Diminishing Return on Investment for Increasing R-Values

Source: edcmag.com / Daniel Overbey, AIA, LEED AP BD+C
In this era of heightened energy consciousness and high-profile projects with "superinsulation," an R-20 roof in Indianapolis might seem a bit lax. However, there is actually a very good reason why ASHRAE, the International Code Council and others have set the mark at these specific levels. The reason has to do with the diminishing return on investment for increasing R-values.