Source: Trenwyth team

Now, consider Table 1, the Maximum Overall Assembly U-Factor Path Table. The Zone 3 U-factor of the whole wall assembly must be 0.11 to meet the IECC 2012 code. In the Maximum Overall Assembly U-Factor Path Table, the Zone 3 U-Factor of the whole wall assembly must be 0.11 to meet 2012 IECC. Architects have but to simply download the free NCMA Thermal Catalog and choose a system that meets this requirement. Option B is to use a wall that has a total U factor of .078 for the entire wall assembly in 2012 code, it's 0.90 in the 2009 code which is 11.11. This translates to an R-value of 12.82.

Compliance Software

Software allows an analysis of the components of an entire building envelope's performance, and enables the use of trade-offs to achieve energy efficiency and compliance, conferring the advantage of more design flexibility. Increased glazing, for example, can be offset by increases in insulation. Usually the analysis is implemented using free easy-to-use software. The software adds efficiency to the process. Basic building data is entered and saved and can be easily modified, with the designer immediately determining whether those changes have achieved compliance. Most, but not all states allow use of prescribed software to show compliance, and some states allow it only for certain counties or other jurisdictions.

Performance Method

This approach requires a total building performance analysis that simulates one full year of building operation. The building is treated as a discrete system, and evaluates the “big picture” of the entire building system, not just the components. It takes into account many more variables, such as window orientation and shading coefficients, and offers credit for renewable energy sources (solar, fuel cells, thermal energy storage). Fee-based software is generally utilized to model the equation and though this method enables greatest design freedom, it also requires the most rigorous analysis.

In terms of air leakage, typical masonry construction has integral advantages over frame wall construction.