R-value of insulation is a value that is used to measure how well a specific type of insulation can resist heat flow.
The higher the R-value, the more effective the material is at preventing heat transfer.
Thermal Resistance is the most important material characteristic that should be defined when specifying insulation. From the formula for calculating, it is apparent that there are two factors affecting the thermal resistance:
-the thickness of the insulation
-thermal conductivity of the material.
An R-value only applies to specific materials, not to systems.
Depending on the facings and thickness, PU can achieve a thermal conductivity as low as 0.022 W/m·K to 0.028 W/m·K. This makes it one of the most efficient insulation materials available on the market. When compared to other materials, a much lower thickness of PU insulation is needed to get the same level of performance.
Insulation ratings are measured in R-values per inch of thickness. An R-value tells you how well a type of insulation can keep heat from leaving or entering your home. Insulation R-values vary based on the type, thickness and density of the insulation material. Typically, a higher insulation R rating means better climate control and better energy efficiency for your home. A higher insulation R-value usually means a higher price point as well.
For every type and material of insulation, check the R-value per inch of thickness that the manufacturer has listed. In general, the insulation’s method of installation can give you an idea of how it compares to other types of insulation.
Simply specifying thickness of material is not enough.
The higher the R-Value the better thermal resistance the product will provide.
R-Value = Thickness (m) / Thermal conductivity (W/mK)
Understanding R-values is useful for knowing how to discuss issues of energy efficiency. The energy required to keep a multi-tenant building warm in the winter and cool in the summer is staggering, as is the accompanying bill. Often, changing how a building is insulated is an effective energy management measure that pays off over a relatively short time frame.