TeachMeFinance.com - explain R-value
R-value The term 'R-value' as it applies to the area of energy can be defined as ' A measure of a material's resistance to heat flow in units of Fahrenheit degrees x hours x square feet per Btu.The higher the R-value of a material, the greater its insulating capability. The R-value of some insulating materials is 3.7 per inch for fiber glass and cellulose,2.5 per inch for vermiculite, and more than 4per inch for foam. All building materials have some R-value. For example, a 4-inch brick has an R-value of 0.8, and half-inch plywood hasan R-value of 0.6. The table below converts the most common 'R' values to inches. For other 'R' values, divide the 'R' value by 3 to get the number of inches'.
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