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R-Value and U-Value Know What They Are

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What is U-Value?

An R-value indicates an insulation’s resistance to heat flow. The higher the R-value, the greater the insulating effectiveness.

The R-value depends on the type of insulation and includes its material, thickness, and density. When calculating the R-value of a multilayered installation, add the R-values of the individual layers. Installing more insulation in your home increases the R-value and the resistance to heat flow.

The effectiveness of an insulation’s resistance to heat flow also depends on how and where the insulation is installed. For example, insulation that is compressed will not provide its full rated R-value. The overall R-value of a wall or ceiling will be somewhat different from the R-value of the insulation itself because some heat flows around the insulation through the studs and joists. Therefore, it’s important to properly install your insulation to achieve the maximum R-value.

The amount of insulation or R-value you’ll need depends on your climate, type of heating and cooling system, and the section of the house you plan to insulate.

What is U-Value?

The rate of heat loss is indicated in terms of the U-factor (U-value) of a window assembly. The lower the U-factor, the greater a window’s resistance to heat flow and the better its insulating properties.

The nationally recognized rating method by the National Fenestration Rating Council (NFRC) is for the whole window, including glazing, frame and spacers. Center-of-glass U-factor is also sometimes referenced, and describes the performance of the glazing alone without the effects of the frame. For most energy efficient windows, the whole window U-factor is higher than the center-of-glass U-factor.

High-performance double-pane windows can have U-factors of 0.30 or lower, while some triple-pane windows can achieve U-factors as low as 0.15.

Low U-factors are most important in heating dominated climates, although they are also beneficial in cooling dominated climates

What is the difference between U-factor and R-value?

While the U-factor is used to express the insulation value of windows, R-value is used for insulation in most other parts of the building envelope (walls, floors, roofs). To compare R-value and U-factor, divide 1 by the U-factor number, E.g.: a 0.25 U-factor equals a 1/0.25 = 4 R-value

Thank you for taking the time to read this article. Call us at 1.877.579.1994 or click here to price your windows and doors project. Come and see us for a Dan Good Deal at 199 Victoria Street South, Kitchener, ON N2G 2C1.