Does absorption of the roof and heat capacity of the roof not play a role?Particularly in moderate climates like Chicago?
Thermal mass or heat capacity of a roofing system will have an impact on its energy efficiency by moderating the temperature swings of the roofing system. The thermal benefits of a massive roof vary depending on the location of the roofing system and the amount of solar radiation the roof absorbs. The thermal mass benefits will be maximized in locations where the roof surface temperature cycles above and below the interior temperature. This may be an effective strategy for the Chicago area.
