Interior storm windows.

This report focuses on the repair and upgrading of existing windows to acceptable levels of air and thermal resistance. Improvements to existing windows can be effectively achieved for as low as 25 to 50 cents per square foot by caulking and weatherstripping the primary window and then installing an inexpensive interior storm window. 27 interior storm window products are examined and details of design, operation and performance are given. Air infiltration test results are also examined and the thermal performance of each window system in terms of whole house energy savings is evaluated.