Heritage Retrofit
This pattern is shaped by
Problem
When improving energy performance in older buildings, the standard approach — wrapping the exterior in foam and replacing all windows — destroys the thick walls, deep reveals, and honest materials that make older buildings worth preserving. But leaving them uninsulated wastes energy and makes them uncomfortable.
Evidence and Discussion
The tension is real: a 1940s brick building has R-4 walls and single-glazed windows. Wrapping it in six inches of EPS and replacing the windows with triple-pane units would improve its energy performance enormously — and destroy everything worth preserving: the depth of the walls, the texture of the brick, the proportions of the windows, the solidity of the construction.
The solution requires specificity. Interior insulation with vapor-permeable materials. Historic windows retained with interior storm windows. Attic insulation first, then basement, then walls. Air sealing at hidden locations.
Therefore
when improving energy performance in buildings worth preserving, work from the inside and the hidden surfaces: insulate the attic first, then the basement, then interior walls with vapor-permeable insulation. Add interior storm windows to retain the original frames. Air-seal at the attic floor, basement rim joist, and around penetrations. Never wrap the exterior. Never replace windows that can be repaired. Aim for 50–60% energy reduction rather than 80–90%, and accept that the remaining gap is the cost of keeping the building's character.