A well insulated home will protect a house from unwanted excess summer heat and winter cold. Heating and cooling costs can account for nearly half of a home’s energy bill and improving a house’s insulation is one of the most cost-effective ways to reducing those costs. A combination of insulation products and construction techniques can maximize a house’s thermal performance and potentially reduce its heating and cooling needs by 30%.
Insulation is measured by “R-values” and R-value requirements of a house will depend on climate conditions, the type of heating used, building design, and the section of the house to be insulated. As an R-value increases, the transfer of heat resistance increases. Insulation may be added in the attic, walls, floors, basement, and crawl spaces of a house to achieve maximum energy savings.
There are several sources of insulation educational material on the internet:
- Department of Energy – Insulation Energy Savers
Provides information and tips on insulation, new construction insulation, and weatherization. 
Department of Energy – Insulation Fact Sheet
A fact sheet that discusses insulation and other topics associated with it, such as installation, R-values, and types of insulation.- Department of Energy’s Zip-Code Insulation Program
Helps identify a house’s current R-value and recommended R-value. - Department of Energy – Map of Recommended R-values for Existing Houses
An interactive map of the United States which displays zones and their respective recommended R-values. 
Edison Electric Institute – Insulation-related incentives and rebates
Provides information about incentives and rebates from various energy providers to improve energy efficiency of existing and newly constructed homes.
http://www.simplyinsulate.com
Has a wealth of information from the North American Insulation Manufacturers Association (NAIMA), ranging from financial incentives listed by state to DOE recommended levels of insulation for each state.