Rather they are affordable custom built and environmentally friendly window insulation panels specifically designed to increase your comfort level and save you money.
Building interior window insulation panels.
Windowtherm insulation panels formerly known as advanced energy panels are interior panels not storm windows and not replacement windows.
Topher belknap is a fellow member of the midcoast green collaborative here in maine and he came up.
Push them into the opening inside your existing windows to create an insulating pocket of air.
Keep the cold air out in the winter.
Energysavr window inserts are effective interior window insulation panels.
Keep the hot air out in the summer.