After the rotten siding was removed, we took the opportunity to insulate and seal the outer walls of the house with a combination of foil-faced fan-fold insulation, expanding foam insulation, Ty-Vek house-wrap, and new window flashing and seals. We anticipate the homeowners seeing as much as a 30% reduction in heating and cooling expenses throughout the year. New "inside the trim" storm windows were added for a further long-term energy savings.