# R-value

Definition
Popular Terms
Unit of heat resistance used as a measure of the effectiveness of insulation in stopping heat flow opposite of conductance. It is computed by determining the thermal conductance of a material expressed as thickness per unit area of the material required to maintain for one hour one unit temperature difference between its two sides. Dividing 1 by thermal conductance gives the material's R-value, and the higher it is the greater the material's heat insulation effectiveness and slower the heat flow through it. In metric units an R-value of 1 equals 0.17 square meter kelvin per watt, equal to 1.13 clo or 1.76 tog for clothing.
A brick-and-mortar building typically has an R-value of 20 which can be enhanced to about 35 by using fiberglass insulation.

## Use 'R-value' in a Sentence

Knowing what the R-value of everything in your industrial complex is will help you be better prepared to avoid a disaster.
My teacher informed me that the resistance to the flow of heat was called the R-Value, which interested me a great deal.
When you want to know what part of your factory to do a certain job in you should take the r-value of the area into account.

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