We have a 28 year old house in a small central Texas town and would like to know how to determine what would be cost effective for us to do to address our high electric bills. I am trying to prepare for retirement in approximately 6 years. We have an approximatley 2600 sq. ft. one story house with 2 central units, one that is 28 years old and the other 19 that service 2 different parts of the house. We adjust them as needed for daily use. We are looking at radiant barrier spray and sheet in the attic, polyurethane foam in the attic, adjusting our air ducts, geothermal systems, and conventional systems.