Given that hot air rises, it's easy to understand how attic insulation can help keep a building warm; say, in the winter, for example. But when winter changes to summer, does the attic insulation help keep the building cool? Or even worse, does attic/roof insulation make the building hotter by resisting the flow of heat up and out?
In the below diagram, my idea is that the R-factor of the attic insulation will resist the flow of heat up and out of the building by impeding flow from zone 1 to zone 2 in the below diagram.Figure 1. Premise: R-factor resists heat flow from zone 1 to zone 2 thus trapping warm air inside the house in the summertime?
How would we quantify the overall effect on house temperature based on this and other competing effects? Both theoretically and empirically?