Less than most people expect. The Galvalume steel exterior reflects heat rather than absorbing it, which reduces interior temperature buildup during Michigan summers. A metal-sided building generally runs cooler on an August afternoon than a dark-shingled one.
Airflow matters more than the siding material. Windows and vents are available options on every style that comes in metal, and placing the building where it catches some shade makes a bigger difference than the choice of exterior.



