Insulating windows for winter

TerrorismIsn'tOkay wrote:
Those plastic kits are great, I did something similar last year. But I'm looking to kick it up a knotch this winter. Maybe I'll use foam board and reflectix on the inside, hoping that the reflectix helps with the condensation and helps the insulation as well.

A piece of extruded foam insulation board cut to friction fit in the window will give you a good insulation result. We used that system extensively when deer hunting near the US-Canada border. Mercury fell to -15f some nights so we were glad we had done that. In the daytime, we pulled a couple of the foam boards for light and to be able to see outside.