Beware of claims such as 40% savings on your energy bills. If saving money is your only goal, consider weather stripping and repairing the windows you have.
Recycled insulation Recycled insulation is a green and non-itch alternative to conventional blanket insulation.
The techniques for laying this are the same, but non-itch insulation makes it a more comfortable process.
(2D) Extend insulation into joist space to reduce air flows. All exterior walls, including (3A) walls between living spaces and unheated garages, shed roofs, or storage areas; (3B) foundation walls above ground level; (3C) foundation walls in heated basements, full wall either interior or exterior. Floors above cold spaces, such as vented crawl spaces and unheated garages. Replacement or storm windows and caulk and seal around all windows and doors.
Also insulate (4A) any portion of the floor in a room that is cantilevered beyond the exterior wall below; (4B) slab floors built directly on the ground; (4C) as an alternative to floor insulation, foundation walls of unvented crawl spaces. Source: Oak Ridge National Laboratory For optimal energy efficiency, your home should be properly insulated from the roof down to its foundation.
The U-factor is a number between 0 and 1: the lower the number, the better. In cold climates, the U-factor is the most important factor for selecting a window.