Which organization provides a calculator for effective R-value?

• A. CHBA
• B. NRCan
• C. ASHRAE
• D. Canadian Wood Council

Answer: (D)

Understanding effective R-value means looking beyond the nominal insulation in a wall to see how the whole assembly performs, including the effects of wood studs, air films, sheathing, and other layers. The Canadian Wood Council focuses on wood-frame construction and provides tools specifically for this type of assembly. Their calculator lets you input typical wood-frame details—such as stud spacing, cavity insulation, and layer materials—and it computes the effective R-value of the complete wall assembly, accounting for thermal bridging from the studs and other practical factors. This makes it a practical resource for designers and builders working with wood framing to estimate real-world performance.

Other organizations offer standards, guidance, or federal energy information, but they don’t provide this targeted tool for calculating the effective R-value of wood-frame assemblies.