R-Value is a measure of thermal resistance used in the building and construction industry. Under uniform conditions it is the ratio of the temperature difference across an insulator and the heat flux CLICK HERE to read more about what the Federal Trade Commission says about R-Value!
The greater the difference between the indoor and outdoor temperature, the more energy it will take to maintain a comfortable temperature in your home. Adding insulation greatly reduces that energy demand. CLICK HERE to read more of what ENERGY.GOV says about living comfortably.