Windows are among the most visible and important features of a historic building. Far too often they are replaced for new windows that are not compatible with the building in terms of style and material. The aesthetic qualities of a building can drastically be altered with inappropriate replacement windows. The argument often given in support of replacements rather than restoration/retrofit is that the old windows are not energy efficient.
The Preservation Green Lab addresses the issue of energy savings through an in depth analysis of window replacement vs. retrofitting. For detailed reading of the report, we direct you to the Green Lab’s website. This is an important study that provides valuable insight into the issue.
Following are key findings of the report (source – Preservation Green Lab):
Retrofit Measures Can Achieve Performance Results Comparable to New Replacement Windows. When the performance for each upgrade option is taken into account, this study shows that there are readily available retrofit measures that can achieve energy savings close to new, high performance replacement windows.
Almost Every Retrofit Option Offers a Better Return on Investment than Replacement Windows. Findings from the cost analysis showed that new, high performance windows are by far the most expensive measure, costing at least double that of common retrofit options when considering materials, installation and general construction commonly required for an existing home. In all climate zones analyzed, cellular shades, interior storm panels and various exterior storm window configurations offer a higher average return on investment compared to new, efficient replacement windows.
The Bottom Line. Retrofitting windows with high performance enhancements can result in substantial energy savings across a variety of climate zones. Selecting options that retain and retrofit existing windows are the most cost effective way to achieve these energy savings and to lower a home’s carbon footprint. Retrofits extend the life of existing windows, avoid production of new materials, reduce waste and preserve a home’s character.