Effective R-Value Calculator

Formula

To calculate the Effective R-Value (ER):

\[ ER = \frac{NV \times PD}{100} \]

Where:

\( ER \) is the Effective R-Value
\( NV \) is the Nominal R-Value
\( PD \) is the Percent Decrease in Performance

What is an Effective R-Value?

The Effective R-Value (ER) represents the actual thermal resistance of insulation after accounting for any decrease in performance over time or due to environmental factors. It helps in assessing the true insulating effectiveness of a material. The effective R-value is used in building and construction to ensure that insulation materials are performing as expected and providing adequate thermal resistance.

Example Calculation

Let's assume the following values:

Nominal R-Value (NV) = 10
Percent Decrease (PD) = 15%

Step 1: Use the Effective R-Value calculation formula:

\[ ER = \frac{10 \times 15}{100} = 1.5 \]

The Effective R-Value is 1.5.