A Better Explanation of Nominal R-Value for Homeowners

October 15, 2017

In simple terms, Nominal R-Value is the rated insulation value that is provided (and advertised) by the manufacturer. For the most part, Nominal R-Value isn’t ever achieved in a real-world application when referring to an overall “assembly” (e.g. a wall assembly consisting of framing, drywall, insulation, etc.). This is why the term Effective R-Value has been introduced – it measures the actual thermal resistance of the overall assembly.

A building (including a residential home) is not usually built from a single construction material, so R-Values must be calculated by factoring in all the construction materials and components. This is why the Effective R-Value of a space is less than the Nominal R-Value.

R-Values vary and fluctuate because of thermal bridging and air leakage, both of which reflect real-world construction. That means that Nominal R-Value will not reflect any of the real world factors – like wood framing, and cavity space, and actual insulation material.

For insulation professionals, it’s important to assess and calculate Effective R-Values so that the property owner has an accurate idea of potential insulation performance. This also allows for energy retrofitting that incorporates an array of existing building materials.

Thermal bridging and R-Values

Thermal bridging occurs in a typical framed wall when the construction materials allow for heat transfer from inside the wall to outside the wall. This dynamic results in significant heat loss in an otherwise well-insulated space. Without addressing thermal bridging, R-Values are reduced.

Air leakage and R-Values

Air leakage is the undesirable flow of air between the interior and exterior of a building envelope. Every home suffers from air leakage, and with a direct effect on energy efficiency and R-Values. In winter, the warm indoor air is escaping out, and in summer, the warm outdoor air is intruding.

Thermal resistance and R-Values

R-Value (Nominal R-Value or Effective R-Value) is the actual capacity of an insulation material to resist heat flow. In other words, higher R-Values means more insulating performance. Insulation professionals use insulation products and installation methods to achieve optimum R-Values.     

Effectively insulating a residential home

Today, most residential homeowners want their homes to be BOTH energy efficient AND comfortable. This means having a home that is properly sealed, insulated, and ventilated. It’s about stopping air movement, preventing air moisture, and providing thermal protection.

R-Values confirm the effectiveness of installed insulation, within the framework of the overall installation space. With a professional installation, property owners are assured that everything is installed according to the building code, and that all code requirements have been met.

Whatever insulation product is installed, it should be done professionally. With Great Northern Insulation, customers are offered the most cost-effective combination of product and installation. Long-term satisfaction is assured, with improved energy efficiency, and savings on utilities.

Homeowners considering energy upgrades can count on Great Northern Insulation for the most effective air sealing, insulation, and ventilation retrofits. GNI does it all from end to end, and everything is company guaranteed. For an in-home assessment and project estimate, call GNI at 1-800-265-1914 or visit the company’s website at www.gni.ca.