I live in the San Joaquin Valley in California. Summer gets up to about 112 degrees. I am considering putting radiant barrier in the attic. I have a fairly new home (1 year old) with R30 blown insulation, but the house still gets very hot. The house is 2000 square feet. I have had very good experiences with radiant barrier in my old house. But I'm not really familiar with the the RB chips.