The cost of providing exterior or interior storm windows, or even replacing the single pane glass in an historic window, can be less than full replacement and offer similar energy savings.

At the Borland Building at Penn State, we used replica replacement windows to replace the deteriorated originals, match their appearance, and improve energy performance.

At the former Strawbridge & Clothier Building, we cleaned and sealed the original steel windows and added interior storm sash with low-E glass to reduce heat loss and improve comfort.

The key factors in a Life Cycle Assessment for windows address:

1. Impact on environment by production
2. Embodied energy in manufacturing and installation
3. Longevity and expected life for in-place use
4. End of use options

Wood windows have a fraction of the environmental impact caused by new PVC or aluminum windows, including CO2 during manufacturing and use of raw materials, especially when considered over a long time span.

Once research has been done to determine the energy savings, LCA and cost for each option or approach, it is useful to set up a matrix with the relative value for each option based on the key criteria, such as Preservation, Energy Savings, Life Cycle Impacts, Appearance and Long Term Cost. A scoring method can make the difference clear for each approach.