semipermanent

pitkäaikainen Neither temporary nor entirely permanent; of indefinite duration.
1997, Greg Stone, https://books.google.com/books?id=FAbYCHfVpz8C&pg=PA6&dq=%22more+semipermanent%22&hl=en&sa=X&ved=0ahUKEwi8vryFmtjOAhVBSmMKHakxBgoQ6AEIJTACv=onepage&q=%22more%20semipermanent%22&f=false Building a Solar-Heated Pit Greenhouse: Storey Country Wisdom Bulletin A-37

Such movable insulation could be applied to the end walls, either in the form of insulating shutters or a more semipermanent arrangement such as the one I use on the north roof of my pit.