Properly insulating and air sealing your attic will help reduce your energy bills up to 25%.
By adding insulation in the attic area over the existing insulation you can reduce energy consumption during the summer and winter days. Unless your home was specially constructed for energy efficiency, you can usually reduce your energy bills by adding more insulation. Many older homes have minimal or below today's standards and may not be up to current energy codes.
To determine whether you should add insulation, you first need to find out how much insulation you already have in your home. A qualified home energy auditor will include an insulation check as a routine part of a whole-house energy assessment. An energy assessment, also known as a home energy audit, will also help identify areas of your home that are in need of air sealing. (Before you insulate, you should make sure that your home is properly air sealed.)