An 8" CMU ( concrete masonry unit ) wall has an R-value of 2.0, If you determine it is necessary to increase insulation, you would elect to install a 1/2" rigid insulation board that has an R-value of 3.2, bringing the total R-value of the CMU wall to only 5.2.
An ICF block or EPS panel have an R-value of 10 per panel and the 6" core of concrete has an R-value of 36, The panel system alone has an R-value of 20.36. This is a 390%+ increase in R-values. This confirms to a homeowner that you will use less energy to heat and cool your home and you will retain heating and cooling much more effectively than in a traditional CMU home. An ICF home will require a small H-Vac system to heat and cool.