WINDOW CHOICE AND MOLD/MILDEW
Most know that today's double pane windows save energy. But other factors contribute to the satisfactory performance of the window, including whether the window frame creates condensation.
In cold climates it is important to install a metal frame window that is "thermally broken". This means a frame with physical discontinuation between the exterior and interior. If the frame is not thermally broken, that is, continuous from cold outside to warm inside, the inside of the frame will be cold. That cold surface will cause condensation of airborne moisture in the space. Eventually, that "sweating" on the frame interior will cause the formation of mold and mildew.
Thermally broken metal frame windows should be installed in any climate where the winter temperature regularly falls to below 55 F.