Thermal Characteristics: R-Values and BTUs

A BTU is the amount of heat that is necessary to increase the temperature of 1 pint of water by a single degree.

An R-Value is the number of hours it takes for 1 BTU to transfer through 1 foot of material with a temperature between both sides of the material of 1 degree Fahrenheit. For example, let’s say that the temperature inside your home is 65 degrees while the temperature outside is 66 degrees. If you have insulation with an R-Value of 13 installed in your walls, it will take 13 hours for a single BTU of heat to transfer through that material. You can imagine, however, that the amount of heat transfer is much higher when there is a higher temperature difference between inside and outside your home.