Another problem with using effective R-values is code compliance. Since effective R-value adjustments typically take in to consideration the benefits of thermal mass, and the benefits of thermal mass change due to the climate, effective R-values calculated in Arizona would be very different from effective R-values calculated in New England. There a few reasons using effective R-values are problematic. Code based R-values remain the same whether in Alaska, Florida and all of the climate zones in between. Code based R-values are reported under strictly defined conditions, such as exterior and interior temperature, still air on the inside of the assembly and a defined wind mph on the outside. Code based R-values are calculated based on either test data or the method described in the ASHRAE Handbook – the series parallel (isothermal planes) method. ![]() It can also take into account other variables, such as thermal lag or annual averages. ![]() Q: For pre-insulated Concrete Masonry systems, what is the difference between code based R-values & effective R-values?įor concrete masonry, effective R-values typically mean that the R-value is adjusted to account for the thermal mass of a CMU wall system.
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