The R-value of insulation is a measure of resistance to heat flow, how much heat it will stop based on the thickness of the insulation. The RSI value of insulation is the metric equivalent of the R-value.
To convert R values to RSI values, divide the R-value by 5.67826
To convert RSI values to R values, multiply RSI by 5.67826

R-value is a number assigned to thermal insulation to measure the insulation's resistance to heat flow. The higher the number, the better the insulation.

Convert the R values to U values

Doors and windows will have energy efficiency ratings expressed as U values. The U-value is the mathematical reciprocal of the R-value and the lower the U-factor, the more energy-efficient the window or door

Interior Finishing