame or sill.  This damage may also be fixed in place of 
  replacing your windows.
  Replacement
  Why replace your windows?  The first situation is you may have a window that can’t be restored or repaired for 
  less than replacing it.  You may also consider window replacement to take advantage in the advances in 
  energy savings in new high-performance windows.  In many cases ENERGY STAR windows will pay for 
  themselves by saving on your energy bill.  And another reason to replace your windows is to improve the 
  appearance and resale value of your home.  New windows improve curb appeal, increase resale value and 
  can reduce your heating and cooling cost.
 
 
 
 
  
Energy Star
  Installing ENERGY STAR qualified windows can lower your energy bill 
  and save your money over single-pane windows.  It may even save you 
  money over existing double-pain, clear-glass windows.  Make sure the 
  windows you choose are high performance ENERGY STAR qualified for 
  your region.